Aktuelle Publikationen der Technischen Fakultät

Jahre: 2019 | 2018

2019

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Abdolhamid Ghodselahi, Fabian Kuhn, Volker Turau
Competitive Concurrent Distributed Scheduling
2019 30th Int. Symp. on Algorithms and Computation (ISAAC)

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Benjamin Völker, Marc Pfeifer, Philipp M Scholl, Bernd Becker
A Versatile High Frequency Electricity Monitoring Framework for Our Future Connected Home
2019 EAI International Conference on Sustainable Energy for Smart Cities, Braga Portugal Springer
KurzfassungIn our homes a lot of devices are powered by electricity with- out us knowing the specific amount. As electricity production has a large, negative environmental impact, we should be more aware about how de- vices consume power and how we can adapt our daily routine to decrease our electricity requirements. Methods such as Non-Intrusive Load Mon- itoring (NILM) can provide the user with precise device level electricity data by measuring at a single point in a houses’ electricity network. However, the time resolution of most off-the-shelf power meters is not sufficient for NILM or the meters are locked down for security reasons. Therefore, we have developed our own versatile energy metering frame- work which consists of a high frequency electricity metering device, a versatile backend for data processing and a webapp for data visualiza- tion. The developed hardware is capable of sampling up to 32 kHz, while the software framework allows to extract other power related metrics such as harmonic content. The system’s application ranges from pro- viding transparent electricity usage to the user up to generating load forecasts with fine granularity.
Mohsen Ghaffari, Fabian Kuhn, Jara Uitto
Conditional Hardness Results for Massively Parallel Computation from Distributed Lower Bounds
2019 60th IEEE Symp. on Foundations of Computer Science (FOCS)

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Kiele P, Pasluosta CF, Stieglitz T
A multi-channel capacitive coupled implantable system to restore natural sensory feedback
2019 Neuroscience 2019, 19.-23.10.2019, Chicago, IL, USA Society for Neuroscience, Band: 2019
KurzfassungThe loss of a limb severely restrains even simple activities of daily life. Prosthetic devices provide functional replacement of the missing limb but still lack of somatosensory perception, which is essential to restore proper object manipulation, the senses of embodiment and agency. Previous studies have demonstrated that natural sensory restoration is possible by electrically stimulating afferent nerves via implanted intrafascicular electrodes. However, assessing the remaining nerves after a limb amputation is usually difficult. Targeted Muscle Reinnervation (TMR) is a surgical intervention to re-route the remaining nerves from the stump to other part of the human body where they become more accessible. Thus, TMR presents as an excellent opportunity for restoring somatosensory feedback via electrical stimulation since sensory nerves also spread out while reinnervating the host muscles. This is specified as Targeted Sensory Reinnervation (TSR). We propose to take advantage of the natural branching of the reinnervated fibers to stimulate somatosensory pathways via an implanted system. Implanted stimulation electrodes are connected to a transcutaneous wireless coupling unit for the provision of energy and signals. A multichannel capacitive coupling approach is proposed for the transcutaneous coupling unit, consisting of extracorporeal electrodes placed on top of the skin and a subcutaneous counterpart. This approach unifies the beauty of eliminating failure due to complex implanted electronics and permanent skin trauma. Flexible and very thin implanted electrode arrays minimize the invasiveness of such a system and therefore foreign body reactions can be reduced. We evaluated the electrical crosstalk behavior of a ten channel coupling unit in an ex vivo study using healthy explanted human skin. Two different transfer strategies with and without direct contact of the metal part of the electrode and the skin tissue were evaluated. While the first provides additional resistive paths through the skin, the latter blocks these with a polymeric insulation layer. To integrate such system with lasting wearable devices (e.g., prostheses’ socket), dry and reusable extracorporeal electrode arrays are required. Requirements on the implanted pickup electrodes are long-term stability and biocompatibility, which comprises thin and flexible arrays. The implication on resorting a selective natural sensory feedback with the proposed implantable system are further discussed.
Vomero M, Boehler C, Liljemalm R, Stieglitz T, Asplund M
A multisite active neuro-technology array for high density recordings and stimulation
2019 Neuroscience 2019, 19.-23.10.2019, Chicago, IL, USA Society for Neuroscience, Band: 2019
KurzfassungIn the field of neurotechnology, there has been a general trend towards miniaturization of implantable probes. Smaller probes allow for better integration with the surrounding tissue and ultimately promote improved longevity for chronic applications. Given the large amount of neurons in the brain (~86 billion), it lies close at hand that selective communication with individual neurons demands smaller electrode contacts for adequately resolving single unit activity. While miniaturization for stiff silicon probes has substantially advanced, there is still a lack of flexible probes providing stimulation and recording at high density. We here present a Multisite Active Neuro-Technology Array (MANTArray) with 32 recording/stimulation sites at a pitch of 24 µm on polyimide (PI) to advance this trend also to polymer-based neural probes. The MANTArrays were fabricated with standard cleanroom lithographic technologies in a design employing multiple metal layers to increase packing density of recording and/or stimulating sites at a minimal device footprint: they are, in fact, only 78 µm wide and 12 µm thick. Connection tracks were embedded below the electrode sites and spread over four metal planes, separated by PI layers. The electrode contacts were coated with Iridium Oxide (IrOx), nanostructured platinum (nanoPt) or PEDOT/PSS to ensure low impedance for the microsized electrode contacts (15x15µm2) and efficient charge injection. An impedance of 45.06 ±1.66kΩ (at 1kHz) could be reached for the 15x15µm2 sites, suggesting excellent recording and stimulation properties. With the presented arrays, it is now possible to place all microelectrodes within e.g. the same layer of one cortical column and allow for neural recordings at exceptional spatial resolution. A large number of densely spaced single neurons can be followed with the MANTArrays even over long implantation times. The implementation of three-dimensional electrode materials, such as nanoPt and PEDOT/PSS, in addition, promotes high signal-to-noise recordings and makes MANTArrays suitable also for microstimulation.
Talya Eden, Nimrod Fiat, Orr Fischer, Fabian Kuhn, Rotem Oshman
Sublinear-Time Distributed Algorithms for Detecting Small Cliques and Even Cycles
2019 33rd International Symposium on Distributed Computing (DISC)

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Bast H, Brosi P, Storandt S
Efficient Generation of Geographically Accurate Transit Maps
2019 ACM
KurzfassungWe present LOOM (Line-Ordering OptimizedMaps), an automatic generator of geographically accurate transit maps. The input to LOOM is data about the lines of a transit network: for each line, its station sequence and geographical course. LOOM proceeds in three stages: (1) construct a line graph, where edges correspond to network segments with the same set of lines following the same course; (2) apply a set of local transformation rules that compute an optimal partial ordering of the lines and speed up the next stage; (3) construct an Integer Linear Program (ILP) that yields a line ordering for each edge and minimizes the total number of line crossings and line separations; and (4) based on the line graph and the computed line ordering, draw the map. As our maps respect the geography of the transit network, they can be used as overlays in typical map services. Previous research either did not take the network geography into account or was only concerned with schematic metro map layouting. We evaluate LOOM on six real-world transit networks, with line-ordering search-space sizes up to 2 × 10267. Using our transformation rules and an improved ILP formulation, we compute optimal line orderings in a fraction of a second for all networks. This enables interactive use of our method in map editors.
M. Becker, F. Balle
Multi-spot ultrasonic welding of Al/Steel-joints for automotive applications
2019 International Congress on Ultrasonics, Brügge
Hügle M, Siegel L, Behrmann O, Hufert FT, Dame G, Urban G
A Lab-on-a-Chip For The Extraction Of Bacterial Nucleic Acids From Whole Human Blood
2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII), Berlin, Germany
KurzfassungWe present a lab-on-a-chip for the extraction of bacterial nucleic acids from whole human blood (WHB). Compared to classical methods, with extraction times between hours and days, the presented chip can lyse the bacteria suspended in WHB and extract their nucleic acids within three minutes. This is achieved by directly coupling thermal lysis to gel-electrophoresis on a single microfluidic platform.
Laubender E, Matylitskaya V, Kostal E, Kasemann S, Urban G, Partel S, Dincer C
Gold nanogap interdigitated arrays for redox cycling amplified dopamine detection
2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII), Berlin, Germany
KurzfassungHere we present the highly sensitive detection of dopamine using gold nanogap IDAs with redox-cycling amplification. Through the combination with a facile electrochemical activation and a chronoamperometric multistep protocol fouling of the gold electrode surface can be prevented and a sensitivity of 14 nA µM⁻¹ with excellent linearity up to 10 µM is achieved. The low-cost and reproducible wafer level fabrication process of the nanogap IDAs plays a key role. Electrode and substrate materials can be nearly arbitrarily chosen. Also the gap sizes could be adjusted down to sub-100 nm dimensions with this versatile approach, allowing for very high signal amplification. In comparison to the current gold standard, fastscan cyclic voltammetry (FSCV) with carbon fiber microelectrodes (CFMEs), which suffers from high background currents, no elaborate data processing and high-end electronic equipment is needed. Employing our flexible, easy and inexpensive method, DA monitoring with a short acquisition period and a detection limit less than 200 nM is successfully demonstrated.
Wieland T, Kotthaus JK, Gmoser H, Assmann J, Urban G
Inhibition of MDR/MRSA Bacterial Biofilms by the Antimicrobial Peptides Esculaentin 1-A and OH-CATH-30 Monitored by a Thermal Sensor System in Real-Time
2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII), Berlin, Germany
KurzfassungIn the present work, we showcase a reusable miniaturized thermal sensor based on sinusoidal excitation for continuous monitoring of biofilms over several days. The sensor measurement system is able to steadily monitor biofilm formation with very low baseline. The presented measurement method utilized for this application is based on the change in thermal properties, specific thermal conductivity and volumetric heat capacity, which leads to different measurement results due to maturation of biofilm. In this work, we describe how the system can detect the inhibition of biofilm formation by the effect of the antimicrobial peptides (AMP) Esculentin 1-a and OH-CATH-30.
Folwill Y, Shah S, Zappe H
Mems-Processed Artificial Muscles with Freely-Programmable Actuation Direction
2019 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII), Berlin, Germany IEEE
Urban S, Kieninger J, Deschner BJ, Kraut M, Dittmeyer R, Urban G, Weltin A
Multiparametric, Spatially Resolved Detection of H2O2 and O2 with Electrochemical Microsensor Array in Synthesis Membrane Microreactors
2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII), Berlin, Germany
KurzfassungWe present an electrochemical microsensor system for the multiparametric detection of dissolved concentrations of hydrogen peroxide (H₂O₂) and oxygen (O₂) inside a direct synthesis membrane microreactor. Both reactants are detected with high sensitivity on the same Pt-based electrode by changing the applied measurement potential in a chronoamperometric protocol. The robust integration of the electrochemical cell in the microreactor was demonstrated and allowed for in situ detection of the spatial gradient of the changing oxygen concentration diffusing through a membrane into the microreactor, emphasizing the capabilities of our monitoring system.
Dornhof J, Kieninger J, Maurer J, Urban G, Weltin A
Next Generation Organ-on-Chip System for Directional Control of Culture Conditions and Metabolic Monitoring of Tumor Organoids
2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII), Berlin, Germany
KurzfassungIn vitro replica of 3D heterogeneous tumor systems are essential models on the path towards personalized chemotherapy in cancer research. Here, we present an organ-on-chip platform with integrated microelectrodes enabling online-monitoring of culture conditions and metabolic parameters of patient-derived, triple-negative breast cancer stem cells. Tumor organoids grow in compartments separated by microfluidic channels, permitting the generation of oxygen and drug gradients as seen in real tumors. Besides the electrochemical analysis, e.g. for oxygen or lactate, the transparent chip also allows characterization with optical methods. Such in situ monitoring systems bear a high potential for replacing animal models in drug research.
Marzioch J, Kieninger J, Weltin A, Urban G
Oxygen Microsensor Array to Study Spatial Efficacy of Photodynamic Therapy in Vitro
2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII), Berlin, Germany
KurzfassungWe present a cell culture monitoring platform to study effects of photodynamic therapy (PDT) on cancer cells. For the first time, it was possible to observe differences in cellular respiration at the transition between treated and untreated tumor cells in the same culture. Therewith more realistic in vitro studies of treatment efficiency and edge effects during PDT are possible. This resembles the spatially limited exposure in the in vivo situation. The sensor platform comprises an optically transparent microsensor chip with an integrated array of electrochemical oxygen microsensors and a LED light source for the photodynamic treatment.
D. Weibel, T. Beck, F. Balle
Fatigue properties and damage of CF-PPS from high to very high cycles
2019 ICCM22, Melbourne Australia

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S. Backe, T. Beck, F. Balle
SHORT-TIME APPROACH FOR FATIGUE LIFE ESTIMATION OF MULTIFUNCTIONAL COMPOSITES
2019 ICCM22, Melbourne Australia

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Janosch Deurer, Fabian Kuhn, Yannic Maus
Deterministic Distributed Dominating Set Approximation in the CONGEST Model
2019 38th ACM Symp. on Principles of Distributed Computing (PODC)

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Philipp Bamberger, Mohsen Ghaffari, Fabian Kuhn, Yannic Maus, Jara Uitto
On the Complexity of Distributed Splitting Problems
2019 38th ACM Symp. on Principles of Distributed Computing (PODC)

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Mohsen Ghaffari, Fabian Kuhn
On the Use of Randomness in Local Distributed Graph Algorithms
2019 38th ACM Symp. on Principles of Distributed Computing (PODC)

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Pfau J, Ganatra D, Weltin A, Urban G, Kieninger J, Stieglitz T
Electrochemical Stability of Thin-Film Platinum as Suitable Material for Neural Stimulation Electrodes
2019 41.- te EMB Conference, 23. - 27. Juli, 2019, Berlin IEEE
KurzfassungOnly thin-film technology can satisfy the requirements of high spatial selectivity at high-channel-count electrode array designs by simultaneously good conformability to the targeted tissue through mechanical flexibility enriching future applications of functional neural stimulation. However, caused by the high impact of the microstructure on the mechanical and electrochemical film properties, varying fabrication processes of the same thin-film makes the difference between acute and chronic long-term stable electrodes. The influence of standard clinical electrical pulsing on flexible polyimide-based thin-film platinum electrodes for neuroprostheses, either sputter deposited or evaporated, and different diameters was assessed and compared. The electrochemical and morphological analysis showed a higher corrosion susceptibility and electrochemical degradation for the sputter deposited platinum electrodes with even total failures of smaller diameters. In contrast, the evaporated thin-films provided itself as more stable and reliable metallization with also smaller electrodes keeping their film integrity intact over the experimental period, -appearing to be the preferable material for improving thinfilm electrodes’ longevity. I
Bernhard Haeupler, Fabian Kuhn, Anders Martinsson, Kalina Petrova, Pascal Pfister
Optimal Strategies for Patrolling Fences
2019 46th Int. Coll. on Automata, Languages, and Programming (ICALP)

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Mohamad Ahmadi, Fabian Kuhn, Shay Kutten, Anisur Rahaman Molla, Gopal Pandurangan
The Communication Cost of Information Spreading in Dynamic Networks
2019 39th IEEE Int. Conf. on Distributed Computing Systems (ICDCS), Dallas, USA
KurzfassungThis paper investigates the message complexity of distributed information spreading in adversarial dynamic net- works. While distributed computations in dynamic networks have been studied intensively over the last years, almost all of the existing work solely focuses on the time complexity of distributed algorithms. In information spreading, the goal is to spread k tokens of information to every node on an n-node network. We consider the amortized (average) message complexity of spreading a token, assuming that the number of tokens is large. In a static network, this basic problem can be solved using (asymptotically optimal) O(n) amortized messages per token. Our focus is on token-forwarding algorithms, which do not manipulate tokens in any way other than storing, copying, and forwarding them. We present two sets of results depending on how nodes send messages to their neighbors: 1. Local broadcast: We show a tight lower bound of \tilde{Ω}(n^2) on the number of amortized local broadcasts, which is matched by the naive flooding algorithm. The lower bound holds for randomized algorithms against a strongly adaptive adversary. 2. Unicast: We study the message complexity as a function of the number of dynamic changes in the network. To facilitate this, we introduce adversary-competitive message complexity as a natural complexity measure for analyzing dynamic networks: The adversary pays a unit cost for every topological change and the message cost of an algorithm is determined as the actual number of messages sent minus the total cost of the adversary. Under this model, we give a deterministic algorithm that obtains an optimal amortized message complexity of O(n) if the number of tokens k is sufficiently large. We also present a randomized algorithm that achieves subquadratic amortized message complexity for much smaller k under an oblivious adversary.
M. Becker
Serielles Ultraschallpunktschweißen von Aluminium/Stahl-Verbunden
2019 Symposium Verbundwerkstoffe und Werkstoffverbunde, Kaiserslautern
M. Becker, F. Balle
Serielles Ultraschallpunktschweißen von Aluminium/Stahl-Verbunden
2019 22. Symposiums für Verbundwerkstoffe und Werkstoffverbunde
Huber S, Lázár Z, Berger M, Paul O
A CMOS Hall-based magnetic multisensor system free from parasitic effects of temperature and package stress
2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII, Berlin/Germany , Seiten: 134 - 137
Berger M, Becker F, Paul O
Guidelines for multisensor system calibration with and without regularization
2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII, Berlin/Germany , Seiten: 2103 - 2106
Morikawa Y, Ayub S, Paul O, Kawano T, Ruther P
Highly stretchable kirigami structure with integrated LED chips and electrodes for optogenetic experiments on perfused hearts
2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII, Berlin/Germany , Seiten: 2484 - 2487
John Augustine, Mohsen Ghaffari, Robert Gmyr, Kristian Hinnenthal, Fabian Kuhn, Jason Li, Christian Scheideler
Distributed Computation in Node-Capacitated Networks
2019 31st ACM Symp. on Parallelism in Algorithms and Architectures (SPAA)
KurzfassungIn this paper, we study distributed graph algorithms in networks in which the nodes have a limited communication capacity. Many distributed systems are built on top of an underlying network- ing infrastructure, for example by using a virtual communication topology known as an overlay network. Although this underlying network might allow each node to directly communicate with a large number other nodes, the amount of communication that a node can perform in a fixed amount of time is typically much more limited. We introduce the node-capacitated clique model as an abstract communication model, which allows us to study the effect of nodes having limited communication capacity on the complexity of distributed graph computations. In this model, the n nodes of a network are connected as a clique and communicate in synchronous rounds. In each round, every node can exchange messages of O (log n) bits with at most O (log n) other nodes. When solving a graph problem, the input graph G is defined on the same set of n nodes, where each node initially knows the identifiers of all its neighbors in G. To initiate research on the node-capacitated clique model, we present distributed algorithms for the Minimum Spanning Tree (MST), BFS Tree, Maximal Independent Set, Maximal Matching, and Vertex Coloring problems. We show that even with only O(logn) concurrent interactions per node, the MST problem can still be solved in polylogarithmic time. In all other cases, the runtime of our algorithms depends linearly on the arboricity of G, which is a constant for many important graph families such as planar graphs.

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Benjamin Völker, Philipp M Scholl, Bernd Becker
Semi-Automatic Generation and Labeling of Training Data for Non-intrusive Load Monitoring
2019 e-Energy '19 Proceedings of the Tenth ACM International Conference on Future Energy Systems ACM New York, NY, USA ©2019, Band: 10, Seiten: 17 - 23
KurzfassungUser awareness is one of the main drivers to reduce unnecessary energy consumption in our homes. This awareness, however, requires individual energy data of the devices we own. A retrofittable way to get this data is to use Non-Intrusive Load Monitoring methods. Most of these methods are supervised and require to collect labeled ground truth data in advance. Labeling on-phases of devices is already a tedious process, but if further information about internal device states are required (e.g. intensity of an HVAC), manual labeling methods are infeasible. We propose a novel data collection and labeling method for Non-Intrusive Load Monitoring. This method uses intrusive sensors directly connected to the monitored devices. A post-processing step classifies the connected devices into four categories and exposes internal state sequences in a semi-automatic way. We evaluated our labeling method with a sample dataset comparing the amount of recognized events, states and classified device category. The event detector achieved a total F1 score of 86.52 % for devices which show distinct states in its power signal. Using our framework, the overall labeling effort is cut by more than half (42%).
Philipp Bamberger, Fabian Kuhn, Yannic Maus
Local Distributed Algorithms in Highly Dynamic Networks
2019 33rd IEEE Int. Parallel and Distributed Processing Symposium (IPDPS)
KurzfassungWe define a generalization of local distributed graph problems to (synchronous round-based) dynamic networks and present a framework for developing algorithms for these problems. The algorithms should satisfy non-trivial guarantees in every round. The guarantees should be stronger the more stable the graph has been during the last few rounds and coincide with the definition of the static graph problem if no topological change appeared recently. Moreover, if only a constant neighborhood around some part of the graph is stable during an interval, the algorithms should quickly converge to a solution for this part of the graph that remains unchanged throughout the interval. We demonstrate our generic framework with two classic distributed graph problems, namely (degree+1)-vertex coloring and maximal independent set (MIS). To illustrate the given guarantees consider the vertex coloring problem: Any conflict between two nodes caused by a newly inserted edge is resolved within T = O(log n) rounds. During this conflict resolving both nodes always output colors that are not in conflict with their respective ‘old‘ neighbors. The largest color that a node is allowed to output is determined by the number of distinct neighbors that it has seen in the last T rounds.
Leonie Feldbusch, Felix Winterer, Johannes Gramsch, Linus Feiten, Bernd Becker
SMILE goes Gaming: Gamification in a Classroom Response System for Academic Teaching
2019 11th International Conference on Computer Supported Education (CSEDU)
KurzfassungThe classroom response system SMILE (SMartphones In LEctures) is regularly used in academic lectures. Among others, it enables lecturers to start quizzes that can be answered anonymously by students on their smartphones. This aims at both activating the students and giving them feedback about their understanding of the current content of the lecture. But even though many students use SMILE in the beginning of a course, the number of active participants tends to decrease as the term progresses. This paper reports the results of a study looking at incorporating gamification into SMILE to increase the students’ motivation and involvement. Game elements such as scores, badges and a leaderboard have been integrated paired with a post-processing feature enabling students to repeat SMILE quizzes outside of the lectures. The evaluations show that the gamification approach increased the participation in SMILE quizzes significantly.
Marc Pfeifer, Philipp M. Scholl, Rainer Voigt, Bernd Becker
Active Stereo Vision with High Resolution on an FPGA
2019 27th IEEE Annual International Symposium on Field-Programmable Custom Computing Machines Proceedings of the 27th IEEE Annual International Symposium on Field-Programmable Custom Computing Machines, Seiten: 118 - 126
KurzfassungWe present a novel FPGA based active stereo vision system, tailored for the use in a mobile 3D stereo camera. For the generation of a single 3D map the matching algorithm is based on a correlation approach, where multiple stereo image pairs instead of a single one are processed to guarantee an improved depth resolution. To efficiently handle the large amounts of incoming image data we adapt the algorithm to the underlying FPGA structures, e.g. by making use of pipelining and parallelization. Experiments demonstrate that our approach provides high-quality 3D maps at least three times more energy-efficient (5.5 fps/W) than comparable approaches executed on CPU and GPU platforms. Implemented on a Xilinx Zynq-7030 SoC our system provides a computation speed of 12.2 fps, at a resolution of 1.3 megapixel and a 128 pixel disparity search space. As such it outperforms the currently best passive stereo systems of the Middlebury Stereo Evaluation in terms of speed and accuracy. The presented approach is therefore well suited for mobile applications, that require a highly accurate and energy-efficient active stereo vision system.
S. Kartmann, D. Kopp, M. Masoumi, R. Zengerle, H. Zappe, P. Koltay
Thermischer Einweg-Strömungssensor auf Basis einer flexiblen Polyimid-Folie
2019 MicroTEC Südwest Clusterkonferenz, Freiburg, 20.-21.03.2019
Kurzfassung---
M. Lehnert, E. Kipf, F. Schlenker, R. Zengerle, N. Borst, F. von Stetten
Multiplex Mediator Probe Real-Time PCR - Optimization and Guideline Development through Systematic Characterisation of Label Free Mediator Probes and Fluorogenic Universal Reporters
2019 9th Gene Quantification Event qPCR dPCR & NGS 2019, 18 - 22 March 2019, in Freising-Weihenstephan, Germany
KurzfassungMediator Probe PCR is a powerful and robust real-time PCR technology for multiplex DNA detection and quantification. It uses label free mediator probes, for molecular detection of nucleic acids during DNA amplification, in combination with fluorogenic universal reporters for signal generation. During PCR, target sequence specific mediator probes are cleaved by the polymerase and a generic sequence, the mediator, is set free. In the second step the mediator binds to the universal reporter, where it is extended by the polymerase. This generates a strong fluorescence signal increase. Due to the separation of DNA detection and signal generation many advantages arise. Mediator probes are not limited in their design by properties of the target sequence and a standard set of highly optimised fluorogenic universal reporters can be used for multiplex Mediator Probe PCR, right from the start.1 In the last years Mediator Probe PCR evolved from an innovative new method to an optimised and robust multiplexing technology. This was achieved by systematic characterisation of its molecular processes, which again was advantaged by the separation of DNA detection and signal generation. A DoE approach was used for the optimisation of Mediator Probes, focusing on their binding strengths.2 In parallel, a set of universal reporters with improved signal-to-noise ratios was established by successive testing over 40 molecular structures with different fluorophore-quencher labels and configurations.1 As a result, distinct guidelines exist, which enable fast adaption of new DNA targets and facilitate multiplex Mediator Probe PCR design. The capability of the technology was shown by highly sensitive, precise and specific multiplex Mediator Probe real-time PCRs in different areas of molecular diagnostics. These fields include monitoring of oncological disease, detection of pathogens or analysis of food samples.1,3
Shah R, Kretschmer S, Nehlich J, Ataman C, Zappe H
Compact OCT probe for flexible endoscopy enabled by piezoelectric scanning of a fiber/lens assembly
2019 SPIE OPTO, 2019, San Francisco, California, United States SPIE
Vilches Exposito S, Ataman C, Zappe H
Interferometric fiber-based real-time distance sensor for endoscopic applications
2019 SPIE BiOS, 2019, San Francisco, California, United States SPIE, Band: 10868
C. Klose, L. Bohn, M. Klingele, S. Thiele, R. Zengerle, M. Breitwieser, S. Vierrath
Dynamic Quantification of Water Generation and Migration in Polymer Electrolyte Membrane Fuel Cells
2019 FDFC 2019 - 8th International Conference on Fundamentals and Development of Fuel Cells, Nantes/France
KurzfassungBy applying direct membrane deposition (DMD), Klingele et al. were able to highly improve the power density of a polymer electrolyte membrane fuel cell[1]. The main difference of DMD to the conventionally used catalyst coated membrane (CCM) method lies within the interface of polymer electrolyte membrane (PEM) and catalyst layer (CL) (see Figure 1a). With equal membrane thickness and equal catalyst layer, Klingele et al. could increase the power density by a factor of 1.39 (see Figure 1b) by using DMD[2], compared to a state-of-the-art CCM. Vierrath et al. carried out an impedance spectroscopy study and revealed a lower charge transfer resistance as main contributor for the high improvement (see Figure 1b), and suggested a better water back diffusion from the cathode through the membrane as main cause[3]. The significant impact of the PEM|CL interface on the charge transfer resistance can frequently be found in literature[4]. However, direct proof of the influence of the PEM|CL interface on the water management within a fuel cell is challenging. In this work, we present a method to obtain insight into the water generation and migration within fuel cells by comparing the relative humidity (RH) of inlet and outlet gases. In our new experiment, the anode is fed with completely dry gas, whereas the cathode gas is humidified to 12 % RH. The RH is measured at the anode outlet of the fuel cell (see Figure 1c). Although fed with dry gases, at open circuit, we are able to measure an RH of 3.75 %. At open circuit, this can only be caused by water back diffusion from the humidified cathode side of the cell through the membrane to the anode. We further measure a reduction of RH with increasing current density, which we attribute to the osmotic drag opposing the diffusion. The reduction of anode outlet RH per unit of drawn current in this setup can be quantified to (0.049 ± 0.001) %/(mA/cm2). In future research, we aim to use this new method to show the influence of different membrane and CL configurations, such as DMD and CCM, on the water management in fuel cells.
A. Reiterer,, D. Störk,, K. Wäschle,, A. Leydecker,, M. Leidinger
Automatisierte Interpretation von 3D-Daten - Stand der Technik und zukünftige Entwicklungen
2019 1. Kolloquium Straßenbau in der Praxis; Ostfildern TAE Technische Akademie Esslingen, Technische Akademie Esslingen; F. Schäfer, Seiten: 453 - 456
M. Leidinger,, A. Reiterer,, D. Steiger
Pavement Profile Scanner PPS-Plus - Unerreichte Präzision bei hohen Geschwindigkeiten
2019 1. Kolloquium Straßenbau in der Praxis; Ostfildern TAE Tagungshandbuch 2019, TAE Technische Akademie Esslingen; F. Schäfer, Seiten: 327 - 331
Stieglitz T
Flexible Multielectrode Arrays as Implantable Interface to the Central and Peripheral Nervous System.
2019 Department of Biomedical Engineering, University of Basel
Klein E, Kaku Y, Paul O, Ruther P
Flexible µLED-based optogenetic tool with integrated µ-lens array and conical concentrators providing light extraction improvements above 80%
2019 IEEE MEMS 2019, Seoul, Korea , Seiten: 632 - 635
Sharma K, Dholipet Nagendra Kumar S, Paul O, Ruther P
Microfluidic neural probes with buried channels fabricated using continuous flow XeF³ etching of silicon
2019 IEEE MEMS 2019, Seoul, Korea , Seiten: 569 - 572
Mohsen Ghaffari, Jara Uitto
Sparsifying Distributed Algorithms with Ramifications in Massively Parallel Computation and Centralized Local Computation
2019 30th ACM-SIAM Symposium on Discrete Algorithms (SODA)
Ujwala P.,, Pentek Q.,, Hein S.,, Miernik A.,, Reiterer A.
Image based 3D reconstruction of the bladder using structure-from-motion – Proof of principle in a phantom model
2019 European Association of Urology
Kurzfassung#AM19-1411
B. Shanahan, T. Böhm, B. Britton, S. Holdcroft, S. Vierrath, S. Thiele, M. Breitwieser
30 μm thin hexamethyl-p-terphenyl poly(benzimidazolium) anion exchange membrane for vanadium redox flow batteries
2019 The International Flow Battery Forum, Lyon/France, 09 - 11 July 2019
B. Shanahan, T. Böhm, B. Britton, S. Holdcroft, R. Zengerle, S. Vierrath, S. Thiele, M. Breitwieser
30 μm thin hexamethyl-p-terphenyl poly(benzimidazolium) anion exchange membrane for vanadium redox-flow batteries
2019 Electrochem Commun, Band: 102, Seiten: 37 - 40
KurzfassungWe present the first results of an anion exchange ionomer membrane, hexamethyl-p-terphenyl poly(benzimidazolium) (HMT-PMBI), in a vanadium redox flow battery. Anion exchange membranes exhibit superior vanadium crossover suppression compared to proton exchange membranes due to the Gibbs–Donnan effect. HMT-PMBI was benchmarked against a similarly thin Nafion XL membrane which allowed us to compare differences based solely on chemical properties of the ionomer materials. We report cycling data of 45 cycles at a current density of 150 mA/cm2 with excellent coulombic efficiency of >99.4%, energy efficiency of 80.6–74.2% and a low ohmic resistance of 0.219–0.255 Ω cm2. In addition, a three times lower self-discharge rate is obtained for the HMT-PMBI membrane compared to Nafion XL. HMT-PMBI is therefore a potential alternative for PFSA based ionomers in VRFB applications.
Marx M, Rombach S, Nessler S, De Dorigo D, Manoli Y
A 141μW High Voltage MEMS Gyroscope Drive Interface Circuit based on Flying Capacitors
2019 IEEE Journal Solid-State Circuits (JSSC), Band: 54, Nummer: 2, Seiten: 511 - 523
F. Suárez Sandoval, S.M. Torres Delgado, A. Moazenzadeh, U. Wallrabe
A 2D magnetoinductive wave device for freer wireless power transfer
2019 IEEE Tansactions of Power Electronics, Band: 34, Nummer: 11, Seiten: 10433 - 10445
S. Nessler, S. Kartmann, L. Mutter, C. Grandauer, M. Marx, R. Zengerle, Y. Manoli
A Capacitive Readout Circuit for a Disposable Low-Cost Pressure and Flow Sensor with 200 Pa or 170 nl/s Resolution
2019 IEEE Sensors, 27. – 30. October 2019, Montreal / Canada
Nessler S, Kartmann S, Mutter L, Grandauer C, Marx M, Zengerle R, Manoli Y
A Capacitive Readout Circuit for a Disposable Low-Cost Pressure and Flow Sensor with 200 Pa or 170 nl/s Resolution
2019 Proceedings of the IEEE Sensors
Kuehn J, Manoli Y
A Fingertip-Shaped Tactile Sensor with Machine-Learning-Based Sensor-To-Information Processing
2019 Proceedings of the International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors (TRANSDUCERS & EUROSENSORS)
Amayreh M, Baaken G, Behrends J, Manoli Y
A Fully Integrated Current-Mode Continuous-Time Delta-Sigma Modulator For Biological Nanopore Read-Out
2019 IEEE Transactions on Biomedical Circuits and Systems ( TBCAS), Band: 13, Nummer: 1, Seiten: 225 - 236
Krawat D, Marx M, Nessler S, Biegler H, Dienger M, Rockstroh J, Dehé A, Manoli Y
A Lorentz Force Magnetometer with 600 nT/√Hz Resolution over a Bandwidth of 480 Hz utilizing Force Feedback and CMOS Readout Electronics
2019 Proceedings of the IEEE Sensors
Christoph Scholl, Jie-Hong Roland Jiang, Ralf Wimmer, Aile Ge-Ernst
A PSPACE Subclass of Dependency Quantified Boolean Formulas and Its Effective Solving
2019 33th AAAI Conference on Artificial Intelligence (AAAI-19)
KurzfassungDependency quantified Boolean formulas (DQBFs) are a powerful formalism, which subsumes quantified Boolean formulas (QBFs) and allows an explicit specification of dependencies of existential variables on universal variables. This enables a succinct encoding of decision problems in the NEXPTIME complexity class. As solving general DQBFs is NEXPTIME complete, in contrast to the PSPACE completeness of QBF solving, characterizing DQBF subclasses of lower computational complexity allows their effective solving and is of practical importance. Recently a DQBF proof calculus based on a notion of fork extension, in addition to resolution and universal reduction, was proposed by Rabe in 2017. We show that this calculus is in fact incomplete for general DQBFs, but complete for a subclass of DQBFs, where any two existential variables have either identical or disjoint dependency sets over the universal variables. We further characterize this DQBF subclass to be SigmaP3 complete in the polynomial time hierarchy. Essentially using fork extension, a DQBF in this subclass can be converted to an equisatisfiable 3QBF with only a linear increase in formula size. We exploit this conversion for effective solving of this DQBF subclass and point out its potential as a general strategy for DQBF quantifier localization. Experimental results show that the method outperforms state-of-the-art DQBF solvers on a number of benchmarks, including the 2018 DQBF evaluation benchmarks.
Christoph Scholl, Jie-Hong Roland Jiang, Ralf Wimmer, Aile Ge-Ernst
A PSPACE Subclass of Dependency Quantified Boolean Formulas and Its Effective Solving
2019 Honolulu, HI, USA Proceedings of the 33rd AAAI Conference on Artificial Intelligence (AAAI), AAAI Press
KurzfassungDependency quantified Boolean formulas (DQBFs) are a powerful formalism, which subsumes quantified Boolean formulas (QBFs) and allows an explicit specification of dependencies of existential variables on universal variables. This enables a succinct encoding of decision problems in the NEXPTIME complexity class. As solving general DQBFs is NEXPTIME complete, in contrast to the PSPACE completeness of QBF solving, characterizing DQBF subclasses of lower computational complexity allows their effective solving and is of practical importance. Recently a DQBF proof calculus based on a notion of fork extension, in addition to resolution and universal reduction, was proposed by Rabe in 2017. We show that this calculus is in fact incomplete for general DQBFs, but complete for a subclass of DQBFs, where any two existential variables have either identical or disjoint dependency sets over the universal variables. We further characterize this DQBF subclass to be Sigma_3^P complete in the polynomial time hierarchy. Essentially using fork extension, a DQBF in this subclass can be converted to an equisatisfiable 3QBF with only a linear increase in formula size. We exploit this conversion for effective solving of this DQBF subclass and point out its potential as a general strategy for DQBF quantifier localization. Experimental results show that the method outperforms state-of-the-art DQBF solvers on a number of benchmarks, including the 2018 DQBF evaluation benchmarks.
Shui B, De Dorigo D, Herbawi A, Ruther P, Paul O, Manoli Y, Kuhl M
A Slim Needle Neural Probe with 160 Active Recording Sites and Selectable ADCs
2019 Proceedings of the IEEE Biomedical Circuits and Systems Conference (BioCAS)
Behrmann O, Hügle M, Bronsert P, Herde B, Heni J, Schramm M, Hufert FT, Urban G, Dame G
A lab-on-a-chip for rapid miRNA extraction
2019 Plos One, Band: 14, Nummer: 12, Seite: e0226571
KurzfassungWe present a simple to operate microfluidic chip system that allows for the extraction of miRNAs from cells with minimal hands-on time. The chip integrates thermoelectric lysis (TEL) of cells with native gel-electrophoretic elution (GEE) of released nucleic acids and uses non-toxic reagents while requiring a sample volume of only 5 μl. These properties as well as the fast process duration of 180 seconds make the system an ideal candidate to be part of fully integrated point-of-care applications for e.g. the diagnosis of cancerous tissue. GEE was characterized in comparison to state-of-the-art silica column (SC) based RNA recovery using the mirVana kit (Ambion) as a reference. A synthetic miRNA (miR16) as well as a synthetic snoRNA (SNORD48) were subjected to both GEE and SC. Subsequent detection by stem-loop RT-qPCR demonstrated a higher yield for miRNA recovery by GEE. SnoRNA recovery performance was found to be equal for GEE and SC, indicating yield dependence on RNA length. Coupled operation of the chip (TEL + GEE) was characterized using serial dilutions of 5 to 500 MCF7 cancer cells in suspension. Samples were split and cells were subjected to either on-chip extraction or SC. Eluted miRNAs were then detected by stem-loop RT-qPCR without any further pre-processing. The extraction yield from cells was found to be up to ~200-fold higher for the chip system under non-denaturing conditions. The ratio of eluted miRNAs is shown to be dependent on the degree of complexation with miRNA associated proteins by comparing miRNAs purified by GEE from heat-shock and proteinase-K based lysis.

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Phillip M Scholl, Benjamin Völker, Bernd Becker, Kristof Van Laerhoven
A multi-media exchange format for time-series dataset curation
In: Human Activity Sensing: Corpus and Applications
2019, Springer International Publishing, Seiten: 111 - 119, ISBN: 9783030130015
KurzfassungExchanging data as character-separated values (CSV) is slow, cumbersome and error-prone. Especially for time-series data, which is common in Activity Recognition, synchronizing several independently recorded sensors is challenging. Adding second level evidence, like video recordings from multiple angles and time-coded annotations, further complicates the matter of curating such data. A possible alternative is to make use of standardized multi-media formats. Sensor data can be encoded in audio format, and time-coded information, like annotations, as subtitles. Video data can be added easily. All this media can be merged into a single container file, which makes the issue of synchronization explicit. The incurred performance overhead by this encoding is shown to be negligible and compression can be applied to optimize storage and transmission overhead.
Vierhub-Lorenz Valentin Predehl Katharina, Wolf Sebastian Christoph S. Werner Christoph S., Kühnemann, Frank, Reiterer, Alexander
A multispectral tunnel inspection system for simultaneous moisture and shape detection
2019 SPIE Remote Sensing, 2019, Strasbourg, France , Band: Vol. 11157, 111570T
KurzfassungIn this paper, we present the implementation of a differential-absorption measurement-technique for surface moisture detection into a laser scanner aiding modern tunnel inspections. The use of laser scanners for tunnel inspections can reduce costly tunnel closures and provide digital data, compliant with modern building information modeling (BIM). Unfortunately, available systems are typically limited to pure 3D mapping. The Fraunhofer Institute for Physical Measurement Techniques IPM is developing a novel multi-parameter laser scanning system. For the first time, this system allows the simultaneous measurement of 3D-geometry, remission and surface moisture. The scanner measures simultaneously with two collinear laser beams with distinct wavelengths. One is centered at the absorption band of water at 1450 nm wavelength, while the other, with 1320 nm wavelength, is used as an intensity reference. The intensity ratio gives a good estimate of the surface water content. Additionally, the power of both lasers is modulated with a high frequency. This enables simultaneous measurement of the distance by comparing the phase difference of the backscattered light with a local reference. With this approach, we are able to record up to two million points per second containing distance, intensity and moisture information. Besides the technical implementation, we present point clouds from multiple test objects and surfaces. The presented data nicely demonstrates the ability to differentiate between absolute intensity variations, e.g. caused by dirt, and actual water contamination.
A. Müller, M. C. Wapler, U. Wallrabe
A quick and accurate method to determine the Poisson’s ratio and the coefficient of thermal expansion of PDMS
2019 Soft Matter, Band: 15, Seiten: 779 - 784
D. Kuhner, L.D.J. Fiederer, J. Aldinger, F. Burget, M. Völker, R.T. Schirrmeister, C. Do, J. Boedecker, B. Nebel, T. Ball, W. Burgard
A service assistant combining autonomous robotics, flexible goal formulation, and deep-learning-based brain–computer interfacing
2019 Robot Auton Syst, Band: 116, Seiten: 98 - 113
Meszéna D, Kerekes B A, Pál I, Orbán G, Fiáth R, Holzhammer T, Ruther R, Ulbert I, Márton G
A silicon-based spiky probe providing improved cell accessibility during in vitro slice recordings
2019 Sensors and Actuators B: Chemical, Band: 297, Seite: 126649
KurzfassungAims: In this study, we introduce an edge-type laminar silicon probe suitable for improved cell accessibility during in vitro brain slice recordings. With protruding contact sites, the spiky probe provides high signal yield and quality while approaching cells located deeper in the tissue. Methods. The spiky probe comprises an angled shank carrying 32 protruding contact sites with three possible spacing of 25 μm, 50 μm and 100 μm. The angled shank makes the probe compatible with large microscope objectives used typically in two-photon imaging, in vitro. Spiky probes were batch manufactured with high precision using the etching before grinding technology and bonded to a custom designed printed circuit board. A quantitative comparison of the performance was made against a commercially available surface probe. To investigate the long-term stability of contact sites, the spiky probe was repeatedly inserted in seven experiments (17 insertions, in total) using Wistar rat hippocampal slices, in vitro. Impedance magnitudes and phase angles were compared before and after the extensive usage. Results: Single unit activities were recorded with higher neuronal yield and higher amplitudes compared to the surface probe. Impedances did not increase significantly after reusing the probe in multiple experiments. Furthermore, we were able to detect extracellular action potentials from the same single unit on multiple, adjacent contact sites. Finally, we separated the recorded single units into putative cell types based on their extracellular waveforms. Conclusion and outlook: The spiky probes were proved to be optimal solutions to record extracellular spike waveforms, in vitro. The improved signal quality allowed us to distinguish between putative interneurons and principal cells. In future works, integrative experiments using these probes may provide multi-modal data for cellular electrophysiology resulting in a deeper understanding of single cell contributions to mass neural activity.
Wülfing Jan M, Kumar Sreedhar S, Boedecker Joschka, Riedmiller Martin, Egert Ulrich
Adaptive Long-term Control of Biological Neural Networks with Deep Reinforcement Learning
2019 Neurocomputing, Band: 342, Seiten: 66 - 74
Hofmann A, Höweling A, Bohn N, Müller M, Binder J R, Hanemann T
Additives for Cycle Life Improvement of High-Voltage LNMO-Based Li-Ion Cells
2019 Chemelectrochem, Band: 6, Seiten: 5255 - 5263
KurzfassungIn this empirical study, five electrolyte additives, namely, lithium bis(oxalato) borate, lithium difluoro(oxalato) borate, 1-vinyl-1,2,4-triazole, 1-vinyl imidazole and dimethyl-2,5-dioxahexane dioate are described and compared regarding their effect in LNMO//graphite cells. The additives were selected from a preliminary study of 59 potential additives. The basis electrolyte mixture is DMC/EC+1 M LiPF6 (LP30) for all cells. All additives are able to enhance the cycle life at room temperature and at elevated temperatures (50 °C) significantly compared to the non-additive electrolyte blend (basis electrolyte). The cell enhancement is discussed based on the solid-electrolyte interface (SEI) and metal-ion content on anode side. The aim of the study is to suggest promising already known as well as new additives that are able to overcome the issue of rapid capacity fading of LNMO-based cells when the cells are cycled up to 4.8–5.0 V vs. Li/Li+, especially at higher temperatures.
Minet Y, Nuno dos Reis L, Buse K, Breunig I
Adiabatic Frequency Conversion in Non-Centrosymmetric High-Q Optical Microresonators
2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC), Munich, IEEE
KurzfassungMicroresonators are a versatile and efficient system platform for optical frequency conversion. Here, the non-linear response of material polarization is used for frequency synthesis. For example in WGRs made of non-centrosymmetric materials, tunable OPOs have been realized, and in WGRs made of centrosymmetric materials frequency combs were generated. Another way for frequency conversion is adiabatic tuning. Here, the optical length of the circumference of the resonator is changed during its ringdown time. This induces a frequency shift of the circulating light. So far different methods have been demonstrated. Free electrons generated by laser pulses, induce a change of the refractive index. By this method the wavelength can be tuned by some nanometers. The free electrons however lower the quality factor of the resonator. Moreover the repetition rate is limited by the time it takes for the free electrons to recombine. Another method is to change the frequency adiabatically via the AC-Kerr effect. Here, again second pump laser is needed. With this method the quality factor is not affected, but the achieved frequency shift is smaller compared to that for the free-electron method.
Uwe Wagschal, Thomas Waldvogel, Thomas Metz, Samuel Weishaupt, Linus Feiten, Bernd Becker, Kamal Singh
Alle gegen Alle? Die Mehrpersonendebatte der kleinen Parteien in der Analyse
In: Die Bundestagswahl 2017: Analysen der Wahl-, Parteien-, Kommunikations- und Regierungsforschung
2019, Springer Fachmedien Wiesbaden, Seiten: 461 - 482, ISBN: 978-3-658-25050-8
KurzfassungDer Beitrag analysiert eine TV-Debatte zur Bundestagswahl 2017 mit einem Mehrpersonenpodium unter Beteiligung der "kleinen" Parteien. Auf Basis von Echtzeit- und Umfragedaten formuliert der Beitrag nach eingehender Analyse fünf zentrale Befunde: 1) Je weiter politisch die Debattenteilnehmer auseinanderliegen, desto polarisierter und konfliktiver ist die Debatte. 2) Anhänger, die sich politisch einem Lager zurechnen bewerten auch den bzw. die Repräsentanten dieses Lagers deutlich besser. 3) Debattenteilnehmer anderer politischer Lager werden systematisch schlechter bewertet. 4) Ein besonderer Bias durch die Moderation liegt für die untersuchte Debatte nicht vor. 5) Die direkte Bedeutung von TV-Debatten für die Wahlentscheidung ist begrenzt.
Marx M, Cuignet X, Nessler S, De Dorigo D, Manoli Y
An Automatic MEMS Gyroscope Mode Matching Circuit Based on Noise Observation
2019 IEEE Transactions on Circuits and Systems II: Express Briefs (TCAS II), Band: 66, Nummer: 5, Seiten: 743 - 747
Fuks L, Awad N, Hutter F, Lindauer M
An Evolution Strategy with Progressive Episode Lengths for Playing Games
2019 Proceedings of the International Joint Conference on Artificial Intelligence (IJCAI’19)
Sato S, Weidlich A
Analysis of Avoided Transmission Through Decentralized Photovoltaic and Battery Storage Systems
2019 IEEE T Sustain Energ, Band: Forthcoming
KurzfassungDecentralized renewable energy systems can be low-carbon power sources, and promoters of local economies. It is often argued that decentralized generation also helps reducing transmission costs, as generation is closer to the load, thus utilizing the transmission system less. The research presented here addresses the question whether or not, or under what circumstances this effect of avoided transmission can actually be seen for a community-operated cluster of photovoltaic (PV) power plants in two sample locations, one in Germany and one in Japan. For the analysis, the newly developed instrument of MPI-MPE diagrams is used, which plot the maximum power import (MPI) and maximum power export (MPE) in relation to the reference case of no local generation. Results reveal that for moderately sized PV systems without battery storage, avoided transmission can be seen in the Japanese model location, but not in Germany. It was also found that an additional battery storage can lead to avoided transmission in both locations, even for large sizes of installed PV capacity.

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Brox T., Lou Z., Nguyen D. T., Klar M.
Anomaly Detection With Multiple-Hypotheses Predictions
2019 ICML 2019
KurzfassungIn one-class-learning tasks, only the normal case (foreground) can be modeled with data, whereas the variation of all possible anomalies is too erratic to be described by samples. Thus, due to the lack of representative data, the wide-spread discriminative approaches cannot cover such learning tasks, and rather generative models, which attempt to learn the input density of the foreground, are used. However, generative models suffer from a large input dimensionality (as in images) and are typically inefficient learners. We propose to learn the data distribution of the foreground more efficiently with a multi-hypotheses autoencoder. Moreover, the model is criticized by a discriminator, which prevents artificial data modes not supported by data, and enforces diversity across hypotheses. Our multiple-hypotheses-based anomaly detection framework allows the reliable identification of out-of-distribution samples. For anomaly detection on CIFAR-10, it yields up to 3.9% points improvement over previously reported results. On a real anomaly detection task, the approach reduces the error of the baseline models from 6.8% to 1.5%.

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Ates H, Schneider N, Bruch R, Weber W, Urban G, Dincer C
Antibody-free Assay for Electrochemical ß-lactam Monitoring
2019 MicroTAS 2019, Basel, Switzerland
KurzfassungIn this work, an antibody-free on-chip assay is introduced for electrochemical monitoring ß-lactam levels in untreated human plasma samples, using a microfluidic polymer-based biosensor. This is achieved by re-designing the penicillin-binding protein 3 production methodology and utilizing casein, instead of bovine serum albumin, as surface blocker. The applicability of the on-chip assay is successfully demonstrated by on-chip calibration of piperacillin (a commonly prescribed ß-lactam) in human plasma, resulting a limit of detection of 440 pg ml⁻¹ along with a broad dynamic range up to 100 μg ml⁻¹ and an inter-assay coefficient of variation below 13%.
Boehler C, Aqrawe Z, Asplund M
Applications of PEDOT in bioelectronic medicine
2019 Bioelectronics in Medicine, Band: 2, Nummer: 2
KurzfassungThe widespread use of conducting polymers, especially poly(3,4-ethylene dioxythiophene) (PEDOT), within the space of bioelectronics has enabled improvements, both in terms of electrochemistry and functional versatility, of conventional metallic electrodes. This short review aims to provide an overview of how PEDOT coatings have contributed to functionalizing existing bioelectronics, the challenges which meet conducting polymer coatings from a regulatory and stability point of view and the possibilities to bring PEDOT-based coatings into large-scale clinical applications. Finally, their potential use for enabling new technologies for the field of bioelectronics as biodegradable, stretchable and slow-stimulation materials will be discussed.
Goeppert J, Braun S, Pellhammer D, Amayreh M, Leicht J, Keller M, Manoli Y
Area Constrained Multi-Source Power Management for Thermoelectric Energy Harvesting
2019 Proceedings of the European Solid-State Circuits Conference (ESSCIRC)
X Lyu, H Gao, P Diehle, F Altmann, K Tarantik, K Schmitt, J Wöllenstein
Au-Pd@ Meso-Co3O4: A Promising Material For New Generation Pellistor with Low Working Temperature
2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII) IEEE, Seiten: 1195 - 1198
KurzfassungThe working temperature of pellistors using 3-dimensional mesoporous Co 3 O 4 (meso-Co 3 O 4 ) supported Au-Pd, Au-Pd@meso-Co 3 O 4 , is significantly reduced to 300 °C, thereby avoiding possible catalytic poisoning at high temperatures inherent in conventional pellistors. Our results indicate that meso-Co 3 O 4 has a great advantage over the commercially available Co 3 O 4 with respect to sensing performance. The coverage of Au-Pd on Co 3 O 4 influences the sensor behavior. Besides, the number of deposited layers has an impact on the pellistor performance. 15-layer-deposition of Au-Pd@meso-Co 3 O 4 delivers the best result. This development towards a decreased working temperature can be anticipated as the new concept to design robust pellistors with low power consumption.
Stieglitz T, Cvancara P, Lenarz T
Auditory nerve implants: surgical access and implantation procedure of flexible foil-based electrode arrays
2019 Annual Meeting of the German Society of Biomedical Engineering (25–26 September 2019, Frankfurt am Main) Biomed Eng-biomed Te, Band: 64, Nummer: s2, Seite: 131
Saikia T, Marrakchi Y, Zela A, Hutter F, Brox T
AutoDispNet: Improving Disparity Estimation with AutoML
2019 International Conference of Computer Vision
Grell M, Dincer C, Le T, Lauri A, Nunez Bajo E, Kasimatis M, Barandun G, Maier SA, Cass AEG, Güder F
Autocatalytic Metallization of Fabrics Using Si Ink, for Biosensors, Batteries and Energy Harvesting
2019 Adv Funct Mater, Band: 29, Seite: 1804798
KurzfassungCommercially available metal inks are mainly designed for planar substrates (for example, polyethylene terephthalate foils or ceramics), and they contain hydrophobic polymer binders that fill the pores in fabrics when printed, thus resulting in hydrophobic electrodes. Here, a low‐cost binder‐free method for the metallization of woven and nonwoven fabrics is presented that preserves the 3D structure and hydrophilicity of the substrate. Metals such as Au, Ag, and Pt are grown autocatalytically, using metal salts, inside the fibrous network of fabrics at room temperature in a two‐step process, with a water‐based silicon particle ink acting as precursor. Using this method, (patterned) metallized fabrics are being enabled to be produced with low electrical resistance (less than 3.5 Ω sq⁻¹). In addition to fabrics, the method is also compatible with other 3D hydrophilic substrates such as nitrocellulose membranes. The versatility of this method is demonstrated by producing coil antennas for wireless energy harvesting, Ag–Zn batteries for energy storage, electrochemical biosensors for the detection of DNA/proteins, and as a substrate for optical sensing by surface enhanced Raman spectroscopy. In the future, this method of metallization may pave the way for new classes of high‐performance devices using low‐cost fabrics.

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Kaljaca D., Mayer N., Vroegindeweij B., Mencarelli A., Van Henten E., Brox T.
Automated Boxwood Topiary Trimming with a Robotic Arm and Integrated Stereo Vision
2019 IEEE/RSJ International Conference on Intelligent Robots and Systems
KurzfassungThis paper presents an integrated hardware-software solution to perform fully automated robotic bush trimming to user-specified shapes. In contrast to specialized solutions that can trim only bushes of a certain shape, the approach ensures flexibility via a vision-based shape fitting module that allows fitting an arbitrary mesh into a bush at hand. A trimming planning method considers the available degrees of freedom of the robot arm to achieve effective cutting motions. The performance of the mesh fitting module is assessed in multiple experiments involving both artificial and real plants with a variety of shapes. The trimming accuracy of the overall approach is quantitatively evaluated by inspecting the bush pointcloud before and after robotic trimming, and measuring the change in the deviation from the originally computed target mesh.

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Springer Springer, Springer
Automated Machine Learning - Methods, Systems, Challenges
Hutter Frank, Kotthoff Lars, Vanschoren Joaquin
B. Johannsen, L. Müller, D. Baumgartner, L. Karkossa, S.M. Früh, N. Bostanci, M. Karpíšek, R. Zengerle, N. Paust, K. Mitsakakis
Automated Pre-Analytic Processing of Whole Saliva Using Magnet-Beating for Point-of-Care Protein Biomarker Analysis
2019 Micromachines, Band: 10, Nummer: 12, Seite: 833
KurzfassungSaliva offers many advantages for point-of-care (PoC) diagnostic applications due to non-invasive, easy, and cost-effective methods of collection. However, the complex matrix with its non-Newtonian behavior and high viscosity poses handling challenges. Several tedious and long pre-analytic steps, incompatible with PoC use, are required to liquefy and homogenize saliva samples before protein analysis can be performed. We apply magnet-beating to reduce hands-on time and to simplify sample preparation. A magnet in a chamber containing the whole saliva is actuated inside a centrifugal microfluidic cartridge by the interplay of centrifugal and magnetic forces. Rigorous mixing, which homogenizes the saliva sample, is then initiated. Consequently, fewer manual steps are required to introduce the whole saliva into the cartridge. After 4 min of magnet-beating, the processed sample can be used for protein analysis. The viscosity of whole saliva has been reduced from 10.4 to 2.3 mPa s. Immunoassay results after magnet-beating for three salivary periodontal markers (MMP-8, MMP-9, TIMP-1) showed a linear correlation with a slope of 0.99 when compared to results of reference method treated samples. Conclusively, magnet-beating has been shown to be a suitable method for the pre-analytic processing of whole saliva for fully automated PoC protein analysis.
B. Johannsen, L. Müller, D. Baumgartner, L. Karkossa, S. Früh, N. Bostanci, M. Karpíšek, R. Zengerle, N. Paust, K. Mitsakakis
Automated pre-analytic processing of whole saliva on a centrifugal microfluidic platform for protein biomarker analysis
2019 MicroTAS, 27. – 31. October 2019, Basel/Switzerland
P. Juelg, M. Specht, E. Kipf, M. Lehnert, C. Eckert, M. Keller, T. Hutzenlaub, F. von Stetten, R. Zengerle, N. Paust
Automated serial dilutions for high-dynamic-range assays enabled by fill-level-coupled valving in centrifugal microfluidics
2019 Lab Chip, Band: 19, Seiten: 2205 - 2219
KurzfassungWe introduce a new concept for centrifugal microfluidics that enables fully automated serial dilution generation without any additional means besides temperature control. Key feature is time-independent, serial valving of mixing chambers by fill-level-coupled temperature change rate (FLC-TCR) actuated valving. The automated dilution is realized under continuous rotation which enables reliable control of wetting liquids without the need of any additional fabrication steps such as hydrophobic coatings. All fluidic features are implemented in a monolithic fashion and disks are manufactured by foil thermoforming for scalable manufacturing. The new valving concept is demonstrated to reliably prevent valving if the diluted sample is not added to the mixing chamber (n = 30) and ensures valving if the dilution stage is completed (n = 15). Accuracy and precision of the automated serial dilution are verified by on-disk generation of qPCR standard curve dilutions and compared with manually generated reference dilutions. In a first step, the 5-log-stages standard curves are evaluated in a commercial qPCR thermocycler revealing a linearity of R² ≥ 99.92 % for the proposed LabDisk method vs. R² ≥ 99.67 % in manual reference dilutions. In a second step, the disk automated serial dilution is combined with on-disk qPCR thermocycling and readout, both inside a LabDisk Player. A 4-log-stages linearity of R² ≥ 99.81 % and a sensitivity of one leukemia associated ETV6-RUNX1 mutant DNA copy in a background of 100,000 wild-type DNA copies is achieved.
Polian Ilia, Gay Mael, Paxian Tobias, Sauer Matthias, Becker Bernd
Automatic Construction of Fault Attacks on Cryptographic Hardware Implementations
In: Automated Methods in Cryptographic Fault Analysis
2019, Springer, Seiten: 151 - 170,
Lachner-Piza D, Jacobs J, Bruder JC, Schulze-Bonhage A, Stieglitz T, Duempelmann M
Automatic detection of high-frequency-oscillations and their sub-groups co-occurring with interictal-epileptic-spikes.
2019 J Neural Eng
KurzfassungObjective: High-Frequency-Oscillations (HFO) and Interictal-Epileptic-Spikes (IES) are spatial biomarkers of the epileptogenic-zone. Those HFO spatially and temporally co-occurring with IES (IES-HFO) are potentially superior biomarkers, their use is however challenged by the difficulty in detecting the low amplitude HFO riding the high-amplitude and steep-waveform of IES. We aim to develop an automatic HFO detector with an improved performance with respect to current methods and that also correctly distinguishes IES-HFO from IES occurring in isolation (isol-IES). We also aim to validate the biomarker-value of the automatic detections by utilizing them to localize a surrogate of the epileptogenic-zone. Approach: We developed automatic-detectors of HFO-Ripples (80-250 Hz), HFO-FastRipples (250-500Hz) and IES based on kernelized support-vector-machines (SVM). The training of the HFO-detectors was based on visually marked HFO and the parameter optimization during this training-process promoted the correct discernment between IES-HFO and isol-IES. Both HFO-detectors were benchmarked against other published detectors using databases with both visually marked and simulated gold-standards. The IES-detector was trained with a publicly available simulated database and tested against both simulated and visually marked gold-standards. To validate the detections' biomarker-value, the detectors were run on intracranial-EEGs from 8 patients and each with durations of 2 to 3 days, the detections' cumulated per-channel occurrence-rate was then used to predict the seizure-onset-zone as a surrogate of the epileptogenic-zone. Results: The HFO-detectors obtained at least 21 more F1-score points than previously published algorithms at the lowest signal-to-noise-ratio. The success achieved when discerning between IES-HFO and isol-IES was comparable to that of other published algorithms. The automatically detected IES-HFO and IES-Ripples showed the best biomarker-value to localize the epileptogenic-zone. Significance: The developed detectors are publicly available and provide a reliable tool to further study HFO, IES-HFO and their value as biomarkers. The putative higher biomarker value from IES-HFO was validated on automatically-detected, long-term data.
Lindauer M, Eggensperger K, Feurer M, Biedenkapp A, Marben J, Müller P, Hutter F
BOAH: A Tool Suite for Multi-Fidelity Bayesian Optimization & Analysis of Hyperparameters
2019 arXiv:1908.06756 [cs.LG]
Reichel Christian, Fell Andreas, Hermle Martin, Glunz Stefan
Back-Contacted Back-Junction Si Solar Cells with Locally Overcompensated Diffusion Regions - Comparison of Buried Emitter and Floating Base Design
2019 physica status solidi (a), Band: 216, Nummer: 4, Seite: 1800791
KurzfassungBack-contacted back-junction n-type Si solar cells with locally overcompensated diffusion regions are investigated in two different designs. In the “buried emitter” design, boron-doped (B-doped) emitter diffusions are partially diffused and locally overcompensated by phosphor-doped (P-doped) back surface field (BSF) diffusions, leading to n-type regions that are overlapping the p-type regions. In the “floating base” design, the B-diffusions are diffused on the entire rear side, so that the P-diffusions are separated from the base by the emitter. Hence, p-type regions exist between the n-type regions, creating opposing p-n junctions and a base that is floating. For the latter design with an efficiency of 17.1%, the open-circuit voltage Voc, the short-circuit current density Jsc, and the fill factor FF are significantly reduced by about 25mV, 5mAcm2, and 4%, respectively, compared to the buried emitter design where 678mV, 41.5mAcm2, and 76.1%, respectively, and an efficiency of 21.4% can be achieved. Two-dimensional numerical device simulations reveal that, besides junction and/or shunt leakage currents, recombination at the surface of the emitter and electron transport in the Band P-diffusions due to the opposing p-n junctions are detrimental for the performance of the “floating base” solar cell.
K. Tröndle, F. Koch, G. Finkenzeller, G. B. Stark, R. Zengerle, P. Koltay, S. Zimmermann
Bioprinting of high cell density constructs leads to controlled lumen formation with self‐assembly of endothelial cells
2019 Journal of Tissue Engineering and Regenerative Medicine
KurzfassungActive nutrient supply and waste product removal are key requirements for the fabrication of long term viable and functional tissue constructs of considerable size. This work aims to contribute to the fabrication of artificial perfusable networks with a bioprinting process, based on drop‐on‐demand (DoD) printing of primary endothelial cell (EC) suspension bioink (25 · 106 ± 3 · 106 cells/ml). The process results in prescribed lumen between two hydrogel layers, allowing its integration in common layering based bioprinting processes. Low volume bioink droplets (appr. 10 nl) as building blocks, were deposited between two fibrin or collagen I layers to realize shapeable, cell‐rich aggregates. Unattainable with manual positioning, DoD printing allowed precise fabrication of various designs, such as spheroidal‐, line‐shaped and Y‐branch cellular structures, with a mean lateral extension of 285 ± 81 μm. For basic characterization, the cell suspension building blocks were systematically compared to preformed spheroids of the same cell type, passage and number. Post printing investigations of initially loose cell arrangements showed self‐assembly and formation of central lumen with a mean cross‐sectional area of Ølumen = 6400 μm2 at day 3, lined by a single layer of CD31 positive ECs, as evaluated by confocal microscopy. Originating from this main lumen smaller, undirected side‐branches (Øbranches = 740 μm2) were formed by sprouting cells, inducing a first step towards a simplistic hierarchically organized network. These lumen could prospectively help for tissue construct perfusion in vitro or, potentially, as niche for angiogenesis of host vascularization in implants.
Stevens L, Tucher N, Höhn O, Hauser H, Müller C, Bläsi B
Broadband antireflection Mie scatterers revisited—a solar cell and module analysis
2019 Opt Express, Band: 27, Nummer: 8, Seiten: 524 - 535
Heining K, Kilias A, Janz, P, Häussler, U, Kumar, A, Haas, C A, Egert, U
Bursts with high and low load of epileptiform spikes show context-dependent correlations in epileptic mice
2019 eNeuro, Band: 6, Seite: /ENEURO.02
KurzfassungHypersynchronous network activity is the defining hallmark of epilepsy and manifests in a wide spectrum of phenomena of which electrographic activity during seizures is only one extreme. The aim of this study was to differentiate between different types of epileptiform activity patterns and investigate their temporal succession and interactions. We analyzed local field potentials from freely behaving male mice that had received an intrahippocampal kainate injection to model mesial temporal lobe epilepsy. Epileptiform spikes occurred in distinct bursts. Using machine learning, we derived a scale reflecting the spike load of bursts and three main burst categories that we labeled high-load, medium-load and low-load bursts. We found that bursts of these categories were non-randomly distributed in time. High-load bursts formed clusters and were typically surrounded by transition phases with increased rates of medium-load and low-load bursts. In apparent contradiction to this, increased rates of low-load bursts were also associated with elongated background phases, i.e. periods lacking high-load bursting. Furthermore, the rate of low-load bursts was more strongly correlated with the duration of background phases than the overall rate of epileptiform spikes. Our findings are consistent with the hypothesis that low-level epileptiform activity could promote network stability but could also participate in transitions towards major epileptiform events, depending on the current state of the network.

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Zhou H., Brox T., Facil J., Ummenhofer B., Montesano L., Civera J.
CAM-Convs: Camera-Aware Multi-Scale Convolutions for Single-View Depth
2019 CVPR 2019

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G Urban, J Guttmann, J Kieninger, A Weltin, J Wöllenstein, J Zosel
CO2 Sensing in Medicine
In: Carbon Dioxide Sensing: Fundamentals, Principles, and Applications
2019, Wiley‐VCH Verlag GmbH & Co. KGaA, Seiten: 391 - 413,
KurzfassungBesides the measurement of non-electrical physical parameters such as temperature or blood pressure, the analysis of chemical and biochemical parameters of patients has gained an increasing importance in the past. The exact knowledge of metabolic clinical parameters, especially small molecules in blood and tissue, is essential to assess the patient’s health. Additionally, for emergency patients, the doctor needs a fast, secure, and reliable decision support, not only for diagnosis but also for rapid therapy access. The quantitative and reliable assessment of biochemical parameters is a technical and logistical challenge and mainly based on discrete blood sampling and subsequent analysis. The next desired step would be a continuous monitoring of such metabolites, which is a much more difficult task and only possible for selected analytes.
Bruch R, Urban G, Dincer C
CRISPR/Cas Powered Multiplexed Biosensing
2019 Trends Biotechnol, Band: 37, Nummer: 8, Seiten: 791 - 792
KurzfassungMultiplexed CRISPR/Cas biosensing offers various possibilities for diagnosing different diseases by analyzing many analytes from one single specimen. However, in this relatively new field, nearly no multiplexing approaches exist, as many challenges need to be addressed. We discuss the reasons behind it and possible strategies to push the multiplexing level.
Bruch R, Baaske J, Chatelle C, Meirich M, Madlener S, Weber W, Dincer C, Urban G
CRISPR/Cas13a powered electrochemical microfluidic biosensor for nucleic acid amplification-free miRNA diagnostics
2019 Adv Mater, Band: 31, Nummer: 51, Seite: 1905311
KurzfassungNon-coding small RNAs, such as microRNAs, are becoming the biomarkers of choice for multiple diseases in clinical diagnostics. A dysregulation of these microRNAs can be associated with many different diseases, such as cancer, dementia or cardiovascular conditions. The key for an effective treatment is an accurate initial diagnosis at an early stage, improving the patient’s survival chances. In this work, the first CRISPR/Cas13a powered microfluidic, integrated electrochemical biosensor for the on-site detection of microRNAs is introduced. Through this unique combination, the quantification of the potential tumor markers microRNA miR-19b and miR-20a has been realized without any nucleic acid amplification. With a readout time of 9 minutes and an overall process time of less than 4 hours, a limit of detection of 10 pM was achieved, using a measuring volume of less than 0.6 μl. Furthermore, the feasibility of our biosensor platform to detect miR-19b in serum samples of children, suffering from brain cancer, has been demonstrated. The validation of the obtained results with a standard qRT-PCR method shows the ability of our electrochemical CRISPR powered system to be a low-cost, easily scalable and target amplification-free tool for nucleic acid based diagnostics.

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Cruz M, Vomero M, Zucchini E, Delfino E, Asplund M, Stieglitz T, Fadiga L
Can Crosstalk Compromise the Recording of High-Frequency Neural Signals?
2019 2019 9th International IEEE/EMBS Conference on Neural Engineering (NER), 20-23 March 2019, San Francisco, Ca, USA IEEE
KurzfassungTwo big trends are leading the way to a new generation of thin-film electrocorticography (ECoG) micro electrode arrays (MEAs): miniaturization, which combines higher electrode densities with thinner substrates for conformability purposes; and the pursuit to extend the recording frequency band to 1 kHz and beyond (recording of spikes). When combining these two trends, however, the frequency-dependent phenomenon of crosstalk emerges as a possible setback to the so desired spatial selectivity. In this work, high in vivo coherences at 1 kHz between electrodes with neighboring tracks are reported when using the MuSA (Multi-Species Array) as recording ECoG MEA on rats. These results suggest a high degree of crosstalk between closely routed electrodes, even if placed far apart on the array, and are corroborated by coherence plots of control recordings in vitro in phosphate buffered saline (PBS). As means to estimate the combined leakage resistance and capacitance between the signal lines and the targeted brain tissue, an impedance spatial sweep over the 32 tracks routing the MuSA electrodes is performed in PBS in a two-electrode electrochemical impedance spectroscopy setup. This study should raise awareness of crosstalk as an important aspect to consider when aiming for high-quality, high-density and high-frequency neural recordings.
Jünger F, Rohrbach A
Can cells sense approaching particles before contact? A thermal noise study.
2019 submitted
Dönch I, Tran TA, David L, Montembault A, Viguier E, Gorzelanny C, Sudre G, Cachon T, Louback-Mohamed M, Horbelt N, Peniche-Covas C, Osorio-Madrazo A
Cellulose Nanofiber-Reinforced Chitosan Hydrogel Composites for Intervertebral Disc Tissue Repair
2019 Biomimetics, Band: 4, Nummer: 1, Seite: 19
KurzfassungThe development of non-cellularized composites of chitosan (CHI) hydrogels, filled with cellulose nanofibers (CNFs) of the type nanofibrillated cellulose, was proposed for the repair and regeneration of the intervertebral disc (IVD) annulus fibrosus (AF) tissue. With the achievement of CNF-filled CHI hydrogels, biomaterial-based implants were designed to restore damaged/ degenerated discs. The structural, mechanical and biological properties of the developed hydrogel composites were investigated. The neutralization of weakly acidic aqueous CNF/CHI viscous suspensions in NaOH yielded composites of physical hydrogels in which the cellulose nanofibers reinforced the CHI matrix, as investigated by means of microtensile testing under controlled humidity. We assessed the suitability of the achieved biomaterials for intervertebral disc tissue engineering in ex vivo experiments using spine pig models. Cellulose nanofiber-filled chitosan hydrogels can be used as implants in AF tissue defects to restore IVD biomechanics and constitute contention patches against disc nucleus protrusion while serving as support for IVD regeneration.
M. Schulz, F. von Stetten, R. Zengerle, N. Paust
Centrifugal Step Emulsification: How Buoyancy Enables High Generation Rates of Monodisperse Droplets
2019 Langmuir : the ACS Journal of Surfaces and Colloids
KurzfassungWe demonstrate that buoyancy in centrifugal step emulsification enables substantially higher generation rates of monodisperse droplets compared to pressure driven set-ups. Step emulsification in general can produce droplets in comparatively simple systems (only one moving liquid) with a low CV of <5% in droplet diameter and with a minimum dead volume. If operated below a critical capillary number, the droplet diameter is defined by geometry and surface forces only. Above that critical capillary number, however, jetting occurs, leading to an increased droplet diameter and CV. Consequently, generation rates of monodisperse droplets are limited in pressure-driven systems. In this paper, we show that centrifugal step emulsification can overcome this limitation by applying sufficient buoyancy to the system. The buoyancy, induced by the centrifugal field and a density difference of the continuous and disperse phase, supports droplet necking by pulling the forming droplet away from the nozzle. The influence of buoyancy is studied using specific microfluidic designs that allow for supplying different buoyancies to the same droplet generation rates. For a droplet diameter of 100 μm, droplet generation at rates above 2.8k droplets per second and nozzle were reached, which is an increase of more than a factor of 8 in comparison to pressure-driven systems.
Medesi A, Nötzel D, Wohlgemuth J, Franzreb M, Hanemann T
Ceramic Injection Moulding using 3D-Printed Mould Inserts
2019 Ceramics in Modern Technologies, Band: 2, Nummer: 2, Seiten: 104 - 110
KurzfassungIn general, micromilled mould inserts made of steel, aluminum or brass are used today for ceramic injection moulding (CIM) processes. However, tool making via mechanical subtractive manufacturing processes as micromilling is time- and cost-effective and the use of 3D printed mould inserts becomes an attractive alternative to metal mould inserts. In this paper, we report about the use of 3D printed mould inserts for CIM of alumina microreactor parts. It was observed that mould inserts printed using the Polyjet technology were very well suited for functional prototyping via CIM. The mould inserts surface was found without visible thermally introduced damage after twenty CIM process cycles. In contrast to the high quality of mould inserts printed using the PolyJet technology, mould inserts made via fused deposition modeling (FDM) technology revealed as not applicable for the purpose of this study. The mould inserts manufactured using FDM-printer exhibit significantly higher surface roughness, larger longitudinal deflection and manufacturing-related undercuts along the edges of the 3D printed microstructure.
Nötzel D, Hanemann T, Eickhoff R
Charakterisierung additiv gefertigter keramischer Bauteile via FFF-Verfahren
2019 Keramische Zeitschrift, Band: 71, Nummer: 6, Seiten: 56 - 61
KurzfassungEine preiswerte Formgebung komplexer dreidimensionaler keramischer Bauteile in kleinen Stückzahlen ist nach wie vor eine Herausforderung. Daher entwickeln wir eine Prozesskette und Materialien, mit deren Hilfe Bauteile mittels Fused Filament Fabrication (FFF) gedruckt und anschließend gesintert werden können. In diesem Artikel stellen wir die Abbildegenauigkeit, erreichbare Dichte und Gefügeuntersuchungen vor. The inexpensive shaping of complex three-dimensional ceramic components in small numbers is still a challenge. We are therefore developing a process chain and materials that can be used to print components using Fused Filament Fabrication (FFF) and then sinter them. In this article, we present the imaging accuracy, achievable density and microstructural investigations.
C Pannek, C Weber, T Vetter, R Pohle, L Engel, A Eberhardt, K R Tarantik, M L Bauersfeld, J Wöllenstein
Colorimetric Sensor System for the Detection of Low Co-Concentrations in Real Fire Tests
2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII) IEEE, Seiten: 1345 - 1348
KurzfassungA novel colorimetric sensor system for the detection of carbon monoxide (CO) in low ppm concentrations for early fire gas detection is described. Due to its low power consumption and low fabrication costs the sensor enables the integration into a commercial fire detector.Screen printing methods for depositing thin films allow a fast gas interaction and a high degree of integration of the sensor system. The response of the sensor system to carbon monoxide was characterized both in the laboratory and in real firing tests.
Elsaegh S, Zschieschang U, Borchert J, Klauk H, Zappe H, Manoli Y
Compact DC Modeling of Organic Thin-film Transistors Including Their Parasitic Non-linear Contact Effects Based on a Novel Extraction Method
2019 IEEE Transactions on Electron Devices, Band: 66, Nummer: 11, Seiten: 4907 - 4914
Luderer C., Messmer C., Biour M., Hermle M.
Contact Resistivity of the TCO/a-Si:H/c-Si Heterojunction
In: 36th EU PVSEC
2019, , Seite: 538–540,
Kurzfassungsiehe pdf!
Jeremy T. Fineman, Seth Gilbert, Fabian Kuhn, Calvin Newport
Contention Resolution on a Fading Channel
2019 Distrib Comput, Band: 32, Nummer: 6, Seiten: 517 - 533
KurzfassungIn this paper, we study upper and lower bounds for contention resolution on a single hop fading channel; i.e., a channel where receive behavior is determined by a signal to interference and noise ratio equation. The best known previous solution solves the problem in this setting in O(log^2 n/ log log n) rounds, with high probability in the system size n. We describe and analyze an algorithm that solves the problem in O(log n+log R)rounds, where R is the ratio between the longest and shortest link, and is a value upper bounded by a polynomial in n for most feasible deployments. We complement this result with an Ω(log n) lower bound that proves the bound tight for reasonable R. We note that in the classical radio network model (which does not include signal fading), high probability contention resolution requires Ω(log^2 n) rounds. Our algorithm, therefore, affirms the conjecture that the spectrum reuse enabled by fading should allow distributed algorithms to achieve a significant improvement on this log^2 n speed limit. In addition, we argue that the new techniques required to prove our upper and lower bounds are of general use for analyzing other distributed algorithms in this increasingly well-studied fading channel setting.

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Galindo-Leon EE, Stitt I, Pieper F, Stieglitz T, Engler G, Engel AK
Context-specific modulation of intrinsic coupling modes shapes multisensory processing.
2019 Sci Adv, Band: 5, Nummer: 4, Seiten: eaar7633 - eaar7633
KurzfassungIntrinsically generated patterns of coupled neuronal activity are associated with the dynamics of specific brain states. Sensory inputs are extrinsic factors that can perturb these intrinsic coupling modes, creating a complex scenario in which forthcoming stimuli are processed. Studying this intrinsic-extrinsic interplay is necessary to better understand perceptual integration and selection. Here, we show that this interplay leads to a reconfiguration of functional cortical connectivity that acts as a mechanism to facilitate stimulus processing. Using audiovisual stimulation in anesthetized ferrets, we found that this reconfiguration of coupling modes is context specific, depending on long-term modulation by repetitive sensory inputs. These reconfigured coupling modes lead to changes in latencies and power of local field potential responses that support multisensory integration. Our study demonstrates that this interplay extends across multiple time scales and involves different types of intrinsic coupling. These results suggest a previously unknown large-scale mechanism that facilitates multisensory integration.
J. Li, J. Macdonald, F. von Stetten
Correction: Review: a comprehensive summary of a decade development of the recombinase polymerase amplification
2019 Analyst, Band: 144, Seiten: 31 - 67
KurzfassungNucleic acid amplification has permeated every field in the life sciences since the introduction of the classic polymerase chain reaction (PCR) method in 1983. Yet, despite its fundamental reach, PCR has been constrained within the walls of a laboratory, due to its requirement for a sophisticated thermocycling machine, limiting external application in low-resource settings. New isothermal amplification strategies are seeking to break through traditional laboratory boundaries by providing nucleic acid replication at constant temperatures. Of these methods, recombinase polymerase amplification (RPA) is one of the fastest developing, experiencing rapid uptake and market, even though it was introduced comparatively late. Critically, RPA’s technology potentiates highly accessible and sensitive nucleic acid amplification outside of laboratory, and even self-testing. Here we provide a comprehensive review of the equipmentfree simplicity of RPA over its first decade of development. Our review includes key knowledge of RPA technology, such as its reaction components, mechanism, sensitivities and specificities, and distinctive detection methods. The review also provides know-how for developing RPA assays, and information about commercially available RPA reaction kits and accessories. We summarise critical RPA experimental tips and issues available through data mining the published literature, to assist researchers in mastering the RPA reaction. We also outline influential hotspots of RPA development, and conclude with outlooks for future development and implications for eclipsing PCR and further revolutionising the life sciences.

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R Jana, L Pastewka
Correlations of non-affine displacements in metallic glasses through the yield transition
2019 J Phys Mater, Band: 2, Seite: 045006
KurzfassungWe study correlations of non-affine displacements during simple shear deformation of Cu–Zr bulk metallic glasses in molecular dynamics calculations. In the elastic regime, our calculations show exponential correlation with a decay length that we interpret as the size of a shear transformation zone in the elastic regime. This correlation length becomes system-size dependent beyond the yield transition as our calculation develops a shear band, indicative of a diverging length scale. We discuss these observations in the context of a recent proposition of yield as a first-order phase transition.
Steven Carr, Nils Jansen, Ralf Wimmer, Alexandru Constantin Serban, Bernd Becker, Ufuk Topcu
Counterexample-Guided Strategy Improvement for POMDPs using Recurrent Neural Networks
2019 Macao, China Proceedings of the 28th International Joint Conference on Artificial Intelligence (IJCAI)
KurzfassungWe study strategy synthesis for POMDPs. The particular problem is to determine strategies that provably adhere to (probabilistic) temporal logic constraints. This problem is computationally intractable and theoretically hard. We propose a novel method that combines techniques from machine learning and formal verification. First, we train an RNN to encode POMDP strategies. The RNN accounts for memory-based decisions without the need to expand the full belief space of a POMDP. Secondly, we restrict the RNN-based strategy to represent a finite-memory strategy and implement it on a specific POMDP. For the resulting finite Markov chain, efficient formal verification techniques provide provable guarantees against temporal logic specifications. If the specification is not satisfied, counterexamples supply diagnostic information. We use this information to improve the strategy by iteratively training the RNN. Numerical experiments show that the proposed method elevates the state of the art in POMDP solving by up to three orders of magnitude in terms of solving times and model sizes.

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Loshchilov Ilya, Hutter Frank
Decoupled Weight Decay Regularization
2019 International Conference on Learning Representations
N. Bosh, Müller C, H. Mozaffari-Jovein
Deformation twinning in cp-Ti and its effect on fatigue cracking
2019 Mater Charact
Dornhof J, Urban G, Kieninger J
Deposition of Copper Nanofilms by Surface-Limited Redox Replacement of Underpotentially Deposited Lead on Polycrystalline Gold
2019 J Electrochem Soc, Band: 166, Nummer: 1, Seiten: D3001 - D3005
KurzfassungElectrochemical atomic layer deposition (E-ALD) of copper on polycrystalline gold is a promising method to achieve highly reproducible nanofilms. Cu films of more than 30 nm were deposited by the repetitive execution of underpotential deposition (UPD) of lead and a subsequent surface limited redox replacement by Cu. Both steps were carried out in the same solution. The method enables, in contrast to conventional gas phase ALD, the deposition of layers with different height on the same substrate. Deposit growth in this one-pot system was monitored in-situ with an electrochemical quartz crystal microbalance. Film thickness, measured by optical profilometry, was compared to the number of deposition cycles and indicated a highly linear dependency. Obtained layers were characterized by means of atomic force and scanning electron microscopy and showed a slight roughening with almost no increase in the effective surface area. Energy dispersive X-ray measurements confirmed the purity of deposited Cu nanofilms. It was shown, that even with a simple setup, the described method allows the reproducible deposition of Cu on polycrystalline Au.

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Nomura M, Yanagisawa R, Zimmermann P, Ruther P, Paul O
Design of Planar Si Thermoelectric Generators with Phononic Crystal Patterning
2019 Sensor Mater, Band: 31, Nummer: 9, Seiten: 2803 - 2810
KurzfassungThis paper presents the design and optimization of planar poly-Si thermoelectric generators (TEGs) for energy harvesting application. Temperature and electric potential distributions are simulated using material parameters, which were experimentally obtained from test structures, by the finite element method to evaluate the performance of TEGs. TEGs with unpatterned membranes or membranes with phononic crystal (PnC) nanostructures are investigated to evaluate the increase in power density by nanopatterning. The power density is increased by PnC nanopatterning with larger holes and the optimal bridge length decreases owing to a higher thermal resistance. The series of simulations shows that nanopatterning increases the power density 2.5 times at a smaller bridge length and is also advantageous from the viewpoint of mechanical strength.
Robinson JT, Pohlmeyer E, Gather MC, Kemere C, Kitching JE, Malliaras GG, Marblestone A, Shepard KL, Stieglitz T, Xie C
Developing Next-Generation Brain Sensing Technologies—A Review
2019 IEEE Sens J, Band: 19, Nummer: 22, Seiten: 10163 - 10175
KurzfassungAdvances in sensing technology raise the possibility of creating neural interfaces that can more effectively restore or repair neural function and reveal fundamental properties of neural information processing. To realize the potential of these bioelectronic devices, it is necessary to understand the capabilities of emerging technologies and identify the best strategies to translate these technologies into products and therapies that will improve the lives of patients with neurological and other disorders. Here, we discuss emerging technologies for sensing brain activity, anticipated challenges for translation, and perspectives for how to best transition these technologies from academic research labs to useful products for neuroscience researchers and human patients.
Klaas Björn, Baulig Claudia, Predehl,Katharina, Schwarzer, Stefan
Development of a multispectral scanning lidar system for measuring wind velocity, air temperature and moisture
2019 SPIE Remote Sensing, 2019, Strasbourg, France
KurzfassungMeasurements of atmospheric parameters, such as wind velocity, air temperature and moisture, provide important information for a diverse set of ﬁelds, ranging from estimating energy output of wind farms to predicting extreme weather events to understanding urban climatology. Performing these measurements quickly, reliably and with high accuracy presents a yet unsolved challenge. Especially when working in or close to complex terrain, such as forests, hillsides or urban landscapes, no available system can properly perform such measurements. The Fraunhofer Institute for Physical Measurement Techniques IPM is developing a novel multispectral scanning LiDAR system. The goal is to simultaneously and accurately measure wind speed, air temperature and moisture over complex terrain for the ﬁrst time. We present the current state of a scanner system for synchronized steering of multiple laser beams from diﬀerent LiDAR units towards positions in the commonly visible intersection volume, subtending up to 7/8th of the full solid angle. We also present the state of an in-house developed Doppler Wind LiDAR and our current proposal for a combined wind, air temperature and water vapor LiDAR.
Stemmler, Simon, Werner, Christoph S., Reiterer, Alexander
Development of a time-of-ﬂight laser scanning system for underwater applications
2019 SPIE Remote Sensing, 2019, Strasbourg, France , Band: 111500M, 11150 (1-6)
KurzfassungAn increasing number of underwater construction projects demand a solution for precise and highly resolved infrastructure monitoring which cannot be addressed by conventional sonar systems. We present an optical ranging system based on the pulsed time-of-ﬂight method incorporating a signal-processing toolchain especially equipped for mapping technical infrastructure. This allows us to handle multiple returns from objects which are only separated by a 15 cm gap. A high lateral resolution of 4 mm in combination with a high measurement rate of 50 000 measurements per second allows the reconstruction of ﬁne details. The measurement range can reach several 10 m, depending on the water quality. Further, we present the system design of our scanner and discuss ﬁrst results obtained in an underwater measurement range.
A. van Belkum, T. T. Bachmann, G. Lüdke, J. G. Lisby, G. Kahlmeter, A. Mohess, K. Becker, J. P. Hays, N. Woodford, K. Mitsakakis, J. Moran- Gilad, J. Vila, H. Peter, J. H. Rex, W. M. Dunne Jr., and the JPIAMR AMR-RDT Working Group
Developmental roadmap for antimicrobial susceptibility testing systems
2019 Nat Rev Microbiol, Band: 17, Seiten: 51 - 62
KurzfassungAntimicrobial susceptibility testing (AST) technologies help to accelerate the initiation of targeted antimicrobial therapy for patients with infections and could potentially extend the lifespan of current narrow-spectrum antimicrobials. Although conceptually new and rapid AST technologies have been described, including new phenotyping methods, digital imaging and genomic approaches, there is no single major, or broadly accepted, technological breakthrough that leads the field of rapid AST platform development. This might be owing to several barriers that prevent the timely development and implementation of novel and rapid AST platforms in health-care settings. In this Consensus Statement, we explore such barriers, which include the utility of new methods, the complex process of validating new technology against reference methods beyond the proof-of-concept phase, the legal and regulatory landscapes, costs, the uptake of new tools, reagent stability, optimization of target product profiles, difficulties conducting clinical trials and issues relating to quality and quality control, and present possible solutions.
K. Philipp, F. Lemke, S. Scholz, U. Wallrabe, M.C. Wapler, N. Koukourakis, J.W. Czarske
Diffraction-limited axial scanning in thick biological tissue employing an aberration correcting adaptive lens
2019 Scientific Reports, Ergänzungsband: 9:9532, Seite: 11pp
Yi Q, Cai D, Xiao M, Nie M, Cui Q, Cheng J, Li C, Feng J, Urban G, Xu Y-C, Lan Y, Du W
Direct antimicrobial susceptibility testing of bloodstream infection on SlipChip
2019 Biosens Bioelectron, Band: 135, Seiten: 200 - 207
KurzfassungThis paper describes an integrated microfluidic SlipChip device for rapid antimicrobial susceptibility testing (AST) of bloodstream pathogens in positive blood cultures. Unlike conventional AST methods, which rely on an overnight subculture of positive blood cultures to obtain isolated colonies, this device enables direct extraction and enrichment of the bacteria from positive blood cultures by dielectrophoresis. SlipChip technology enables parallel inoculation of the extracted bacteria into nanoliter-scale broth droplets to perform multiplexed ASTs simultaneously. The nanoliter confinement in the droplets increases the effective inoculation amount of the bacteria, shortens the diffusion distance of nutrient elements and gases, and allows faster growth and proliferation rates. Entropy-based image analysis used for the characterization of bacterial susceptibility patterns eliminates the requirement for single-cell morphological analysis and fluorescence labeling. As a proof-of-concept, the susceptibility patterns of Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 6538p, and a positive blood culture containing Escherichia coli against several broad-spectrum antibiotics were determined by the SlipChip device. The on-chip AST results were well matched with those respectively reported by the broth microdilution method and a BD Phoenix Automated Microbiology System. Reliable AST results can be reported to clinicians within 3–8 h using this simple device after positive blood culture, allowing earlier proper administration of antimicrobial therapy.
Dincer C, Bruch R, Costa-Rama E, Fernández-Abedul MT, Merkoçi A, Manz A, Urban G, Güder F
Disposable Sensors in Diagnostics, Food, and Environmental Monitoring
2019 Adv Mater, Band: 31, Nummer: 30, Seite: 1806739
KurzfassungDisposable sensors are low-cost and easy-to-use sensing devices intended for short-term or rapid single-point measurements. The growing demand for fast, accessible, and reliable information in a vastly connected world makes disposable sensors increasingly important. The areas of application for such devices are numerous, ranging from pharmaceutical, agricultural, environmental, forensic, and food sciences to wearables and clinical diagnostics, especially in resource-limited settings. The capabilities of disposable sensors can extend beyond measuring traditional physical quantities (for example, temperature or pressure); they can provide critical chemical and biological information (chemo- and biosensors) that can be digitized and made available to users and centralized/decentralized facilities for data storage, remotely. These features could pave the way for new classes of low-cost systems for health, food, and environmental monitoring that can democratize sensing across the globe. Here, a brief insight into the materials and basics of sensors (methods of transduction, molecular recognition, and amplification) is provided followed by a comprehensive and critical overview of the disposable sensors currently used for medical diagnostics, food, and environmental analysis. Finally, views on how the field of disposable sensing devices will continue its evolution are discussed, including the future trends, challenges, and opportunities.

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F. Schlenker, E. Kipf, S. Jenne, N. Borst, J. Lüddecke, K. Dormanns, T. Hutzenlaub, J. Steinert, N. Paust, R. Zengerle, F. von Stetten, P. Juelg
Doubling the order of color-multiplexing by photobleaching in Mediator Probe droplet digital PCR
2019 EACR-ESMO Joint Conference on Liquid Biopsies, Bergamo/Italien, 15. – 17. 05. 2019
Megnin C, Mauck M, Hertkorn D, Hanemann T, Mueller C
ELECTROPHORETIC DEPOSITION OF BiVO4 LAYERS ON FTO SUBSTRATES FOR PHOTO ELECTRO-CHEMICAL CELLS
2019 Ceramics-Silikaty, Band: 63, Nummer: 1, Seiten: 124 - 130
KurzfassungIn this paper the deposition of BiVO4 onto fluorine doped tin oxide (FTO) substrates by electrophoretic deposition (EPD) is presented. The BiVO4 powder was fabricated by a mixed oxide route and added by a solvent and dispersant to achieve the suspension for EPD. The particle size, sintering parameters, and crystal structure of the powder were characterized by laser light diffraction, dilatometer, and X-ray diffraction, respectively. EPD was performed at deposition voltages between 12.5 V and 100 V resulting in layer thicknesses in the range of 0.5 μm and 2.8 μm after sintering. The current density of the layers was determined for frontside and backside illumination of the FTO substrates at different wavelengths in the range between 400 nm and 600 nm. The band gap was determined at 515 nm, which corresponds to 2.5 eV. The maximum external quantum efficiency (EQE) was measured at 440 nm and backside illumination.

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A. Müller, M.C. Wapler, U. Wallrabe
Economical rapid-prototyping of aspherical lenses
2019 EOS World of Photonics Congress 2019, Munich, Germany PJ Web of Conferences, Band: 215, Nummer: 04001
Ledernez L, Engesser F, Altenburger M, Urban G, Bergmann M
Effect of Transient Spark Disinfection on Various Endodontics Relevant Bacteria
2019 Plasma Medicine, Band: 9, Nummer: 2, Seiten: 121 - 128
KurzfassungThe in-vitro efficacy of the Transient Spark Disinfection was examined on different types of bacteria that are relevant in the field of endodontics, in particular E. faecalis. The device is so constructed that it can be inserted down to the apex of prepared root canals and the method can be applied in conventional, regenerative and reparative endodontics. Starting with a bacterial load of 0.2 ml of undiluted 10⁹ bacteria / ml spread on a Petri dish, the 3-minute treatment lead to a 10⁶ CFU/cm² reduction of the bacterial load over a surface area that is relevant in this indication.
C. Siber, L. Lautscham, J. Schoendube, P. Reichert, F. Stumpf, S. Zimmermann, R. Zengerle, P. Koltay
Effective acoustic field generation in diposable dispensing cartridges for acustophoretic particle focusing
2019 Transducers 2019, Berlin, 23.06. - 27.06.2019
Qussous R, Künzel T, Weidlich A
Effects of a Coal Phase-Out on Market Dynamics: Results from a Simulation Model for Germany
2019 16th International Conference on the European Energy Market

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Messmer Christoph, Fell Andreas, Feldmann Frank, Wohrle Nico, Schon Jonas, Hermle Martin
Efficiency Roadmap for Evolutionary Upgrades of PERC Solar Cells by TOPCon: Impact of Parasitic Absorption
2019 IEEE Journal of Photovoltaics
Kurzfassungsiehe PDF
Elsken Thomas, Metzen Jan, Hutter Frank
Efficient Multi-Objective Neural Architecture Search via Lamarckian Evolution
2019 International Conference on Learning Representations
Koch J, Schuettler M, Pasluosta C, Stieglitz T
Electrical connectors for neural implants: design, state of the art and future challenges of an underestimated component.
2019 J Neural Eng
KurzfassungTechnological advances in electrically active implantable devices have increased the complexity of hardware design. In particular, the increasing number of stimulation and recording channels requires innovative approaches for connectors that interface electrodes with the implant circuitry. This work aims to provide a common theoretical ground for implantable connector development with a focus on neural applications. Aspects and experiences from several disciplines are compiled from an engineering perspective to discuss the state of the art of connector solutions. Whenever available, we also present general design guidelines. Degradation mechanisms, material stability and design rules in terms of biocompatibility and biostability are introduced. Considering contact physics, we address the design and characterization of the contact zone and review contaminants, wear and contact degradation. For high-channel counts and body-like environments, insulation can be even more crucial than the electrical connection itself. Therefore, we also introduce the requirements for electrical insulation to prevent signal loss and distortion and discuss its impact on the practical implementation. A final review is dedicated to the state of the art connector concepts, their mechanical setup, electrical performance and the interface to other implant components. We conclude with an outlook for possible approaches for the future generations of implants.
Weltin A, Ganatra D, Durisin M, Urban G, Kieninger J
Electrochemical Protocols Upgrade Conventional Noble Metal Electrodes to Long-term Stable Sensors at the Tissue/Electrode Interface
2019 IEEE EMBC, Berlin, Germany Proc. 41th Int. Conf. of the IEEE Eng. in Medicine and Biology Soc. (EMBC), Band: 1, Seiten: 1 - 1
Pfau J, Ganatra D, Weltin A, Urban G, Kieninger J, Stieglitz T
Electrochemical Stability of Thin-Film Platinum as Suitable Material for Neural Stimulation Electrodes
2019 IEEE EMBC, Berlin, Germany
Kleber C, Lienkamp K, Ruhe J, Asplund M
Electrochemically Controlled Drug Release from a Conducting Polymer Hydrogel (PDMAAp/PEDOT) for Local Therapy and Bioelectronics.
2019 Adv Healthc Mater, Seiten: e1801488 - e1801488
KurzfassungIn this study, the release of fluorescein from a photo‐crosslinked conducting polymer hydrogel made from a hydrogel precursor poly(dimethylacrylamide‐co‐4‐methacryloyloxy benzophenone (5%)‐co‐4‐styrenesulfonate (2.5%)) (PDMAAp) and the conducting polymer poly(3,4‐ethylenedioxythiophene) (PEDOT) is investigated. Fluorescein, here used as a model for a drug, is actively released through application of an electrical trigger signal. The detected quantity is more than six times higher in comparison to that released from a conventional PEDOT/polysterene sulfonate (PSS) system. Release profiles, drug dose, and timing can be tailored by the application of different trigger signals and pretreatments. To demonstrate that the novel drug release system can be used for a drug relevant for local delivery to a neural interface, experiments are furthermore performed with the anti‐inflammatory drug dexamethasone (Dex). The conducting polymer hydrogel facilitates the active release of Dex, in comparison to the previously used PEDOT/Dex. It is suggested that PEDOT/PDMAAp is an interesting alternative for conducting polymer based drug release systems, with the potential to offer more volume for storage, yet retaining the excellent electrochemical properties known for PEDOT electrodes.
Neelisetty KK, Mu X, Gutsch S, Vahl A, Molinari A, Von Seggern F, Hansen M, Scherer T, Zacharias M, Kienle L, Kiran Chakravadhanula VS Kübel C
Electron Beam Effects on Oxide Thin Films-Structure and Electrical Property Correlations
2019 Microsc Microanal, Band: 25, Nummer: 3, Seite: 592-600
KurzfassungIn situ transmission electron microscope (TEM) characterization techniques provide valuable information on structure–property correlations to understand the behavior of materials at the nanoscale. However, understanding nanoscale structures and their interaction with the electron beam is pivotal for the reliable interpretation of in situ/ex situ TEM studies. Here, we report that oxides commonly used in nanoelectronic applications, such as transistor gate oxides or memristive devices, are prone to electron beam induced damage that causes small structural changes even under very low dose conditions, eventually changing their electrical properties as examined via in situ measurements. In this work, silicon, titanium, and niobium oxide thin films are used for in situ TEM electrical characterization studies. The electron beam induced reduction of the oxides turns these insulators into conductors. The conductivity change …

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Wurster L, Shah R, Placzek F, Kretschmer S, Niederleithner M, Ginner L, Ensher J, Minneman M, Hoover E, Zappe H, Drexler W, Leitgeb R, Ataman C
Endoscopic optical coherence tomography angiography using a forward imaging piezo scanner probe
2019 J Biophotonics, Band: 12, Nummer: 4
Petrini FM, Valle G, Bumbasirevic M, Barberi F, Bortolotti D, Cvancara P, Hiairrassary A, Mijovic P, Sverrisson AO, Pedrocchi A, Divoux JL, Popovic I, Lechler K, Mijovic B, Guiraud D, Stieglitz T, Alexandersson A, Micera S, Lesic A, Raspopovic S
Enhancing functional abilities and cognitive integration of the lower limb prosthesis.
2019 Sci Transl Med, Band: 11, Nummer: 512
KurzfassungLower limb amputation (LLA) destroys the sensory communication between the brain and the external world during standing and walking. Current prostheses do not restore sensory feedback to amputees, who, relying on very limited haptic information from the stump-socket interaction, are forced to deal with serious issues: the risk of falls, decreased mobility, prosthesis being perceived as an external object (low embodiment), and increased cognitive burden. Poor mobility is one of the causes of eventual device abandonment. Restoring sensory feedback from the missing leg of above-knee (transfemoral) amputees and integrating the sensory feedback into the sensorimotor loop would markedly improve the life of patients. In this study, we developed a leg neuroprosthesis, which provided real-time tactile and emulated proprioceptive feedback to three transfemoral amputees through nerve stimulation. The feedback was exploited in active tasks, which proved that our approach promoted improved mobility, fall prevention, and agility. We also showed increased embodiment of the lower limb prosthesis (LLP), through phantom leg displacement perception and questionnaires, and ease of the cognitive effort during a dual-task paradigm, through electroencephalographic recordings. Our results demonstrate that induced sensory feedback can be integrated at supraspinal levels to restore functional abilities of the missing leg. This work paves the way for further investigations about how the brain interprets different artificial feedback strategies and for the development of fully implantable sensory-enhanced leg neuroprostheses, which could drastically ameliorate life quality in people with disability.
M. Wehrle, F. Koch, S. Zimmermann, P. Koltay, R. Zengerle, G. B. Stark, S. Strassburg, G. Finkenzeller
Examination of Hydrogels and Mesenchymal Stem Cell Sources for Bioprinting of Artificial Osteogenic Tissues
2019 Cellular and Molecular Bioengineering, Seiten: 1 - 15
KurzfassungMesenchymal stem cells (MSCs) represent a very important cell source in the field of regenerative medicine and for bone and cartilage tissue engineering applications. Three-dimensional (3D) bioprinting has the potential to improve the classical tissue engineering concept as this technique allows the printing of cells with high spatial control of cell allocation within a 3D construct. In this study, we systematically compared different hydrogel blends for 3D bioprinting of MSCs by testing their cytocompatibility, ability to support osteogenic differentiation and their mechanical properties. In addition, we compared four different MSC populations isolated from different human tissues for their osteogenic differentiation capacity in combination with different hydrogels. The aim of this study was to identify the best MSC source and the most suitable hydrogel blend for extrusion-based bioprinting of 3D large-scaled osteogenic constructs.
Steib S, Klamroth S, Gassner H, Pasluosta C, Eskofier B, Winkler J, Klucken J, Pfeifer K
Exploring gait adaptations to perturbed and conventional treadmill training in Parkinson's disease: Time-course, sustainability, and transfer.
2019 Hum Movement Sci, Band: 64, Seiten: 123 - 132
KurzfassungBackground Gait impairment is a major motor symptom in Parkinson’s disease (PD), and treadmill training is an effective non-pharmacological treatment option. Research question In this study, the time course, sustainability and transferability of gait adaptations to treadmill training with and without additional postural perturbations were investigated. Methods 38 PD patients (Hoehn & Yahr 1–3.5) were randomly allocated to eight weeks of treadmill training, performed twice-weekly for 40 min either with (perturbation treadmill training [PTT], n = 18) or without (conventional treadmill training [CTT], n = 20) additional perturbations to the treadmill surface. Spatiotemporal gait parameters were assessed during treadmill walking on a weekly basis (T0–T8), and after three months follow-up (T9). Additional overground gait analyses were performed at T0 and T8 to investigate transfer effects. Results Treadmill gait variability reduced linearly over the course of 8 weeks in both groups (p < .001; Cohen’s d (range): −0.53 to −0.84). Only the PTT group significantly improved in other gait parameters (stride length/time, stance-/swing time), with stride time showing a significant between-group interaction effect (Cohen’s d = 0.33; p = .05). Additional between-group interactions indicated more sustained improvements in stance (Cohen’s d = 0.85; p = .02) and swing time variability in the PTT group (Cohen’s d = 0.82; p = .03) at T9. Overground gait improvements at T8 existed only in stance (d = -0.73; p = .04) and swing time (d = 0.73; p = .04). Discussion Treadmill stride-to-stride variability reduced substantially and linearly, but transfer to overground walking was limited. Adding postural perturbations tended to increase efficacy and sustainability of several gait parameters. However, since between-group effects were small, more work is necessary to support these findings.
Kotz F, Risch P, Arnold K, Sevim S, Puigmarti-Luis J, Quick A, Thiel M, Hrvnevich A, Dalton P. D., Helmer D, Rapp B
Fabrication of arbitrary three-dimensional suspended hollow microstructures in transparent fused silica glass
2019 Nat Commun, Band: 10, Nummer: 1, Seiten: 1 - 7
KurzfassungFused silica glass is the preferred material for applications which require long-term chemical and mechanical stability as well as excellent optical properties. The manufacturing of complex hollow microstructures within transparent fused silica glass is of particular interest for, among others, the miniaturization of chemical synthesis towards more versatile, configurable and environmentally friendly flow-through chemistry as well as high-quality optical waveguides or capillaries. However, microstructuring of such complex three-dimensional structures in glass has proven evasive due to its high thermal and chemical stability as well as mechanical hardness. Here we present an approach for the generation of hollow microstructures in fused silica glass with high precision and freedom of three-dimensional designs. The process combines the concept of sacrificial template replication with a room-temperature molding process for fused silica glass. The fabricated glass chips are versatile tools for, among other, the advance of miniaturization in chemical synthesis on chip.
Roth J, Rohrbach A
Fast TIRF-SIM imaging of dynamic, low-fluorescent biological samples
2019 submitted
J. Weisemann, G. B. Stevens, T. van Oordt, N. Krez, K. Dormanns, M. Karle, F. von Stetten, A. Rummel
Fast automatic detection of Botulinum neurotoxin by the BoNT LabDisk assay: results of a trans-european performance study
2019 Toxins 2019, Copenhagen/Denmark, 16. - 19.01.2019
KurzfassungBotulinum Neurotoxins (BoNT) are the most toxic naturally occurring substances for humans. After potential intoxication and occurrence of botulism symptoms, urgent detection of causative BoNT is highly desirable for successful medical treatment. The mouse bioassay (MBA) as gold standard requires a large number of mice, takes several days and is not suitable for point-of-care. Here, we developed an automatic in vitro assay to detect BoNT in complex biological matrices. The assay detects specific cleavage of SNARE proteins by BoNTs by fluorescent read out in a centrifugal microfluidic cartridge, termed BoNT LabDisk (BLD). The generic LabDisk comprises two different peptides able to distinguish between BoNT/ACE and BDF, respectively. The BLD prototype system was tested in a trans-European performance study by five naïve laboratories with expertise in BoNT detection to demonstrate practical applicability and performance of the BLD system. Eight blinded samples containing three complex biological matrices (human serum, bean juice, carrot juice) or buffer spiked with 10-1000 pM of BoNT/A and D were provided. Stability of samples was confirmed by mouse hemidiaphragm assay prior to shipment. The laboratories detected absence or presence of BoNT/A in 34 of the 40 samples correctly (85% accuracy). In three of ten bean juice or serum samples problems occurred due to high viscosity which requires improvement of sample preparation. In another three samples, signals close to background led to misinterpretation by experimentators. Altogether, the performance study showed that handling of the BLD assay is very easy, fast and practicable. The current detection limit is close to that of MBA. In conclusion, the BLD system allows the detection of functionally active BoNT in short assay times with low limits of detection within different matrices, without the need of animals or animal based reagents. The next step will be the adaption of the BLD assay for a direct serotyping of BoNT/A-F.
S. Backe, F. Balle, B. Hannemann, S. Schmeer, U.P. Breuer
Fatigue properties of multifunctional metal‐ and carbon‐fibre‐reinforced polymers and intrinsic capabilities for damage monitoring
2019 Fatigue Fract Eng M, Nummer: 42, Seiten: 143 - 151
Bryant, K., Grossi, G., Kaiser, A.
Feminist Interventions on the Sex/Gender Question in Neuroimaging Research
2019 The Scholar & Feminist Online; published by the Barnard Center for research on women., Nummer: 15.2
Roiz M, Werner C, Breunig I, Vaini M
Femtosecond-Driven Up-Conversion in a Radially Poled LiNbO3 Microresonator
2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC), Munich, IEEE
KurzfassungNowadays, there are plenty of different techniques developed for the generation of Optical Frequency Combs (OFCs), but Mode Locked Laser (MLL) OFC is still the most commonly used and commercially available one [1]. Although MLLs are capable of producing very high-peak power OFCs with femtosecond pulse durations, it is sometimes challenging to apply them directly for a number of reasons. First, MLLs typically produce OFCs with repetition frequencies (f r ) below 1 GHz, so additional filtering of the unwanted modes is required for the applications in telecommunications, astrocombs etc. Second, many spectral regions - namely mid-infrared, visible and ultraviolet - are difficult to access by MLLs, which implies the use of external parametric up- and down-conversion. One promising platform for such spectral transfer is high Q-factor optical microresonators based on second order (χ (2) ) nonlinear crystals, since not only do they provide the desired spectral transfer, but also open up opportunities for the miniaturization of the system. In addition, such microresonators support whispering gallery modes that possess very low mode volumes, making it possible to enhance nonlinear χ (2) processes. This is a significant advantage over the already existing bulk analogs.
A Eberhardt, M-L Bauersfeld, K Schmitt, J Wöllenstein
Filterrotationsspektrometer für den Nachweis von Ethen im ppb-Bereich
2019 20. GMA/ITG-Fachtagung Sensoren und Messsysteme, Nürnberg, Germany , Seiten: 328 - 333
KurzfassungEthen ist eines der wichtigsten Phytohormone im Reifungsprozess klimakterischer Früchte. Die Menge des emittierten Ethens liefert Informationen über den aktuellen Reifezustand dieser Früchte. Deshalb kann es in der Lieferkette für die Umsetzung fortschrittlicher Prozesse, wie dem First-Expired-First-Out-Prozess (FEFO), eingesetzt werden. Diese Arbeit beschreibt den aktuellen Stand der Entwicklung eines kostengünstigen Filterrotationsspektrometers für den Nachweis von Ethen in der klimakterischen Reifephase von Früchten. Das Spektrometer basiert im Wesentlichen auf Komponenten, die auch in nichtdispersiven Infrarotsensoren (NDIR) zum Einsatz kommen. Durch eine modellbasierte Auswertung der Spektren konnte die Stabilität eines ersten Laborprototyps gegenüber klassischen NDIR-Sensoren deutlich verbessert werden. In Verbindung mit einer optimierten Langwegzelle konnte die Nachweisgrenze bis auf 150 ppb reduziert werden.
Fiath R, Raducanu BC, Musa S, Andrei A, Lopez CM, Welkenhuysen M, Ruther P, Aarts A, Ulbert I
Fine-scale mapping of cortical laminar activity during sleep slow oscillations using high-density linear silicon probes
2019 J Neurosci Meth, Band: 316, Seiten: 58 - 70
D. Kainz, S. Früh, T. Hutzenlaub, R. Zengerle, N. Paust
Flow control for lateral flow strips with centrifugal microfluidics
2019 Lab Chip
KurzfassungLateral flow strips (LFSs) are widely used for clinical diagnostics. The restricted flow control of the current designs is one challenge to the development of quantitative and highly sensitive LFSs. Here, we present a flow control for LFSs using centrifugal microfluidics. In contrast to previously presented implementations of lateral flow membranes into centrifugal microfluidic cartridges, we direct the flow radially outwards through the membrane. We control the flow using only the centrifugal force, thus it is independent of membrane wetting properties and permeability. The flow rate can be decreased and increased, enabling control of incubation times for a wide variety of samples. We deduced a formula as a guideline for the integration of chromatographic membranes into centrifugal microfluidic disks to ensure that all the sample liquid flows through the membrane, hence safely avoiding bypass flow around the membrane. We verified the calculated operation conditions using different membranes, different flow rates, and different sample viscosities.
D. Kainz, S. Früh, T. Hutzenlaub, R. Zengerle, N. Paust
Flow profile through exposed porous media in centrifugal microfluidics
2019 MicroTAS, 27. – 31. October 2019, Basel/Switzerland
Abdel-Khalek H, Schäfer M, Vásquez Torres RA, Unnewehr J, Weidlich A
Forecasting Cross-Border Power Transmission Capacities in Central Western Europe Using Artificial Neural Networks
2019 Energy Informatics, Band: 2, Ergänzungsband: 1, Seiten: 1 - 13

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Anelis Kaiser
Frauen in den Ingenieurswissenschaften: Zwischen Irritation und Negierung
2019 querelles-net Rezensionszeitschrift fuer Frauen- und Geschlechterfoschung, Band: 20, Nummer: 3, Seiten: 1 - ff
KurzfassungTrotz Bemühungen auf Ebene der Gleichstellung sind Frauen nach wie vor im MINT-Bereich an deutschen Hochschulen unterrepräsentiert. Was mögen die Gründe dafür sein? Mit den Methoden der Sozialwissenschaften untersuchen Wissenschaftler*innen die Ursachen für diese Geschlechter-Disbalance. So auch Inka Greusing in ihrer Dissertationsschrift, in der sie auf verschiedene immanente Strukturen in unseren Köpfen, in unserem Verhalten und in den Studiengängen hinweist. Dadurch wird klar, dass Maßnahmen zur Veränderung der Situation nach wie vor notwendig sind. Die Analyse von Inka Greusing stellt einen sorgfältig ausgearbeiteten Beitrag für das Forschungsfeld Gender Studies in den MINT-Fächern dar.
Szabados J, Breunig I, Buse K
Frequency Comb Generation and Conversion in Non-Centrosymmetric Optical Microresonators
2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC), Munich, IEEE
KurzfassungOptical frequency combs have become the key technology in optical precision measurements [1], bear a high potential for broadband, high-resolution molecular spectroscopy [2] and are promising to advance future optical clocks [3]. For low-power, compact and mobile applications, high-repetition-rate combs such as continuous-wave-pumped Kerr combs [4] and soliton frequency combs based on a third-order nonlinearity [5] have turned out to be especially useful. Thus far, most of these frequency combs operate in the near-infrared (NIR) spectral regime around 1550 nm for reasons such as chromatic material dispersion. Many applications ranging from astronomical spectroscopy, optical clocks and quantum physics all the way to molecular sensing, however, require the frequency combs to be centered in the ultraviolet (UV), visible (VIS) and mid-infrared (MIR) spectral regimes [3,6-8].
Villouis A, Kondratiev N, Breunig I, Puzyrev D N, Skryabin D V
Frequency combs in a microring optical parametric oscillator
2019 Opt Lett, Band: 44, Seite: 4443
KurzfassungWe report the soliton frequency comb generation in microring optical parametric oscillators operating in the downconversion regime and with the simultaneous presence of the χ(2) and Kerr nonlinearities. The combs are studied considering a typical geometry of a bulk LiNbO3 toroidal resonator with the normal group velocity dispersion spanning an interval between the pump and the downconverted signal. We have identified critical power signaling a transition between the relatively low pump power predominantly χ(2) combs and the high pump power ones shaped by the competition between the χ(2) and Kerr nonlinearities.
M. Bühler, P. Holzapfel, D. McLaughlin, S. Thiele
From catalyst coated membranes to porous transport electrode based configurations in PEM water electrolyzers
2019 J Electrochem Soc, Band: 166, Seite: F1070
KurzfassungSo far the superior cell polarization behavior of membrane electrode assemblies (MEAs) using catalyst coated membranes (CCMs) as compared to those using porous transport electrodes (PTEs) was a paradigm in proton exchange membrane water electrolyzers (PEMWEs). However, this paradigm was so far neither systematically investigated nor understood. In this study, we investigate the changes in PEMWE polarization behavior upon gradually changing the MEA from a full CCM toward a full PTE-type configuration. We explain all observed findings based on the idea for a structural model of discontinuous catalyst layers. Our results show, that for current densities above 750 mA cm−2, PTE-based MEAs can result in a better polarization behavior than CCMs. Therefore, the prevailing paradigm was disproved. CCMs showed better kinetics, while PTE-type configurations performed more reproducible than CCMs despite rougher surfaces. Due to the trend of a stabilizing HFR-free cell voltage, an improved mass transport behavior of the PTE-type configurations at high current densities is assumed. Within the error-tolerance, no clear differences between PTE and CCM-based configurations in ohmic resistance could be determined. We conclude that PTE-based configurations for PEMWE, as alternatives to standard CCM-configurations, could be highly important for future manufacturing techniques depending on the application's needs.
S Li, L Pastewka, P Gumbsch
Glass formation by severe plastic deformation of crystalline Cu|Zr nano-layers
2019 Acta Mater, Band: 165, Seiten: 577 - 586
KurzfassungWe use molecular dynamics simulation to study the formation of glasses during severe plastic deformation of crystalline Cu|Zr nano-layers in a simple shear geometry. The early stage of plasticity is governed by dislocation plasticity. Dislocation-interface interaction induces interface roughening and slow atomic-level intermixing around interfaces. A solid-state crystal-to-amorphous transition starts near the interfaces. At high strain, the interfaces are refined to merge, leading to the formation of an intermixed glassy zone that eventually spans our simulation cell. Dislocation emission is then fully suppressed and strain is fully accommodated by this glassy phase. We characterize the crystal-to-amorphous transition using local structural measures, such as the pair distribution function and Voronoi analysis. The onset of glass formation occurs at a critical shear strain that increases with layer thickness. Our simulations indicate that the parameter controlling this onset is the theoretical affine interface distance, i.e. the amorphization occurs at a critical value of around 3-4 nm that increases slightly with the increase of layer thickness. Our work provides insights on mechanically driven glass formation in multicomponent systems, as e.g. realized in ball-mills or high-pressure torsion experiments.
Y.-T. Kao, T. S. Kaminski, W. Postek, J. Guzowski, K. Makuch, A. Ruszczak, F. von Stetten, R. Zengerle, P. Garstecki
Gravity-driven microfluidic assay for digital enumeration of bacteria and for antibiotic susceptibility testing
2019 Lab Chip
KurzfassungThe alarming dynamics of antibiotic-resistant infections calls for the development of rapid and point-of-care (POC) antibiotic susceptibility testing (AST) methods. Here, we demonstrated the first completely stand-alone microfluidic system that allowed the execution of digital enumeration of bacteria and digital antibiograms without any specialized microfluidic instrumentation. A four-chamber gravity-driven step emulsification device generated ∼2000 monodisperse 2 nanoliter droplets with a coefficient of variation of 8.9% of volumes for 95% of droplets within less than 10 minutes. The manual workload required for droplet generation was limited to the sample preparation, the deposition into the sample inlet of the chip and subsequent orientation of the chip vertically without an additional pumping system. The use of shallow chambers imposing a 2D droplet arrangement provided superior stability of the droplets against coalescence and minimized the leakage of the reporter viability dye between adjacent droplets during long-term culture. By using resazurin as an indicator of the growth of bacteria, we were also able to reduce the assay time to ∼5 hours compared to 20 hours using the standard culture-based test.
L Pastewka, A Greiner
HPC with Python: An MPI-parallel implementation of the Lattice Boltzmann Method
In: Proceedings of the 5th bwHPC Symposium
2019, Tübingen Library Publishing, Seiten: 101 - 118, ISBN: 978-3-946552-25-3
KurzfassungThe Lattice Boltzmann Method is well suited for high-performance computational fluid dynamics. We show by means of a common two-dimensional test case, the lid-driven cavity problem, that excellent parallel scaling can be achieved in an implementation based on pure Python, using the numpy library and the Message Passing Interface. We highlight opportunities and pitfalls for the implementation of parallel high-performance codes in the high-level language Python.
Gay Maël, Paxian Tobias, Upadhyaya Devanshi, Becker Bernd, Polian Ilia
Hardware-Oriented Algebraic Fault Attack Framework with Multiple Fault Injection Support
2019 2019 Workshop on Fault Diagnosis and Tolerance in Cryptography (FDTC), IEEE, Seiten: 25 - 32
Szabados J, Brasch V, Herr S, Obrzud E, Jia Y, Lecomte S, Buse K, Breunig I, Herr T
High repetition rate frequency comb up-and down-conversion in synchronously driven microresonators
2019 Laser Resonators, Microresonators, and Beam Control XXI, San Francisco, CA, United States Proceedings of SPIE, Band: 10904, Seite: 109040D
KurzfassungOptical frequency combs are a key technology for optical precision measurements. So far, most frequency combs operate in the near-infrared regime (NIR). Many applications, however, require combs in the ultraviolet (UV), visible (VIS) or mid-infrared (MIR) spectral ranges. This can be achieved by making use of nonlinear-optical processes. In this contribution, we demonstrate the efficient conversion of frequency combs with a repetition rate of 21 GHz to UV, VIS and MIR wavelengths in a synchronously driven high-Q microresonator with second-order optical nonlinearity. This opens up a new path for applications including, but not limited to, molecular sensing and quantum optics.
Subbiah N, Feng Q, Wilde J
High-Temperature Pressure Sensor Package and Characterization of thermal stress in the assembly up to 500 °C
2019 IEEE 69th Electronic Components and Technology Conference , Seiten: 878 - 883
Klein E, Gossler C, Paul O, Schwarz U T, Ruther P
High-yield indium-based wafer bonding for large-area multi-pixel optoelectronic probes for neuroscientific research
2019 J Micromech Microeng, Band: 29, Seiten: 095006 - 095015
Z. Shu, B. Gerdes, M. Fechtig, R. Zengerle, P. Koltay
Highly conductive flexible and 3D metallization on flexible and textile substrates via StarJet Technology
2019 12th International Symposium on Flexible Organic Electronics (ISFOE19) 1-4 July 2019, Thessaloniki, Greece
KurzfassungHighly conductive metallizations are crucial for large area organic and printed electronics. State-of-the-art printing technologies such as inkjet printing and screen printing are still facing critical challenges regarding achieving high electrical conductivity and reducing the manufacturing costs. Moreover, additional post-processes such as thermal, photonic or laser sintering are either not compatible with the flexible substrates or expensive. On the contrary, the non-contact StarJet printing technology provides direct metallization from molten metal microdroplets and continuously Jet. It bases on a pneumatically driven printhead that features a heatable reservoir and an interchangeable nozzle chip with a star-shaped orifice geometry. Thanks to the pneumatic driven mechanism, materials with high melting temperature such as solder or aluminium alloys can be printed. Single-pass conductive features, printed via StarJet, exhibit high electrical conductance (7.5 Ω/m for 250 μm linewidth), high aspect ratio, i.e. high layer thickness (70 – 300 μm), and require no post-treatment. Examples of electrically functional, direct metallization were demonstrated on silicon solar cells and PCB boards. In this contribution, we demonstrate that the StarJet technology is also compatible with temperature sensitive flexible substrates such as polymer foils and textiles. The printed solder lines exhibit not only high electrical conductance but also high mechanical stability (i.e. adhesion) and high flexibility. The printed solder lines on polymer foils and textile can stand shear forces of up to 3000 mN and at the same time tolerate substrate bending at the radius of 5 mm. Furthermore, because the printed solder droplets fuse together, freestanding structures with different angles can also be printed via controlling process parameters. In summary, the StarJet technology shows high potential in direct metallization for large area flexible and wearable electronics and 3D electronic applications.
C Pannek, T Vetter, M Oppmann, C Weber, A Eberhardt, M Dold, M-L Bauersfeld, M Henfling, S Trupp, B Schug, J Wöllenstein, K Mandel
Highly sensitive reflection based colorimetric gas sensor to detect CO in realistic fire scenarios
2019 Sensors and Actuators B: Chemical, Band: 306, Seite: 127572
KurzfassungFor early fire detection, the measurement of low and small rising concentrations of the fire typical gas carbon monoxide (CO) is essential. The approach presented herein integrates a highly sensitive colorimetric material into a low cost gas sensor system. The gas sensitive color dye is hosted by silica nanoparticle based supraparticles and then processed to a so-called gas sensor stripe. Changes in the CO concentration enable a change of the sensor stripes color, which is easily detectable as a change of the light that is reflected by the stripe. A diffusion chamber protects the gas sensitive film against harmful environmental influences and interfering light. The capability of the gas sensor system is demonstrated in lab as well as real fire tests. In case of the latter, standardized real fire tests are conducted, as well as realistic mixtures of plastics and wood are smoldered. The developed sensors react in real time to the slowly rising CO concentration during the test fires. Even small amounts of CO (<20 ppm) are reliably detectable.
Kotz F, Risch P, Helmer D, Rapp B
High‐Performance Materials for 3D Printing in Chemical Synthesis Applications
2019 Adv Mater, Band: 0, Seiten: 1 - 7
Kurzfassung3D printing has emerged as an enabling technology for miniaturization. High‐precision printing techniques such as stereolithography are capable of printing microreactors and lab‐on‐a‐chip devices for efficient parallelization of biological and biochemical reactions under reduced uptake of reactants. In the world of chemistry, however, up until now, miniaturization has played a minor role. The chemical and thermal stability of regular 3D printing resins is insufficient for sustaining the harsh conditions of chemical reactions. Novel material formulations that produce highly stable 3D‐printed chips are highly sought for bringing chemistry up‐to‐date on the development of miniaturization. In this work, a brief review of recent developments in highly stable materials for 3D printing is given. This work focuses on three highly stable 3D‐printable material systems: transparent silicate glasses, ceramics, and fluorinated polymers. It is further demonstrated that 3D printing is also a versatile technique for surface structuring of polymers to enhance their wetting performance. Such micro/nanostructuring is key to selectively wetting surface patterns that are versatile for chemical arrays and droplet synthesis. To bridge the gap between miniaturization of chemical reactors and 3D printing, novel high‐performance materials are required which can withstand the harsh conditions during chemical synthesis. Here, recent progress in the development of materials for 3D printing of transparent glass and for 3D printing of transparent glass, ceramics and fluoropolymers is highlighted.
D Groeneveld, H Groß, A-L Hansen, T Dankwort, J Hansen, J Wöllenstein, W Bensch, L Kienle, J König
High‐Pressure Sintering of Rhombohedral Cr2S3 Using TZM Tools
2019 Adv Eng Mater, Band: 21, Nummer: 11, Seite: 1900430
KurzfassungThe influence of sintering parameters on the physical properties and the chemical structure of rhombohedral Cr2S3 (rh‐Cr2S3) was investigated using high pressures and high temperatures. The densification of the powder was performed applying the high‐pressure field‐assisted sintering technique/spark plasma sintering. Using a titanium‐zirconium‐molybdenum (TZM) alloy as sintering tool, it was possible to increase the magnitude of the applied pressure to several hundred MPa at temperatures as high as 1223 K. A relative density of up to 99.9% was achieved at a sintering temperature of 1223 K and a pressure of 395 MPa. The presence of phase‐pure rh‐Cr2S3 is proven by x‐ray diffraction analysis and transmission electron microscopy. The Seebeck coefficients of the self‐doped samples change dramatically with the sintering temperatures ranging between −650 µV K−1 and −350 µV K−1. The densities and the thermal conductivities of the sintered samples increase with increasing sintering temperatures. The electrical conductivity is largely increased compared to the thermal conductivity potentially due to the current‐assisted high‐pressure sintering.
Krämer S, Wöhrle J, Meyer P, Urban G, Roth G
How to copy and paste DNA microarrays
2019 Sci Rep-uk, Band: 9, Seite: 13940
KurzfassungAnalogous to a photocopier, we developed a DNA microarray copy technique and were able to copy patterned original DNA microarrays. With this process the appearance of the copied DNA microarray can also be altered compared to the original by producing copies of different resolutions. As a homage to the very first photocopy made by Chester Charlson and Otto Kornei, we performed a lookalike DNA microarray copy exactly 80 years later. Those copies were also used for label-free real-time kinetic binding assays of apo-dCas9 to double stranded DNA and of thrombin to single stranded DNA. Since each DNA microarray copy was made with only 5 µl of spPCR mix, the whole process is cost-efficient. Hence, our DNA microarray copier has a great potential for becoming a standard lab tool.
Fiederer, L. D., Völker, M., Schirrmeister, R. T., Burgard, W., Boedecker, J., Ball, T.
Hybrid Brain-Computer-Interfacing for Human-Compliant Robots: Inferring Continuous Subjective Ratings with Deep Regression
2019 Front Neurorobotics, Seiten: 13 - 76
Ludmila Cojocaru, Karl Wienands, Ulas Erdil, Patricia SC Schulze, Laura E Mundt, Alexander J Bett, Matthias Breitwieser, Florian Lombeck, Mario Prescher, Lutz Kirste, Severin Vierrath, Jan Christoph Goldschmidt, Stefan W Glunz
Hybrid Evaporation/Spray-Coating Process for a Simplified and Controllable Production of Perovskite Solar Cells
2019 IEEE J Photovolt, Band: 10, Nummer: 1, Seiten: 276 - 286
KurzfassungRecently, hybrid processing using evaporation and spin-coating has been applied for the fabrication of perovskite silicon tandem solar cells with record power conversion efficiencies (PCEs) of 25.2%. To achieve large area, high-throughput production of solar cells, spray-coating, a well-known scalable method used in the industry, has advantages over spin-coating. Therefore, we apply a hybrid method using the evaporation of PbI 2 and spraying of methylammonium iodide (MAI) for the fabrication of perovskite solar cells. This article presents a systematic study of sprayed MAI amount and processing parameters on the performance of solar cells. We find clear correlations between the processing parameters of the sprayed MAI, the crystallinity of CH 3 NH 3 PbI 3 and the PCE of the resulting PSCs. High crystallinity and morphology of the CH 3 NH 3 PbI 3 film is achieved using a slow nozzle speed of 30 mm·s −1 …
Böhm A, Tatarchenko M, Schmidt T.
ISOO_DL^V2 - Semantic Instance Segmentation of Touching and Overlapping Objects
2019 IEEE International Symposium on Biomedical Imaging
KurzfassungWe present ISOO_DL^V2 - a method for semantic instance segmentation of touching and overlapping objects. We introduce a series of design modifications to the prior framework, including a novel mixed 2D-3D segmentation network and a simplified post-processing procedure which enables segmentation of touching objects without relying on object detection. For the case of overlapping objects where detection is required, we upgrade the bounding box parametrization and allow for smaller reference point distances. All these novelties lead to substantial performance improvements and enable the method to deal with a wider range of challenging practical situations. Additionally, our framework can handle object sub-part segmentation. We evaluate our approach on both real-world and synthetically generated biological datasets and report state-of-the-art performance.

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Post Regina, Niewelt Tim, Schön Jonas, Schindler Florian, Schubert Martin
Imaging Interstitial Iron Concentrations in Gallium-Doped Silicon Wafers
2019 physica status solidi (a), Band: 121, Seite: 1800655
KurzfassungIn this work, the established method of iron imaging is transferred from B-doped silicon to Ga-doped material. For this purpose, the pairing and splitting conditions are investigated and a preparation procedure suggested that ensures a sufficient fraction of iron–gallium pairing and splitting, respectively. Furthermore the defect parameters available in literature are compared and evaluated for a suitable description of the injection dependent carrier lifetime measurements. A parameter set that enables a coherent and adequate iron evaluation is suggested. Thus, a robust method for spatially resolved determination of the interstitial iron concentration in Ga-doped silicon wafers is presented.
F. Hegge, J. Sharman, R. Moroni, S. Thiele, R. Zengerle, M. Breitwieser, S. Vierrath
Impact of Carbon Support Corrosion on Performance Losses in Polymer Electrolyte Membrane Fuel Cells
2019 J Electrochem Soc, Band: 166, Seiten: F956 - F962
KurzfassungCorrosion of the carbon support leads to a severe decay in the performance of PEM fuel cells, mainly due to an increase in the oxygen transport resistance. To investigate the effect of degradation on oxygen transport, we cycled MEAs between 1−1.5 V and analyzed the electrode structure with FIB-SEM tomography at various ageing states. The tomography results show that the electrode structure changes over 1000 cycles in terms of thickness (7.8 to 6.5 μm), porosity (44 to 38%) and diffusivity (9 to 8 105 m2s−1). Limiting current measurements in the wet (hydrogen/air) and dry state (hydrogen pumping) allowed the pressure dependent and pressure independent mass transport resistances to be distinguished and to quantify the impact of product water. The pressure independent resistance increased from 24 to 41 sm−1. Considering the marginal contribution of the catalyst pore space resistance (3 to 4 sm−1) it is concluded that the largest portion of the increase (50%) is caused by an increased local mass transport resistance. This is due to a decrease of the electrode roughness factor (282 to 169). The limiting current under wet conditions shows that another 44% could stem from a change in the wetting behavior, while 6% remains unexplained.
Maus S., Lohmüller S., Mu D., Schön J., Niewelt T., Wolf A., Preu R.
Impact of POCl3 Diffusion Process Parameters on Oxygen Precipitation in Czochralski-Grown Silicon
In: 36th EU PVSEC
2019, , Seite: 151–156,
Kurzfassungsiehe pdf!
J-K Boerman, J-K van Harberden, C Pannek, K Schmitt, K Tarantik, M-L Bauersfeld, J. Wöllenstein
Improvement Methods for Colorimetric Gas Sensor for Use in Indoor Livestock Farming
2019 Eurosensors 2018 Multidisciplinary Digital Publishing Institute Proceedings, Band: 2, Nummer: 13, Seite: 769
KurzfassungDifferent published colorimetric sensors were investigated with the ultimate goal to develop a colorimetric sensor for a closed livestock farm, applicable in a rough environment. The methods were investigated to improve the lack of sensitivity, roughness, and reproduction of colorimetric sensors. The methods investigated varied from changing matrices, changing substrates, treatment of the substrates, and investigation of the distribution by camera of the chemical thin layer and investigation on temperature, water and cross interference of several other gases in the livestock gas matrix. Results showed that with changing several important parameters, other than only the choice of a color indicator results in a serious improvement of the sensor specification and an improved performance necessary for the rough circumstances in livestock farming.
F. Hegge, E. Cruz Ortiz, S. Thiele, S. Vierrath
Improving the performance of low loaded PEMWE electrodes
2019 2nd International Conference on Electrolysis (ICE), Loen / Norway, 9. – 13. 06.2019
Chauvière L, Pothof F, Gansel K S, Klon-Lipok J, Aarts A A A, Holzhammer T, Paul O, Singer J W, Ruther P
In vivo recording quality mechanically decoupled floating versus skull-fixed silicon-based neural probes
2019 Front Neurosci-switz, Band: 13
Katalin Fazekas, Armin Biere, Christoph Scholl
Incremental Inprocessing in SAT Solving
2019 10th International Conference on Theory and Applications of Satisfiability Testing (SAT), Springer-Verlag, Nummer: 11628, Seiten: 136 - 154
KurzfassungIncremental SAT is about solving a sequence of related SAT problems efficiently. It makes use of already learned information to avoid repeating redundant work. Also preprocessing and inprocessing are considered to be crucial. Our calculus uses the most general redundancy property and extends existing inprocessing rules to incremental SAT solving. It allows to automatically reverse earlier simplification steps, which are inconsistent with literals in new incrementally added clauses. Our approach to incremental SAT solving not only simplifies the use of inprocessing but also substantially improves solving time.
P. Juelg, M. Specht, M. Meyer, E. Kipf, F. Schlenker, F. Baensch, S. Neumann, F. von Stetten, R. Zengerle, N. Paust, M. Fillies, R. Kirschner-Schwabe, S. Groeneveld-Krentz, M. Lehnert, C. Eckert, T. Hutzenlaub
Individual Response Monitoring Assay (IRMA) – Standardization Of Personalized Multiplex Biomarker Quantification
2019 EACR-ESMO Joint Conference on Liquid Biopsies, Bergamo/Italien, 15. – 17.05. 2019
Graf D, Burchard S, Crespo J, Megnin C, Gutsch S, Zacharias M, Hanemann T
Influence of Al2O3 Nanoparticle Addition on a UV Cured Polyacrylate for 3D Inkjet Printing
2019 Polymers-basel, Band: 11, Seite: 633
KurzfassungThe brittleness of acrylic photopolymers, frequently used in 3D Inkjet printing, limits their utilization in structural applications. In this study, a process was developed for the production and characterization of an alumina-enhanced nanocomposite with improved mechanical properties for Inkjet printing. Ceramic nanoparticles with an average primary particle size (APPS) of 16 nm and 31 nm, which was assessed via high-resolution scanning electron microscopy (HRSEM), were functionalized with 3.43 and 5.59 mg/m² 3-(trimethoxysilyl)propyl methacrylate (MPS), respectively, while being ground in a ball mill. The suspensions of the modified fillers in a newly formulated acrylic mixture showed viscosities of 14 and 7 mPa∙s at the printing temperature of 60 °C. Ink-jetting tests were conducted successfully without clogging the printing nozzles. Tensile tests of casted specimens showed an improvement of the tensile strength and elongation at break in composites filled with 31 nm by 10.7% and 74.9%, respectively, relative to the unfilled polymer.
Graf D, Burchard S, Crespo J, Megnin C, Gutsch G, Zacharias Z, Hanemann T
Influence of Al2O3 Nanoparticle Addition on a UV Cured Polyacrylate for 3D Inkjet Printing
2019 Polymers-basel, Band: 11, Nummer: 4, Seite: 633
KurzfassungThe brittleness of acrylic photopolymers, frequently used in 3D Inkjet printing, limits their utilization in structural applications. In this study, a process was developed for the production and characterization of an alumina-enhanced nanocomposite with improved mechanical properties for Inkjet printing. Ceramic nanoparticles with an average primary particle size (APPS) of 16 nm and 31 nm, which was assessed via high-resolution scanning electron microscopy (HRSEM), were functionalized with 3.43 and 5.59 mg/m² 3-(trimethoxysilyl) propyl methacrylate (MPS), respectively, while being ground in a ball mill. The suspensions of the modified fillers in a newly formulated acrylic mixture showed viscosities of 14 and 7 mPa∙ s at the printing temperature of 60 C. Ink-jetting tests were conducted successfully without clogging the printing nozzles. Tensile tests of casted specimens showed an improvement of the tensile strength and elongation at break in composites filled with 31 nm by 10.7% and 74.9%, respectively, relative to the unfilled polymer.
Messmer Christoph, Bivour Martin, Luderer Christoph, Tutsch Leonard, Schon Jonas, Hermle Martin
Influence of Interfacial Oxides at TCO/Doped Si Thin Film Contacts on the Charge Carrier Transport of Passivating Contacts
2019 IEEE Journal of Photovoltaics, Seite: to be published
Kurzfassungsiehe PDF
Lima F, Mescheder U, Leiste H, Müller C
Influence of current density on the adhesion of seedless electrodeposited copper layers on silicon
2019 Surf Coat Tech, Band: 375, Seiten: 554 - 564
Kuehn J, Jaeger J, Kuhl M, Manoli Y
Informationsverarbeitung mit Maschinellem Lernen für Taktile Sensoren
2019 Proceedings of the Mikrosystemtechnik-Kongress, Seiten: 518 - 521
Okujeni Samora, Egert Ulrich
Inhomogeneities in network structure and excitability govern initiation and propagation of spontaneous burst activity
2019 Frontiers in Neuroscience, Band: 13, Seite: 543
Schube Jörg, Fellmeth Tobias, Jahn Mike, Keding Roman, Glunz Stefan
Inkjet‐ and FlexTrail‐Printing with Low Silver Consumption for Silicon Heterojunction Solar Cells
2019 physica status solidi (RRL) - Rapid Research Letters, Band: 3, Seite: 1900186
KurzfassungBifacial busbarless silicon heterojunction (SHJ) solar cells with an edge length of 156.8mm are metalized using a commercially available Ag nanoparticle ink on the front side. By means of inkjet-printing, a maximum conversion efficiency of 23.3% is achieved. The influence of the inkjet-printed layer number per contact finger, which is varied from one to five, on cell performance is investigated in detail. Optima are found for one and two layers, which ensure both high efficiency and low silver consumption. Furthermore, a novel metallization technology, called FlexTrail-printing, is introduced. Using the same ink as in the case of inkjet-printing, the finger width is reduced from 75 1 to 16 1 μm. This results in an enhanced short-circuit current density and, therefore, a maximum conversion efficiency of 23.7%. Only 0.3 0.1 mg Ag nanoparticle ink (deposited at 25 C substrate temperature) is consumed during FlexTrail-printing on a large-area wafer (area of 244.3 cm2) with a front grid of 80 fingers.
H.G.B. Gowda, U. Wallrabe
Integrated Sensor System to Control the Temperature Effects and the Hysteresis on Adaptive Fluid-membrane Piezoelectric lenses
2019 ISOT 2019, 20th Int. Symposium of Optomechatronics Technology, Goa, India
Clemente F, Valle G, Controzzi M, Strauss I, Iberite F, Stieglitz T, Granata G, Rossini PM, Petrini FM, Micera S, Cipriani C
Intraneural sensory feedback restores grip force control and motor coordination while using a prosthetic hand.
2019 J Neural Eng, Band: 16, Nummer: 2
KurzfassungObjective. Tactile afferents in the human hand provide fundamental information about hand-environment interactions, which is used by the brain to adapt the motor output to the physical properties of the object being manipulated. A hand amputation disrupts both afferent and efferent pathways from/to the hand, completely invalidating the individual's motor repertoire. Although motor functions may be partially recovered by using a myoelectric prosthesis, providing functionally effective sensory feedback to users of prosthetics is a largely unsolved challenge. While past studies using invasive stimulation suggested that sensory feedback may help in handling fragile objects, none explored the underpinning, relearned, motor coordination during grasping. In this study, we aimed at showing for the first time that intraneural sensory feedback of the grip force improves the sensorimotor control of a transradial amputee controlling a myoelectric prosthesis. Approach. We performed a longitudinal study testing a single subject (clinical trial registration number NCT02848846). A stacking cups test (CUP) performed over two weeks aimed at measuring the subject's ability to finely regulate the grip force applied with the prosthesis. A pick and lift test (PLT), performed at the end of the study, measured the level of motor coordination, and whether the subject transferred the motor skills learned in the CUP to an alien task. Main results. The results show that intraneural sensory feedback increases the subject's ability in regulating the grip force and allows for improved performance over time. Additionally, the PLT demonstrated that the subject was able to generalize and transfer her manipulation skills to an unknown task and to improve her motor coordination. Significance. Our findings suggest that intraneural sensory feedback holds the potential of restoring functionally effective tactile feedback. This opens up new possibilities to improve the quality of life of amputees using a neural prosthesis.
B Bierer, P Kress, H‐J Nägele, A Lemmer, S Palzer
Investigating flexible feeding effects on the biogas quality in full‐scale anaerobic digestion by high resolution, photoacoustic‐based NDIR sensing
2019 Eng Life Sci, Band: Wiley Online Library
KurzfassungIn future energy systems based on renewable energies, biogas plants can make a significant contribution to stabilizing the electricity grids. However, this requires load‐flexible and demand‐oriented electricity production by means of flexible feed management. However, these flexible feeding strategies using greatly oscillating, temporally varying high mass loads may lead to critical process failures of the anaerobic digestion process. Currently there is no online, high resolution gas quality measurement technique to detect and prevent biological process failures available. In this contribution, we present a miniaturized, low‐cost biogas quality measurement system providing data with high precision and high temporal resolution to overcome this technology gap. To highlight the capabilities of the system we have installed it using a bypass to the main biogas duct after hydrogen sulfide removal at a full‐scale research biogas plant. During a three‐month field trial the effect of flexible feeding on the biogas quality has been monitored. The results demonstrate long‐term stability of the sensor solution and reveal the effects of changing feeding frequency and composition on gas quantity and quality, which cannot be detected with commercially available state‐of‐the‐art sensing systems.
Tülümen M, Hanemann T, Piotter V, Stenzel D
Investigation of Feedstock Preparation for Injection Molding of Oxide–Oxide Ceramic Composites
2019 Journal of Manufacturing and Materials Processing, Band: 3, Nummer: 1, Seite: 324
Erhardt JB, Lottner T, Martinez J, Ozen AC, Schuettler M, Stieglitz T, Ennis DB, Bock M
It's the little things: On the complexity of planar electrode heating in MRI.
2019 Neuroimage, Band: 195, Seiten: 272 - 284
KurzfassungNeurological disorders are increasingly analysed and treated with implantable electrodes, and patients with such electrodes are studied with MRI despite the risk of radio-frequency (RF) induced heating during the MRI exam. Recent clinical research suggests that electrodes with smaller diameters of the electrical interface between implant and tissue are beneficial; however, the influence of this electrode contact diameter on RF-induced heating has not been investigated. In this work, electrode contact diameters between 0.3 and 4 mm of implantable electrodes appropriate for stimulation and electrocorticography were evaluated in a 1.5 T MRI system. In situ temperature measurements adapted from the ASTM standard test method were performed and complemented by simulations of the specific absorption rate (SAR) to assess local SAR values, temperature increase and the distribution of dissipated power. Measurements showed temperature changes between 0.8 K and 53 K for different electrode contact diameters, which is well above the legal limit of 1 K. Systematic errors in the temperature measurements are to be expected, as the temperature sensors may disturb the heating pattern near small electrodes. Compared to large electrodes, simulations suggest that small electrodes are subject to less dissipated power, but more localized power density. Thus, smaller electrodes might be classified as safe in current certification procedures but may be more likely to burn adjacent tissue. To assess these local heating phenomena, smaller temperature sensors or new non-invasive temperature sensing methods are needed.
Nessler S, Kartmann S, Mutter L, Grandauer C, Marx M, Manoli Y
Kapazitive Ausleseschaltung fuer einen Einweg-Druck und Flusssensor fuer medizinische Anwendungen
2019 Proceedings of the Mikrosystemtechnik-Kongress, Seiten: 614 - 617
S. Burger, L. Drechsel, A. Homann, F. von Stetten, R. Zengerle, N. Paust
LabSlice XL – A centrifugal microfluidic cartridge for the automated bio-chemical processing of industrial process water
2019 Transducers, Berlin, 23. - 27. 06. 2019
Runge Frederic, Stoll Danny, Falkner Stefan, Hutter Frank
Learning to Design RNA
2019 International Conference on Learning Representations
Meinert T, Rohrbach A
Light-sheet microscopy with length-adaptive Bessel beams
2019 Biomed Opt Express, Band: 10, Nummer: 2, Seiten: 670 - 681

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Schubert Martin, Schindler Florian, Schön Jonas, Kwapil Wolfram, Benick Jan, MüCller Ralph, Heinz Friedemann, Fell Andreas, Riepe Stephan, Morishige Ashley
Limiting defects in n‐type multicrystalline silicon solar cells
2019 physica status solidi (a)
KurzfassungMulticrystalline solar cells made from n‐type silicon feedstock have shown record efficiencies of 22.3% in a TOPCon cell structure. Still, material related carrier recombination limits the attainable efficiency. In this article, we summarize findings of metallic impurity and structural defect concentration present in n‐type mc silicon and elaborate on their limiting properties on carrier lifetime and cell performance. Applying a dedicated model for carrier recombination at precipitate‐silicon interfaces it is demonstrated that carrier recombination at metallic precipitates may dominate in the analyzed material. Direct evidence of the recombination activity of iron precipitates in n‐type silicon is given by an analysis of intentionally grown iron precipitates: From a comparison of μXRF analyses of differently sized iron precipitates and local carrier recombination from μPL a direct correlation to enhanced carrier recombination is found. From these results, it is concluded that high‐performance n‐type mc silicon is limited by recombination at (decorated) structural defects namely dislocation clusters and grain boundaries whereas defects in the inner grains are not limiting the efficiency potential. Finally, cell degradation under illumination and elevated temperature for n‐type multicrystalline silicon solar cells are discussed.
S Dalvi, A Gujrati, SR Khanal, L Pastewka, A Dhinojwala, TDB Jacobs
Linking energy loss in soft adhesion to surface roughness
2019 P Natl Acad Sci Usa
KurzfassungA mechanistic understanding of adhesion in soft materials is critical in the fields of transportation (tires, gaskets, and seals), biomaterials, microcontact printing, and soft robotics. Measurements have long demonstrated that the apparent work of adhesion coming into contact is consistently lower than the intrinsic work of adhesion for the materials, and that there is adhesion hysteresis during separation, commonly explained by viscoelastic dissipation. Still lacking is a quantitative experimentally validated link between adhesion and measured topography. Here, we used in situ measurements of contact size to investigate the adhesion behavior of soft elastic polydimethylsiloxane hemispheres (modulus ranging from 0.7 to 10 MPa) on 4 different polycrystalline diamond substrates with topography characterized across 8 orders of magnitude, including down to the angstrom scale. The results show that the reduction in apparent work of adhesion is equal to the energy required to achieve conformal contact. Further, the energy loss during contact and removal is equal to the product of the intrinsic work of adhesion and the true contact area. These findings provide a simple mechanism to quantitatively link the widely observed adhesion hysteresis to roughness rather than viscoelastic dissipation.
M. Solihul Mu’min, T. Böhm, R. Moroni, R. Zengerle, S. Thiele, S. Vierrath, M. Breitwieser
Local hydration in ionomer composite membranes determined with confocal Raman microscopy
2019 Journal of Membrane Science, Band: 585, Seiten: 126 - 135
KurzfassungWater management in electrochemical energy applications like fuel cells has a crucial impact on performance, in particular on the ionic conduction of ionomer membranes. To strengthen the understanding of water management in such devices, we report a novel method for non-destructive measurements of the hydration of composite membranes based on confocal Raman microscopy. Composite membranes were produced by spray-coating of Nafion into a mesh of electrospun poly(vinylidene fluoride-co-hexafluoropropylene)/polyvinylpyrrolidone (PVDF-HFP/PVP) blend nanofibers. Hydration levels of several pure nanofiber meshes and nanofiber/Nafion composites were evaluated by linear least squares fitting of reference Raman spectra to hyperspectral images. We found that spectral contribution of water to nanofiber spectra depends on the PVDF-HFP/PVP ratio and is independent from fiber diameter. Further, we were able to reliably determine nanofiber polymer composition of single fibers based on Raman spectroscopy. Raman imaging of composite membranes was performed at ambient air and fully hydrated conditions to study the local hydration in PVDF-HFP/PVP/Nafion composites as well as in a Nafion XL membrane. 2D through-plane mappings revealed that the nanofiber hydration positively correlated with PVP content. In the Nafion XL membrane, the polytetrafluoroethylene-based reinforcement was verified as a hydrophobic layer sandwiched between Nafion ionomer, which showed a more than 10% reduced hydration compared to the outer Nafion layers. These results motivate the use of confocal Raman microscopy as a novel method to investigate the local water distribution in ionomer composite membranes that are widely used in electrochemical energy conversion.
Aile Ge-Ernst, Christoph Scholl, Ralf Wimmer
Localizing Quantifiers for DQBF
2019 Proceedings of the Conference on Formal Methods in Computer Aided Design (FMCAD), IEEE Computer Society Press
KurzfassungDependency quantified Boolean formulas (DQBFs)are a powerful formalism, which subsumes quantified Boolean formulas (QBFs) and allows an explicit specification of dependencies of existential variables on universal variables. Driven by the needs of various applications that can be encoded by DQBFs in a natural, compact, and elegant way, research on DQBF solving has emerged in the past few years. However, most works focus on closed DQBFs in prenex form (where all quantifiers are placed in front of a propositional formula), and non-prenex DQBFs have almost not been studied in the literature. In this paper we provide a formal definition for syntax and semantics of non-closed non-prenex DQBFs and prove useful properties enabling quantifier localization. Moreover, we make use of our theory by integrating quantifier localization into a state-of-the art DQBF solver. Experiments with prenex DQBF benchmarks, including those from the QBFEVAL’18 competition, clearly show that quantifier localization pays off in this context.
Aile Ge-Ernst, Christoph Scholl, Ralf Wimmer
Localizing Quantifiers for DQBF
2019 Proceedings of the 2019 Conference on Formal Methods in Computer Aided Design (FMCAD), Clark W. Barrett, Jin Yang
KurzfassungDependency quantified Boolean formulas (DQBFs) are a powerful formalism, which subsumes quantified Boolean formulas (QBFs) and allows an explicit specification of dependencies of existential variables on universal variables. Driven by the needs of various applications that can be encoded by DQBFs in a natural, compact, and elegant way, research on DQBF solving has emerged in the past few years. However, most works focus on closed DQBFs in prenex form (where all quantifiers are placed in front of a propositional formula), and non-prenex DQBFs have almost not been studied in the literature. In this paper we provide a formal definition for syntax and semantics of non-closed non-prenex DQBFs and prove useful properties enabling quantifier localization. Moreover, we make use of our theory by integrating quantifier localization into a state-of-the- art DQBF solver. Experiments with prenex DQBF benchmarks, including those from the QBFEVAL'18 competition, clearly show that quantifier localization pays off in this context.
de la Oliva N, Del Valle J, Delgado-Martinez I, Mueller M, Stieglitz T, Navarro X
Long-Term Functionality of Transversal Intraneural Electrodes Is Improved By Dexamethasone Treatment.
2019 Ieee T Neur Sys Reh, Band: 27, Nummer: 3, Seiten: 457 - 464
KurzfassungNeuroprostheses aimed to restore lost functions after a limb amputation are based on the interaction with the nervous system by means of neural interfaces. Among the different designs, intraneural electrodes implanted in peripheral nerves represent a good strategy to stimulate nerve fibers to send sensory feedback and to record nerve signals to control the prosthetic limb. However, intraneural electrodes, as any device implanted in the body, induce a foreign body reaction (FBR) that results in the tissue encapsulation of the device. The FBR causes a progressive decline of the electrode functionality over time due to the physical separation between the electrode active sites and the axons to interface. Modulation of the inflammatory response has arisen as a good strategy to reduce the FBR and maintain electrode functionality. In this study transversal intraneural multi-channel electrodes (TIMEs) were implanted in the rat sciatic nerve and tested for 3 months to evaluate stimulation and recording capabilities under chronic administration of dexamethasone. Dexamethasone treatment significantly reduced the threshold for evoking muscle responses during the follow-up compared to saline-treated animals, without affecting the selectivity of stimulation. However, dexamethasone treatment did not improve the signal-to-noise ratio of the recorded neural signals. Dexamethasone treatment allowed to maintain more working active sites along time than saline treatment. Thus, systemic administration of dexamethasone appears as a useful treatment in chronically implanted animals with neural electrodes as it increases the number of functioning contacts of the implanted TIME and reduces the intensity needed to stimulate the nerve.
Lucija Rakocevic, Laura E Mundt, Robert Gehlhaar, Tamara Merckx, Tom Aernouts, Martin C Schubert, Stefan W Glunz, Jef Poortmans
Loss Analysis in Perovskite Photovoltaic Modules
2019 Solar RRL, Band: 3, Nummer: 12
Taschwer A, Butz N, Koehler M, Rossbach D, Manoli Y
Low-Power Neurostimulator ASIC mit frei konfigurierbarer Pulsform
2019 Proceedings of the Mikrosystemtechnik-Kongress, Seiten: 213 - 214
Wang Z, Hofmann A, Hanemann T
Low-flammable electrolytes with fluoroethylene carbonate based solvent mixtures and lithium bis(trifluoromethanesulfonyl)imide for lithium-ion batteries
2019 Electrochim Acta, Band: 298, Seiten: 960 - 972
U. Karakus, T. Thamamongood, K. Ciminski, W. Ran, S. C. Günther, M. O. Pohl, D. Eletto, C. Jeney, D. Hoffmann, S. Reiche, J. Schinköthe, R. Ulrich, J. Wiener, M. G. B. Hayes, M. W. Chang, A. Hunziker, E. Yángüez, T. Aydillo, F. Krammer, J. Oderbolz, M. Meier, A. Oxenius, A. Halenius, G. Zimmer, C. Benner, B. G. Hale, A. García-Sastre, M. Beer, M. Schwemmle, S. Stertz
MHC class II proteins mediate cross-species entry of bat influenza viruses
2019 Nature, Band: 567, Seiten: 109 - 112
KurzfassungZoonotic influenza A viruses of avian origin can cause severe disease in individuals, or even global pandemics, and thus pose a threat to human populations. Waterfowl and shorebirds are believed to be the reservoir for all influenza A viruses, but this has recently been challenged by the identification of novel influenza A viruses in bats1,2. The major bat influenza A virus envelope glycoprotein, haemagglutinin, does not bind the canonical influenza A virus receptor, sialic acid or any other glycan1,3,4, despite its high sequence and structural homology with conventional haemagglutinins. This functionally uncharacterized plasticity of the bat influenza A virus haemagglutinin means the tropism and zoonotic potential of these viruses has not been fully determined. Here we show, using transcriptomic profiling of susceptible versus non-susceptible cells in combination with genome-wide CRISPR–Cas9 screening, that the major histocompatibility complex class II (MHC-II) human leukocyte antigen DR isotype (HLA-DR) is an essential entry determinant for bat influenza A viruses. Genetic ablation of the HLA-DR α-chain rendered cells resistant to infection by bat influenza A virus, whereas ectopic expression of the HLA-DR complex in non-susceptible cells conferred susceptibility. Expression of MHC-II from different bat species, pigs, mice or chickens also conferred susceptibility to infection. Notably, the infection of mice with bat influenza A virus resulted in robust virus replication in the upper respiratory tract, whereas mice deficient for MHC-II were resistant. Collectively, our data identify MHC-II as a crucial entry mediator for bat influenza A viruses in multiple species, which permits a broad vertebrate tropism.
Feißt M, Li C, Wilde J
Material Model and Simulation of Multilayer-AgSn-Foils for Transient-Liquid-Phase Bonding of Sensor Elements
2019 20th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems (EuroSimE), Hannover, pp.1-6
Rohrbach A, Meyer T, Kress H
Measuring stepwise binding of a thermally fluctuating particle to a cell membrane without labeling
2019 submitted
A. Müller, M.C. Wapler, U. Wallrabe
Micro-optical System for depth-controlled Bessel beam arrays
2019 Int. Conference on Optical MEMS and Nanophotonics, Daejeon, Korea , Seiten: 184 - 185
Bruch R, Baaske J, Chatelle C, Weber W, Urban G, Dincer C
MicroRNA diagnostics on an electrochemical biosensor via CRISPR/Cas13a technology
2019 MicroTAS 2019, Basel, Switzerland
M. Specht, J. Schemberg, T. Förster, S. Burger, M. Rombach, N. Paust, R. Zengerle, F. von Stetten, G. Gastrock, M. Karle
Microfluidic App for centrifugal separation and purification of lymphatic cancer cells from whole blood
2019 MST-Kongress, 28. - 30.Oktober 2019, Berlin
Takeuchi K, Takama N, Kim B, Sharma K, Paul O, Ruther P
Microfluidic chip to interface porous microneedles for ISF collection
2019 Biomed Microdevices, Band: 21, Nummer: 28
C Weber, M El-Safoury, A Eberhardt, K Schmitt, J Wöllenstein
Miniaturisierte photoakustische Detektoren für den Nachweis fluorhaltiger Kältemittel
2019 20. GMA/ITG-Fachtagung Sensoren und Messsysteme, Nürnberg, Germany , Seiten: 322 - 327
KurzfassungDurch die Umstellung auf klimafreundliche Kältemittel im KFZ-Bereich, kam es in den letzten Jahren zu einer wachsenden Nachfrage nach Messtechnik für diese Kältemittel. Wir präsentieren im Folgenden unsere Arbeiten an photoakustischen Detektoren für die flourhaltigen Kältemittel R123a und R1234yf. Durch Simulationen konnten die Detektordimensionen optimal für beide Kältemittel ausgelegt und somit zuverlässige und empfindliche Detektorelemente geschaffen werden. Das in ersten Versuchen bestimmte Signal-zu-Rausch-Verhältnis reicht aus, um das Kältemittel R1234yf mit einer Auflösung 0,5 vol.% über den gesamten Konzentrationsbereich zuverlässig bestimmen zu können.
F. Lemke, P.M. Weber, U. Wallrabe, M.C. Wapler
Miniaturized piezo-actuated adaptive prism for biaxial optical scanning
2019 Int. Conference on Optical MEMS and Nanophotonics 2019, Daejeon, Korea , Seiten: 222 - 223
S. Hin, N. Paust, M. Rombach, J. Lueddecke, M. Specht, R. Zengerle, K. Mitsakakis
Minimizing ethanol carry-over in centrifugal microfluidic nucleic acid extraction by advanced bead handling and management of diffusive mass transfer
2019 Transducers 2019 - EUROSENSORS XXXIII, 23.-27. Juni 2019 - Berlin, Germany
KurzfassungWe present three concepts for centrifugal microfluidics reducing ethanol carry-over in magnetic bead-based nucleic acid (NA) extraction. Ethanol carry-over is critical regarding inhibition of downstream NA amplification. We identified two possible carry-over pathways: Liquid co-transport within bead-clusters and vapor diffusion. For the first time, we integrated magnetic bead handling in centrifugal microfluidics at continuous rotation aiming to avoid liquid co-transport within bead-clusters. Consequently, no significant contribution to ethanol carry-over could be assigned anymore to liquid cotransport. Major carry-over was attributed to diffusive transport of ethanol vapor. Countermeasures reduced this from 9.7 % (v/v) to 0.4 % (v/v), below the critical level for inhibition of downstream amplification reactions.
T Hess, LM Maier, P Corhan, O Schäfer-Welsen, J Wöllenstein, K Bartholomé
Modelling cascaded caloric refrigeration systems that are based on thermal diodes or switches
2019 Int J Refrig, Band: 103, Seiten: 2015 - 222
KurzfassungSolid state cooling based on caloric materials has a large potential, because there is no need for fluid refrigerants. The state of the art system approach relies on a heat transfer fluid, which is pumped back and forth through a regenerator of caloric material. This system approach has fundamental limitations regarding the cycle frequency. Different system approaches are considered. One is the utilization of fast thermal diodes or switches. The aim of this work is to provide a universal model to describe a cooling system based on caloric materials using thermal diodes or switches. The heat capacitance of the caloric material is defined to be constant, allowing a lumped elements representation. An analytical model based on an analogy to an electrical low pass filter is introduced. The analytical model is compared with good agreement to lumped elements simulations and measurement data from the literature. It is shown, that the newly introduced cut-off frequency as merit for the potential cycle frequency is proportional to the heat transfer coefficient of the diodes/switches in flux direction and inverse proportional to the length scale of the caloric material in heat flux direction. Different heat transfer mechanisms are discussed as basis for such thermal diodes and switches in combination with different caloric effects. To increase the cycle frequency compared to state of the art systems, latent heat transfer is a promising candidate for all caloric effects, whereas for example a dry press contact for a magnetocaloric system presents many challenges.
Seifaei M, Schillinger D, Kuhl M, Keller M, Zschieschang U, Klauk H, Manoli Y
Modified Bootstrap Switching Scheme for Organic Digital Integrated Circuits
2019 IEEE Solid-State Circuits Letters (SSC-L), Band: 2, Nummer: 10, Seiten: 219 - 222
P. Holzapfel, M. Bühler, C. Pham, S. Thiele
Molybdenum sulphide based cathodes for PEM water electrolysis – catalyst synthesis and loading variation
2019 EFCD Conference 15.-18. September 2019, La Grande Motte, France
Bett Alexander, Schulze Patricia, Winkler Kristina, Kabakli Özde, Bivour Martin, Cojocaru Ludmila, Ketterer Ines, Mundt Laura, Tutsch Leonard, Hermle Martin, Glunz Stefan, Goldschmidt Jan, Kamat Prashant, Angelis Filippo, Di Carlo Aldo
Monolithic perovskite silicon tandem solar cells with high-bandgap perovskite absorber exceeding 1.8 V open-circuit voltage
In: Proceedings of the 11th International Conference on Hybrid and Organic Photovoltaics
2019, Fundació Scito, Fundació Scito,
Margret Keuper,, S. Tang,, B. Andres,, Thomas Brox,, B. Schiele
Motion segmentation and multiple object tracking by correlation co-clustering
2019 IEEE T Pattern Anal
KurzfassungModels for computer vision are commonly defined either w.r.t. low-level concepts such as pixels that are to be grouped, or w.r.t. high-level concepts such as semantic objects that are to be detected and tracked. Combining bottom-up grouping with top-down detection and tracking, although highly desirable, is a challenging problem. We state this joint problem as a co-clustering problem that is principled and tractable by existing algorithms. We demonstrate the effectiveness of this approach by combining bottom-up motion segmentation by grouping of point trajectories with high-level multiple object tracking by clustering of bounding boxes. We show that solving the joint problem is beneficial at the low-level, in terms of the FBMS59 motion segmentation benchmark, and at the high-level, in terms of the Multiple Object Tracking benchmarks MOT15, MOT16 and the MOT17 challenge, and is state-of-the-art in some metrics.
Mohamed Abou-Hussein, Stefan H. Müller, Joschka Boedecker
Multimodal Spatio-Temporal Information in End-to-End Networks for Automotive Steering Prediction
2019 International Conference on Robotics and Automation
Ying Chris, Klein Aaron, Real Esteban, Christiansen Eric, Murphy Kevin, Hutter Frank
Nas-bench-101: Towards reproducible neural architecture search
2019 Thirty-sixth International Conference on Machine Learning
Springer
Networked Systems- 6th International Conference, Netys 2018
ISBN: 9783030055288
Podelski
Elsken Thomas, Metzen Jan, Hutter Frank
Neural Architecture Search: A Survey
2019 Journal of Machine Learning Research, Band: 20, Nummer: 55, Seiten: 1 - 21
Claret CR, Herget GW, Kouba L, Wiest D, Adler J, von Tscharner V, Stieglitz T, Pasluosta C
Neuromuscular adaptations and sensorimotor integration following a unilateral transfemoral amputation.
2019 J Neuroeng Rehabil, Band: 16, Nummer: 1, Seiten: 115 - 115
KurzfassungBackground: Following an amputation, the human postural control system develops neuromuscular adaptations to regain an effective postural control. We investigated the compensatory mechanisms behind these adaptations and how sensorimotor integration is affected after a lower-limb transfemoral amputation. METHODS: Center of pressure (CoP) data of 12 unilateral transfemoral amputees and 12 age-matched able-bodied subjects were recorded during quiet standing with eyes open (EO) and closed (EC). CoP adjustments under each leg were recorded to study their contribution to posture control. The spatial structure of the CoP displacements was characterized by measuring the mean distance, the mean velocity of the CoP adjustments, and the sway area. The Entropic Half-Life (EnHL) quantifies the temporal structure of the CoP adjustments and was used to infer disrupted sensory feedback loops in amputees. We expanded the analysis with measures of weight-bearing imbalance and asymmetry, and with two standardized balance assessments, the Berg Balance Scale (BBS) and Timed Up-and-Go (TUG). RESULTS: There was no difference in the EnHL values of amputees and controls when combining the contributions of both limbs (p = 0.754). However, amputees presented significant differences between the EnHL values of the intact and prosthetic limb (p < 0.001). Suppressing vision reduced the EnHL values of the intact (p = 0.001) and both legs (p = 0.028), but not in controls. Vision feedback in amputees also had a significant effect (increase) on the mean CoP distance (p < 0.001), CoP velocity (p < 0.001) and sway area (p = 0.007). Amputees presented an asymmetrical stance. The EnHL values of the intact limb in amputees were positively correlated to the BBS scores (EO: ρ = 0.43, EC: ρ = 0.44) and negatively correlated to the TUG times (EO: ρ = - 0.59, EC: ρ = - 0.69). CONCLUSION: These results suggest that besides the asymmetry in load distribution, there exist neuromuscular adaptations after an amputation, possibly related to the loss of sensory feedback and an altered sensorimotor integration. The EnHL values suggest that the somatosensory system predominates in the control of the intact leg. Further, suppressing the visual system caused instability in amputees, but had a minimal impact on the CoP dynamics of controls. These findings points toward the importance of providing somatosensory feedback in lower-limb prosthesis to reestablish a normal postural control.
H Gao, X Lyu, K Schmitt, J Wöllenstein, K Tarantik
Niedertemperatur-Pellistoren aus mesoporösem Au-Pd@ Co3O4
2019 20. GMA/ITG-Fachtagung Sensoren und Messsysteme, Nürnberg, Germany , Seiten: 498 - 503
KurzfassungDurch die Verwendung von mesoporösem Co3O4 als Trägermaterial für einen bimetallischen Au-Pd-Katalysator wird die Arbeitstemperatur von sogenannten Pellistoren für den Methannachweis von ca. 450 °C bei herkömmlichen Al2O3-Sensoren mit Pd-Katalysator auf 300 °C reduziert. Hierdurch werden die möglichen Vergiftungen der verwendeten Katalysatoren bei höheren Temperaturen, die bei herkömmlichen Pellistoren inhärent sind, verringert. Die erzielten Ergebnisse zeigen, dass mesoporöses Co3O4 vorteilhaft gegenüber kommerziell erhältlichem polykristallinem Co3O4 in Bezug auf die katalytische Umsetzung ist. Die Au-Pd-Bedeckung des Co3O4 beeinflusst das Verhalten des Sensors. Außerdem hat die Anzahl der mit einer Mikropipette (0,2 μL/Schicht) aufgebrachten Schichten Einfluss auf das Pellistorsignal. Die Entwicklung bimetallischer katalytischer Nanomaterialien auf Spinell-basierten Trägern für den Niedertemperaturnachweis brennbarer Gase verbessert den Explosionsschutz entscheidend, verringert die Heizleistungsaufnahme und des Katalysators durch Silane.
F. Lemke, Y. Frey, B.P. Bruno, K. Philipp, N. Koukourakis, J. Czarske, U. Wallrabe, M.C. Wapler
Non-linear simulation of the aspherical deformation of piezo-glass membrane lenses including hysteresis and fabrication effects
2019 Smart Mater Struct, Band: 28, Ergänzungsband: 055024, Seite: 13pp
Peter Ochs,, J. Fadili,, Thomas Brox
Non-smooth non-convex Bregman minimization: unification and new algorithms
2019 J Optimiz Theory App
KurzfassungWe propose a unifying algorithm for non-smooth non-convex optimization. The algorithm approximates the objective function by a convex model function and finds an approximate (Bregman) proximal point of the convex model. This approximate minimizer of the model function yields a descent direction, along which the next iterate is found. Complemented with an Armijo-like line search strategy, we obtain a flexible algorithm for which we prove (subsequential) convergence to a stationary point under weak assumptions on the growth of the model function error. Special instances of the algorithm with a Euclidean distance function are, for example, Gradient Descent, Forward{Backward Splitting, ProxDescent, without the common requirement of a \Lipschitz continuous gradient". In addition, we consider a broad class of Bregman distance functions (generated by Legendre functions), replacing the Euclidean distance. The algorithm has a wide range of applications including many linear and non-linear inverse problems in signal/image processing and machine learning.
Benjamin Thiemann, Linus Feiten, Pascal Raiola, Bernd Becker, Matthias Sauer
On Integrating Lightweight Encryption in Reconfigurable Scan Networks
2019 To appear in IEEE European Test Symposium
KurzfassungReconfigurable Scan Networks (RSNs) are a powerful tool for testing and maintenance of embedded systems, since they allow for flexible access to on-chip instrumentation such as built-in self-test and debug modules. The deployment of RSNs, however, can be exploited by malicious users as a side-channel in order to gain information about sensitive data or intellectual property and to recover secret keys. Hence, implementing appropriate countermeasures to secure the access to and data integrity of embedded instrumentation is of high importance. In this paper we present a novel hardware and software combined approach to ensure data privacy in IEEE Std 1687 (IJTAG) RSNs. To do so, both a secure IJTAG compliant plug-and-play instrument wrapper and a versatile software toolchain are introduced. The wrapper demonstrates the necessary architectural adaptations required when using a lightweight stream cipher, whereas the software toolchain provides a seamless integration of the testing workflow with stream cipher. The applicability of the method is demonstrated by an FPGA-based implementation. We report on the performance of the developed instrument wrapper, which is empirically shown to have only a small impact on the workflow in terms of hardware overhead, operational costs and test time overhead.
Pascal Raiola, Benjamin Thiemann, Jan Burchard, Ahmed Atteya, Natalia Kapstova, Hans-Joachim Wunderlich, Bernd Becker, Matthias Sauer
On Secure Data Flow in Reconfigurable Scan Networks
2019 To appear in Conf. on Design, Automation and Test in Europe
S. Bär, T. Oerther, M. Weigel, A. Müller, P. Hucker, J.G. Korvink, C. Ko, M.C. Wapler, J. Leupold
On the application of balanced steady-state free precession to MR Microscopy
2019 Magn Reson Mater Phy
Weidlich A, Zaidi A
Operational Flexibility of Small-Scale Electricity-Coupled Heat Generating Units
2019 Technology and Economics of Smart Grids and Sustainable Energy, Band: 4, Nummer: 8, Seiten: 1 - 16
KurzfassungHeat generation that is coupled with electricity usage, like combined heat and power generators or heat pumps, can provide operational flexibility to the electricity sector. In order to make use of this in an optimized way, the flexibility that can be provided by such plants needs to be properly quantified. This paper proposes a method for quantifying the flexibility provided through a cluster of such heat generators. It takes into account minimum operational time and minimum down-time of heat generating units. Flexibility is defined here as the time period over which plant operation can be either delayed or forced into operation, thus providing upward or downward regulation to the power system on demand. Results for one case study show that a cluster of several smaller heat generation units does not provide much more delayed operation flexibility than one large unit with the same power, while it more than doubles the forced operation flexibility. Considering minimum operational time and minimum down-time of the units considerably limits the available forced and delayed operation flexibility, especially in the case of one large unit.

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Risso G, Valle G, Iberite F, Strauss I, Stieglitz T, Controzzi M, Clemente F, Granata G, Rossini PM, Micera S, Baud-Bovy G
Optimal integration of intraneural somatosensory feedback with visual information: a single-case study.
2019 Sci Rep-uk, Band: 9, Nummer: 1, Seiten: 7916 - 7916
KurzfassungProviding somatosensory feedback to amputees is a long-standing objective in prosthesis research. Recently, implantable neural interfaces have yielded promising results in this direction. There is now considerable evidence that the nervous system integrates redundant signals optimally, weighting each signal according to its reliability. One question of interest is whether artificial sensory feedback is combined with other sensory information in a natural manner. In this single-case study, we show that an amputee with a bidirectional prosthesis integrated artificial somatosensory feedback and blurred visual information in a statistically optimal fashion when estimating the size of a hand-held object. The patient controlled the opening and closing of the prosthetic hand through surface electromyography, and received intraneural stimulation proportional to the object’s size in the ulnar nerve when closing the robotic hand on the object. The intraneural stimulation elicited a vibration sensation in the phantom hand that substituted the missing haptic feedback. This result indicates that sensory substitution based on intraneural feedback can be integrated with visual feedback and make way for a promising method to investigate multimodal integration processes.
M. Bühler, P. Holzapfel, F. Hegge, M. Bierling, S. Vierrath, S. Thiele
Optimization of porous transport electrodes for PEM water electrolysis
2019 J Mater Chem A, Band: 165, Seite: F305
KurzfassungIn this study we investigate the potential of porous transport electrode (PTE) based membrane electrode assemblies (MEAs) for proton exchange membrane water electrolysis. The focus is on the overpotential determining anodic PTE for the oxygen evolution reaction. The influences of catalyst loading, ionomer content and porous titanium substrate on the polarization behavior are analyzed. The comparison of a porous fiber-sintered substrate with a powder-sintered substrate shows no significant differences in the kinetic and mass transport regions. Ohmic losses, however, are lower for fiber PTEs above a catalyst loading of 1.0 mgIrO2 cm−2. Variations of the Nafion content in the catalyst layer reveal changes of mass transport and ohmic losses and have an influence on the reproducibility. Varying the noble metal loading and therefore the thickness of the applied catalyst layer influences the kinetic region and ohmic resistance of the MEAs. The best compromise between reproducibility and performance is found for a loading of 1.4 mgIrO2 cm−2 and 9 wt% Nafion. The stable operation of the aforementioned PTE is shown in a 200 h durability test at 2 A cm−2.
Rajaeipour P, Banerjee K, Zappe H, Ataman C
Optimization-based open-loop control of phase modulators for adaptive optics
2019 SPIE BiOS, 2019, San Francisco, California, United States , Band: 10886
Rajaeipour P, Banerjee K, Zappe H, Ataman C
Optimization-based real-time open-loop control of an optofluidic refractive phase modulator
2019 Appl Optics, Band: 58, Nummer: 4, Seiten: 1064 - 1072
Makansi O., Ilg E., Çiçek Ö, Brox T.
Overcoming Limitations of Mixture Density Networks: A Sampling and Fitting Framework for Multimodal Future Prediction
2019 CVPR 2019 IEEE T Vis Comput Gr
KurzfassungFuture prediction is a fundamental principle of intelligence that helps plan actions and avoid possible dangers. As the future is uncertain to a large extent, modeling the uncertainty and multimodality of the future states is of great relevance. Existing approaches are rather limited in this regard and mostly yield a single hypothesis of the future or, at the best, strongly constrained mixture components that suffer from instabilities in training and mode collapse. In this work, we present an approach that involves the prediction of several samples of the future with a winner-takes-all loss and iterative grouping of samples to multiple modes. Moreover, we discuss how to evaluate predicted multimodal distributions, including the common real scenario, where only a single sample from the ground-truth distribution is available for evaluation. We show on synthetic and real data that the proposed approach triggers good estimates of multimodal distributions and avoids mode collapse.

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Rostami N, Graf D, Schranzhofer L, Hild S, Hanemann T
Overcoming oxygen inhibition effect by TODA in acrylate-based ceramic-filled inks
2019 Prog Org Coat, Band: 130, Seiten: 221 - 225
KurzfassungPolymerization of an acrylate-based ink, filled with aluminum oxide nanoparticles, which is going to be used in PolyJet™ technology (Stratasys Ltd., Israel), was investigated. In a free-radical photopolymerization of acrylates, oxygen inhibits polymerization and results in a decreased monomer conversion. The presented research shows the influence of TODA (2-[2-(2-methoxyethoxy)ethoxy]acetic acid) on the polymerization degree and mitigation of the oxygen inhibition effect. By incorporating 20–40 vol% of TODA into the system, full polymerization of acrylate in air atmosphere can be achieved. This is due to dissociable hydrogens in the TODA structure. In addition, TODA can overcome agglomeration of the aluminum oxide nanoparticles in the ceramic-filled ink due to steric stabilization.

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Medesi A, Nötzel D, Hanemann T
PVB/PEG-Based Feedstocks for Injection Molding of Alumina Microreactor Components
2019 Materials, Band: 12, Nummer: 8, Seite: 1219

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Manzouri F., Duempelmann M., Heller S., Woias P., Schulze-Bonhage A.
Patient-based feature optimization of a seizure detector for closed-loop stimulation
2019 Brain Stimulation, Band: 12, Nummer: 2, Seite: 411
B. Kar, U. Wallrabe
Performance enhancement of an ultrasonic power transfer system through a tightly coupled solid media using a KLM model.
2019 Power MEMS 2019, Krakow, Poland
Stieglitz T, Gueli C, Salcher R B
Personalized cochlear implants: A design study on foil-based substrates to adapt to the helical structure of cochlea.
2019 Annual Meeting of the German Society of Biomedical Engineering (25–26 September 2019, Frankfurt am Main) Biomed Eng-biomed Te, Band: 64, Nummer: s2, Seite: 27
H-F Pernau, M El-Safoury, M Dufner, C Weber, K Schmitt, J Wöllenstein, B Willing
Photoakustisches Gasmesssystem zur Bestimmung des Schwefeldioxidgehaltes in Schiffsabgasen
2019 20. GMA/ITG-Fachtagung Sensoren und Messsysteme, Nürnberg, Germany , Seiten: 425 - 429
KurzfassungAb dem Jahr 2020 gelten weltweit auf den Ozeanen strengere Grenzwerte für die Emission von SO2 in Schiffsabgasen. Diese können entweder über schwefelarmen Treibstoff oder durch den Einbau von Filteranlagen erreicht werden, wobei in letzteren der SO2-Ausstoß permanent gemessen werden muss. Wir präsentieren erste Feldtest-Messungen eines photoakustischen SO2-Messsystems, das seit August 2018 auf einem Schiff auf der Ostsee unterwegs ist.
Eggensperger K, Lindauer M, Hutter F
Pitfalls and Best Practices in Algorithm Configuration
2019 Journal of Artificial Intelligence Research (JAIR), Band: 64, Seiten: 861 - 893
Fine, C., Jordan-Young, B., Kaiser, A., & Rippon, G. (translated from “Plasticity, plasticity, plasticity …" (2013)).
Plasticidad, plasticidad, plasticidad… y la rigidez del problema del sexo.
2019 The Scholar & Feminist Online; published by the Barnard Center for research on women, Nummer: 15.2
Bucher V, Weinmann M, Bergmann M, Stieglitz T, Urban G
Polymere Barriereschichten für Elektronik in harscher Umgebung
WOMag, Band: 6, 2019
Löwe R, Hanemann T, Hofmann A
Polymerizable Ionic Liquids for Solid-State Polymer Electrolytes
2019 Molecules, Band: 24, Nummer: 2, Seite: 324
M. Bühler, P. Holzapfel, M. Bierling, S. Thiele
Porous transport electrodes for PEM water electrolysis: improved performance via studying materials interfaces
2019 ICE Conference 9.-13. Juni 2019, Loen, Norway
Piotter V, Tülümen M, Hanemann T, Hoffmann M, Ehreiser B
Powder Injection Molding of Oxide Ceramic CMC
2019 Key Engineering Materials, Band: 809, Seiten: 148 - 152
KurzfassungCeramic Matrix Composites (CMC) offer improved mechanical properties, especially higher toughness, preferably at elevated temperatures. Fields of application are, for example, highly hot stressed components of aero engines. Processing of Ceramic Matrix Composites by powder injection molding would offer attractive economic benefits. Therefore, development of a process chain for the ceramic injection molding of Al2O3 short fiber CMC had started by feedstock preparation and characterization. Fiber content varied between 10 to 50 vol.% whereas for binder a well-examined system from KIT was chosen. The fiber content showed a minor effect on the rheological properties but fiber orientation depended strongly on the apparent shear profile. The sintering behavior was affected as well, i.e. higher densities were achieved.
Schäfer M, Hofmann F, Abdel-Khalek H, Weidlich A
Principal Cross-Border Flow Patterns in the European Electricity Markets
2019 16th International Conference on the European Energy Market

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Feißt M, Kustermann J, Schuhmacher A, Wilde J
Process Optimization of Foil-Based Transient Liquid Phase Bonding for Die Attachment
2019 42nd International Spring Seminar on Electronics Technology (ISSE), Wrozlaw
Wanapinit N, Weidlich A, Thomsen J
Promoting flexibility from prosumers through a generic characteristic flexibility model
2019 11. Internationale Energiewirtschaftstagung an der TU Wien
KurzfassungEnergy systems require flexibility - an ability to respond to changes - to integrate higher shares of variable renewable energy. On the whole, flexibility potential from prosumers is significant and stems from various processes. As each flexibility option is unique, before utilization, its potential first must be assessed. This paper presents a universal flexibility model, so called generic characteristic flexibility model (GCM), as tool to characterize and assess most, if not all, flexibility options from prosumers. GCM establishes a generic flexible process with components representing physical parts, e.g. machine and storage, and various administrative decisions, e.g. changes in output delivery or operating hours. Each component is described with essential characteristics and constraints. As demonstrations, three flexible systems representing various sectors – a district heating system, a household appliance, and a production process - are characterized and modelled using GCM. Flexibility in these systems is utilized to minimize costs under time-varying electricity prices and subject to operational constraints. This in turn proves the concept of a universal flexibility model. GCM eases burdens of actors - flexibility providers and users - to develop assessment tools for each flexibility options. Its pre-defined structure and characteristics also support identification of flexible processes and communication between actors. Thus, it helps promoting the utilization of flexibility from prosumers.

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B.P. Bruno, A.R. Fahmy, M. Stürmer, U. Wallrabe, M.C. Wapler
Properties of piezoceramic materials in high electric field actuator applications
2019 Smart Material Structures, Band: 28, Ergänzungsband: 015029, Seite: 14pp
H Groß, T Dankwort, A-L Hansen, U Schürmann, V Duppel, M Poschmann, A Meingast, D Groeneveld, J König, W Bensch, L Kienle, W Bensch, L Kienle, J König
Purification by SPS and formation of a unique 3D nanoscale network: the showcase of Ni–Cr–S
2019 J Mater Chem C
KurzfassungThe occurrence of a unique 3D nanoscale network in Ni–Cr–S, treated via spark-plasma sintering, was discovered with a variety of ex situ and in situ TEM and XRD techniques. The starting material, consisting of a heterogeneous mixture of different phases, could be purified upon application of the sintering process. The obtained samples showed a network of chemically segregated domains being either Ni rich and Cr deficient or vice versa. These domains could be proven to intergrow fully coherently in 3D, thus establishing a unique microstructure. Electron beam irradiation caused the initial Cr3S4-type structures to transform into the disordered NiAs-type. The disordering is characterised by significant short-range ordering as indicated by the appearance of prominent diffuse scattering. Thermoelectric characterisation at room temperature indicated an n-type semiconductor behaviour with thermal and electrical conductivities similar to usual thermoelectric materials, however with a low Seebeck coefficient and a low power factor of 49.3 μW m−1 K−2.
Aile Ge-Ernst, Christoph Scholl, Ralf Wimmer
Quantifier Localization for DQBF
2019 Int'l Workshop on Logic and Synthesis
KurzfassungDependency quantified Boolean formulas (DQBFs) are a powerful formalism, which subsumes quantified Boolean formulas (QBFs) and allows an explicit specification of dependencies of existential variables on universal variables. Driven by the needs of various applications which can be encoded by DQBFs in a natural, compact, and elegant way, research on DQBF solving has emerged in the past few years. However, research focused on closed DQBFs in prenex form (where all quantifiers are placed in front of a propositional formula) and non-prenex DQBFs have almost not been studied in the literature. In this paper we provide a formal definition for syntax and semantics of non-closed non-prenex DQBFs and prove useful properties enabling quantifier localization. Moreover, we make use of our theory by integrating quantifier localization into a state-of-the-art DQBF solver. Experiments with prenex DQBF benchmarks including those from the QBFEVAL’18 competition clearly show that quantifier localization pays off in this context.
Aile Ge-Ernst, Christoph Scholl, Ralf Wimmer
Quantifier Localization for DQBF
CoRR, Band: abs/1905.04755, 2019
Mundt Laura, Kwapil Wolfram, Yakoob Mohammed, Herterich Jan, Kohlstadt Markus, Wurfel Uli, Schubert Martin, Glunz Stefan
Quantitative Local Loss Analysis of Blade-Coated Perovskite Solar Cells
2019 ´, Seite: 1–8
KurzfassungMicroRNAs (miRNAs) are post-transcriptional regulators that repress the expression of their targets. They are known to work cooperatively with genes and play important roles in numerous cellular processes. Identification of miRNA regulatory modules (MRMs) would aid deciphering the combinatorial effects derived from the many-to-many regulatory relationships in complex cellular systems. Here, we develop an effective method called BiCliques Merging (BCM) to predict MRMs based on bicliques merging. By integrating the miRNA/mRNA expression profiles from The Cancer Genome Atlas (TCGA) with the computational target predictions, we construct a weighted miRNA regulatory network for module discovery. The maximal bicliques detected in the network are statistically evaluated and filtered accordingly. We then employed a greedy-based strategy to iteratively merge the remaining bicliques according to their overlaps together with edge weights and the gene-gene interactions. Comparing with existing methods on two cancer datasets from TCGA, we showed that the modules identified by our method are more densely connected and functionally enriched. Moreover, our predicted modules are more enriched for miRNA families and the miRNA-mRNA pairs within the modules are more negatively correlated. Finally, several potential prognostic modules are revealed by Kaplan-Meier survival analysis and breast cancer subtype analysis.
Bohm T, Joseph K, Kirsch M, Moroni R, Hilger A, Osenberg M, Manke I, Johnston M, Stieglitz T, Hofmann UG, Haas CA, Thiele S
Quantitative synchrotron X-ray tomography of the material-tissue interface in rat cortex implanted with neural probes.
2019 Sci Rep-uk, Band: 9, Nummer: 1, Seiten: 7646 - 7646
KurzfassungNeural probes provide many options for neuroscientific research and medical purposes. However, these implantable micro devices are not functionally stable over time due to host-probe interactions. Thus, reliable high-resolution characterization methods are required to understand local tissue changes upon implantation. In this work, synchrotron X-ray tomography is employed for the first time to image the interface between brain tissue and an implanted neural probe, showing that this 3D imaging method is capable of resolving probe and surrounding tissue at a resolution of about 1 micrometer. Unstained tissue provides sufficient contrast to identify electrode sites on the probe, cells, and blood vessels within tomograms. Exemplarily, we show that it is possible to quantify characteristics of the interaction region between probe and tissue, like the blood supply system. Our first-time study demonstrates a way for simultaneous 3D investigation of brain tissue with implanted probe, providing information beyond what was hitherto possible.
P Nitzsche, C Dinc, K Schmitt, J Wöllenstein
Quantum cascade laser-based tunable laser absorption spectroscopy for the detection of stable isotopes of CO2
2019 20. GMA/ITG-Fachtagung Sensoren und Messsysteme , Seiten: 130 - 135
KurzfassungWe present a conceptual design and results on the determination of three stable carbon dioxide (CO2) isotopologues. The isotopic analyses have been performed using a quantum cascade laser (QCL)-based tunable laser absorption spectroscopy (TLAS) setup. A mid-infrared (MIR), tunable and narrow linewidth QCL is used as a light source to probe absorption lines at around 4.3 μm. Tuning the QCL in this selected region permits the simultaneous detection of three absorption lines of CO2 isotopologues including 16O12C16O, 16O13C16O and 16O12C18O. The result shows that the wavelength conversion method using the reference gas cell is well-suited for this technique.
Breunig I, Buse K
Quasi-phase matching in integrated lithium-niobate whispering galleries
2019 Laser Resonators, Microresonators, and Beam Control XXI, San Francisco, CA, United States Proceedings of SPIE, Band: 10904, Seite: 1090403
KurzfassungWhispering-gallery resonators (WGRs) made of lithium niobate are very attractive for nonlinear-optical frequency conversion due to their small mode volumes and high Q-factors. To achieve phase matching, methods like birefringent phase matching and quasi phase matching (QPM) have been employed in millimeter-sized bulk WGRs. Among these, the latter provides ultimate flexibility in terms of wavelengths and polarization of the interacting waves. Integrated on-chip WGRs are in particular very appealing due to the possibility of building photonic circuits and the usage of highly-parallel and thus scalable semiconductor manufacturing techniques. Integrated WGRs are, however, fabricated on thin-film substrates. This leads to one major drawback: QPM is hard to achieve, since it is difficult to realize periodically-poled thin films by field-assisted domain inversion. We report on a method to resolve this issue. First, we do domain engineering in bulk material. Next, we bond this sample on a quartz substrate by direct wafer bonding and finally we polish the lithium niobate to a 2-μm-thick film. By lithography and reactive-ion etching we structure waveguide rings with 200 μm diameter into the thin film. Subsequent polishing of the waveguide sidewalls decreases surface-scattering losses and enables on-chip WGRs with quality factors exceeding one million. This allowed us to demonstrate for the first time quasi-phase matched second-harmonic generation in integrated WGRs, pumped by light with 1550 nm wavelength, obtaining a normalized conversion efficiency of 0.9 ‰/mW. Being now able to deploy type-0 and type-ii phase matching opens entirely new possibilities for frequency conversion with on-chip WGRs.
Uluda M, Szabados J, Breunig I, Buse K
Radially-Poled Stoichiometric Lithium Tantalate Microresonators for Nonlinear-Optical Applications
2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC), Munich, IEEE
KurzfassungWhispering gallery-mode microresonators guide light by total internal reflection and exhibit exceptionally high quality factors and small mode volumes. If such a microresonator is fabricated from a nonlinear-optical material, one can benefit from these properties for efficient optical frequency conversion. One of the well-known second-order nonlinear-optical materials for these microresonators is periodically-poled lithium niobate (PPLN) because of its high second-order susceptibility and wide transmission window. Thus PPLN-based whispering gallery-mode microresonators are efficient platforms for higher-harmonic generation of ultraviolet light using a near-infrared pump source in the telecom range [1], for low-input-power optical parametric oscillation [2] and for frequency comb up- and down-conversion from the near-infrared region to the visible, ultraviolet and mid-infrared regions [3].
F. Koch, M. Wehrle, K. Tröndle, P. Koltay, G. Finkenzeller, R. Zengerle, S. Zimmermann
Rapid assessment of combined drop on demand and extrusion-based bioprinting with controlled shear stress and high shape fidelity
2019 Transducers 2019 - EUROSENSORS XXXIII 23. -27. Juni 2019 - Berlin, Germany
KurzfassungWe present a novel combination of drop on demand (DoD) and extrusion-based bioprinting to generate highprecision patterns of cells inside large hydrogel volumes. Extrusion-based bioprinting has the great advantage of enabling a fast deposition of high viscous cell-loaded hydrogel with reasonable precision. Compromises between high shape fidelity and cell viability, as well as short process times often require many iterations of optimizing process parameters and varying compositions of the hydrogel. To limit the multitude of parameters during extrusion-based bioprinting, a method for rapid process assessment was developed. This enables to define limits for printing temperature, flow rate and nozzle size from basic rheological measurements with regard to the biological and mechanical requirements. The combination of extrusion-based bioprinting with DoD bioprinting allows for precise deposition of low viscous cell suspension and adjustable concentrations of crosslinking agent. Together, the technologies were used to print a bone replacement model by using the predefined process parameters. Adiposed-derived stem cells (ASC) prone to osteogenic differentiation were homogenously extruded in a cuboid structure of 10x10x5 mm. Human umbilical vein endothelial cells (HUVEC) were printed as highly dense cell suspension lines inside the extruded hydrogel to allow a potential vascularization of the structure in vivo.
F. Koch, M. Wehrle, K. Tröndle, P. Koltay, G. Finkenzeller, R. Zengerle, S. Zimmermann
Rapid assessment of extrusion based bioprinting by controlling shear stresses on cells
2019 Transducers 2019, Berlin, 23.06. - 27.06.2019
J. F. Cahill, J. Riba, V. Kertesz
Rapid, Untargeted Chemical Profiling of Single Cells in Their Native Environment
2019 Anal Chem, Band: 91, Seiten: 6118 - 6126
KurzfassungWe report a method that enables untargeted, high throughput, and quantitative mass spectrometric analysis of single cells from cell suspension without needing additional sample preparation procedures (e.g., molecular tagging) through the combination of single-cell printer technology and liquid vortex capture−mass spectrometry (SCP-LVC-MS). The operating principle behind the SCP-LVC-MS technology is single cell isolation via small droplet piezoelectric ejection followed by capture of the droplet into an LVC-MS sampling probe. Once exposed to an appropriate solvent, the cell is lysed, extracted, and analyzed by MS. The SCP-LVC-MS approach was validated by measuring the lipid composition of microalgae, Chlamydomonas reinhardtii (ChRe) and Euglena gracilis (EuGr), and HeLa cells in their native growth media. Numerous diacylglyceryltrimethylhomo-Ser (DGTS), phosphatidylcholine (PC), monogalactosyldiacylglycerol (MGDG), and digalactosyldiacylglycerol (DGDG) lipids were observed in single cells. Continuous solvent flow ensures that cells are analyzed rapidly, and no signal carryover between cells is observed. ChRe and EuGr microalgae mixed together in the same solution were differentiated cell-by-cell in real-time based on differences between levels of diacylglyceryltrimethylhomo-Ser (DGTS) and phosphatidylcholine (PC) lipids measured in each cell. Several DGTS lipids present in ChRe were quantified with single-cell resolution by normalizing to a DGTS(32:0) internal standard added to the LVC probe solvent during analysis. Quantitative peak areas were validated by comparing to bulk lipid extracts. Lastly, peak area distributions comprised of hundreds of cells were compared for ChRe after 5 days of nitrogen-limited and normal growth conditions, which show clear differences and the ability to resolve cellular population differences with single-cell resolution.
A. Müller, M.C. Wapler, U. Wallrabe
Rapid-Prototyping Prozess für stark asphärische Mikrolinsen-Arrays.
2019 Mikrosystemtechnikkongress 2019 Berlin, Germany VDE-Verlag 2019, Seiten: 88 - 91
Banerjee K, Rajaeipour P, Zappe H, Ataman C
Refractive opto-fluidic wavefront modulator with electrostatic push-pull actuation
2019 SPIE BiOS, 2019, San Francisco, California, United States , Band: 10886
T. Boehm, M. S. Mu’min, R. Moroni, S. Thiele, S. Vierrath, M. Breitwieser
Resolving structure and properties in ionomer composite membranes with Confocal Raman Microscopy
2019 Workshop on Ion Exchange Membranes for Energy Applications, Bad Zwischenahn, 25. -27. Juni 2019
J Kapp, C Weber, K Schmitt, H-F Pernau, J Wöllenstein
Resonant Photoacoustic Spectroscopy of NO2 with a UV-LED Based Sensor
2019 Sensors-basel, Band: 19, Nummer: 3, Seite: 724
KurzfassungNitrogen dioxide (NO2) is a poisonous trace gas that requires monitoring in urban areas. Accurate measurement in sub-ppm concentrations represents a wide application field for suitable economical sensors. We present a novel approach to measure NO2 with a photoacoustic sensor using a T-shaped resonance cell. An inexpensive UV-LED with a peak wavelength of 405 nm as radiation source as well as a commercial MEMS microphone for acoustic detection were used. In this work, a cell has been developed that enables a “non-contact” feedthrough of the divergent LED beam. Thus, unwanted background noise due to absorption on the inside walls is minimized. As part of the development, an acoustic simulation has been carried out to find the resonance frequencies and to visualize the resulting standing wave patterns in various geometries. The pressure amplitude was calculated for different shapes and sizes. A model iteratively optimized in this way forms the basis of a construction that was built for gas measurement by rapid prototyping methods. The real resonance frequencies were compared to the ones found in simulation. The limit of detection was determined in a nitrogen dioxide measurement to be 200 ppb (6 σ) for a cell made of aluminum.
J. F. Hess, S. Zehnle, P. Juelg, T. Hutzenlaub, R. Zengerle, N. Paust
Review on pneumatic operations in centrifugal microfluidics
2019 Lab Chip, Band: 22, Seiten: 3745 - 3770
KurzfassungCentrifugal microfluidics allows for miniaturization, automation and parallelization of laboratory workflows. The fact that centrifugal forces are always directed radially outwards has been considered a main drawback for the implementation of complex workflows leading to the requirement of additional actuation forces for pumping, valving and switching. In this work, we review and discuss the combination of centrifugal with pneumatic forces which enables transport of even complex liquids in any direction on centrifugal systems, provides actuation for valving and switching, offers alternatives for mixing and enables accurate and precise metering and aliquoting. In addition, pneumatics can be employed for timing to carry out any of the above listed unit operations in a sequential and cascaded manner. Firstly, different methods to generate pneumatic pressures are discussed. Then, unit operations and applications that employ pneumatics are reviewed. Finally, a tutorial section discusses two examples to provide insight into the design process. The first tutorial explains a comparatively simple implementation of a pneumatic siphon valve and provides a workflow to derive optimum design parameters. The second tutorial discusses cascaded pneumatic operations consisting of temperature change rate actuated valving and subsequent pneumatic pumping. In conclusion, combining pneumatic actuation with centrifugal microfluidics allows for the design of robust fluidic networks with simple fluidic structures that are implemented in a monolithic fashion. No coatings are required and the overall demands on manufacturing are comparatively low. We see the combination of centrifugal forces with pneumatic actuation as a key enabling technology to facilitate compact and robust automation of biochemical analysis.
R E Bernhardsgrütter, C J Hepp, K Schmitt, M Jägle, H-F Pernau, J Wöllenstein
Robust and Flexible Thermal Sensor Using the 3-Omega-Method to Investigate Thermal Properties of Fluids
2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII) IEEE, Seiten: 1909 - 1912
KurzfassungThis paper presents a platinum thin film sensor able to investigate the thermal properties of a fluid whereas the sensing element is protected against corrosion by an intermediate stainless-steel wall. Progress claims include: 1) the 3-omega method is applied to investigate fluids which are not directly adjacent to the sensitive layer, 2) the 3-omega-method is applied for a meander structure, 3) a theoretical model is developed and agrees well with the experiment. These findings can have a key role for future stand-alone sensors measuring thermal parameters, or for sensors which combine several measurement principles, e.g. the 3-omega method for thermal parameter detection and the thermal flow meters for flow speed measurements.
A Gola, L Pastewka
Scratching Cu|Au Nanolaminates
2019 Lubricants, Band: 7, Nummer: 5, Seite: 44
KurzfassungWe used molecular dynamics simulations to study the scratching of Cu|Au nanolaminates of 5 nm layer thickness with a nanoscale indenter of 15 nm radius at normal forces between 0.5μ N and 2μ N. Our simulations show that Au layers wear quickly while Cu layers are more resistant to wear. Plowing was accompanied by the roughening of the Cu|Au heterointerface that lead to the folding of the nanolaminate structure at the edge of the wear track. Our explorative simulations hint at the complex deformation processes occurring in nanolaminates under tribological load.
L Engel, KR Tarantik, I Benito-Altamirano, C Pannek, JD Prades, J Wöllenstein
Screen-Printable Colorimetric Sensors for the Monitoring of Toxic Gases in Ambient Air
2019 IEEE International Conference on Flexible and Printable Sensors and Systems (FLEPS) IEEE, Seiten: 1 - 3
KurzfassungWe present a fast and simple method to monitor toxic gases in ambient air based on a visible color change of a printed paper sensor, which can be evaluated using a camera (e.g. smartphone) or naked eye. This study focuses on the developent of gas-sensitve pastes for the processing of the colorimetic material by screen printing. Indicators for the detection of ammonia (NH 3 ), hydrogen sulfide (H 2 S) and formaldehyde (CH 2 O) were examined in closer detail. The sensing proberties of the respective indicator towards the target gas was characterized via UV/Vis spectroscopy in reflection.
L Engel, K Tarantik, C Pannek, J Wöllenstein
Screen-Printed Sensors for Colorimetric Detection of Hydrogen Sulfide in Ambient Air
2019 Sensors-basel, Band: 19, Nummer: 5, Seite: 1182
KurzfassungA fast and sensitive method to monitor hydrogen sulfide (H2S) in ambient air based on a visible color change of a printed disposable sensor has been developed. As gas-sensitive material, an immobilized copper(II) complex of the azo dye 1-(2-pyridylazo)-2-naphtol (H-PAN) was synthesized and prepared in an ethyl cellulose matrix for screen printing. If H2S is present in ambient air, the gas sensitive layer changes its color from purple to yellow. A pre-primed polyethylene (PE) foil and a coated offset paper served as the printing substrate. The colorimetric response to the target gas was measured by UV/Vis spectroscopy in reflection at H2S concentrations between 1 to 20 ppm. Possible cross-sensitivities of the printed sensors towards methane (CH4), formaldehyde (CH2O), carbon monoxide (CO), ammonia (NH3), and nitrogen dioxide (NO2), as well as the long-term stability was investigated. Furthermore, reflection measurements of the Cu-PAN complex on an amorphous silica powder under gas admission served as preliminary test for the subsequent paste development.
Brown T, Schäfer M, Greiner M
Sectoral Interactions as Carbon Dioxide Emissions Approach Zero in a Highly-Renewable European Energy System
2019 Energies, Band: 12, Seite: 1032
KurzfassungMeasures to reduce carbon dioxide emissions are often considered separately, in terms of electricity, heating, transport, and industry. This can lead to the measures being prioritised in the wrong sectors, and neglects interactions between the sectors. In addition, studies often focus on specific greenhouse gas reduction targets, despite the uncertainty regarding what targets are desirable and when. In this paper, these issues are examined for the period after 2030 in an existing openly-available, hourly-resolved, per-country, and highly-renewable model of the European energy system, PyPSA-Eur-Sec-30, that includes electricity, land transport, and space and water heating. A parameter sweep of different reduction targets for direct carbon dioxide emissions is performed, ranging from no target down to zero direct emissions. The composition of system investments, the interactions between the energy sectors, shadow prices, and the market values of the system components are analysed as the carbon dioxide limit changes. Electricity and land transport are defossilised first, while the reduction of emissions in space and water heating is delayed by the expense of new components and the difficulty of supplying heat during cold spells with low wind and solar power generation. For deep carbon dioxide reduction, power-to-gas changes the system dynamics by reducing curtailment and increasing the market values of wind and solar power. Using this model setup, cost projections for 2030, and optimal cross-border transmission, the costs of a zero-direct-emission system in these sectors are marginally cheaper than today’s system, even before the health and environmental benefits are taken into account.

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Okujeni S, Egert U
Self-organization of modular network architecture by activity-dependent neuronal migration and outgrowth
2019 Elife, Band: 8, Seite: e47996
Alexander J Bett, Kristina M Winkler, Martin Bivour, Ludmila Cojocaru, Özde Ş Kabakli, Patricia SC Schulze, Gerald Siefer, Leonard Tutsch, Martin Hermle, Stefan W Glunz, Jan Christoph Goldschmidt
Semi-Transparent Perovskite Solar Cells with ITO Directly Sputtered on Spiro-OMeTAD for Tandem Applications
2019 Acs Appl Mater Inter, Band: 11, Nummer: 49, Seiten: 45796 - 4580
KurzfassungPerovskite silicon tandem solar cells have the potential to overcome the efficiency limit of single-junction solar cells. For both monolithic and mechanically stacked tandem devices, a semi-transparent perovskite top solar cell, including a transparent contact, is required. Usually, this contact consists of a metal oxide buffer layer and a sputtered transparent conductive oxide. In this work, semi-transparent perovskite solar cells in the regular n–i–p structure are presented with tin-doped indium oxide (ITO) directly sputtered on the hole conducting material Spiro-OMeTAD. ITO process parameters such as sputter power, temperature, and pressure in the chamber are systematically varied. While a low temperature of 50 °C is crucial for good device performance, a low sputter power has only a slight effect, and an increased chamber pressure has no influence on device performance. For the 5 × 5 mm2 perovskite cell with a …
R. Zhu, U. Wallrabe, P. Woias, M.C. Wapler, U. Mescheder
Semi-rigid ring-shaped electrode dielectric electroactive polymer membrane as buckling actuator
2019 J Micromech Microeng, Band: 29, Ergänzungsband: 055001, Seite: 10pp
Zhu R., Wallrabe U., Woias P., Wapler M., Mescheder U.
Semi-rigid ring-shaped electrode dielectric electroactive polymer membrane as buckling actuator
2019 Nanotechnology, Band: 29, Nummer: 5, Seite: 055001
A. Brunauer, F. von Stetten, S.M. Früh
Sensitive detection of Pseudomonas aeruginosa based on recombinase polymerase amplification combined with an immunological assay
2019 Molecular Diagnostics Europe, Lissabon/Portugal, 06. - 09.05.2019
Petrini FM, Bumbasirevic M, Valle G, Ilic V, Mijovic P, Cvancara P, Barberi F, Katic N, Bortolotti D, Andreu D, Lechler K, Lesic A, Mazic S, Mijovic B, Guiraud D, Stieglitz T, Alexandersson A, Micera S, Raspopovic S
Sensory feedback restoration in leg amputees improves walking speed, metabolic cost and phantom pain.
2019 Nat Med, Band: 25, Nummer: 9, Seiten: 1356 - 1363
KurzfassungConventional leg prostheses do not convey sensory information about motion or interaction with the ground to above-knee amputees, thereby reducing confidence and walking speed in the users that is associated with high mental and physical fatigue1,2,3,4. The lack of physiological feedback from the remaining extremity to the brain also contributes to the generation of phantom limb pain from the missing leg5,6. To determine whether neural sensory feedback restoration addresses these issues, we conducted a study with two transfemoral amputees, implanted with four intraneural stimulation electrodes7 in the remaining tibial nerve (ClinicalTrials.gov identifier NCT03350061). Participants were evaluated while using a neuroprosthetic device consisting of a prosthetic leg equipped with foot and knee sensors. These sensors drive neural stimulation, which elicits sensations of knee motion and the sole of the foot touching the ground. We found that walking speed and self-reported confidence increased while mental and physical fatigue decreased for both participants during neural sensory feedback compared to the no stimulation trials. Furthermore, participants exhibited reduced phantom limb pain with neural sensory feedback. The results from these proof-of-concept cases provide the rationale for larger population studies investigating the clinical utility of neuroprostheses that restore sensory feedback.
Koebele L, Rohrbach A
Shape, switch and block: Confocal light-sheet microscopy with sectioned Bessel beams and STED
2019 submitted
Schiffmacher A, Litzenberger L, Wilde J
Silver Sintering on Organic Substrates for the Embedding of Power Semiconductor Devices
2019 IEEE 69th Electronic Components and Technology Conference
H.G.B. Gowda, U. Wallrabe
Simulation of an adaptive fluid-membrane piezoelectric lens
2019 Micromachines-basel, Band: 10, Nummer: 797
M. Jordão, R. Sankowski, S. Brendecke, S. Sagar, G. Locatelli, Y. Tai, T. Tay, E. Schramm, S. Armbruster, N. Hagemeyer, O. Groß, D. Mai, M. Kerschensteiner, D. Grün, M. Prinz, Çiçek Ö, Schmidt T.
Single-cell profiling identifies myeloid cell subsets with distinct fates during neuroinflammation
2019 Science, Band: 363, Nummer: 6425, Seite: 7554
KurzfassungThe innate immune cell compartment is highly diverse in the healthy central nervous system (CNS), including parenchymal and non-parenchymal macrophages. However, this complexity is increased in inflammatory settings by the recruitment of circulating myeloid cells. It is unclear which disease-specific myeloid subsets exist and what their transcriptional profiles and dynamics during CNS pathology are. Combining deep single-cell transcriptome analysis, fate mapping, in vivo imaging, clonal analysis, and transgenic mouse lines, we comprehensively characterized unappreciated myeloid subsets in several CNS compartments during neuroinflammation. During inflammation, CNS macrophage subsets undergo self-renewal, and random proliferation shifts toward clonal expansion. Last, functional studies demonstrated that endogenous CNS tissue macrophages are redundant for antigen presentation. Our results highlight myeloid cell diversity and provide insights into the brainâ€™s innate immune system.

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T. Boehm, R. Moroni, M. Breitwieser, S. Thiele, S. Vierrath
Spatially Resolved Quantification of Ionomer Degradation in Fuel Cells by Confocal Raman Microscopy
2019 J Electrochem Soc, Band: 166, Nummer: 7, Seiten: F3044 - F3051
Cruz-Matias I, Ayala Dolors, Hiller D, Gutsch S, Zacharias M, Estrade S, Peiro F
Sphericity and roundness computation for particles using the extreme vertices model
2019 J Comput Sci-neth, Band: 30, Seiten: 28 - 40
KurzfassungShape is a property studied for many kinds of particles. Among shape parameters, sphericity and roundness indices had been largely studied to understand several processes. Some of these indices are based on length measurements of the particle obtained from its oriented bounding box (OBB). In this paper we follow a discrete approach based on Extreme Vertices Model and devise new methods to compute the OBB and the mentioned indices. We apply these methods to synthetic sedimentary rocks and to a real dataset of silicon nanocrystals (Si NC) to analyze the obtained results and compare them with those obtained with a classical voxel model.
P. Juelg, M. Specht, M. Meyer, E. Kipf, F. Schlenker, F. Bänsch, S. Neumann, F. von Stetten, R. Zengerle, N. Paust, M. Fillies, R. Kirschner-Schwabe, S. Groeneveld-Krentz, M. Lehnert, C. Eckert, T. Hutzenlaub
Standardization of Personalized Multiplex Biomarker Quantification: Individual Response Monitoring Assay (IRMA)
2019 MST-Kongress, 28. - 30.Oktober 2019, Berlin
B. Johannsen, L. Karkossa, D. Baumgartner, L. Müller, R. Zengerle, K. Mitsakakis
Storage of protein coated beads on point-of-care microfluidic cartridges for immunoassay applications
2019 MNE 2019, 23-26.09.2019, Rhodes/Greece
R Jana, D Savio, VL Deringer, L Pastewka
Structural and elastic properties of amorphous carbon from simulated quenching at low rates
2019 Model Simul Mater Sc
KurzfassungWe generate representative structural models of amorphous carbon (a-C) from constant-volume quenching from the liquid with subsequent relaxation of internal stresses in molecular dynamics simulations using empirical and machine-learning interatomic potentials. By varying volume and quench rate we generate structures with a range of density and amorphous morphologies. We find that all a-C samples show a universal relationship between hybridization, bulk modulus and density despite having distinctly different cohesive energies. Differences in cohesive energy are traced back to slight changes in the distribution of bond-angles that will likely be linked to thermal stability of these structures.
Feldmann Frank, Schön Jonas, Niess Jürgen, Lerch Wilfried, Hermle Martin
Studying dopant diffusion from Poly-Si passivating contacts
2019 Solar Energy Materials and Solar Cells, Band: 200, Seite: 109978
KurzfassungThe diffusion of dopants from the poly-Si layer through the interfacial oxide into the crystalline silicon wafer is studied experimentally and via numerical simulation. It is found that phosphorus piles up at the poly-Si/SiOx interface but boron readily diffuses through the oxide into the silicon and thereby forms a less shallow junction which adversely affects surface passivation. Although boron diffusion was suppressed by using a nitrided oxide – realized by a plasma oxidation process – a reduction in passivation was observed due to deterioration of the interface. Via 1D and 3D process simulation it was established that diffusion through pinholes contributed little to the aggregate diffusion profiles measured by ToF-SIMS but direct diffusion through the oxide was the main diffusion mechanism. The segregation coefficient at the poly-Si/SiOx interface and the diffusivity in SiOx were determined. Using these parameters simulation-based predictions were conducted in order to pave the way for future optimization of hole-selective passivating contacts.
Kwapil Wolfram, Wasmer Sven, Fell Andreas, Greulich Johannes, Schubert Martin
Suns-ILIT: Contact-less determination of local solar cell current-voltage characteristics.
2019 Solar Energy Materials and Solar Cells, Band: 191, Seite: 71–77
KurzfassungWe present a novel method to analyze the local current-voltage I-V characteristics of both solar cells and cell precursors. The method, which we call “Suns-ILIT”, is based on illuminated lock-in thermography (ILIT) measurements and photoluminescence imaging (PLI) in open-circuit conditions with varying illumination intensities. Compared to conventional techniques for the determination of local solar cell parameters, the advantage of Suns-ILIT lies in the high accuracy while imposing minimal requirements on the sample. In particular, no electrical contact to the sample is needed. We derive the necessary equations from the contributions to the power dissipation and investigate the impact of the Peltier heating and cooling on the final outcome. The method is applied to a standard multicrystalline silicon PERC solar cell for demonstration.
A Gola, G-P Zhang, L Pastewka, R Schwaiger
Surface flaws control strain localization in the deformation of Cu|Au nanolaminate pillars
2019 Mrs Commun, Band: 9, Nummer: 3, Seiten: 1067 - 1071
KurzfassungThe authors carried out matched experiments and molecular dynamics simulations of the compression of nanopillars prepared from Cu|Au nanolaminates with up to 25 nm layer thickness. The stress–strain behaviors obtained from both techniques are in excellent agreement. Variation in the layer thickness reveals an increase in the strength with a decreasing layer thickness. Pillars fail through the formation of shear bands whose nucleation they trace back to the existence of surface flaws. This combined approach demonstrates the crucial role of contact geometry in controlling the deformation mode and suggests that modulus-matched nanolaminates should be able to suppress strain localization while maintaining controllable strength.
S.M. Früh, D.M. Kainz, T. Hutzenlaub, R. Zengerle, N. Paust
Tailor-made immunological reactions in lateral flow strips enables by total flow control
2019 Wissenschaftsforum Chemie, Aachen, 15. -18.09.2019
Ralf Wimmer, Christoph Scholl, Bernd Becker
The (D)QBF Preprocessor HQSpre – Underlying Theory and Its Implementation
2019 Journal on Satisfiability, Boolean Modeling and Computation, Band: 11, Nummer: 1, Seiten: 3 - 52
KurzfassungPreprocessing turned out to be an essential step for SAT, QBF, and DQBF solvers to reduce/modify the number of variables and clauses of the formula, before the formula is passed to the actual solving algorithm. These preprocessing techniques often reduce the computation time of the solver by orders of magnitude. In this paper, we present the preprocessor HQSpre that was developed for Dependency Quantified Boolean Formulas (DQBFs) and that generalizes different preprocessing techniques for SAT and QBF problems to DQBF. We give a presentation of the underlying theory together with detailed proofs as well as implementation details contributing to the efficiency of the preprocessor. HQSpre has been used with obvious success by the winners of the DQBF track, and, even more interestingly, the QBF tracks of QBFEVAL’18.
Ralf Wimmer, Christoph Scholl, Bernd Becker
The (D)QBF Preprocessor HQSpre – Underlying Theory and Its Implementation
2019 Journal on Satisfiability, Boolean Modeling and Computation, Band: 11, Nummer: 1, Seiten: 3 - 52
KurzfassungPreprocessing turned out to be an essential step for SAT, QBF, and DQBF solvers to reduce/modify the number of variables and clauses of the formula, before the formula is passed to the actual solving algorithm. These preprocessing techniques often reduce the computation time of the solver by orders of magnitude. In this paper, we present the preprocessor HQSpre that was developed for Dependency Quantified Boolean Formulas (DQBFs) and that generalizes different preprocessing techniques for SAT and QBF problems to DQBF. We give a presentation of the underlying theory together with detailed proofs as well as implementation details contributing to the efficiency of the preprocessor. HQSpre has been used with obvious success by the winners of the DQBF track, and, even more interestingly, the QBF tracks of QBFEVAL’18.
Mohamad Ahmadi, Abdolhamid Ghodselahi, Fabian Kuhn, Anisur Rahaman Molla
The Cost of Global Broadcast in Dynamic Radio Networks
2019 Theor Comput Sci
KurzfassungWe study the time complexity of single and multi token broadcast in adversarial dynamic radio networks. Initially, k tokens (which are k pieces of information) are distributed among the n nodes of a network and all the tokens need to be disseminated to all the nodes in the network. We first consider the single-token broadcast problem (i.e., the case k=1). By presenting upper and lower bounds, we show that the time complexity of single-token broadcast depends on the amount of stability and connectivity of the dynamic network topology and on the adaptiveness of the adversary providing the dynamic topology. Then, we give two generic algorithms which allow to transform generalized forms of single-token broadcast algorithms into multi-token broadcast (k-token broadcast) algorithms. Based on these generic algorithms, we obtain k-token broadcast algorithms for a number of different dynamic network settings. For one of the modeling assumptions, our algorithm is complemented by a lower bound which shows that the upper bound is close to optimal.
Boehler C, Vomero M, Liljemalm R, Stieglitz T, Asplund M
The MANTArray - a Multisite Active Neuro-Technology Array for High Density Recordings and Stimulation.
2019 41st Annual Conference on Engineering in Biology Society IEEE/EMBC, Berlin, July, 2019.
Würfel Uli, Perdigón Toro Lorena, Kurpiers Jona, Wolff Christian, Caprioglio Pietro, Rech Jeromy, Zhur Jingshuai, Zhan Xiaowei, You Wei, Shoaee Safa, Neher Dieter, Stolterfoht Martin
The Recombination between Photogenerated and Electrode-Induced Charges Dominates the Fill Factor Losses in Optimized Organic Solar Cells
2019 The Journal of Physical Chemistry Letters
KurzfassungCharge extraction in organic solar cells (OSCs) is commonly believed to be limited by bimolecular recombination of photogenerated charges. Yet, the fill factor of OSCs is usually almost entirely governed by recombination processes that scale with the first-order of the light intensity. This linear loss was often interpreted to be a consequence of geminate or trap-assisted recombination. Numerical simulations show that this linear dependence is a direct consequence of the large amount of excess dark charge near the contact. The first-order losses increase with decreasing mobility of minority carriers and we discuss the impact of several material and device parameters on this loss mechanism. This work highlights that OSCs are especially vulnerable to injected charges as a result of their poor charge transport properties. This implicates that dark charges need to be better accounted for when interpreting electro-optical measurements and charge collection based on simple figures of merit. Charge extraction in organic solar cells (OSCs) is commonly believed to be limited by bimolecular recombination of photogenerated charges. Yet, the fill factor of OSCs is usually almost entirely governed by recombination processes that scale with the first-order of the light intensity. This linear loss was often interpreted to be a consequence of geminate or trap-assisted recombination. Numerical simulations show that this linear dependence is a direct consequence of the large amount of excess dark charge near the contact. The first-order losses increase with decreasing mobility of minority carriers and we discuss the impact of several material and device parameters on this loss mechanism. This work highlights that OSCs are especially vulnerable to injected charges as a result of their poor charge transport properties. This implicates that dark charges need to be better accounted for when interpreting electro-optical measurements and charge collection based on simple figures of merit.// Charge extraction in organic solar cells (OSCs) is commonly believed to be limited by bimolecular recombination of photogenerated charges. Yet, the fill factor of OSCs is usually almost entirely governed by recombination processes that scale with the first-order of the light intensity. This linear loss was often interpreted to be a consequence of geminate or trap-assisted recombination. Numerical simulations show that this linear dependence is a direct consequence of the large amount of excess dark charge near the contact. The first-order losses increase with decreasing mobility of minority carriers and we discuss the impact of several material and device parameters on this loss mechanism. This work highlights that OSCs are especially vulnerable to injected charges as a result of their poor charge transport properties. This implicates that dark charges need to be better accounted for when interpreting electro-optical measurements and charge collection based on simple figures of merit.
Rafizadeh Saeid, Wienands Karl, Mundt Laura, Bett Alexander, Schulze Patricia, Andreani Lucio, Hermle Martin, Glunz Stefan, Goldschmidt Jan
The Role of Surface Passivation Layer Preparation on Crystallization and Optoelectronic Performance of Hybrid Evaporated-Spincoated Perovskite Solar Cells
2019 IEEE Journal of Photovoltaics, Seite: 1–8
KurzfassungThe main advantages of the organic–inorganic halide perovskite solar cell technology are high efficiencies achieved after short development time in combination with rather simple solutionbased processing. In this paper, we address remaining challenges by presenting a low-temperature two-step hybrid evaporationspincoating method that combines high reproducibility with easy fabrication and high stabilized efficiencies, which is compatible with the processing of pervoskite silicon tandem solar cells and avoids using hazardous solvents such as dimethylformamide and dimethylsulfoxide. Lead iodide (PbI2) is thermally evaporated and subsequently converted into a compact crystalline perovskite layer by methylammonium iodide spincoating. Moreover, the role of the interface passivation between perovskite absorber and electron transport layer on crystallization and optoelectronic properties of the perovskite absorber is investigated within a systematic thickness and concentration variation of [6, 6]-phenyl-C61-butyric acid methyl ester passivation layer and by analyzing charge extraction with spatial and time resolved photoluminescence measurements. With an optimized charge extraction, 18.2% stabilized efficiency under one sun illumination is achieved. This is the highest value reported so far for the single junction perovskite solar cells made by a two-step hybrid evaporation-spincoating method.
Ruf T, Mauck M, Megnin C, Winkler M, Hillebrecht H, Hanemann T
The influence on sintering and properties of sodium niobate (NaNbO3) ceramics by “non-stoichiometric” precursor compositions
2019 Materials Chemistry and Physics, Band: 229, Seiten: 437 - 447
KurzfassungNaNbO3 powders from different processing routes and various near equimolar concentrations of metal ions were sintered to ceramics and investigated concerning their structural and electric properties. The particle sizes obtained from two different conventional solid state reactions and one solvent – based route were in the range of 40 nm - 10 μm and the variation of precursor composition covered 48–52 mol% Na. Sintering temperatures were defined by the deviation from the equimolar composition between 950 and 1375 °C, which is due to the coexistence of second phases Na3NbO4, Na2Nb4O11 and NaNb3O8. Small particle sizes (40 nm–3 μm) on deviation from equimolar composition resulted in higher relative densities at lower sintering temperatures. The coexistence of second phases influences structural and electric characteristics. The former were investigated by X-ray Diffraction (XRD) for phase analysis, Scanning Electron Microscopy (SEM) for defining grain sizes and Energy-Dispersive X-ray (EDX) spectroscopy for deciding the elemental composition. The impact on electrical conductivity and dielectric properties are examined by impedance spectroscopy and the resulting d33 coefficients of 15–29 pC/N are measured by Berlincourt method.

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J.P. Hays, K. Mitsakakis, S. Luz, A. van Belkum, K. Becker, A. van den Brue, S. Harbarth, J. H. Rex, G. Skov Simonsen, G. Werner, V. Di Gregori, G. Lüdke, T. van Staa, J. Moran-Gilad, T. T. Bachmann, on behalf of the JPIAMR AMR-RDT
The successful uptake and sustainability of rapid infectious disease and antimicrobial resistance point-of-care testing requires a complex ‘mix-and-match’ implementation package
2019 Eur J Clin Microbiol, Band: 38, Seiten: 1015 - 1022
KurzfassungThe emergence and spread of antimicrobial resistance is one of the major global issues currently threatening the health and wealth of nations, with effective guidelines and intervention strategies urgently required. Such guidelines and interventions should ideally be targeted at individuals, communities, and nations, requiring international coordination for maximum effect. In this respect, the European Joint Programming Initiative on Antimicrobial Resistance Transnational Working Group ‘Antimicrobial Resistance - Rapid Diagnostic Tests’ (JPIAMR AMR-RDT) is proposing to consider a ‘mix-and-match’ package for the implementation of point-of-care testing (PoCT), which is described in this publication. The working group was established with the remit of identifying barriers and solutions to the development and implementation of rapid infectious disease PoCT for combatting the global spread of antimicrobial resistance. It constitutes a multi-sectoral collaboration between medical, technological, and industrial opinion leaders involved in in vitro diagnostics development, medical microbiology, and clinical infectious diseases. The mix-and-match implementation package is designed to encourage the implementation of rapid infectious disease and antimicrobial resistance PoCT in transnational medical environments for use in the fight against increasing antimicrobial resistance.
Wieland T, Kotthaus K, Bergmann M, Ledernez L, Altenburger M, Urban G
Thermal sensor system for the measurement of biofilm formation and bactericidal efficacy by the transient spark disinfection in real-time
2019 6th International Conference on Bio-Sensing Technology, Kuala Lumpur, Malaysia
B.P. Bruno, A. Treffer, R. Grunwald, U. Wallrabe
Thermally actuated free-form MEMS mirrors
2019 Int. Conference on Optical MEMS and Nanophotonics 2019, Daejeon, Korea , Seiten: 82 - 83
Linseis V., Völklein F., Reith H., Nielsch K., Woias P.
Thermoelectric properties of Au and Ti nanofilms, characterized with a novel measurement platform
2019 15th European Conference on Thermoelectrics Materials Today: Proceedings, Band: 8, Seiten: 517 - 522
KurzfassungRecently we reported on a unique, chip based measurement platform for the complete characterization of the in-plane thermoelectric properties of thin film samples. For the validation of the platform, good thermoelectric materials with a low thermal conductivity and large Seebeck coefficient have already been characterized. In order to check the capability of the platform, with regard to new material classes and applications, we performed measurements of the electrical conductivity σ, thermal conductivity λ and Seebeck coefficient S of two 100 nm Au and Ti thin film samples with considerably larger thermal and electrical transport values. The measured thermoelectric properties of both films show clear size effects, with a remarkably reduced electrical and thermal conductivity as well as Seebeck coefficient, compared to the bulk material, respectively. The Lorenz number of the thin films, which are calculated from the measured electrical and thermal conductivities, are equal to the bulk value, predicted by the Wiedemann–Franz law.
Widyaya V T, Müller C, Al-Ahmad A, Lienkamp K
Three-Dimensional, Bifunctional Microstructured Polymer Hydrogels Made From Polyzwitterions and Antimicrobial Polymers
2019 Langmuir, Seiten: 1211 - 1226
Maier D, Laubender E, Basavanna A, Schumann S, Güder F, Urban G, Dincer C
Toward Continuous Monitoring of Breath Biochemistry: A Paper-Based Wearable Sensor for Real-Time Hydrogen Peroxide Measurement in Simulated Breath
2019 Acs Sensors, Band: 4, Nummer: 11, Seiten: 2945 - 2951
KurzfassungExhaled breath contains a large amount of biochemical and physiological information concerning one’s health and provides an alternative route to noninvasive medical diagnosis of diseases. In the case of lung diseases, hydrogen peroxide (H₂O₂) is an important biomarker associated with asthma, chronic obstructive pulmonary disease, and lung cancer and can be detected in exhaled breath. The current method of breath analysis involves condensation of exhaled breath, is not continuous or real time, and requires two separate and bulky devices, complicating the periodic or long-term monitoring of a patient. We report the first disposable paper-based electrochemical wearable sensor that can monitor exhaled H₂O₂ in artificial breath calibration-free and continuously, in real time, and can be integrated into a commercial respiratory mask for on-site testing of exhaled breath. To improve precision for sensing H₂O₂, we perform differential electrochemical measurement by amperometry in which screen-printed Prussian Blue-mediated and nonmediated carbon electrodes are used for differential analysis. We were able to measure H₂O₂ in simulated breath in a concentration-dependent manner in real time, confirming its functionality. This proposed system is versatile, and by modifying the chemistry of the sensing electrodes, our method of differential sensing can be extended to continuous monitoring of other analytes in exhaled breath.

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Lindauer M, Feurer M, Eggensperger K, Biedenkapp A, Hutter F
Towards Assessing the Impact of Bayesian Optimization’s Own Hyperparameters
2019 IJCAI 2019 DSO Workshop
Biedenkapp A, Bozkurt H, Hutter F, Lindauer M
Towards White-box Benchmarks for Algorithm Control
2019 IJCAI 2019 DSO Workshop
P. Koltay
Towards a generic 3D-Bioprinting Platform
2019 IS2M Annual Meeting, 3D & 4D printing in Upper Rhine Valley, Mulhouse/France, 06. - 07. 06. 2019
A. Brunauer, B. Breiner, D. Kainz, R. Verboket, F. von Stetten, R. Zengerle, N. Paust, T. Hutzenlaub, Susanna M. Früh
Towards digital diagnostic devices - From smart membrane cartridges to highly integrated test stripes
2019 Diagnostics-4-Future, 27. – 28. 11. 2019, Konstanz
M. Buehler, F. Hegge, P. Holzapfel, S. Thiele
Towards direct membrane deposition (DMD) for PEM water electrolyzers – development of innovative electrodes deposited directly on porous transport substrates
2019 f-cell Stuttgart, 18.- 19. September 2018
Landenberger B, Rohrbach A
Towards non-blind optical tweezing: Finding grabbing positions by off-focus interferometric 3D imaging of refractive index changes
2019 submitted
Ledernez L, Bruch R, Altenburger M, Bergmann M, Urban G
Transient Spark for Bacterial Cleaning of Dental Microcavities
2019 Plasma Medicine, Band: 9, Nummer: 1, Seiten: 39 - 48
KurzfassungIn this work, we present a method that can be used for the disinfection of microcavities such as tooth root canals. The device is aimed to be introduced inside the root canal. The parameters are chosen so that it produces ROS to inactivate bacteria and develops little to no temperature increase within the root canal. Its effect on bacteria is demonstrated using E. coli spread on Agar in a Petri dish.
Herr S, Buse K, Breunig I
Tunable single-frequency lasing in a microresonator
2019 Opt Express, Band: 27, Nummer: 11, Seiten: 15351 - 15358
KurzfassungWhispering-gallery-mode resonators made of laser-active materials can serve as efficient microphotonic coherent light sources. However, the majority of experimental realizations relies on expensive pump light sources like narrow-linewidth or pulsed laser systems, which is inappropriate for most applications. In order to overcome this, we present a whispering-gallery laser system without the need for an expensive pump light source and at the same time with unprecedented laser performance: A laser-active resonator made of Nd:YVO 4 is non-resonantly excited, employing a low-cost laser diode without any external frequency stabilization, emitting up to 100 mW optical power around 810 nm wavelength. Continuous-wave single-frequency lasing at 1064 nm wavelength is achieved with directed laser light emission in the mW-regime. The temporal power and frequency stability are within ±1.5 % and ±30 MHz, respectively. Modehop-free frequency fine-tuning is achieved exceeding 11 GHz tuning range by changing the temperature of the cavity. Faster tuning can be expected when applying geometric or electro-optic instead of thermal tuning.
Boehler C, Oberueber F, Asplund M
Tuning drug delivery from conducting polymer films for accurately controlled release of charged molecules.
2019 J Control Release, Band: 304, Seiten: 173 - 180
KurzfassungSpatio-temporally controlled drug release based on conducting polymer films offers a powerful technology to improve the tissue integration for implantable neuroprobes. We here explore the release efficiency of such systems in order to improve the understanding of the release mechanism and allow for optimized implementation of this technology into future drug release applications. By exposing drug loaded PEDOT coatings of different thicknesses to a multitude of release signals, along with optimizing the steps during the polymer synthesis, we could identify a highly reproducible electrostatically controlled drug release next to a slow diffusion driven release component. The release efficiency was moreover observed to be higher for a cyclic voltammetry signal in comparison to release driven by a constant potential. Biphasic current pulses, as used during neural stimulation, did not allow for long enough diffusion times to yield efficient active drug expulsion from the polymer films. A quantitative analysis could confirm an overall linear dependency between drug release and film thickness. The amount of drug released in response to the trigger signals was however not linearly correlated with the amount of charge applied. By combining these findings we could develop a model which accurately describes the drug release mechanism from a PEDOT film. The proposed model thereby points the way for how actively controlled, and diffusion related, release can be tuned for obtaining delivery dynamics tailored to specific applications.
Alexander J Bett, Patricia SC Schulze, Kristina M Winkler, Özde S Kabakli, Ines Ketterer, Laura E Mundt, S Kasimir Reichmuth, Gerald Siefer, Ludmila Cojocaru, Leonard Tutsch, Martin Bivour, Martin Hermle, Stefan W Glunz, Jan Christoph Goldschmidt
Two‐terminal Perovskite silicon tandem solar cells with a high‐Bandgap Perovskite absorber enabling voltages over 1.8 V
2019 Prog Photovoltaics
Thorsten Falk,, Dominic Mai,, Robert Bensch,, Özgün Çiçek,, Ahmed Abdulkadir,, Yassine Marrakchi,, Anton Böhm,, J. Deubner,, Z. Jäckel,, K. Seiwald,, A. Dovzhenko,, O. Tietz,, C. Dal Bosco,, S. Walsh,, D. Saltukoglu,, T. Tay,, M. Prinz,, K. Palme,, M. Simons,, I. Diester,, Thomas Brox,, Olaf Ronneberger
U-Net – Deep Learning for Cell Counting, Detection, and Morphometry
2019 Nat Methods
KurzfassungU-Net is a generic deep-learning solution for frequently occurring quantification tasks such as cell detection and shape measurements in biomedical image data. We present an ImageJ plugin that enables non-machine-learning experts to analyze their data with U-Net on either a local computer or a remote server/cloud service. The plugin comes with pretrained models for single-cell segmentation and allows for U-Net to be adapted to new tasks on the basis of a few annotated samples.

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M.C. Wapler, U. Wallrabe
Ultrafast and compact varifocal lens.
2019 IEEE MicroElectro Mechanicals Systems, MEMS 2019, Seoul, Korea 2019 , Seiten: 938 - 941
M.C. Wapler, U. Wallrabe
Ultraschnelle und ultrakompakte adaptive Linse
2019 Mikrosystemtechnikkongress 2019 ,Berlin, Germany VDE Verlag Berlin, Seiten: 186 - 188
F. Staab, F. Balle
Ultrasonic torsion welding of ageing-resistant Al/CFRP joints: Properties, microstructure and joint formation
2019 Ultrasonics, Nummer: 93, Seiten: 139 - 144
Bruch R, Urban G, Dincer C
Unamplified gene sensing via Cas9 on graphene
2019 Nat Biomed Eng, Band: 3, Seiten: 419 - 420
KurzfassungAn electrical biosensor that relies on the binding of target nucleic acid sequences to Cas9 immobilized on a graphene field-effect transistor enables the rapid detection of mutations in purified samples without the need for nucleic acid amplification.

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Messmer C., Fell A., Feldmann F., Schön J., Hermle M.
Upgrade PERC with TOPCon: Efficiency Potential by Taking into Account the Electrical Gains and Optical Losses
In: 36th EU PVSEC
2019, ,
Kurzfassungsiehe pdf!
Sturman B, Podivilov E, Werner C, Breunig I
Vectorial perturbation theory for axisymmetric whispering gallery resonators
2019 Phys Rev A, Band: 99, Seite: 013810
KurzfassungWe propose a vectorial perturbation theory for axially symmetric, generally nonspherical whispering gallery resonators made of isotropic and anisotropic optical materials. It is based on analysis of the leading terms in the coupled equations for independent light-field components, as derived from Maxwell's equations, and true boundary conditions. Strong localization of the whispering gallery modes (WGMs) near the resonator rim, controlled by the azimuth modal number m, is the main prerequisite for our analysis. The theory gives high-precision expressions for the WGM frequencies and modal functions, including the evanescent effects. One of important applications of the theory is analysis of anticrossings of the WGM resonances in anisotropic resonators detected in experiments. Simple relations for the frequency avoidance gaps during the anticrossings are derived and compared with experimental data obtained in lithium-niobate-based WGM resonators. We show also that the vectorial effects substantially restrict the field of applicability of the scalar WGM models.
Sebastian Weydner-Volkmann, Linus Feiten
Vertrauensstiftende Videoüberwachung?
2019 digma: Zeitschrift für Datenrecht und Informationssicherheit, Band: 19, Nummer: 4, Seiten: 218 - 221
Wendler D, De Dorigo D, Manoli Y
Vollstaendig versenkbare neuronale Sonde mit 144 Kanaelen und einem Inkrementellen Delta-Sigma-A/D-Umsetzer unter jeder Elektrode
2019 Proceedings of the Mikrosystemtechnik-Kongress, Seiten: 436 - 439
J. Zhang, L. Tai, P. Yun, Y. Xiong, M. Liu, J. Boedecker, W. Burgard
Vr-goggles for robots: Real-to-sim domain adaptation for visual control
2019 IEEE Robotics and Automation Letters, Band: 4, Nummer: 2, Seiten: 1148 - 1155
Schössler T, Schön F, Lemier C, Urban G
Wafer level approach for the investigation of the long-term stability of resistive platinum devices at elevated temperatures
2019 IEEE International Reliability Physics Symposium (IRPS), Monterey, USA
KurzfassungIn this work, we present a new wafer level based approach to evaluate the long-term stability of thin film platinum resistors. This approach enables on the one hand the evaluation of hundreds of devices manufactured with the same processes parameters and exposed to the same stress conditions. Thus, statistical relevant conclusions can be drawn with respect to drift levels in the sub-percent range. On the other hand, the drift pattern on the wafer gives hints to the cause of drift. First investigations with this new approach show a significant influence of the silicon oxide stoichiometry of silicon-rich oxide cover layers on platinum resistors at stress temperatures of only 140°C to 250°C.
Kleber C, Lienkamp K, Rühe J, Asplund M
Wafer‐Scale Fabrication of Conducting Polymer Hydrogels for Microelectrodes and Flexible Bioelectronics
2019 Advanced Biosystems, Band: 3, Nummer: 8
KurzfassungFuture‐oriented directions in neural interface technologies point towards the development of multimodal devices that combine different functionalities such as neural stimulation, neurotransmitter sensing, and drug release within one platform. Conducting polymer hydrogels (CPHs) are suggested as materials for the coating of standard metal electrodes to add functionalities such as local delivery of therapeutic drugs. However, to make such coatings truly useful for multimodal devices, it is necessary to develop process technologies that allow the micropatterning of CPHs onto selected electrode sites. In this study, a wafer‐scale fabrication procedure is presented, which is used to coat the CPH, based on the hydrogel P(DMAA‐co‐5%MABP‐co‐2,5%SSNa) and the conducting polymer poly(3,4‐ethylenedioxythiophene) (PEDOT), onto flexible neural probes. The resulting material has favorable properties for the generation of recording electrodes and in addition offers a convenient platform for biofunctionalization. By controlling the PEDOT content within the hydrogel matrix, charge injection limits of up to 3.7 mC cm−2 are obtained. Long‐term stability is tested by immersing coated samples in phosphate‐buffered saline solution at 37 °C for 1 year. Non‐cytotoxicity of the coatings is confirmed with a direct cell culture test using a fluorescent neuroblastoma cell line.
Tatarchenko M, Brox T., Richter S. R., Ranftl R., Li Z., Koltn V.
What Do Single-view 3D Reconstruction Networks Learn?
2019 CVPR 2019 IEEE T Vis Comput Gr
KurzfassungConvolutional networks for single-view object reconstruction have shown impressive performance and have become a popular subject of research. All existing techniques are united by the idea of having an encoder-decoder network that performs non-trivial reasoning about the 3D structure of the output space. In this work, we set up two alternative approaches that perform image classification and retrieval respectively. These simple baselines yield better results than state-of-the-art methods, both qualitatively and quantitatively. We show that encoder-decoder methods are statistically indistinguishable from these baselines, thus indicating that the current state of the art in single-view object reconstruction does not actually perform reconstruction but image classification. We identify aspects of popular experimental procedures that elicit this behavior and discuss ways to improve the current state of research.

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Breunig I, Buse K
Whispering gallery optical parametric oscillators: Just a scientific oddity?
2019 Nonlinear Frequency Generation and Conversion: Materials and Devices XVIII, San Francisco, CA, United States Proceedings of SPIE, Band: 10902, Seite: 10902T
KurzfassungOptical parametric oscillators (OPOs) convert the frequency of laser light to almost arbitrary values. Nowadays, they serve as wavelength-agile light sources for spectroscopic applications as well as photon generators for quantum-optical experiments. Conventional OPOs are based on a nonlinear-optical crystal surrounded by a mirror cavity. Regarding the cavity, one often finds the following rule of thumb: the more waves are resonant, the lower is the oscillation threshold and the more difficult is the wavelength tuning. In whispering-gallery-resonator-based OPOs (WGR OPOs), light is guided by total internal reflection in a millimeter-sized spheroidally-shaped nonlinear-optical crystal. Thus, these devices are intrinsically triply resonant. Indeed, they provide microwatt-level oscillation thresholds, i.e., the lowest values of all OPO configurations. However, following the abovementioned rule, their applicability in fields beyond fundamental science might be questionable, because the most striking feature of an OPO, i.e., the wavelength tunability, is hampered. Nevertheless, several experimental studies revealed that the output wavelengths of WGR OPOs could be tuned in well-defined steps over hundreds of nanometers by temperature variation. Combined with strategies for mode-hop free tuning, it is possible, e.g., to tune the output wavelength in a controlled way until it meets MHz-wide resonances. This is sufficient for high-resolution spectroscopy. WGR OPOs are nowadays operated around various center frequencies, covering the visible-to-mid-infrared spectral range. These light sources - despite of their intrinsic triple resonance - might serve as compact and wavelength-agile devices for various applications.
Tobias Seufert, Christoph Scholl
fbPDR: In-depth Combination of Forward and Backward Analysis in Property Directed Reachability
2019 Conference on Design, Automation and Test in Europe (DATE)
KurzfassungWe describe a thoroughly interweaved forward and backward version of PDR/IC3 called fbPDR. Motivated by the complementary strengths of PDR and Reverse PDR and by related work showing the benefits of collaboration between the two, fbPDR lifts the combination to a new level. We lay the theoretical foundations for sharing information represented by learned lemmas between PDR and Reverse PDR and demonstrate the effectiveness of our approach on benchmarks from the Hardware Model Checking Competition.
Tobias Seufert, Christoph Scholl
fbPDR: In-depth Combination of Forward and Backward Analysis in Property Directed Reachability (extended abstract)
2019 GI/ITG/GMM Workshop “Methoden und Beschreibungssprachen zur Modellierung und Verifikation von Schaltungen und Systemen”
KurzfassungWe describe a thoroughly interweaved forward and backward version of PDR/IC3 called fbPDR. Motivated by the com- plementary strengths of PDR and Reverse PDR, fbPDR enables beneficial collaboration between the two and lifts the combination to a new level. We lay the theoretical foundations for sharing information between PDR and Reverse PDR and demonstrate the effectiveness of our approach on benchmarks from the Hardware Model Checking Competition.

2018

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M. Becker
Untersuchungen zum seriellen Ultraschallpunktschweißen von Aluminium/Stahl-Verbunden
2018 DGM Fachausschuss Hybride Werkstoffe und Strukturen zusammen mit dem Arbeitskreis Mischverbindungen mit Aluminium des Fachausschusses Aluminium, Kaiserslautern
Rickert J, Schuettler M, Stolle C, Wenzel F, Grigat N, Kohler F, Obert M, Rieger S, Stieglitz T, Ball T
Brain interchange: A novel brain computer interface system.
2018 Society for Neuroscience Meeting 3.-7.11.2018, San Diego, CA, USA SfN
KurzfassungTreatments of neurological disorders utilizing active implantable devices which interact with the activity of the brain are demonstrating increasingly promising advances. Next to the continuous improvement of established therapies for movement disorders, Epilepsy and chronic pain, new therapies for depression, paralysis and many more are under investigation. The current technology available for the development of these treatments is derived from the first active implants, the cardiac pacemakers, developed in mid to late 20th century: battery powered devices with few channels and limited intelligence. The Brain Interchange technology, developed in a joint effort by the University of Freiburg and CorTec, is a new system, enabling battery-free, intelligent closed-loop applications with up to 32 channels in its first version. The implantable part, including a novel hermetic encapsulation, custom electronics and firmware, were presented last year. The electrode technology will be presented in a companion poster. Here we present the progress in the development of the external parts and the software of the system and discuss potential applications. The first version of the external parts of the system manages power and communication with the implant, as well as the software for controlling the system. Physically, these parts consist of a head piece, a relay- and a controller unit. The main functions, accessible via a graphical user interface, are: managing recording and stimulation, measuring impedance and reading out humidity, temperature, supply voltage and unique ID of the implant. A filter pipeline for signal processing and feature extraction, suitable for computationally demanding closed-loop algorithms, and the control of external devices with minimal latency has also been implemented. For future collaboration partners programmable interfaces for C++, Matlab and Python are available. The development has been done under ISO-13485 and according to EN 62304. Potential applications range from closed-loop stimulation for the treatment of Parkinson’s disease or Epilepsy to the control of assistive technology in chronic paralysis or for rehabilitation purposes. Further applications could lie in closed-loop treatments in the peripheral nervous system.
Johnston M, Boehm T, Joseph K, Asplund M, Hofman U G, Thiele S, Haas C A,
Semi-automated quantification of the CNS immune response at the probe-tissue-interface.
2018 Society for Neuroscience Meeting 3.-7.11.2018, San Diego, CA, USA SfN
KurzfassungThe design of microelectrodes for electrical stimulation or recording of neuronal activity increasingly focuses on biocompatibility. Still, implantation of a cortical probe evokes a sustained sterile inflammatory response (SIR) within brain tissue. This manifests in activation of microglia, astrocytic scarring, neurodegeneration, and other molecular and morphological changes that may ultimately lead to failure of the device. To visualize the extent of the spatially limited tissue response, immunohistochemistry (IHC) is the well-established method of choice. But while qualitative assessment of resulting microscopic images can be easily accomplished, quantitative analysis poses a larger challenge to the investigator. This is partly due to the large number of images required to adequately represent the SIR, but also accounted for by high variability within and across tissue sections and animals. To this point there have been several publications that employed custom-built codes for quantification of IHC signals at the implantation sites of cortical electrodes. However, these differ greatly with respect to their evaluation methods and are not provided for open access. Hence, it is difficult to compare the extent of the SIR across different or even identical electrode types utilized by different groups. We therefore aimed at creating a semi-automated quantification method that allows fast and flexible delineation of the signal-intensity distribution from the site of lesion towards healthy brain tissue, based on the widely used software tools ImageJ and MATLAB. In this study cortical implantation of lithographically fabricated, flexible polyimide probes (10µm thickness with iridium oxide electrodes) was performed on adult Sprague Dawley rats. After different survival times transversal tissue sections were immunohistochemically stained and imaged with an epifluorescence microscope. Subsequent signal quantification was performed in concentric distance bins with flexibly adaptable size (the shape of the latter is determined by the respective cavity shape of the individual image). Processing artifacts can optionally be selected and excluded from the analysis. Apart from that normalization parameters can be modified towards the needs of the study design. This also yields the possibility of using differently processed and/or imaged tissue sections within one experimental population. Our approach provides a novel, straightforward tool for quantification of IHC-images that is versatile and adaptable for various purposes.
Johnston M, Boehm T, Joseph K, Asplund M, Hofman U G, Thiele S, Haas C A
Semi-automated quantification of the CNS immune response at the probe-tissue-interface.
2018 Society for Neuroscience Meeting 3.-7.11.2018, San Diego, CA, USA SfN
KurzfassungThe design of microelectrodes for electrical stimulation or recording of neuronal activity increasingly focuses on biocompatibility. Still, implantation of a cortical probe evokes a sustained sterile inflammatory response (SIR) within brain tissue. This manifests in activation of microglia, astrocytic scarring, neurodegeneration, and other molecular and morphological changes that may ultimately lead to failure of the device. To visualize the extent of the spatially limited tissue response, immunohistochemistry (IHC) is the well-established method of choice. But while qualitative assessment of resulting microscopic images can be easily accomplished, quantitative analysis poses a larger challenge to the investigator. This is partly due to the large number of images required to adequately represent the SIR, but also accounted for by high variability within and across tissue sections and animals. To this point there have been several publications that employed custom-built codes for quantification of IHC signals at the implantation sites of cortical electrodes. However, these differ greatly with respect to their evaluation methods and are not provided for open access. Hence, it is difficult to compare the extent of the SIR across different or even identical electrode types utilized by different groups. We therefore aimed at creating a semi-automated quantification method that allows fast and flexible delineation of the signal-intensity distribution from the site of lesion towards healthy brain tissue, based on the widely used software tools ImageJ and MATLAB. In this study cortical implantation of lithographically fabricated, flexible polyimide probes (10µm thickness with iridium oxide electrodes) was performed on adult Sprague Dawley rats. After different survival times transversal tissue sections were immunohistochemically stained and imaged with an epifluorescence microscope. Subsequent signal quantification was performed in concentric distance bins with flexibly adaptable size (the shape of the latter is determined by the respective cavity shape of the individual image). Processing artifacts can optionally be selected and excluded from the analysis. Apart from that normalization parameters can be modified towards the needs of the study design. This also yields the possibility of using differently processed and/or imaged tissue sections within one experimental population. Our approach provides a novel, straightforward tool for quantification of IHC-images that is versatile and adaptable for various purposes.
Valle G, Mazzoni A, Iberite F, D'Anna E, Strauss I, Granata G, Controzzi M, Clemente F, Rognini G, Cipriani C, Stieglitz T, Petrini FM, Rossini PM, Micera S
Biomimetic intraneural sensory encoding enhances sensation naturalness, tactile sensitivity and manual dexterity in a bidirectional prosthesis.
2018 Society for Neuroscience Meeting 3.-7.11.2018, San Diego, CA, USA SfN
KurzfassungThe lack of sensory feedback during grasping is a very important limitation of current hand prostheses, which affects their everyday usability. In the last years several research groups have demonstrated that nerve stimulation by implantable peripheral nerve interfaces can be reliably used to restore sensory feedback to upper limb amputees. They have shown that direct neural stimulation of peripheral nerves can effectively provide tactile information to the amputees, controlling the sensation intensity by modulating either the amplitude or the frequency of the injected stimuli. However, efforts are still necessary to identify encoding strategies converting tactile information into neural stimulation patterns capable of eliciting percepts that are both felt as natural and effective for prosthesis control. In this study, we compared the naturalness and efficacy of a set of encoding strategies based on biomimetic (model-driven) frequency modulation, amplitude modulation, or combinations of both. Such strategies were used to deliver neural stimulation to a trans-radial amputee implanted with intraneural electrodes (TIMEs). Frequency modulation was based on a biomimetic model (TouchSim) able to reproduce nerve activation patterns of the multifaceted mechanics of the skin and mechano-transduction. It was perceived as more natural, while amplitude modulation enabled better performance in tasks requiring fine identification of the applied force. Notably, hybrid encoding strategies involving both amplitude and frequency modulation were able to convey at least as much information as the amplitude modulation (for the completion of tasks), and were perceived at least as natural as the frequency modulation. The hybrid strategies improved the gross manual dexterity of the subjects during functional tasks while maintaining high manual accuracy. They also improved the level of prosthesis embodiment and reduced abnormal body perceptions of the phantom limb (“telescoping”). Encoding strategies based on the combination of biomimetic frequency modulation and amplitude modulation are able to provide highly sensitive and natural percepts and should be preferred in bidirectional prosthesis use.
Bast H, Brosi P, Storandt S
Efficient Generation of Geographically Accurate Transit Maps
2018 SIGSPATIAL
KurzfassungWe present LOOM (Line-Ordering Optimized Maps), a fully automatic generator of geographically accurate transit maps. The input to LOOM is data about the lines of a given transit network, namely for each line, the sequence of stations it serves and the geographical course the vehicles of this line take. We parse this data from GTFS, the prevailing standard for public transit data. LOOM proceeds in three stages: (1) construct a so-called line graph, where edges correspond to segments of the network with the same set of lines following the same course; (2) construct an ILP that yields a line ordering for each edge which minimizes the total number of line crossings and line separations; (3) based on the line graph and the ILP solution, draw the map. As a naive ILP formulation is too demanding, we derive a new custom-tailored formulation which requires significantly fewer constraints. Furthermore, we present engineering techniques which use structural properties of the line graph to further reduce the ILP size. For the subway network of New York, we can reduce the number of constraints from 229,000 in the naive ILP formulation to about 3,700 with our techniques, enabling solution times of less than a second. Since our maps respect the geography of the transit network, they can be used for tiles and overlays in typical map services. Previous research work either did not take the geographical course of the lines into account, or was concerned with schematic maps without optimizing line crossings or line separations.
Stieglitz T, Vomero M, Joseph K, Johnston M, Ciarpella F, Kirsch M, Boehm T, Fagida L, Thiele S, Haas C A, Hofmann U G, Asplund M
How flexibility and probe size influence chronic reliability: A study on batch processed polyimide-based intracortical neural arrays.
2018 Society for Neuroscience Meeting 3.-7.11.2018, San Diego, CA, USA SfN
KurzfassungFor short and long term neural applications, it is desirable to reduce or ideally eliminate the foreign body response to the implanted devices. One way to do so is to minimize the size of the device and thus the bending stiffness of the implant affecting the soft brain tissue. Recent findings in the field of neural engineering have led to the development of ultra-thin and ultra-flexible intracortical electrode arrays, presumably “invisible” for the host tissue and unable to trigger a noticeable immune response in long-term applications. However, reduced probe size comes at the cost of fewer individual electrodes, more challenging handling and fabrication, as well as mechanical properties less suited for chronic in vivo experiments. It is therefore important to better understand which design parameters offer the best trade-off. In this study, we compare two kinds of polyimide-based electrode arrays which differ only in their width: one kind is only 30 µm wide while the other has a width of 100 µm. Both device types are 12 µm thick and display electrodes 20 µm in diameter, spaced so that they target each one of the six cortical layers. The devices were chronically implanted into the brain of adult rat models and different time points were selected for perfusion and subsequent evaluation and quantification of the differences in the elicited immune response of the brain (via immunohistochemistry). Some of the probes were also used for long term recording of electrophysiological activity. Control devices (i.e. identical but without connector) were used to study the influence of the connector and cement on the short and long term tissue reaction to the implants. The wider probes (100 µm width) featured a pair of identical electrodes per cortical layer (instead of a single one) with the aim to achieve a better reconstruction of the neuronal configuration and status around the probe. The study’s goal is to systematically investigate the influence of selected geometrical parameters on the performance of thin-film polyimide based neural prostheses in vivo. Key concept: This study is part of a bigger project which aims to find a clear answer to the question “how small does a neural probe have to be to become invisible for the host tissue and yet to record long term high quality signals?”
Badi M, Wurth S, Kaeser M, Cvancara P, Stieglitz T, Courtine G, Capogrosso M, Bloch J, Rouiller E, Micera S
Neuroanatomical, computational, and experimental evidences for the use of intraneural peripheral nerve stimulation to induce fine hand movements.
2018 Society for Neuroscience Meeting 3.-7.11.2018, San Diego, CA, USA SfN
KurzfassungCervical spinal cord injury (SCI) and stroke severely impact grasping movements required for activities of daily living. Intraneural peripheral nerve stimulation enables specific activation of passing fibers. This paradigm has restored precise leg movements in animal models of SCI and selective sensation in human amputees. Intraneural peripheral nerve stimulation may also restore fine grasping in paralyzed hands, but this possibility has not been investigated. Here, we assess the feasibility of using intrafascicular electrical stimulation of peripheral nerves to produce precise hand movements in the non-human primate (NHP). We first extensively characterized the branching points of the median, radial, and ulnar nerves to their target muscles in the adult macaca fascicularis in order to identify the optimal implantation site for intraneural electrodes. We then reconstructed the tridimensional structure of the identified portion of each nerve in order to analyze the fascicular organization within the nerve at this level. Additionally, we assessed the distribution of motor fibers within the fascicles using immunohistochemistry. The obtained data was used to build realistic computational models of intraneural peripheral nerve stimulation for each nerve. The simulations confirmed the advantages of using intrafascicular electrodes to induce precise hand movements, demonstrating the possibility to selectively recruit patches of motor fibers without a priori knowledge of the electrode placement. We validated these results during electrophysiology experiments using transverse intrafascicular multichannel electrodes (TIMEs) implanted in the nerves of anesthetized NHPs. The stimulation achieved a selective recruitment of wrist and finger flexors and extensors in a reproducible manner across animals. We exploited these results to determine stimulation sequences that aimed at reproducing the muscle activation patterns underlying different grasping movements. For this, we mapped the obtained muscle recruitment maps to continuous EMG recordings during behavioral experiments and automatically optimized the selection of stimulation channels for each phase of the movement such as to reproduce the desired EMG pattern. Taken together, these results suggest encouraging evidences for the usability of the TIMEs to restore fine hand control after paralysis.
Gkogkidis CA, Bentler C, Wang X, Scheiwe C, Cristina Schmitz H, Stieglitz T, Ball T
Neurophysiological recording and stimulation using an off-the-shelf component wireless brain implant.
2018 Society for Neuroscience Meeting 3.-7.11.2018, San Diego, CA, USA SfN
KurzfassungBrain implants are increasingly used in neuroscientific research and medical applications. The requirements for such implants are diverse due to different experimental paradigms, scientific problem to address and demands by the researcher or clinician. To overcome these requirements, brain implants that can be built in a customized fashion might be beneficial. We previously introduced such a research grade wireless brain implant, developed exclusively using off-the-shelf components, which allows for quick and customized assembly. To verify the operability of the device during recording and stimulation, we present neurophysiological data obtained in an ovine animal model. During general anesthesia, the 63-channel µECoG electrode array was placed on the cortex of the sheep brain and both auditory and electrical stimuli were used to evoke neurophysiological responses which were recorded at a sampling rate of 4 kHz. Experiments performed in this study were conducted according to EU Directive 2010/63/EU and approved by the Animal Committee of the University of Freiburg and the Regierungspraesidium Freiburg, Germany. We show that our off-the-shelf research grade brain implant is capable to reliably record neurophysiological brain activity and electrically stimulate, evoking cortico-cortical responses, under in vivo conditions. The obtained neurophysiological activity showed clear responses with distinct spatio-temporal patterns to both auditory stimuli and cortical electrical stimulation, the latter with response patterns systematically depending on the exact stimulation site. In addition, spectral analysis revealed a neurophysiological frequency profile of the recorded activity which is in agreement with the well-known frequency power-law, i.e., the frequency-dependent linear decrease of log-log absolute spectral power. The presented neurophysiological data are in agreement with previously published recording and stimulation results obtained in sheep using different implantable devices that were not off-the-shelf. The results and their neurobiological implications as presented here highlight that off-the-shelf component brain interfacing devices are feasible and thus open up new avenues for implant-based research, especially when flexible requirements have to be addressed, as it is often the case in basic neuroscientific research. In the future we want to expand our approach to higher channel counts (128-channel high-resolution µECoG electrode arrays), higher recording sampling rate, and functional systems beyond the auditory system, as further use cases of our implant concept in neurotechnological research.
Petrini FM, Valle G, Bumbasirevic M, Barberi F, Guiraud D, Stieglitz T, Micera S, Raspopovic S
Sciatic intraneural stimulation evokes selective sensations from the phantom leg of trans-femoral amputees.
2018 Society for Neuroscience Meeting 3.-7.11.2018, San Diego, CA, USA SfN
KurzfassungLeg amputation destroys the communication between brain and environment during walking. Leg amputees rely on practically inexistent and often uncomfortable haptic feedback from the stump-socket interaction to monitor ground and obstacles contact, climb stairs, or walk in challenging environments. The lack of sensory feedback causes specific impairments to subjects that do not perceive the prosthesis as part of their body and risk falls, have decreased mobility, increased cognitive burden during walking resulting in prosthesis abandonment. In hand amputees, to restore the bidirectional communication, nerve interfaces have directly linked sensors readout from robotic hands to direct stimulation of nerves above injury. We believe that this strategy could also restore sensations from missing legs, with many scientific and technological barriers to overcome. It has never been proved that the electrical stimulation of the leg nerves by implantable neural interfaces can induce reliable sensations from missing leg and foot. In this work we developed a leg prosthesis restoring sensory feedback by means of direct nerve stimulation injected through transversal intraneural electrodes (TIME) implanted in the sciatic nerve. The stimulation was driven by the readout of pressure sensors placed under the prosthetic foot, and an encoder embedded in the prosthetic knee. We assessed the capability of 3 transfemoral amputees to recognize, blindfolded and acoustically insulated, the location where the prosthetic foot was touched and the degree of flexion of the prosthetic knee. The subjects were asked to recognize only touch, only flexion and then both conditions at the same time. We compared the performance when sensory feedback was restored and when no nerve stimulation was delivered. We found that single and double condition-tasks were executed on average respectively with a success rate of about 85% and 75%, when sensory feedback was provided. Without nerve stimulation the average success rate dropped to 25%.
Bast H, Brosi P
Sparse Map-Matching in Public Transit Networks with Turn Restrictions
2018 SIGSPATIAL
KurzfassungWe investigate the following map-matching problem: given a sequence of stations taken by a public transit vehicle and given the underlying network, find the most likely geographical course taken by that vehicle.We provide a newalgorithm and tool, which is based on a hidden Markov model and takes characteristics of transit networks into account. Our tool can be useful for the visualization of transit lines in map services, for transit data providers, and for an on-line matching of live passenger GPS data to a public transit vehicle. We evaluate our tool on real-world data, and compare it against two baselines. The shapes produced by our tool are very close to the true shapes. We have made our software publicly available,enabling full reproducibility of our results.
Johnston M, Böhm T, Joseph K, Asplund M, Hofmann UG, Thiele S, Stieglitz T, Haas CA
QUANTIFY – a semi-automated quantification of the CNS immune response at the probe-tissue-interface.
2018 Society for Neuroscience Meeting, Nov. 3rd-7th, 2018, San Diego, Ca, USA
Mohsen Ghaffari, Fabian Kuhn
Derandomizing Distributed Algorithms with Small Messages: Spanners and Dominating Set
2018 32nd International Symposium on Distributed Computing (DISC)
KurzfassungThis paper presents improved deterministic distributed algorithms, with O(log n)-bit messages, for some basic graph problems. The common ingredient in our results is a deterministic distributed algorithm for computing a certain hitting set, which can replace the random part of a number of standard randomized distributed algorithms. This deterministic hitting set algorithm itself is derived using a simple method of conditional expectations. As one main end-result of this derandomized hitting set, we get a deterministic distributed algorithm with round complexity 2^O(sqrt{log n * log log n}) for computing a (2k-1)-spanner of size O~(n^{1+1/k}). This improves considerably on a recent algorithm of Grossman and Parter [DISC'17] which needs O(n^{1/2-1/k} * 2^k) rounds. We also get a 2^O(sqrt{log n * log log n})-round deterministic distributed algorithm for computing an O(log^2 n)-approximation of minimum dominating set; all prior algorithms for this problem were either randomized or required large messages.
Mohamad Ahmadi, Fabian Kuhn, Rotem Oshman
Distributed Approximate Maximum Matching in the CONGEST Model
2018 32th Int. Symp. on Distributed Computing (DISC), New Orleans, USA
KurzfassungWe study distributed algorithms for the maximum matching problem in the CONGEST model, where each message must be bounded in size. We give new deterministic upper bounds, and a new lower bound on the problem. We begin by giving a distributed algorithm that computes an exact maximum (unweighted) matching in bipartite graphs, in O(n log n) rounds. Next, we give a distributed algorithm that approximates the fractional weighted maximum matching problem in general graphs. In a graph with maximum degree at most Delta, the algorithm computes a (1-eps)-approximation for the problem in time O(log(Delta W)/eps^2), where W is a bound on the ratio between the largest and the smallest edge weight. Next, we show a slightly improved and generalized version of the deterministic rounding algorithm of Fischer [DISC '17]. Given a fractional weighted maximum matching solution of value f for a given graph G, we show that in time O((log^2(Delta)+log^*n)/eps), the fractional solution can be turned into an integer solution of value at least (1-eps)f for bipartite graphs and (1-\eps).f.(g-1)/g for general graphs, where g is the length of the shortest odd cycle of G. Together with the above fractional maximum matching algorithm, this implies a deterministic algorithm that computes a (1-eps).f.(g-1)/g-approximation for the weighted maximum matching problem in time O(log(Delta W)/eps^2 + (log^2(Delta)+log^* n)/eps). On the lower-bound front, we show that even for unweighted fractional maximum matching in bipartite graphs, computing an (1 - O(1/sqrt{n}))-approximate solution requires at least Omega(D+sqrt{n}) rounds in CONGEST (ignoring log factors). This lower bound requires the introduction of a new 2-party communication problem, for which we prove a tight lower bound.
Mohsen Ghaffari, Fabian Kuhn
Distributed MST and Broadcast with Fewer Messages, and Faster Gossiping
2018 32nd International Symposium on Distributed Computing (DISC)
KurzfassungWe present a distributed minimum spanning tree algorithm with near-optimal round complexity of O~(D+sqrt{n}) and message complexity O~(min{n^{3/2}, m}). This is the first algorithm with sublinear message complexity and near-optimal round complexity and it improves over the recent algorithms of Elkin [PODC'17] and Pandurangan et al. [STOC'17], which have the same round complexity but message complexity O~(m). Our method also gives the first broadcast algorithm with o(n) time complexity - when that is possible at all, i.e., when D=o(n) - and o(m) messages. Moreover, our method leads to an O~(sqrt{nD})-round GOSSIP algorithm with bounded-size messages. This is the first such algorithm with a sublinear round complexity.
Marthe Bonamy, Paul Ouvrard, Mikaël Rabie, Jukka Suomela, Jara Uitto
Distributed Recoloring
2018 32nd International Symposium on Distributed Computing (DISC)
KurzfassungGiven two colorings of a graph, we consider the following problem: can we recolor the graph from one coloring to the other through a series of elementary changes, such that the graph is properly colored after each step? We introduce the notion of distributed recoloring: The input graph represents a network of computers that needs to be recolored. Initially, each node is aware of its own input color and target color. The nodes can exchange messages with each other, and eventually each node has to stop and output its own recoloring schedule, indicating when and how the node changes its color. The recoloring schedules have to be globally consistent so that the graph remains properly colored at each point, and we require that adjacent nodes do not change their colors simultaneously. We are interested in the following questions: How many communication rounds are needed (in the deterministic LOCAL model of distributed computing) to find a recoloring schedule? What is the length of the recoloring schedule? And how does the picture change if we can use extra colors to make recoloring easier? The main contributions of this work are related to distributed recoloring with one extra color in the following graph classes: trees, 3-regular graphs, and toroidal grids.
Jan Frederick Unnewehr, Hans-Peter (Igor) Waldl, Thomas Pahlke, Iván Herráez
Reducing operational costs of offshore HVDC energy export systems through optimized maintenance
2018 17th Wind Integration Workshop
Robert Gmyr, Kristian Hinnenthal, Irina Kostitsyna, Fabian Kuhn, Dorian Rudolph, Christian Scheideler, Thim Strothmann
Forming Tile Shapes with Simple Robots
2018 24th International Conference on DNA Computing and Molecular Programming (DNA 24) Springer
KurzfassungMotivated by the problem of manipulating nanoscale materials, we investigate the problem of reconfiguring a set of tiles into certain shapes by robots with limited computational capabilities. As a first step towards developing a general framework for these problems, we consider the problem of rearranging a connected set of hexagonal tiles by a single deterministic finite automaton. After investigating some limitations of a single-robot system, we show that a feasible approach to build a particular shape is to first rearrange the tiles into an intermediate structure by performing very simple tile movements. We introduce three types of such intermediate structures, each having certain advantages and disadvantages. Each of these structures can be built in asymptotically optimal O(n^2) rounds, where n is the number of tiles. As a proof of concept, we give an algorithm for reconfiguring a set of tiles into an equilateral triangle through one of the intermediate structures. Finally, we experimentally show that the algorithm for building the simplest of the three intermediate structures can be modified to be executed by multiple robots in a distributed manner, achieving an almost linear speedup in the case where the number of robots is reasonably small.
Mohsen Ghaffari, David G. Harris, Fabian Kuhn
On Derandomizing Local Distributed Algorithms
2018 59th IEEE Symposium on Foundations of Computer Science (FOCS)
KurzfassungThe gap between the known randomized and deterministic local distributed algorithms underlies arguably the most fundamental and central open question in distributed graph algorithms. In this paper, we combine the method of conditional expectation with network decompositions to obtain a generic and clean recipe for derandomizing LOCAL algorithms. This leads to significant improvements on a number of problems, in cases resolving known open problems. Two main results are: - An improved deterministic distributed algorithm for hypergraph maximal matching, improving on Fischer, Ghaffari, and Kuhn [FOCS '17]. This yields improved algorithms for edge-coloring, maximum matching approximation, and low out-degree edge orientation. The last result gives the first positive resolution in the Open Problem 11.10 in the book of Barenboim and Elkin. - Improved randomized and deterministic distributed algorithms for the Lovász Local Lemma, which get closer to a conjecture of Chang and Pettie [FOCS '17].
Pfau J, Ganatra D, Weltin A, Urban G, Kieninger J, Stieglitz T
Electrochemical Stability of Thin-Film Platinum as Suitable Material for Neural Stimulation Electrodes.
2018 52nd Annual Conference of the German Society for Biomedical Engineering, DGBMT“ , Aachen, 26.09-28.09.18
Pasluosta C, Kiele P, Stieglitz T
Eliciting somatosensory percepts via multi-channel wireless electrical stimulation of afferent nerves .
2018 2018 52nd Annual Conference of the German Society for Biomedical >Engineering, DGBMT" , Aachen, 26.09-28.09.18
Matthias Althoff, Stanley Bak, Xin Chen, Chuchu Fan, Marcelo Forets, Goran Frehse, Niklas Kochdumper, Yangge Li, Sayan Mitra, Rajarshi Ray, Christian Schilling, Stefan Schupp
ARCH-COMP18 Category Report: Continuous and Hybrid Systems with Linear Continuous Dynamics
2018
Kondov I, Faubert P, Müller C
Virtual design of nickel-based electrocatalysts for the oxygen reduction reaction
2018 E-MRS European Materials Research Society Warschau
Ledford, Noah, Paul, Hanna, Isakov, Matti, Hiermaier, Stefan
High rate loading of hybrid joints in a Split Hopkinson Tension Bar
2018 International Conference on the Mechanical and Physical Behaviour of Materials under Dynamic Loading (DYMAT)/Arcachon EPJ Web of Conferences, Band: 183
KurzfassungBonded joints are nowadays seen as one of the preferred joining methods in aerospace applications. However, the difficulty in certifying bond strength and the relatively low energy absorption capability of the joint are barriers to widespread adoption. The use of a hybrid joint, that is, the combination of a mechanical and a bonded joint, allows for a fail-safe design and offers improved performance of the joint. The quasi-static properties of hybrid joints have been investigated by a number of researchers. In contrast, the high rate loading regime has been only sparsely investigated. In this work, hybrid joints are tested in quasi-static and high rate loading in order to analyze their loading rate dependence. The hybrid joint studied is a composite-aluminum double lap shear joint with Sikaforce 7752 adhesive and Hi-Lite-315 countersunk titanium bolts. In order to quantitatively analyze the high rate behavior of the hybrid joints and their respective sub-components, additional tests are carried out on simply bonded and simply bolted specimens. The high rate characterization was performed with a Split Hopkinson Tension Bar. The main challenges for these tests are the relatively large specimen size and complex specimen geometry needed to properly characterize the joint behavior, which both are in contradiction with the assumptions of the classical Split Hopkinson Bar-analysis. In this paper we describe an approach to solve these challenges based on an elastic wave analysis of the system.
Banerjee K, Rajaeipour P, Ataman C, Zappe H
An Optofiuidic Refractive Phase Modulator with an Electrostatic 2D Actuator Array
2018 International Conference on Optical MEMS and Nanophotonics (OMN), Lausanne, Switzerland IEEE
Bast H, Schnelle N
Efficient and Convenient SPARQL+Text Search: A Quick Survey
2018 Reasoning Web International Summer School 2018 Springer, Cham, Seiten: 26 - 34
KurzfassungThis is a quick survey about efficient search on a text corpus combined with a knowledge base. We provide a high-level description of two systems for searching such data efficiently. The first and older system, Broccoli, provides a very convenient UI that can be used without expert knowledge of the underlying data. The price is a limited query language. The second and newer system, QLever, provides an efficient query engine for SPARQL+Text, an extension of SPARQL to text search. As an outlook, we discuss the question of how to provide a system with the power of QLever and the convenience of Broccoli. Both Broccoli and QLever are also useful when only searching a knowledge base (without additional text).
Pasluosta C, Kiele P, Stieglitz T
Toward a Multi-Channel Wireless System for Electrical Stimulation of Peripheral Nerves: Modelling and Simulation of Signal Transmission.
2018 22nd Annual Conference of the International Functional Electrical Stimulation Society, IFESS" , Nottwil, 28.08-31.08.18
Robert Gmyr, Kristian Hinnenthal, Irina Kostitsyna, Fabian Kuhn, Dorian Rudolph, Christian Scheideler
Shape Recognition by a Finite Automaton Robot
2018 43rd Symposium on Mathematical Foundations of Computer Science (MFCS)
KurzfassungMotivated by the problem of shape recognition by nanoscale computing agents, we investigate the problem of detecting the geometric shape of a structure composed of hexagonal tiles by a finite-state automaton robot. In particular, in this paper we consider the question of recognizing whether the tiles are assembled into a parallelogram whose longer side has length l = f(h), for a given function f(*), where h is the length of the shorter side. To determine the computational power of the finite-state automaton robot, we identify functions that can or cannot be decided when the robot is given a certain number of pebbles. We show that the robot can decide whether l = ah+b for constant integers a and b without any pebbles, but cannot detect whether l = f(h) for any function f(x) = omega(x). For a robot with a single pebble, we present an algorithm to decide whether l = p(h) for a given polynomial p(*) of constant degree. We contrast this result by showing that, for any constant k, any function f(x) = omega(x^(6k + 2)) cannot be decided by a robot with k states and a single pebble. We further present exponential functions that can be decided using two pebbles. Finally, we present a family of functions f_n(*) such that the robot needs more than n pebbles to decide whether l = f_n(h).
Sebastian Brandt, Seth Pettie, Jara Uitto
Fine-grained Lower Bounds on Cops and Robbers
2018 26th Annual European Symposium on Algorithms (ESA)
KurzfassungCops and Robbers is a classic pursuit-evasion game played between a group of g cops and one robber on an undirected N-vertex graph G. We prove that the complexity of deciding the winner in the game under optimal play requires Omega (N^{g-o(1)}) time on instances with O(N log^2 N) edges, conditioned on the Strong Exponential Time Hypothesis. Moreover, the problem of calculating the minimum number of cops needed to win the game is 2^{Omega (sqrt{N})}, conditioned on the weaker Exponential Time Hypothesis. Our conditional lower bound comes very close to a conditional upper bound: if Meyniel's conjecture holds then the cop number can be decided in 2^{O(sqrt{N}log N)} time. In recent years, the Strong Exponential Time Hypothesis has been used to obtain many lower bounds on classic combinatorial problems, such as graph diameter, LCS, EDIT-DISTANCE, and REGEXP matching. To our knowledge, these are the first conditional (S)ETH-hard lower bounds on a strategic game.
Mohsen Ghaffari, Fabian Kuhn, Yannic Maus, Juho Hirvonen
Improved Distributed Delta-Coloring
2018 ACM Symposium on Principles of Distributed Computing (PODC)
KurzfassungWe present a randomized distributed algorithm that computes a $\Delta$-coloring in any non-complete graph with maximum degree $\Delta \geq 4$ in $O(\log \Delta) + 2^{O(\sqrt{\log\log n})}$ rounds, as well as a randomized algorithm that computes a $\Delta$-coloring in $O((\log \log n)^2)$ rounds when $\Delta \in [3, O(1)]$. Both these algorithms improve on an $O(\log^3 n/\log \Delta)$-round algorithm of Panconesi and Srinivasan~[STOC'1993], which has remained the state of the art for the past 25 years. Moreover, the latter algorithm gets (exponentially) closer to an $\Omega(\log\log n)$ round lower bound of Brandt et al.~[STOC'16].
Alt MT, Mittnacht A, Stieglitz T
Implantable Glass Waveguides and Coating Materials for Chronic Optical Medical Applications.
2018 40th International Conference of the IEEE Engineering in Medicine and Biology Society, 17.-21.07.2018, Oahu, Hawaii, USA IEEE, Seiten: 4595 - 4598
KurzfassungAn innovative fabrication process of glass waveguides on silicon substrates for miniaturized implants is presented. Thin glass was bonded on oxidized silicon wafers and patterned using wet etching. Multimode waveguides with different shapes and a low surface roughness as well as low scattering of light were successfully fabricated. For efficient coupling of light and accurate alignment, KOH-grooves were etched in the silicon with respect to the glass waveguides to attach optical fibers from external light sources. Towards higher biostability, several coating and cladding materials were evaluated in accelerated in vitro tests in 60°C PBS. TiO2, SiC polyimide, Parylene C and SU-8 showed a very stable optical transmittance after 320 days in accelerated aging while PECVD Si3N4 showed significant changes within the first days.
Kahn S, Scholz D, Ordonez JS, Stieglitz T
PDMS Gasket Underfill for Long-Term Insulation of High Density Interconnects in Active Implantable Medical Devices
2018 40th International Conference of the IEEE Engineering in Medicine and Biology Society, 17.-21.07.2018, Oahu, Hawaii, USA , Seiten: 2941 - 2944
KurzfassungThis work presents reliability investigations of silicone gasket as solid underfill for interconnection interfaces in hybrid implant systems with high channel count flexible electrode arrays and hermetically packed electronics. The gasket is fabricated by laser structuring thin sheet of silicone rubber. The surface activation of silicone sheet ensures mechanical bonds with the mating surfaces thereby improving the mechanical stability of the assembly and the insulation of the interconnects. The gasket samples with 10 × 10 openings for interconnect pads, each with diameter of 270 μm and a center to center pitch size of 490 μm, were sandwiched between a polyimide array and a metallized ceramic substrate. The gasket maintained high insulation impedance of 15 ± 0.30 MΩ between the adjacent interconnects with markedly capacitive behavior (phase angle, -89 °) after 17 weeks in soaked conditions under accelerated aging at 60 °C. The gasket also survived electrical stresses and sustained high impedance (10.93 MΩ with phase angle of -88 °) when subjected to constant 3 VDC for 100 days.
Orr Fischer, Tzlil Gonen, Fabian Kuhn, Rotem Oshman
Possibilities and Impossibilities for Distributed Subgraph Detection
2018 30th on Symposium on Parallelism in Algorithms and Architectures (SPAA)
KurzfassungIn the distributed subgraph detection problem, we are given a fixed subgraph H, and the network must decide whether the network graph contains a copy of H or not. Subgraph detection can be solved in a constant number of rounds if message size is unbounded, but in the CONGEST model, where each message has bounded size, it can have high round complexity. Distributed subgraph detection has received significant attention recently, with new upper and lower bounds, but several fundamental questions remain open. In this paper we prove new possibility and impossibility results for subgraph detection in the CONGEST model. We show for the first time that some subgraphs require superlinear --- in fact, nearly quadratic --- running time, even in small-diameter networks. We also study cycle-detection, and show that any even cycle can be detected in sublinear time (in contrast to odd cycles, which require linear time). For the special case of triangle-detection, we show that deterministic algorithms require $Omega(log n)$ total communication even in graphs of degree 2, and that one-round randomized algorithms must send $Omega(Δ)$ bits in graphs of degree Δ, improving on the recent results of [Abboud et. al.]. Finally, we extend a recent lower bound of [Izumi, Le Gall] on listing all triangles to cliques of any size.
Pascal Raiola, Michael A. Kochte, Ahmed Atteya, Laura Rodríguez Gómez, Hans-Joachim Wunderlich, Bernd Becker, Matthias Sauer
Detecting and Resolving Security Violations in Reconfigurable Scan Networks
2018 IEEE International Symposium on On-Line Testing and Robust System Design
Banerjee K, Rajaeipour P, Ataman C, Zappe H
A highly-miniaturized optofluidic refractive adaptive optics system
2018 Imaging and Applied Optics 2018, Orlando, Florida, USA Imaging and Applied Optics, OSA Publishing
Mohsen Ghaffari, Fabian Kuhn, Yannic Maus, Jara Uitto
Deterministic Distributed Edge-Coloring with Fewer Colors
2018 50th ACM Symposium on Theory of Computing (STOC)
KurzfassungWe present a deterministic distributed algorithm, in the $\LOCAL$ model, that computes a $(1+o(1))\Delta$-edge-coloring in polylogarithmic-time, so long as the maximum degree $\Delta=\tilde{\Omega}(\log n)$. For smaller $\Delta$, we give a polylogarithmic-time $3\Delta/2$-edge-coloring. These are the first deterministic algorithms to go below the natural barrier of $2\Delta-1$ colors, and they improve significantly on the recent polylogarithmic-time $(2\Delta-1)(1+o(1))$-edge-coloring of Ghaffari and Su [SODA'17] and the $(2\Delta-1)$-edge-coloring of Fischer, Ghaffari, and Kuhn [FOCS'17], positively answering the main open question of the latter. The key technical ingredient of our algorithm is a simple and novel gradual packing of judiciously chosen near-maximum matchings, each of which becomes one of the color classes.
Erhardt JB, Martinez JA, Cork TE, Gessner I, Mathur S, Stieglitz T, Ennis DB
Assessment of Iron Oxide Nanoparticle Concentration for Distinct Intercranial EEG Electrode Localization in MRI.
2018 Proceedings of the 26th scientific meeting, International Society for Magnetic Resonance in Medicine, Paris, France , Seiten: 4057 - 4057
KurzfassungIntercranial EEG (icEEG) electrodes are implanted for pre-surgical assessment of cortical electrical activity in patients with epilepsy. MRI helps to localize the implant with respect to the individual’s anatomy and fMRI can improve understanding of the neuropathology. However, the magnetic susceptibility artifacts caused by the metal components of commercially available implants produce MRI artifacts that compromise the results especially in the direct vicinity of the implants. Next generation “thin-film” implants which feature 100x less metal thickness can mitigate these artifacts, but thin-film implants produce inconspicuous MRI signal voids in many clinical MRI sequences. Imperatively, physicians need to know the implant position and the value of EEG increases with the precision of electrode localization. Therefore, we investigated various concentrations of super paramagnetic iron oxide (SPIO) nanoparticles (NP) to label thin-film implants for localization in MRI using a range of sequences. In particular, we aim to create a marker that conspicuously renders the implant, enables spatial localization of the individual electrodes, and keeps disruptive imaging artifacts small.
Stieglitz T
Stability of materials and flexible neural probes for recording, electrical and optical stimulation.
2018 Colloquium des SFB 889 "Cellular Mechanisms of Sensory Processing", Universitätsmedizin Göttingen, 19.06.2018, Göttingen
Fabian Kuhn, Yannic Maus, Simon Weidner
Deterministic Distributed Ruling Sets of Line Graphs
2018 Int. Coll. on Structural Information and Communication Complexity (SIROCCO)
KurzfassungAn $(\alpha,\beta)$-ruling set of a graph $G=(V,E)$ is a set $R\subseteq V$ such that for any node $v\in V$ there is a node $u\in R$ in distance at most $\beta$ from $v$ and such that any two nodes in $R$ are at distance at least $\alpha$ from each other. The concept of ruling sets can naturally be extended to edges, i.e., a subset $F\subseteq E$ is an \emph{$(\alpha,\beta)$-ruling edge set} of a graph $G=(V,E)$ if the corresponding nodes form an $(\alpha,\beta)$-ruling set in the line graph of $G$. This paper presents a simple deterministic, distributed algorithm, in the CONGEST ~ model, for computing $(2,2)$-ruling edge sets in $O(\logstar n)$ rounds. Furthermore, we extend the algorithm to compute ruling sets of graphs with bounded \emph{diversity}. Roughly speaking, the diversity of a graph is the maximum number of maximal cliques a vertex belongs to. We devise $(2,O(\diversity))$-ruling sets on graphs with diversity $\diversity$ in $O(\diversity+\logstar n)$ rounds. This also implies a fast, deterministic $(2,O(\rank))$-ruling edge set algorithm for hypergraphs with rank at most \rank. Furthermore, we provide a ruling set algorithm for general graphs that for any $B\geq 2$ computes an $\big(\alpha, \alpha \ceil{\log_B n}\big)$-ruling set in $O(\alpha \cdot B \cdot \log_B n)$ rounds in the CONGEST model. The algorithm can be modified to compute a $\big(2, \beta \big)$-ruling set in $O(\beta \degree^{2/\beta} + \logstar n)$ rounds in the CONGEST model, which matches the currently best known such algorithm in the more general LOCAL model.
Weidlich A, Künzel T, Klumpp F
Bidding Strategies for Flexible and Inflexible Generation in a Power Market Simulation Model
2018 1st International Workshop on Energy Market Engineering ACM e-Energy 2018, Band: 1, Nummer: 1, Seiten: 532 - 537
KurzfassungThis paper presents an electricity market simulation model that focuses on the distinction between flexible and inflexible generation, and formulates bidding strategies for capacities of either type. Bid formulation for flexible power plants, storage and demand response units at a balancing power market and an energy exchange market are described, and exemplary results from the simulation model are presented. It is shown that the simulation model can realistically reproduce market outcomes for the example of the German market zone, and that it can also simulate negative market prices. Results reveal that power plants could be deployed in a more flexible manner than they are currently done in actual market operation, where larger variations of output are avoided especially for nuclear and lignite-fired power plants. The model can be used for analyzing future energy scenarios of high shares of variable renewable energy (VRE), and help answering research questions related to the required system flexibility for balancing out VRE fluctuations.
Benjamin Völker, Philipp M Scholl, Bernd Becker
Towards the Fusion of Intrusive and Non-intrusive Load Monitoring - A Hybrid Approach
2018 e-Energy '18 Proceedings of the Ninth International Conference on Future Energy Systems/Karlsruhe, Germany , Seiten: 436 - 438
KurzfassungWith Electricity as a fundamental part of our life, its production has still large, negative environmental impact. Therefore, one strain of research is to optimize electricity usage by avoiding its unnecessary consumption or time its consumption when green energy is available. The shift towards an Advanced Metering Infrastructure (AMI) allows to optimize energy distribution based on the current load at residence level. However, applications such as Demand Management and Advanced Load Forecasting require information further down at device level, which cannot be provided by standard electricity meters nor existing AMIs. Hence, different approaches for appliance monitoring emerged over the past 30 years which are categorized into Intrusive systems requiring multiple distributed sensors and Non-Intrusive systems requiring a single unobtrusive sensor. Although each category has been individually explored, hybrid approaches have received little attention. Our experiments highlight that variable consumer devices (e.g. PCs) are detrimental to the detection performance of non-intrusive systems. We further show that their influence can be inhibited by using sensor data from additional intrusive sensors. Even fairly straightforward sensor fusion techniques lead to a classification performance (F1) gain from 84.88 % to 93.41 % in our test setup. As this highlights the potential to contribute to the global goal of saving energy, we define further research directions for hybrid load monitoring systems

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Stieglitz T, Cvancara P, Mueller M, Eickenscheidt M, Liljemalm R, Fiedler E, Kahn S
Implantable microelectrodes - opportunites and challenges with respect to selectivity, stability and reliabilty.
2018 World Congress on Medical Physics and Biomedical Engineering (IUPESM 2018), June 3-8, 2018, Prague, Tschechien
KurzfassungMiniaturized electrode arrays for electrical stimulation in neural implants have to be stable, functional and reliable over the life-time of the implant, which is at best at least as long as the life time of the recipient. While cardiac pacemaker and cochlear implant electrodes stay stable for long time due to well established materials and precision mechanics manufacturing, more complex implants with higher channel count and integration density requires different technologies as well as materials. It is not only the dimension of thin-film metals that is more demanding than the one of solid electrode sheets in cochlear implants, cardiac, spinal cord and brain pacemakers but also the fact that surface effects predominate and promote corrosion mechanisms that are hardly seen in the established applications. In addition, adhesion of metals and polymer insulation is of utmost importance for device longevity and reliability. How can these challenges be combined with the target specifications for high spatial selectivity and the possibility of current steering when using multipolar stimulation paradigms ? This presentation combines material sciences foundations with requirements of electrical stimulation in movement rehabilitation to discuss opportunites and challenges in development of miniaturized electrode arrays. Examples include delivery of sensory feedback via stimulation of afferent fibers in the peripheral nervous system and recording of neural signals from the central nervous system as input parameter in brain-computer-interface applications to control movement of either artificial or paralyzed limbs. Results from preclinical as well as from human clinical trials are presented to discuss material-tissue interactions and microsystem stability in chronic implantation scenarios and the influence of these findings to spatial selectivity that is needed for sophisticated movement rehabilitation by functional electrical stimulation.
Watson, Erkai, Maas, Hans-Gerd, Schaefer, Frank, Hiermaier, Stefan
Trajectory based 3D fragment tracking in hypervelocity impact experiments
2018 Symposium "Towards Photogrammetry 2020"/Riva del Garda ISPRS, 2018 (The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-2, Band: XLII-2
KurzfassungCollisions between space debris and satellites in Earth’s orbits are not only catastrophic to the satellite, but also create thousands of newfragments, exacerbating the space debris problem. One challenge in understanding the space debris environment is the lack of data onfragmentation and breakup caused by hypervelocity impacts. In this paper, we present an experimental measurement technique capableof recording 3D position and velocity data of fragments produced by hypervelocity impact experiments in the lab. The experimentalsetup uses stereo high-speed cameras to record debris fragments generated by a hypervelocity impact. Fragments are identified andtracked by searching along trajectory lines and outliers are filtered in 4D space (3D + time) with RANSAC. The method is demonstratedon a hypervelocity impact experiment at 3.2 km/s and fragment velocities and positions are measured. The results demonstrate thatthe method is very robust in its ability to identify and track fragments from the low resolution and noisy images typical of high-speedrecording.
Tucher Nico, Höhn Oliver, Bläsi Benedikt, Goldschmidt Jan Christoph
Advanced module optics of textured perovskite silicon tandem solar cells
2018 SPIE Photonics Europe, 2018, Strasbourg, France Photonics for Solar Energy Systems VII,, Band: 10688, Seiten: 1068805-1 - 1068805-5
KurzfassungPerovskite silicon tandem solar cells can overcome the efficiency limit of single junction silicon solar cells. Optical modeling plays a crucial role for the device optimization but it becomes complex if optically thin and thick layers as well as interface textures, such as random pyramids, are involved. Within this work, the OPTOS simulation formalism is applied in order to compare perovskite silicon tandem solar cells with planar and textured front side. Modeling the configuration with planar front side and textured rear exhibits a matched photocurrent density of 18.2 mA/cm2. For the system with textured front and planar rear side the reduced reflectance leads to a photocurrent density of 19.6 mA/cm2 although parasitic absorption in the Spiro-OMeTAD and ITO layers increases. Taking into account the full module stack in the OPTOS simulation shows an increased front side reflectance and parasitic absorption in the EVA. The difference between the resulting photocurrent densities (17.8 mA/cm2 and 18.9 mA/cm2) demonstrates the optical superiority of the investigated system with textured front side not only at cell level but also in the full module stack.

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Stieglitz T
Introduction to Optogenetics.
2018 Fachgruppe Intelligente Implantate, microTEC Südwest, 16.05.2018, Rottweil (2018)
Ruther P
LED-based MEMS Tools for Optogenetic Applications Aside from Cerebral Tissue
2018 ICAN – International Conference for Advanced Neurotechnology, University of Michigan, Ann Arbor, USA, 7./8. May 2018
Stieglitz T
Stability and Functionality of Thin-film Recording and Stimulation Electrodes in the Peripheral and Central Nervous System.
2018 International Conference on Advanced Neurotechnologies (ICAN), May 6-8, 2018, Ann Arbor, MI, USA
Klein E, Gossler C, Paul O, Ruther P
Thin-film LED Arrays on Flexible Substrates With Improved Thermomechanical Behaviour
2018 ICAN – International Conference for Advanced Neurotechnology, University of Michigan, Ann Arbor, USA, 7./8. May 2018
Stevens L, Hauser H, Höhn O, Tucher N, Wellens C, Jahn R, Glaubitt W, Müller C, Bläsi B
Nanoimprinted sol-gel materials for antireflective structures on silicon solar cells
2018 SPIE Photonics Europe, 2018, Strasbourg, France
KurzfassungSilicon solar cells are typically textured by means of wet chemical etching in order to enhance absorption. Within this work, we apply an optically functional layer onto a planar silicon surface. This layer is made of a high refractive index sol-gel material and can be patterned by nanoimprint lithography (NIL). In first experiments, we investigated various sol-gel based TiO2 precursors and evaluated their refractive index as well as the possibility to apply them in NIL. The refractive index was determined to be up to 2.25 using ellipsometry. This result was achieved with a solution composed of amorphous TiO2 precursors mixed with ethanol and 1,5-pentanediol. The topography of the patterned TiO2 layers were investigated using an atomic force microscope (AFM) and a scanning electron microscope (SEM) revealing a period of 1 μm and a pattern depth of 60 nm after sintering. Furthermore, optical modeling was used to optimize the structure parameters in order to minimize the weighted reflectance of an encapsulated silicon solar cell

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Ahmed Atteya, Michael Kochte, Matthias Sauer, Pascal Raiola, Bernd Becker, Hans-Joachim Wunderlich
Online Prevention of Security Violations in Reconfigurable Scan Networks
2018 IEEE European Test Symposium
Johanna Sepulveda, Damian Aboul-Hassan, Georg Sigl, Bernd Becker, Matthias Sauer
Towards the Formal Verification of Security Properties of a Network-on-Chip Router
2018 IEEE European Test Symposium
Felix Neubauer, Jan Burchard, Pascal Raiola, Jochen Rivoir, Bernd Becker, Matthias Sauer
Efficient Generation of Parametric Test Conditions for AMS Chips with an Interval Constraint Solver
2018 IEEE VLSI Test Symposium (VTS'18)
KurzfassungThe characterization of analog-mixed signal (AMS) silicon requires a suitable pattern set able to exercise the parametric operational space to - among other tasks - validate the correct (specified) working behaviour of the device under test. As experience shows, most of the unexpected problems occur for very specific value combinations of a few test condition variables that were not expected to have an influence. Additionally, restrictions on the operational conditions have to be taken into account. We present a method to efficiently create a set of test conditions to cover such a constrained search space with a user-defined density. First, an initial test condition set is generated using quasirandom Sobol sequences. Secondly, we analyse the test conditions to identify and fill uncovered areas in the parameter space using the in-house interval constraint solver iSAT3. The applicability of the method is demonstrated by experimental results on a 19-dimensional search space using a realistic set of constraints.
Stevens L, Hauser H, Höhn O, Tucher T, Wellens C, Jahn R, Glaubitt W, Müller C, Bläsi B
Nanoimprinted sol-gel- materials as antireflective structures for silicon solar cells
2018 SPIE Konferenz Straßburg 2018 SPIE Konferenz Straßburg
S. Vierrath, M. Breitwieser, C. Klose, M. Klingele, S. Thiele
Novel approaches to tailor the PEM|electrode interface for fuel cells with increased power density
2018 innBW Wissenschaftlertreffen Stuttgart, 21.04.2018
F. Staab, F. Balle
Ultraschalltorsionsschweißen von alterungsbeständigen Al/CFK-Verbunden – Konzepte, Prozess und Eigenschaften
2018 3. Hybrid Materials and Structures, Bremen
Stieglitz T
Bioelektronische Medizin-Versprechen und Herausforderungen.
2018 microTEC Südwest Clusterkonzerenz 2018, 16.-17.04.2018, Konzerthaus Freiburg
Stieglitz T
Neurostimulation zur Wiederherstellung sensorischen Feedbacks.
2018 MedTech Summit, 11.-12.04.2018, Messe Nürnberg
Linus Feiten, Karsten Scheibler, Bernd Becker, Matthias Sauer
Using different LUT paths to increase area efficiency of RO-PUFs on Altera FPGAs
2018 TRUDEVICE Workshop, Dresden
KurzfassungDelay-based PUFs are well suited to be implemented on FPGA chips. A delay line is commonly achieved by routing the signal through a number of adjacent lookup tables (LUTs). This however uses only one of all possible routings per LUT. We suggest to implement RO-PUFs using all possible routings that can be configured at runtime, which allows to gather much more device-specific information per chip area. Furthermore, the number of PUF response bits can be increased even further without extra hardware or software if a certain degree of correlations among the response bits is accepted. The degree of correlations is proportional to the growth of response bits, so a design decision can be made. To make this decision, a metric to quantify the degree of correlations is needed, which has so far been mostly neglected in the analyses of PUF implementations.
Stieglitz T
When technology hits the nerve-intelligent implants in neurological treatment and rehabilitation.
2018 XPOMET, Die Convention für Innovation und Hightech in der Medizin, 21.-23.03.2018, Leipzig
Dominik Jan Schott, Muhammad Faisal, Fabian Höflinger, Leonhard M Reindl
A Multichannel Acoustic Chirp-Spread Modulation Approach Towards Diver-to-Diver Communication
2018 Hammamet, Tunesien 2018 15th International Multi-Conference on Systems, Signals & Devices (SSD), IEEE, Seiten: 475 - 479
KurzfassungIn this work, we propose a single and multiband chirp signals for communication in the air and underwater channel. A Raspberry Pi based transceiver system and MATLAB are used for the demodulation of the chirp signals. The experiments, for both air and water, are conducted in static conditions, that is the transmitter and receiver are fixed. To increase the efficiency of signal processing, down-conversion or bandpass sampling is implemented on the receiver side. We use transmission bands between 60~kHz and 70kHz to reduce the impact of divers' communication on the maritime ecosystem and its natural communication bands. The structure of the demodulation is discussed in detail with focus on the frame detection and decision algorithm. In several different settings, we demonstrate the performance of this approach and transmit data of up to 12 Byte with data rates of 100 and 200 bit/s over 0.25 m in air and 4.5 m in water inside a highly echoic environment.

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Hoschke, Klaus, Pfaff, Aron, Fleig, Luisa, Bierdel, Marius, Jaecklein, Martin, Riedel, Werner, Hiermaier, Stefan
A parametric mesostructural approach for robust design of additive manufacturing parts
2018 Fraunhofer Direct Digital Manufacturing Conference (DDMC)/Berlin Fraunhofer Direct Digital Manufacturing Conference DDMC 2018, Band: 1
KurzfassungAdditive Manufacturing (AM) allows for production of potentially complex design solutions and motivates the use of Structural Optimization tools in product development to chase the structural limit of a design problem and its solution concept. Scratching on the limits of the material strength, design solutions can lack robustness concerning simplifications in model assumptions and uncertainties. However, the design freedom with AM can also actively be used to enhance robustness and reliability of solutions. To this end, an approach is presented that introduces Parametric Mesostructures into selective areas of the Additive Design. Structural members and coherent mechanical characteristics of these mesostructures can significantly reduce local stress peaks and can account for uncertainties, e.g. direction of load application. Their design is motivated by Structural Optimization and analysis results. Implementation of the approach is demonstrated and discussed on the example of a structural aircraft component.
Felix Neubauer, Jan Burchard, Pascal Raiola, Jochen Rivoir, Bernd Becker, Matthias Sauer
High-Coverage AMS Test Space Optimization by Efficient Parametric Test Condition Generation
2018 GI/ITG Workshop “Testmethoden und Zuverlässigkeit von Schaltungen und Systemen”
Ruther P
Interfacing the brain with micromachined implants
2018 TU Einhoven
Uwe Wagschal, Thomas Metz, Thomas Waldvogel, Bernd Becker, Linus Feiten, Samuel Weishaupt
Online real-time-response measurement in real life settings: the Debat-O-Meter
2018 Cologne 20th General Online Research Conference (GOR)
KurzfassungPolitical debates have attracted substantial public and academic attention due to their prominent role in election campaigns. Reaching a tremendous number of potential voters, TV debates concentrate the electoral contest into a one-evening format that covers all major topics and main contenders. As "miniature campaigns" they reach many undecided and serve as (often the only) source of direct campaign information for voters less sophisticated or attentive to politics. In recent years Real Time Response Measurement gained international importance in political communication research.
F. Staab, F. Balle
Prozessuntersuchungen zum Ultraschallschweißen von alterungsbeständigen Al/CFK-Übergangsstrukturen
2018 DGM-Fachausschuss „Hybride Werkstoffe und Strukturen", Dortmund
Stieglitz T
“Wenn Technik den Nerv trifft… Miniaturisierte Implantate in der Neurotechnik und für Elektrozeutika”
2018 Fachtagung Kunststoff trifft Medizintechnik, 31.01.-01.02.2018, Leipzig (2018).
Stieglitz T
Bioelektronische Medizin‑Versprechen und Herausforderungen
2018 Hochrhein-Seminar, Technisches Gymnasium Waldshut
Paweł Gawrychowski, Fabian Kuhn, Jakub Łopuszański, Konstantinos Panagiotou, Pascal Su
Labeling Schemes for Nearest Common Ancestors through Minor-Universal Trees
2018 29th ACM-SIAM Symposium on Discrete Algorithms (SODA)
KurzfassungPreprocessing a tree for finding the nearest common ancestor of two nodes is a basic tool with multiple applications. Quite a few linear-space constant-time solutions are known and the problem seems to be well-understood. This is however not so clear if we want to design a labeling scheme. In this model, the structure should be distributed: every node receives a distinct binary string, called its label, so that given the labels of two nodes (and no further information about the topology of the tree) we can compute the label of their nearest common ancestor. The goal is to make the labels as short as possible. Alstrup, Gavoille, Kaplan, and Rauhe [Theor. Comput. Syst. 37(3):441-456 2004] showed that O(log n)-bit labels are enough, with a somewhat large constant. More recently, Alstrup, Halvorsen, and Larsen [SODA 2014] refined this to only 2.772 log n, and provided a lower bound of 1.008 log n. We connect the question of designing a labeling scheme for nearest common ancestors to the existence of a tree, called a minor-universal tree, that contains every tree on n nodes as a topological minor. Even though it is not clear if a labeling scheme must be based on such a notion, we argue that all already existing schemes can be reformulated as such. Further, we show that this notion allows us to easily obtain clean and good bounds on the length of the labels. As the main upper bound, we show that 2.318 log n- bit labels are enough. Surprisingly, the notion of a minor- universal tree for binary trees on n nodes has been already used in a different context by Hrubes et al. [CCC 2010], and Young, Chu, and Wong [J. ACM 46(3):416-435, 1999] introduced a very closely related (but not equivalent) notion of a universal tree. On the lower bound side, we show that any minor-universal tree for trees on n nodes must contain at least Omega(n^2.174) nodes. This highlights a natural limitation for all approaches based on defining a minor- universal tree. We complement the existential results with a generic transformation that allows us, for any labeling scheme for nearest common ancestors based on a minor- universal tree, to decrease the query time to constant, while increasing the length of the labels only by lower order terms.

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Yi-Jun Chang, Qizheng He, Wenzheng Li, Seth Pettie, Jara Uitto
The Complexity of Distributed Edge Coloring with Small Palettes
2018 29th ACM-SIAM Symposium on Discrete Algorithms (SODA)
Bast H, Azar Y, Herman G
26st European Symposium on Algorithms - LIPIcs
, Band: 112, 2018
B. Shanahan, B. Britton, S. Holdcroft, R. Zengerle, S. Thiele, M. Breitwieser
30 μm thin, highly conductive PBI-based anion exchange membrane (AEM) for VRFB applications
2018 IFBF - The International Flow Battery Forum, Lausanne/Schweiz, 10. – 12.07.2018
Christian Zimmermann,, T. Welschehold,, C. Dornhege,, W. Burgard,, Thomas Brox
3D Human Pose Estimation in RGBD Images for Robotic Task Learning
2018

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Butz N, Taschwer A, Nessler S, Manoli Y, Kuhl M
A 22V Compliant 56µW Twin-Track Active Charge Balancing Enabling 100% Charge Compensation Even in Monophasic and 36% Amplitude Correction in Biphasic Neural Stimulators
2018 IEEE Journal Solid-State Circuits (JSSC), Band: 53, Nummer: 8, Seiten: 2298 - 2310
Marx M, De Dorigo D, Nessler S, Rombach S, Manoli Y
A 27μW 0.06mm² Background Resonance Frequency Tuning Circuit Based on Noise Observation for a 1.71 mW CT-ΔΣ MEMS Gyroscope Readout System With 0.9°/h Bias Instability
2018 IEEE Journal Solid-State Circuits (JSSC), Band: 53, Nummer: 1, Seiten: 174 - 186
Khatri B, Lappe K, Nötzel D, Pursche K, Hanemann T
A 3D-Printable Polymer-Metal Soft-Magnetic Functional Composite-Development and Characterization
2018 Materials, Band: 11, Seiten: 189-1 - 189-12
KurzfassungIn this work, a 3D printed polymer–metal soft-magnetic composite was developed and characterized for its material, structural, and functional properties. The material comprises acrylonitrile butadiene styrene (ABS) as the polymer matrix, with up to 40 vol. % stainless steel micropowder as the filler. The composites were rheologically analyzed and 3D printed into tensile and flexural test specimens using a commercial desktop 3D printer. Mechanical characterization revealed a linearly decreasing trend of the ultimate tensile strength (UTS) and a sharp decrease in Young’s modulus with increasing filler content. Four-point bending analysis showed a decrease of up to 70% in the flexural strength of the composite and up to a two-factor increase in the secant modulus of elasticity. Magnetic hysteresis characterization revealed retentivities of up to 15.6mT and coercive forces of up to 4.31 kA/m at an applied magnetic field of 485 kA/m. The composite shows promise as a material for the additive manufacturing of passive magnetic sensors and/or actuators.
Shui B, Keller M, Kuhl M, Manoli Y
A 70.1dB 0.0045mm² Low-Power Continuous-Time Incremental Delta-Sigma Modulator for Multi-Site Neural Recording Interfaces
2018 Proceedings of the IEEE International Symposium on Circuits and Systems (ISCAS)
Taschwer A, Butz N, Koehler M, Rossbach D, Manoli Y
A Charge Balanced Neural Stimulator with 3.3V to 49V Supply Compliance and Arbitrary Programmable Current Pulse Shapes
2018 Proceedings of the IEEE Biomedical Circuits and Systems Conference (BioCAS)
Manzouri Farrokh, Heller Simon, Dümpelmann Matthias, Woias Peter, Schulze-Bonhage Andreas
A Comparison of Machine Learning Classifiers for Energy-Efficient Implementation of Seizure Detection
2018 Frontiers in systems neuroscience, Band: 12, Seite: 43
KurzfassungThe closed-loop application of electrical stimulation via chronically implanted electrodes is a novel approach to stop seizures in patients with focal-onset epilepsy. To this end, an energy efficient seizure detector that can be implemented in an implantable device is of crucial importance. In this study, we first evaluated the performance of two machine learning algorithms (Random Forest classifier and support vector machine (SVM)) by using selected time and frequency domain features with a limited need of computational resources. Performance of the algorithms was further compared to a detection strategy implemented in an existing closed loop neurostimulation device for the treatment of epilepsy. The results show a superior performance of the Random Forest classifier compared to the SVM classifier and the reference approach. Next, we implemented the feature extraction and classification process of the Random Forest classifier on a microcontroller to evaluate the energy efficiency of this seizure detector. In conclusion, the feature set in combination with Random Forest classifier is an energy efficient hardware implementation that shows an improvement of detection sensitivity and specificity compared to the presently available closed-loop intervention in epilepsy while preserving a low detection delay.
De Dorigo D, Moranz C, Graf H, Marx M, Shui B, Kuhl M, Manoli Y
A Fully Immersible Deep-Brain Neural Probe with Modular Architecture and a Delta-Sigma ADC Integrated Under Each Electrode for Parallel Readout of 144 Recording Sites
2018 IEEE International Solid-State Circuits Conference (ISSCC), Digest of Technical Papers, Seiten: 462 - 464
Hoch K, Pothof F, Becker F, Paul O, Ruther P
A Magnetic, Micro-spring-suspended System for the Safe Electrical Interconnection of Neural Implants
2018 IEEE MEMS Conf. 2018, Belfast, Ireland , Seiten: 369 - 372
Cai Y, Manoli Y
A Piezoelectric Energy-Harvesting Interface Circuit with Fully Autonomous Conjugate Impedance Matching, 156% Extended Bandwidth, and 0.38μW Power Consumption
2018 IEEE International Solid-State Circuits Conference (ISSCC), Digest of Technical Papers, Seiten: 148 - 150
Bast H, Buchhold B, Haussmann E
A Quality Evaluation of Combined Search on a Knowledge Base and Text
2018 Springer, Seiten: 19 - 26
KurzfassungWe provide a quality evaluation of KB+Text search, a deep integration of knowledge base search and standard full-text search. A knowledge base (KB) is a set of subject–predicate–object triples with a common naming scheme. The standard query language is SPARQL, where queries are essentially lists of triples with variables. KB+Text search extends this by a special occurs-with predicate, which can be used to express the co-occurrence of words in the text with mentions of entities from the knowledge base. Both pure KB search and standard full-text search are included as special cases. We evaluate the result quality of KB+Text search on three different query sets. The corpus is the full version of the English Wikipedia (2.4 billion word occurrences) combined with the YAGO knowledge base (26 million triples). We provide a web application to reproduce our evaluation, which is accessible via http://ad.informatik. uni-freiburg.de/publications.

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Wallis K, Merzinger M, Schindelhauer C, Reich C
A Security Model based Authorization Concept for OPC Unified Architecture
2018 10th International Conference on Advances in Information Technology , Seiten: 8:1 - 8:8
Nessler S, Marx M, Manoli Y
A Self-Test on Wafer Level for a MEM Gyroscope Readout Based on Delta-Sigma Modulation
2018 IEEE Transactions on Circuits and Systems - Part I (TCAS I), Band: 65, Nummer: 3, Seiten: 870 - 880
Hoenicke, Jochen, Nutz, Alexander, Podelski, Andreas
A Tree-Based Approach to Data Flow Proofs
In: VSTTE 2018
2018, Springer,
A Ortiz Perez, B Bierer, L Scholz, J Wöllenstein, S Palzer
A Wireless Gas Sensor Network to Monitor Indoor Environmental Quality in Schools
2018 Sensors-basel, Band: 18, Nummer: 12, Seite: 435
KurzfassungSchools are amongst the most densely occupied indoor areas and at the same time children and young adults are the most vulnerable group with respect to adverse health effects as a result of poor environmental conditions. Health, performance and well-being of pupils crucially depend on indoor environmental quality (IEQ) of which air quality and thermal comfort are central pillars. This makes the monitoring and control of environmental parameters in classes important. At the same time most school buildings do neither feature automated, intelligent heating, ventilation, and air conditioning (HVAC) systems nor suitable IEQ monitoring systems. In this contribution, we therefore investigate the capabilities of a novel wireless gas sensor network to determine carbon dioxide concentrations, along with temperature and humidity. The use of a photoacoustic detector enables the construction of long-term stable, miniaturized, LED-based non-dispersive infrared absorption spectrometers without the use of a reference channel. The data of the sensor nodes is transmitted via a Z-Wave protocol to a central gateway, which in turn sends the data to a web-based platform for online analysis. The results show that it is difficult to maintain adequate IEQ levels in class rooms even when ventilating frequently and that individual monitoring and control of rooms is necessary to combine energy savings and good IEQ.
Kretschmer S, Jäger J, Vilches Exposito S, Ataman C, Zappe H
A bimodal endoscopic imager in a glass package
2018 J Micromech Microeng, Band: 28, Nummer: 10, Seite: 105009
KurzfassungWe present the first endoscopic imaging probe that combines full-field white light video microscopy and 3D optical coherence tomography (OCT) in a single miniaturized instrument. Designed as an instrument for the working channels of conventional endoscopes, the presented system has dimensions of mm3 (l × w × h) and is an important step towards practical multi-modal optical biopsy systems for clinical use. The video modality has a sensor-limited resolution and a total field of view of 10 μm and 1.17 mm in diameter, respectively. The OCT modality works in a scanned imaging arrangement and provides 3D optical tomograms with a lateral resolution of 43.5 μm. An integrated tubular piezoelectric fiber scanner is used to perform en face scanning necessary for the 3D OCT measurements. The entire system is assembled and encapsulated within a glass package fabricated via 3D laser microstructuring, a technology which addresses the major issues of micro-optic assembly precision and biocompatibility.
Ghane-Motlagh R., Kroener M., Goldschmidtboeing F., Danilewsky A., Woias P.
A dynamic method for the measurement of pyroelectric properties of materials
2018 Smart Materials and Structures, Band: 27, Nummer: 8, Seite: 084004
C.-H. Tsai, D.- H. Kuan, S. Zimmermann, J. Schoendube, A. Gross, R. Zengerle, P. Koltay
A highliy parallel microbioreactor for cell line development based on a microtiter plate with functional microfluidic lid
2018 MicroTAS 2018, 11. -15. November 2018, Kaohsiung / Taiwan
Woias P., Heller S., Pelz U.
A highly sensitive and ultra-low-power wake-up receiver for energy-autonomous embedded systems
2018 Journal of Physics: Conference Series, Band: 1052, Seite: 012024
Hügle M, Dame G, Behrmann O, Rietzel R, Karthe D, Hufert F, Urban G
A lab-on-a-chip for preconcentration of bacteria and nucleic acid extraction
2018 Rsc Adv, Band: 8, Seiten: 20124 - 20130
KurzfassungTo improve detection sensitivity, molecular diagnostics require preconcentration of low concentrated samples followed by rapid nucleic acid extraction. This is usually achieved by multiple centrifugation, lysis and purification steps, for instance, using chemical reagents, spin columns or magnetic beads. These require extensive infrastructure as well as time consuming manual handling steps and are thus not suitable for point of care testing (POCT). To overcome these challenges, we developed a microfluidic chip combining free-flow electrophoretic (FFE) preconcentration (1 ml down to 5 ml) and thermoelectric lysis of bacteria as well as purification of nucleic acids by gel-electrophoresis. The integration of these techniques in a single chip is unique and enables fast, easy and space-saving sample pretreatment without the need for laboratory facilities, making it ideal for the integration into small POCT devices. A preconcentration efficiency of nearly 100% and a lysis/gel-electrophoresis efficiency of about 65% were achieved for the detection of E. coli. The genetic material was analyzed by RT-qPCR targeting the superfolder Green Fluorescent Protein (sfGFP) transcripts to quantify mRNA recovery and qPCR to determine DNA background.
Banerjee K, Rajaeipour P, Ataman C, Zappe H
A low-cost, 25-actuator electrostatic deformable mirror with polyimide membrane for adaptive optics microscopy (Best Student Paper Award)
2018 Proceedings of SPIE, Band: 10545, Seite: 105450G
Zhao P, Ataman C, Zappe H
A miniaturized camera objective with 2X optical zoom
2018 Proceedings of SPIE, Band: 10545, Seite: 1054508
Faubert P, Kondov I, Qazzazie D, Yurchenko O, Müller C
A non-noble Cr–Ni-based catalyst for the oxygen reduction reaction in alkaline polymer electrolyte fuel cells
2018 Mrs Commun, Band: 8, Nummer: 1, Seiten: 160 - 167
S. Backe, F. Balle
A novel short-time concept for fatigue life estimation of carbon (CFRP) and metal/carbon fiber reinforced polymer (MCFRP)
2018 Int J Fatigue, Band: 116, Seiten: 317 - 322

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Hoschke, Klaus, Pfaff, Aron, Fleig, Luisa, Bierdel, Marius, Jaecklein, Martin, Riedel, Werner, Hiermaier, Stefan
A parametric mesostructural approach for robust design of additive manufacturing parts
2018 Fraunhofer Direct Digital Manufacturing Conference, DDMC 2018, Fraunhofer Verlag, Stuttgart, Seite: 6
KurzfassungAdditive Manufacturing (AM) allows for production of potentially complex design solutions and motivates the use of Structural Optimization tools in product development to chase the structural limit of a design problem and its solution concept. Scratching on the limits of the material strength, design solutions can lack robustness concerning simplifications in model assumptions and uncertainties. However, the design freedom with AM can also actively be used to enhance robustness and reliability of solutions. To this end, an approach is presented that introduces Parametric Mesostructures into selective areas of the Additive Design. Structural members and coherent mechanical characteristics of these mesostructures can significantly reduce local stress peaks and can account for uncertainties, e.g. direction of load application. Their design is motivated by Structural Optimization and analysis results. Implementation of the approach is demonstrated and discussed on the example of a structural aircraft component.
Agrawal Akshay, Verschueren Robin, Diamond Steven, Boyd Stephen
A rewriting system for convex optimization problems
2018 Journal of Control and Decision, Band: 5, Nummer: 1, Seiten: 42 - 60
Fiath R, Raducanu B C, Musa S, Andrei A, Lopez C M, van Hoof C, Ruther P, Aarts A, Horvath D, Ulbert I
A silicon-based neural probe with densely-packed low-impedance titanium nitride microelectrodes for ultrahigh-resolution in vivo recordings
2018 Biosens Bioelectron, Band: 106, Seiten: 86 - 92
Lachner-Piza D, Epitashvili N, Schulze-Bonhage A, Stieglitz T, Jacobs J, Dumpelmann M
A single channel sleep-spindle detector based on multivariate classification of EEG epochs: MUSSDET.
2018 J Neurosci Meth, Band: 297, Seiten: 31 - 43
KurzfassungStudies on sleep-spindles are typically based on visual-marks performed by experts, however this process is time consuming and presents a low inter-expert agreement, causing the data to be limited in quantity and prone to bias. An automatic detector would tackle these issues by generating large amounts of objectively marked data. NEW METHOD: Our goal was to develop a sensitive, precise and robust sleep-spindle detection method. Emphasis has been placed on achieving a consistent performance across heterogeneous recordings and without the need for further parameter fine tuning. The developed detector runs on a single channel and is based on multivariate classification using a support vector machine. Scalp-electroencephalogram recordings were segmented into epochs which were then characterized by a selection of relevant and non-redundant features. The training and validation data came from the Medical Center-University of Freiburg, the test data consisted of 27 records coming from 2 public databases. RESULTS: Using a sample based assessment, 53% sensitivity, 37% precision and 96% specificity was achieved on the DREAMS database. On the MASS database, 77% sensitivity, 46% precision and 96% specificity was achieved. The developed detector performed favorably when compared to previous detectors. The classification of normalized EEG epochs in a multidimensional space, as well as the use of a validation set, allowed to objectively define a single detection threshold for all databases and participants. CONCLUSIONS: The use of the developed tool will allow increasing the data-size and statistical significance of research studies on the role of sleep-spindles.
K. Losch, S. Schuff, F. Balle, T. Beck, C. Redenbach
A stochastic microstructure model for particle reinforced aluminium matrix composites
2018 J Microsc-oxford
Z. Bagheryan, M. Trotter, L. Becherer, N. Borst, F. von Stetten
A universal approach for electrochemically DNA detection based on mediator displacement LAMP
2018 9th Euro Biosensors & Bioelectronics Congress November 29-30, 2018 Dublin, Ireland
Hiller D, López-Vidrier J, Nomoto K, Wahl M, Bock W, Chlouba T, Trojanek F, Gutsch S, Zacharias M, König D, Maly P, Kopnarski M
Absence of free carriers in silicon nanocrystals grown from phosphorus-and boron-doped silicon-rich oxide and oxynitride
2018 Beilstein J Nanotech, Band: 9, Nummer: 1, Seiten: 1501 - 1511
KurzfassungPhosphorus-and boron-doped silicon nanocrystals (Si NCs) embedded in silicon oxide matrix can be fabricated by plasma-enhanced chemical vapour deposition (PECVD). Conventionally, SiH 4 and N 2 O are used as precursor gasses, which inevitably leads to the incorporation of≈ 10 atom% nitrogen, rendering the matrix a silicon oxynitride. Alternatively, SiH 4 and O 2 can be used, which allows for completely N-free silicon oxide. In this work, we investigate the properties of B-and P-incorporating Si NCs embedded in pure silicon oxide compared to silicon oxynitride by atom probe tomography (APT), low-temperature photoluminescence (PL), transient transmission (TT), and current–voltage (I–V) measurements. The results clearly show that no free carriers, neither from P-nor from B-doping, exist in the Si NCs, although in some configurations charge carriers can be generated by electric field ionization. The absence of free carriers in Si NCs≤ 5 nm in diameter despite the presence of P-or B-atoms has severe implications for future applications of conventional impurity doping of Si in sub-10 nm technology nodes.
Leonore Winterer, Sebastian Junges, Ralf Wimmer, Nils Jansen, Ufuk Topcu, Joost-Pieter Kaoten, Becker B
Abstraktions-basierte Verifikation von POMDPs im Motion-Planning-Kontext
2018 GI/ITG/GMM Workshop “Methoden und Beschreibungssprachen zur Modellierung und Verifikation von Schaltungen und Systemen”
KurzfassungWir untersuchen Pfadplanungsprobleme aus der Robotik und die Berechnung von Stra- tegien, die beweisbare Garantien für Sicherheitseigenschaften liefern. Dabei soll ein Agent mit hoher Wahrscheinlichkeit einen Zielort erreichen, ohne mit einem Hindernis zusammenzustoßen, das sich probabilistisch durch den Raum bewegt. Schwierig wird dieses Problem dadurch, dass der Agent seine Umgebung nur eingeschränkt beobachten kann. Dieses Szenario lässt sich auf na- türliche Art und Weise als ein sogenannter partiell beobachtbarer Markow-Entscheidungsprozess (POMDP) modellieren. Da viele interessante Eigenschaften auf POMDPs unentscheidbar sind, beschäftigt sich die hier vorgestellte Arbeit mit der Entwicklung einer spielbasierten Abstraktionsmethode, um für solche Pfadplanungsprobleme und Sicherheitseigenschaften gute Approximationen zu berechnen.
Vomero M, Porto Cruz MF, Zucchini E, Shabanian A, Delfino E, Carli S, Fadiga L, Ricci D, Stieglitz T
Achieving Ultra-Conformability with Polyimide-Based ECoG Arrays.
2018 Engineering in Medicine and Biology Conference (EMBC) 2018. 17-21 July 2018 . Honolulu, Hawaii, United States IEEE, Seiten: 4464 - 4467
KurzfassungMicro-electrode arrays for electrocorticography (ECoG) represent the best compromise between invasiveness and signal quality, as they are surface devices that still allow high sensitivity recordings. In this work, an assessment of different technical aspects determining the ultimate performance of ultra-conformable polyimide-based μECoG arrays is conducted via a finite element model, impedance spectroscopy measurements and recordings of sensorimotor evoked potentials (SEPs) in rats. The finite element model proves that conformability of thin-film arrays can be achieved with polyimide, a non-stretchable material, by adjusting its thickness according to the curvature of the targeted anatomical area. From the electrochemical characterization of the devices, intrinsic thermal noise of platinum and gold electrodes is estimated to be 3–5 μV. Results show that electrode size and in vitro impedance do not influence the amplitude of the recorded SEPs. However, the use of a reference on-skull (a metal screw), as compared to reference on-array (a metal electrode surrounding the recording area), provides higher-amplitude SEPs. Additionally, the incorporation of a grounded metal shield in the thin-film devices limits crosstalk between tracks and does not compromise the recording capabilities of the arrays.
Butz N, Kalita U, Kuhl M, Manoli Y
Active Charge Balancer with 6.6 to 40V Quad-Rail Power Supply Compliance for Neural Stimulators
2018 Proceedings of the IEEE International Symposium on Circuits and Systems (ISCAS)
Heizmann S, Kilias A, Ruther P, Egert U, Asplund M
Active Control of Dye Release for Neuronal Tracing Using PEDOT-PSS Coated Electrodes
2018 Ieee T Neur Sys Reh, Band: 26, Seiten: 299 - 306
Zimmermann P, Weltin A, Urban G, Kieninger J
Active Potentiometry for Dissolved Oxygen Monitoring with Platinum Electrodes
2018 Sensors, Band: 18, Nummer: 8, Seite: 2404
KurzfassungPotentiometric oxygen monitoring using platinum as the electrode material was enabled by the combination of conventional potentiometry with active prepolarization protocols, what we call active potentiometry. The obtained logarithmic transfer function is well-suited for the measurement of dissolved oxygen in biomedical applications, as the physiological oxygen concentration typically varies over several decades. We describe the application of active potentiometry in phosphate buffered salt solution at different pH and ion strength. Sensitivity was in the range of 60 mV/dec oxygen concentration; the transfer function deviated from logarithmic behavior for smaller oxygen concentration and higher ion strength of the electrolyte. Long-term stability was demonstrated for 60 h. Based on these measurement results and additional cyclic voltammetry investigations a model is discussed to explain the potential forming mechanism. The described method of active potentiometry is applicable to many different potentiometric sensors possibly enhancing sensitivity or selectivity for a specific parameter.

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Linseis V., Völklein F., Reith H., Nielsch K., Woias P.
Advanced platform for the in-plane ZT measurement of thin films
2018 Review of Scientific Instruments, Band: 89, Nummer: 1, Seite: 015110
KurzfassungThe characterization of nanostructured samples with at least one restricted dimension like thin films or nanowires is challenging, but important to understand their structure and transport mechanism, and to improve current industrial products and production processes. We report on the 2nd generation of a measurement chip, which allows for a simplified sample preparation process, and the measurement of samples deposited from the liquid phase using techniques like spin coating and drop casting. The new design enables us to apply much higher temperature gradients for the Seebeck coefficient measurement in a shorter time, without influencing the sample holder's temperature distribution. Furthermore, a two membrane correction method for the 3ω thermal conductivity measurement will be presented, which takes the heat loss due to radiation into account and increases the accuracy of the measurement results significantly. Errors caused by different sample compositions, varying sample geometries, and different heat profiles are avoided with the presented measurement method. As a showcase study displaying the validity and accuracy of our platform, we present temperature-dependent measurements of the thermoelectric properties of an 84 nm Bi87Sb13 thin film and a 15 μm PEDOT:PSS thin film.
Asplund M, Welle CG
Advancing Science: How Bias Holds Us Back.
2018 Neuron, Band: 99, Nummer: 4, Seiten: 635 - 639
MR Chellali, SH Nandam, S Li, MH Fawey, E Moreno-Pineda, L Velasco, T Boll, L Pastewka, R Kruk, P Gumbsch, H Hahn
Amorphous Nickel nanophases inducing ferromagnetism in equiatomic Ni-Ti alloy
2018 Acta Mater, Band: 161, Seiten: 47 - 53
KurzfassungNi50Ti50 nanometer-sized amorphous particles are prepared using inert-gas condensation followed by in situ compaction. Elemental segregation of Ni and Ti is observed in the consolidated nanostructured material. Amorphous, nearly pure Nickel (96%) nanophases form within the amorphous Ni50Ti50 alloy. Combining atom probe tomography and scanning transmission electron microscopy with computer modelling, we explore the formation process of such amorphous nanophase structure. It is shown that the Ni rich amorphous phase in the consolidated nanostructured material is responsible for the ferromagnetic behavior of the sample whereas the rapidly quenched amorphous and crystalline samples with the same chemical composition (Ni50Ti50) were found to be paramagnetic. Due to the high cooling rate obtained using the inert gas condensation technique, an exceptional control over the crystallization processes is possible, promoting the formation of various amorphous phases, which are not obtained by standard rapid quenching techniques. Our findings demonstrate the potential of amorphous metallic nanostructures as advanced technological materials, and useful magnetic compounds.
Kuehn J, Manoli Y
An Application-Specific Field-Programmable Tree Ensemble Architecture
2018 Proceedings of the International Conference on Field Programmable Logic and Applications (FPL), Seiten: 4450 - 4451
E. Kipf, S. Sané, D. Morse, T. Messinger, R. Zengerle, S. Kerzenmacher
An air-breathing enzymatic cathode with extended lifetime by continuous laccase supply
2018 Bioresource Technol, Band: 264, Seiten: 306 - 310
KurzfassungWe present a novel concept of an air-breathing enzymatic biofuel cell cathode combined with continuous supply of unpurified laccase-containing supernatant of the white-rot fungus Trametes versicolor for extended lifetime. The air-breathing cathode design obviates the need for energy-intensive active aeration. In a corresponding longterm experiment at a constant current density of 50 μA cm−2, we demonstrated an increased lifetime of 33 days (cathode potential above 0.430 V vs. SCE), independent of enzyme degradation. The obtained data suggest that theoretically a longer lifetime is feasible. However, further engineering efforts are required to prevent clogging and fouling of the supply tubes. These results represent an important step towards the realization of enzymatic biofuel cell cathodes with extended lifetime and enhanced performance.
Ralf Wimmer, Karina Wimmer, Christoph Scholl, Bernd Becker
Analysis of Incomplete Circuits Using Dependency Quantified Boolean Formulas
In: Advanced Logic Synthesis
2018, Springer International Publishing, André Inácio Reis, Rolf Drechsler, Seiten: 151 - 168, André Inácio Reis, Rolf Drechsler, ISBN: 978-3-319-67294-6
KurzfassungWe consider Dependency Quantified Boolean Formulas (DQBFs), a generalization of Quantified Boolean Formulas (QBFs), and demonstrate that DQBFs are a natural calculus to exactly express the realizability problem of incomplete combinational and sequential circuits with an arbitrary number of (combinational or bounded-memory) black boxes. In contrast to usual approaches for controller synthesis, restrictions to the interfaces of missing circuit parts in distributed architectures are strictly taken into account. We present a solution method for DQBFs together with the extraction of Skolem functions for existential variables, which can directly serve as implementations for the black boxes. First experimental results are provided.
Ralf Wimmer, Karina Wimmer, Christoph Scholl, Bernd Becker
Analysis of Incomplete Circuits using Dependency Quantified Boolean Formulas
In: Advanced Logic Synthesis
2018, Springer, André Ignacio Reis and Rolf Drechsler, Seiten: 151 - 168, André Ignacio Reis and Rolf Drechsler, ISBN: 978-3-319-67294-6
Feißt M, Möller E, Wilde J
Analysis of Transient Thermal-Mechanical Stresses in Power Devices Using Test Chips and Optical Techniques
2018 10th International Conference on Integrated Power Electronics Systems (CIPS), Stuttgart, Seiten: 269 - 273
Talebi Mohammadmahdi, Woias Peter, Cobry Keith
Analysis of impedance data from bubble flow in a glass/SU8 microfluidic device with on-channel sensors
2018 Sensors and Actuators, A: Physical, Band: 279, Seiten: 543 - 552
KurzfassungThis paper presents the design and original fabrication of a fully transparent microfluidic reactor with integrated electrical sensors over the microchannel. The transparent chip design allows for microscale photochemistry, and permits direct, real-time visual and electrical observation. The microchip uses optically transparent indium tin oxide (ITO) electrodes as sensing elements for in-channel phase tracking. High-speed videography was used to validate the electrical measurement data. The device permits visual observation of microchannel bubble flow while simultaneously acquiring electrical data. The aim of this work is to develop and optically verify electrical data acquisition and signal analysis methodologies, which in future applications may be used for inexpensive non-destructive monitoring of two-phase microchannel flows, in systems where detailed visual observation may be infeasible.
Zhang Yajia, Pitchiaya Sethuramasundaram, Cieslik Marcin, Niknafs Yashar, Tien Jean, Hosono Yasuyuki, Iyer Matthew, Yazdani Sahr, Subramaniam Shruthi, Shukla Sudhanshu, Jiang Xia, Wang Lisha, Liu Tzu-Ying, Uhl Michael, Gawronski Alexander, Qiao Yuanyuan, Xiao Lanbo, Dhanasekaran Saravana, Juckette Kristin, Kunju Lakshmi, Cao Xuhong, Patel Utsav, Batish Mona, Shukla Girish, Paulsen Michelle, Ljungman Mats, Jiang Hui, Mehra Rohit, Backofen Rolf, Sahinalp Cenk, Freier Susan, Watt Andrew, Guo Shuling, Wei John, Feng Felix, Malik Rohit, Chinnaiyan Arul
Analysis of the androgen receptor-regulated lncRNA landscape identifies a role for ARLNC1 in prostate cancer progression
2018 Nat Genet, Band: 50, Nummer: 6, Seiten: 814 - 824
KurzfassungThe androgen receptor (AR) plays a critical role in the development of the normal prostate as well as prostate cancer. Using an integrative transcriptomic analysis of prostate cancer cell lines and tissues, we identified ARLNC1 (AR-regulated long noncoding RNA 1) as an important long noncoding RNA that is strongly associated with AR signaling in prostate cancer progression. Not only was ARLNC1 induced by the AR protein, but ARLNC1 stabilized the AR transcript via RNA-RNA interaction. ARLNC1 knockdown suppressed AR expression, global AR signaling and prostate cancer growth in vitro and in vivo. Taken together, these data support a role for ARLNC1 in maintaining a positive feedback loop that potentiates AR signaling during prostate cancer progression and identify ARLNC1 as a novel therapeutic target.
B. Gerdes, M. Breitwieser, T. Kaltenbach, M. Jehle, J. Wilde, R. Zengerle, P. Koltay, L. Riegger
Analysis of the metallic structure of microspheres produced by printing of aluminum alloys from the liquid melt
2018 Mater Res Express, Band: 6, Seite: 036514
KurzfassungThis work presents an analysis of the metallic structure of microspheres produced by drop-on-demand printing of the aluminum alloy AlSi12 directly printed from the liquid melt via StarJet technology. AlSi alloys are commonly used in casting processes, but microdroplets from these materials could potentially be used for additive manufacturing of metal and composite parts. Recently, several printing technologies were presented that enable the drop-on-demand printing of Al-alloy microdroplets. However, the material distribution and metallic structure inside of printed droplets is expected to be significantly different from the bulk material properties, and hardly any data on the microscopic structure of small droplets that have undergone rapid solidification has been published so far. Therefore, a microscopic in-depth study of microdroplets printed directly from the metal melt has been carried out: By the means of energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), Auger electron spectroscopy (AES) and optical microscopy the material properties as well as the droplet morphology are investigated for the first time. The analysis demonstrates that the Al alloy droplets printed via StarJet technology exhibit almost no oxidation during the printing process and can therefore potentially be used for additive manufacturing of metal parts. Moreover, the metallurgical structure inside the droplets is analyzed. It exhibits significant difference to the bulk material in terms of the average secondary dendrite arm spacing.
Linseis, Vincent, Völklein, Friedemann, Reith, Heiko, Woias, Peter, Nielsch, Kornelius
Analytical Investigation of the Limits for the In-Plane Thermal Conductivity Measurement Using a Suspended Membrane Setup
2018 Journal of Electronic Materials, Band: 47, Nummer: 6, Seiten: 3203 - 3209
Wieland T, Behrmann O, Bergmann M, Reyes-Romero D, Hügle M, Dame G, Urban G
Application of a real-time thermal sensor system for the evaluation of anti-microbial surface coatings
2018 Biosensors 2016, Göteborg, Schweden Proceedings
Wieland T, Kotthaus K, Hügle M, Bergmann M, Urban G
Application of a thermal sensor system for the measurement and characterization of biofilm formation removal by the disinfectants ethanol, peracetic and sodium hypochlorite in real-time
2018 MicroTAS 2018, Kaohsiung, Taiwan
Wieland T, Assmann J, Hügle M, Behrmann O, Dame G, Tadros M, Urban G
Application of a thermal sensor system for the measurement in real-time of the inhibition of biofilm formation by anti-microbial peptides
2018 Biosensors 2018, Miami, USA Proceedings
Manuel Ruder, Alexey, Dosovitskiy, Thomas Brox
Artistic style transfer for videos and spherical images
2018 Int J Comput Vision
M.C. Wapler, F. Lemke, G. Alia, U. Wallrabe
Aspherical high-speed varifocal mirror for miniature catadioptric objectives
2018 Opt Express, Band: 26, Nummer: 5, Seiten: 6090 - 6102
A Gola, P Gumbsch, L Pastewka
Atomic-scale simulation of structure and mechanical properties of Cu(1−x)Ag(x)|Ni multilayer systems
2018 Acta Mater, Band: 150, Seiten: 236 - 247
KurzfassungWe use a combination of atom-swap Monte-Carlo (MC) and molecular dynamics (MD) to study the structure and mechanical properties of Cu(1-x)Ag(x)|Ni multilayers with 6 nm layer width for which the Ag-content is used to tune the lattice misfit. We find that the multilayers form a semi-coherent interface with a network of partial dislocations arranged in a regular triangular pattern. A combination of MC and MD was used to equilibrate Cu(1-x)Ag(x)|Ni with x = 0%, 5% and 10%. Ag does not enter the Ni-layer but segregates and precipitates from the Cu layers. We find alloying of Cu and Ni at 600 K. All these findings are in good agreement with the experimental binary phase diagrams of the Cu-Ag, Ag-Ni and Cu-Ni systems. The resulting multilayer structures were then sheared parallel and perpendicular to the normal of the bilayer interface. Initial sliding takes place at the Cu|Ni interface within the misfit dislocation network, followed by emission of partial dislocations into the Cu layer. Flow stress increases with increasing Ag content. Additional calculations of biaxial tension that suppress sliding at the heterointerface show a similar trend. Strengthening can be attributed to Ag precipitates pinning the Cu|Ni heterointerface and to the formation of sessile stacking-fault tetrahedra from the misfit dislocation network whose density increases with the concentration of Ag in the Cu layer.
P. Juelg, M. Specht, E. Kipf, M. Lehnert, C. Eckert, N. Paust, F. von Stetten, R. Zengerle, T. Hutzenlaub
Automation of qPCR based Minimal Residual Disease Monitoring by Centrifugal Microfluidics
2018 11th Symposium on minimal residual cancer, 03. – 05.05.2018, Montpellier, Frankreich
Falkner Stefan, Klein Aaron, Hutter Frank
BOHB: Robust and Efficient Hyperparameter Optimization at Scale
2018 Proceedings of the 35th International Conference on Machine Learning (ICML 2018), Seiten: 1436 - 1445
Chrabąszcz Patryk, Loshchilov Ilya, Hutter Frank
Back to Basics: Benchmarking Canonical Evolution Strategies for Playing Atari
2018 Proceedings of the Twenty-Seventh International Joint Conference on Artificial Intelligence, IJCAI-18, International Joint Conferences on Artificial Intelligence Organization, Seiten: 1419 - 1426
Farahani H, Wagiran R, Yurchenko O, Urban G
Barium Strontium Titanate Humidity Sensor: Impact of Doping on the Structural and Electrical Properties
2018 Eurosensors 2018, Graz, Austria Proceedings, Band: 2, Seite: 1007
KurzfassungThe influence of Mg²⁺ doping (3 mol %) on structural and humidity sensing properties of (Ba₀.₅,Sr₀.₅)TiO₃ (BST) perovskite nanocomposite were studied in details. Microstructural properties revealed the particle size, surface area, and average pore volume diminished for doped sample. For the MgO doped BST sensor, the film resistance and total impedance are changed more than four orders of magnitude in the 20–95% RH range, while BST sensor shows three orders change. The 3 mol % MgO doped sample with maximum hysteresis of 6.1 RH% and response/recovery time of about 30/80 s exhibits faster characteristics compare to pure BST sample with 6.8 RH% hysteresis and response/recovery of 41 s and 98 s, respectively. Transduction mechanism was found based on the proton transfer and further confirmed by a Bode plot and Nyquist complex impedance plane plot.
J. Streeck, C. Hank, M. Neuner, L. Gil-Carrera, M. Kokko, S. Pauliuk, A. Schaadt, S. Kerzenmacher, R. J. White
Bio-electrochemical conversion of industrial wastewater-COD combined with downstream methanol synthesis – an economic and life cycle assessment
2018 Green Chem, Band: 20, Seiten: 2742 - 2762
KurzfassungHerein, a techno-economic and environmental performance evaluation (i.e. Life Cycle Assessment (LCA)) of a 45 kW Microbial Electrolysis Cell (MEC) system is presented in the context of industrial wastewater remediation. This system produces H2 and CO2 – suitable for downstream CH3OH synthesis – based on the bio-electrochemical conversion of chemical industry wastewater with an organic content of 3.9 g(COD) L−1. A cost–benefit analysis indicates that the MEC system hardware costs, share of CO2 captured from the MEC and MEC operating current density (i.e. 1.0 mA cm−2) are crucial parameters influencing the total cost and represent areas for potential cost reductions. It was established based on the present study that MEC system operation with renewable electricity leads to H2 production costs of 4–5.7€ kg(H2) −1 (comparable to H2O electrolysis) and CH3OH production costs of 900€ t(CH3OH) −1. At the current CH3OH market prices, however, the production is currently not profitable. In turn, the cost-efficient construction of the MEC system and the use of less expensive materials could lead to improved CH3OH production economics based on this route. Our results indicate that the use of low-cost materials has greater potential with regard to cost reduction compared to reducing the internal resistance and polarization losses via the use of expensive high-performance materials in MEC construction. A complementary LCA of the proposed system, based on a “cradle-to-gate” definition, indicates that waste-based is superior to fossil-based CH3OH production with respect to global warming potential and cumulated fossil energy demand, provided the system is operated with 100% renewable electricity and CO2 sourced only from the MEC. However, with regard to the impact categories Metal Depletion and Freshwater Eutrophication Potential, the system was found to perform less satisfactorily (i.e. in comparison with fossil-based CH3OH production).
Grüning Björn, Dale Ryan, Chapman Brad, Rowe Jillian, Tomkins-Tinch Christopher, Valieris Renan, Köster Johannes
Bioconda: sustainable and comprehensive software distribution for the life sciences
2018 Nature Methods, Band: 15, Nummer: 7, Seiten: 475 - 476
KurzfassungWe present Bioconda (https://bioconda.github.io), a distribution of bioinformatics software for the lightweight, multi-platform and language-agnostic package manager, Conda. Currently, Bioconda offers a collection of over 2900 software tools, which are continuously maintained, updated, and extended by a growing global community of more than 200 contributors. Bioconda improves analysis reproducibility by allowing users to define isolated environments with defined software versions, all of which are easily installed and managed without administrative privileges.
Stieglitz T, von Metzen R, Stett A
Bioelektronische Medizin-Eine Einführung in eine neue Disziplin.
VDE Health Expertenbeiträge, Band: 1, Seiten: 1 - 4, 2018
J. Peter,, L. Schumacher,, V.Landerer,, Ahmed Abdulkadir,, C.Kaller,, J. Lahr,, S. Kloeppel
Biological Factors Contributing to the Response to Cognitive Training in Mild Cognitive Impairment
2018 J Alzheimers Dis, Band: 61, Nummer: 1, Seiten: 333 - 345
Valle G, Mazzoni A, Iberite F, D'Anna E, Strauss I, Granata G, Controzzi M, Clemente F, Rognini G, Cipriani C, Stieglitz T, Petrini FM, Rossini PM, Micera S
Biomimetic Intraneural Sensory Feedback Enhances Sensation Naturalness, Tactile Sensitivity, and Manual Dexterity in a Bidirectional Prosthesis.
2018 Neuron, Band: 100, Nummer: 1, Seiten: 37 - 45.e7
KurzfassungPeripheral intraneural stimulation can provide tactile information to amputees. However, efforts are still necessary to identify encoding strategy eliciting percepts that are felt as both natural and effective for prosthesis control. Here we compared the naturalness and efficacy of different encoding strategies to deliver neural stimulation to trans-radial amputees implanted with intraneural electrodes. Biomimetic frequency modulation was perceived as more natural, while amplitude modulation enabled better performance in tasks requiring fine identification of the applied force. Notably, the optimal combination of naturalness and sensitivity of the tactile feedback can be achieved with "hybrid" encoding strategies based on simultaneous biomimetic frequency and amplitude neuromodulation. These strategies improved the gross manual dexterity of the subjects during functional task while maintaining high levels of manual accuracy. They also improved prosthesis embodiment, reducing abnormal phantom limb perceptions ("telescoping effect"). Hybrid strategies are able to provide highly sensitive and natural percepts and should be preferred.
K. Tröndle, S. Kartmann, L. Gutzweiler, R. Zengerle, P. Koltay, S. Zimmermann
Bioprinting with spheroids: Automated large-scale production and deposition
2018 3D Cell Culture 2018, 5. - 7. Juni 2018, Freiburg
Jonas Uhrig,, E. Rehder,, B. Fröhlich,, U. Franke,, Thomas Brox
Box2Pix: Single-Shot Instance Segmentation by Assigning Pixels to Object Boxes
2018
Biedenkapp A, Marben J, Lindauer M, Hutter F
CAVE: Configuration Assessment, Visualization and Evaluation
2018 Proceedings of the International Conference on Learning and Intelligent Optimization (LION’18)
Sayed Herbawi A, Christ O, Kiessner L, Mottahi S, Hofmann U G, Paul O, Ruther P
CMOS Neural Probe with 1600 Close-packed Recording Sites and 32 Analog Output Channels
2018 J Microelectromech S
KurzfassungThis paper reports on 1 the development, characterization, and validation of neural probes serving the growing need of neuroscience for miniaturized tools enabling simultaneous high-resolution recording of neural activity in multiple brain areas. The probes consist of a needle-shaped shaft with a crosssection of 100 × 50 μm2 and a length of 10 or 5 mm emerging from a base with dimensions of only 0.55×1.8 mm2. The shafts carry 1600 and 800 recording sites, respectively, grouped into 50 (respectively 25) blocks of 4 × 8 electrodes with an area of 17 × 17 μm2 each, a pitch of 20 μm, and an electrode-to electrode spacing of 3 μm. The probes are fabricated using a commercial 0.18 μm CMOS process followed by dedicated metallization, passivation, and microfabrication steps. Neural signals are accessible through 32 analog output channels via a hierarchical digital addressing scheme implementing an advanced electronic depth control concept giving the option of multiple scanning modes and offering a switching time of 416 μs at a clock frequency of 1 MHz. All output channels are shielded against each other, whereby crosstalk between neighboring channels is measured to be −58 dB at 1 kHz. Absolute impedance values at 1 kHz of single IrOx and Pt electrodes are 230 ± 38 kOhm and 2.2 ± 0.3 MOhm, respectively. In vivo recordings taking advantage of the new addressing concept for high-resolution recordings from multiple brain regions were successfully performed in anesthetized rats.
Eggenhofer Florian, Hofacker Ivo, Backofen Rolf, Honer Zu Siederdissen Christian
CMV - Visualization for RNA and Protein family models and their comparisons
2018 Bioinformatics
KurzfassungSummary: A standard method for the identification of novel RNAs or proteins is homology search via probabilistic models. One approach relies on the definition of families, which can be encoded as covariance models (CMs) or Hidden Markov Models (HMMs). While being powerful tools, their complexity makes it tedious to investigate them in their (default) tabulated form. This specifically applies to the interpretation of comparisons between multiple models as in family clans. The Covariance model visualization tools (CMV) visualize CMs or HMMs to: I) Obtain an easily interpretable representation of HMMs and CMs; II) Put them in context with the structural sequence alignments they have been created from; III) Investigate results of model comparisons and highlight regions of interest. Availability: Source code (http://www.github.com/eggzilla/cmv), web-service (http://rna.informatik.uni-freiburg.de/CMVS). Contact: egg@informatik.uni-freiburg.de, choener@bioinf.uni-leipzig.de. Supplementary information: Supplementary data available online.
S. Adhikari, V. Badilita, U. Wallrabe, J.G. Korvink
Capacitor re-design overcomes the rotation rate limit of MACS Resonators.
2018 Conc. Mag. Res. B
Dongyang C, Behrmann O, Hufert F, Dame G, Urban G
Capacity of rTth polymerase to detect RNA in the presence of various inhibitors
2018 Plos One, Band: 13, Nummer: 1, Seite: e0190041
KurzfassungThe full potential of the real-time reverse transcription polymerase chain reaction (RT-PCR) as a rapid and accurate diagnostic method is limited by DNA polymerase inhibitors as well as reverse transcriptase inhibitors which are ubiquitous in clinical samples. rTth polymerase has proven to be more resistant to DNA polymerase inhibitors present in clinical samples for DNA detection and also exhibits reverse transcriptase activity in the presence of Mn2+ ions. However, the capacity of rTth polymerase, which acts as DNA polymerase and reverse transcriptase, to detect RNA in the presence of various inhibitors has not been investigated in detail. Herein, the inhibitors originating from various clinical samples such as blood, urine, feces, bodily fluids, tissues and reagents used during nucleic acid extraction were employed to evaluate the capacity of rTth polymerase to detect RNA. The results show that the inhibitors have different inhibitory effects on the real-time RT-PCR reactions by rTth polymerase, and the inhibitory effects are concentration dependent. Additionally, the capacity of rTth polymerase to detect RNA in the presence of various inhibitors is better or at least comparable with its capacity to detect DNA in the presence of various inhibitors. As a consequence, RNA may be directly detected in the presence of co-purified inhibitors or even directly from crude clinical samples by rTth polymerase.

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J. Hess, S. Yazar, N. Paust, R. Zengerle, T. Hutzenlaub
Capillary Valve for Microfluidic Foil Chips Fabricated by Micro-Milled Metal Master Tools
2018 MicroTAS 2018, 11. -15. November 2018, Kaohsiung / Taiwan
F. Hegge, R. Moroni, E. Wright, J. Sharman, S. Thiele, S. Vierrath
Catalyst Support Ageing of Polymer Electrolyte Fuel Cells Investigated with Tomography
2018 69th Annual Meeting of the International Society of Electrochemistry (ISE), Bologna/Italy, 02. – 07.09.2018
V Sandfort, J Goldschmidt, J Wöllenstein, S Palzer
Cavity-Enhanced Raman Spectroscopy for Food Chain Management
2018 Sensors-basel, Band: 18, Nummer: 3, Seite: 709
KurzfassungComprehensive food chain management requires the monitoring of many parameters including temperature, humidity, and multiple gases. The latter is highly challenging because no low-cost technology for the simultaneous chemical analysis of multiple gaseous components currently exists. This contribution proposes the use of cavity enhanced Raman spectroscopy to enable online monitoring of all relevant components using a single laser source. A laboratory scale setup is presented and characterized in detail. Power enhancement of the pump light is achieved in an optical resonator with a Finesse exceeding 2500. A simulation for the light scattering behavior shows the influence of polarization on the spatial distribution of the Raman scattered light. The setup is also used to measure three relevant showcase gases to demonstrate the feasibility of the approach, including carbon dioxide, oxygen and ethene.
N. Paust
Centrifugal Microfluidics:Unique operations enabled by artificial buoyancy
2018 Lab-on-a-Chip and Microfluidics Europe 2018, Rotterdam/Niederlande, 05. - 06.06.2018
K. Mitsakakis, W.E. Kaman, G. Elshout, M. Specht, J.P. Hays
Challenges in identifying antibiotic resistance targets for point-of-care diagnostics in general practice
2018 Future Microbiol, Band: 13, Nummer: 10, Seiten: 1157 - 1164
KurzfassungGeneral practitioners stand at the front line of healthcare provision and have a pivotal role in the fight against increasing antibiotic resistance. In this respect, targeted antibiotic prescribing by general practitioners would help reduce the unnecessary use of antibiotics, leading to reduced treatment failures, fewer side-effects for patients and a reduction in the (global) spread of antibiotic resistances. Current ‘gold standard’ antibiotic resistance detection strategies tend to be slow, taking up to 48 h to obtain a result, although the implementation of point-of-care testing by general practitioners could help achieve the goal of targeted antibiotic prescribing practices. However, deciding on which antibiotic resistances to include in a point-of-care diagnostic is not a trivial task, as outlined in this publication.
S Khanal, A Gujrati, SB Vishnubhotla, P Nowakowski, C Bonifacio, L Pastewka, TDB Jacobs
Characterization of small-scale surface topography using transmission electron microscopy
2018 Surf Topogr-metrol, Band: 6, Seite: 045004
KurzfassungMulti-scale surface topography is critical to surface function, yet the very smallest scales are not accessible with conventional measurement techniques. Here we demonstrate two separate approaches for measuring small-scale topography in a transmission electron microscope (TEM). The first technique harnesses "conventional" methods for preparation of a TEM cross-section, and presents how these methods may be modified to ensure the preservation of the original surface. The second technique involves the deposition of the material of interest on a pre-fabricated substrate. Both techniques enable the observation and quantification of surface topography with Ångström-scale resolution. Then, using electron energy loss spectroscopy (EELS) to quantify the sample thickness, we demonstrate that there is no systematic effect of thickness on the statistical measurements of roughness. This result was verified using mathematical simulations of artificial surfaces with varying thickness. The proposed explanation is that increasing the side-view thickness of a randomly rough surface may change which specific features are sampled, but does not significantly alter the character (e.g., root-mean-square (RMS) values and power spectral density (PSD)) of the measured topography. Taken together, this work establishes a new approach to topography characterization, which fills in a critical gap in conventional approaches: i.e., the measurement of smallest-scale topography.
Bruno B, Fahmy A, Stürmer M, Wallrabe U, Wapler M
Characterizing Piezoceramic Materials in High Electric Field Actuator Applications
2018 ACTUATOR 2018, 16th Int. Conference on New Actuators, Bremen, Germany , Seiten: 416 - 419
Feldmann Frank, Nogay Gizem, Löper Philipp, Young David, Lee Benjamin, Stradins Paul, Hermle Martin, Glunz Stefan
Charge carrier transport mechanisms of passivating contacts studied by temperature-dependent J-V measurements
2018 Solar Energy Materials and Solar Cells, Band: 178, Seite: 15–19
KurzfassungThe charge carrier transport mechanism of passivating contacts which feature an ultra-thin oxide layer is investigated by studying temperature-dependent current-voltage characteristics. 4-Terminal dark J-V measurements at low temperatures reveal non-linear J-V characteristics of passivating contacts with a homogeneously grown silicon oxide, which result in an exponential increase in contact resistance towards lower temperature. The attempt to describe the R(T) characteristic solely by thermionic emission of charge carriers across an energy barrier leads to a significant underestimation of the resistance by several orders of magnitude. However, the data can be described properly with the metal-insulator-semiconductor (MIS) theory if tunneling of charge carriers through the silicon oxide layer is taken into account. Furthermore, temperature-dependent light J-V characteristics of solar cells featuring passivating contacts at the rear revealed a FF drop at T<205 K, which is near the onset temperature of the exponential increase in contact resistivity.
Z Li, L Pastewka, I Szlufarska
Chemical aging of large-scale randomly rough frictional contacts
2018 Phys Rev E, Band: 98, Seite: 023001
KurzfassungIt has been shown that contact aging due to chemical reactions in single asperity contacts can have a significant effect on friction. However, it is currently unknown how chemically induced contact aging of friction depends on roughness that is typically encountered in macroscopic rough contacts. Here we develop an approach that brings together a kinetic Monte Carlo model of chemical aging with a contact mechanics model of rough surfaces based on the boundary element method to determine the magnitude of chemical aging in silica-silica contacts with random roughness. Our multiscale model predicts that chemical aging for randomly rough contacts has a logarithmic dependence on time. It also shows that friction aging switches from a linear to a nonlinear dependence on the applied load as the load increase. We discover that surface roughness affects the aging behavior primarily by modifying the real contact area and the local contact pressure, whereas the effect of contact morphology is relatively small. Our results demonstrate how understanding of chemical aging can be translated from studies of single asperity contacts to macroscopic rough contacts.
J. De Fauw,, J. Ledsam,, B. Romera-Paredes,, S. Nikolov,, N. Tomasev,, S. Blackwell,, H. Askham,, X. Glorot,, B. O’Donoghue,, D. Visentin,, G. van den Driessche,, B. Lakshminarayanan,, C. Meyer,, F. Mackinder,, S. Bouton,, K. Ayoub,, R. Chopra,, D. King,, A. Karthikesalingam,, C. Hughes,, R. Raine,, J. Hughes,, D. Sim,, C. Egan,, A. Tufail,, H. Montgomery,, D. Hassabis,, G. Rees,, T. Back,, P. Khaw,, M. Suleyman,, J. Cornebise,, P. Keane,, Olaf Ronneberger
Clinically applicable deep learning for diagnosis and referral in retinal disease
2018 Nat Med, Band: 24, Nummer: 9, Seiten: 1342 - 1350
KurzfassungThe volume and complexity of diagnostic imaging is increasing at a pace faster than the availability of human expertise to interpret it. Artificial intelligence has shown great promise in classifying two-dimensional photographs of some common diseases and typically relies on databases of millions of annotated images. Until now, the challenge of reaching the performance of expert clinicians in a real-world clinical pathway with three-dimensional diagnostic scans has remained unsolved. Here, we apply a novel deep learning architecture to a clinically heterogeneous set of three-dimensional optical coherence tomography scans from patients referred to a major eye hospital. We demonstrate performance in making a referral recommendation that reaches or exceeds that of experts on a range of sight-threatening retinal diseases after training on only 14,884 scans. Moreover, we demonstrate that the tissue segmentations produced by our architecture act as a device-independent representation; referral accuracy is maintained when using tissue segmentations from a different type of device. Our work removes previous barriers to wider clinical use without prohibitive training data requirements across multiple pathologies in a real-world setting.

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Daniel Kuhner, Johannes Aldinger, Felix Burget, Moritz Göbelbecker, Wolfram Burgard, Bernhard Nebel
Closed-Loop Robot Task Planning Based on Referring Expressions
2018 IEEE/RSJ International Conference on Intelligent Robots and Systems, Madrid 2018 Proc. of IEEE/RSJ International Conference on Intelligent Robots and Systems
KurzfassungIncreasing the accessibility of autonomous robots also for inexperienced users requires user-friendly and highlevel control opportunities of robotic systems. While automated planning is able to decompose a complex task into a sequence of steps which reaches an intended goal, it is difficult to formulate such a goal without knowing the internals of the planning system and the exact capabilities of the robot. This becomes even more important in dynamic environments in which manipulable objects are subject to change. In this paper, we present an adaptive control interface which allows users to specify goals based on an internal world model by incrementally building referring expressions to the objects in the world. We consider fetch-and-carry tasks and automatically deduce potential high-level goals from the world model to make them available to the user. Based on its perceptions our system can react to changes in the environment by adapting the goal formulation within the domain-independent planning system.
L Engel, K Tarantik, C Pannek, J Wöllenstein
Colorimetric Detection of Hydrogen Sulfide in Ambient Air
2018 Multidisciplinary Digital Publishing Institute Proceedings , Band: 2, Nummer: 13, Seite: 804
KurzfassungWe present a fast method to monitor hydrogen sulfide (H 2 S) in ambient air based on a visible color change. Therefore, an immobilized copper (II) complex of the azo dye 1-(2-pyridylazo)-2-naphtol (H-PAN) was synthesized and prepared in a matrix for screen printing. Different materials, reaching from opaque paper to transparent foils served as substrate. The reaction of the copper (II) complex (Cu-PAN) to the target gas H 2 S was measured in reflection via UV/VIS spectroscopy.
K Schmitt, KR Tarantik, C Pannek, J Wöllenstein
Colorimetric Materials for Fire Gas Detection—A Review
2018 Chemosensors, Band: 6, Nummer: 2, Seite: 14
KurzfassungThe damage caused by outbreaks of fire continues to be enormous despite ongoing improvements in fire detection and fighting. Therefore, the detection of fires at the earliest possible stage is essential. The latest developments in fire detection devices include the addition of carbon monoxide (CO) or temperature sensors into the widespread smoke detectors, but also alternative solutions are searched for. Advantageous is the direct detection of the most relevant fire gases CO and nitrogen dioxide (NO2), because they are produced very early in a developing fire. A sensitive, selective, and low-cost method to detect these gases is the use of colorimetric materials combined with a compact optical readout. In this review, we take account of recent developments in this research field and provide a comprehensive overview on suitable materials for CO and NO2 detection in fire gas sensing and first steps towards novel fire gas detectors.
Thriene Kerstin, Gruning Bjorn, Bornert Olivier, Erxleben Anika, Leppert Juna, Athanasiou Ioannis, Weber Ekkehard, Kiritsi Dimitra, Nystrom Alexander, Reinheckel Thomas, Backofen Rolf, Has Cristina, Bruckner-Tuderman Leena, Dengjel Jorn
Combinatorial Omics Analysis Reveals Perturbed Lysosomal Homeostasis in Collagen VII-deficient Keratinocytes
2018 Mol Cell Proteomics, Band: 17, Nummer: 4, Seiten: 565 - 579
KurzfassungThe extracellular matrix protein collagen VII is part of the microenvironment of stratified epithelia and critical in organismal homeostasis. Mutations in the encoding gene COL7A1 lead to the skin disorder dystrophic epidermolysis bullosa (DEB), are linked to skin fragility and progressive inflammation-driven fibrosis that facilitates aggressive skin cancer. So far, these changes have been linked to mesenchymal alterations, the epithelial consequences of collagen VII loss remaining under-addressed. As epithelial dysfunction is a principal initiator of fibrosis, we performed a comprehensive transcriptome and proteome profiling of primary human keratinocytes from DEB and control subjects to generate global and detailed images of dysregulated epidermal molecular pathways linked to loss of collagen VII. These revealed downregulation of interaction partners of collagen VII on mRNA and protein level, but also increased abundance of S100 pro-inflammatory proteins in primary DEB keratinocytes. Increased TGF-beta signaling because of loss of collagen VII was associated with enhanced activity of lysosomal proteases in both keratinocytes and skin of collagen VII-deficient individuals. Thus, loss of a single structural protein, collagen VII, has extra- and intracellular consequences, resulting in inflammatory processes that enable tissue destabilization and promote keratinocyte-driven, progressive fibrosis.
Tobias Seufert, Christoph Scholl
Combining PDR and Reverse PDR for Hardware Model Checking
2018 Conference on Design, Automation and Test in Europe (DATE)
KurzfassungIn the last few years IC3 resp. PDR attracted a lot of attention as a SAT-based hardware verification approach without needing to unroll the transition relation as in Bounded Model Checking (BMC). Motivated by different strengths of forward and backward traversal already observed in BDD based model checking and by an exponential complexity gap between original PDR and its reverted counterpart ‘Reverse PDR’ (which starts its analysis with the initial states instead of the unsafe states as in the original PDR), we take a closer look at Reverse PDR and we present a combined forward/backward version of PDR that inherits the advantages of both original and Reverse PDR. Our experimental results on benchmarks from the Hardware Model Checking Competition demonstrate clear benefits of the combined approach.
A Gujrati, SR Khanal, L Pastewka, TDB Jacobs
Combining TEM, AFM, and profilometry for quantitative topography characterization across all scales
2018 Acs Appl Mater Inter, Band: 10, Nummer: 34, Seiten: 29169 - 29178
KurzfassungSurface roughness affects the functional properties of surfaces, including adhesion, friction, hydrophobicity, biological response, and electrical and thermal transport properties. However, experimental investigations to quantify these links are often inconclusive, because surfaces are fractal-like and the values of measured roughness parameters depend on measurement size. Here we demonstrate the characterization of topography of an ultrananocrystalline diamond (UNCD) surface at the Ångström-scale using transmission electron microscopy (TEM), as well as its combination with conventional techniques to achieve a comprehensive surface description spanning eight orders of magnitude in size. We performed more than 100 individual measurements of the nanodiamond film using both TEM and conventional techniques (stylus profilometry and atomic force microscopy). While individual measurements of root-mean-square (RMS) height, RMS slope, and RMS curvature vary by orders of magnitude, we combine the various techniques using the power spectral density (PSD) and use this to compute scale-independent parameters. This analysis reveals that “smooth” UNCD surfaces have an RMS slope greater than one, even larger than the slope of the Austrian Alps when measured on the scale of a human step. This approach of comprehensive multi-scale roughness characterization, measured with Ångström-scale detail, will enable the systematic evaluation and optimization of other technologically relevant surfaces, as well as systematic testing of the many analytical and numerical models for the behavior of rough surfaces.
Backofen Rolf, Gorodkin Jan, Hofacker Ivo, Stadler Peter
Comparative RNA Genomics
2018 Methods Mol Biol, Band: 1704, Seiten: 363 - 400
KurzfassungOver the last two decades it has become clear that RNA is much more than just a boring intermediate in protein expression. Ancient RNAs still appear in the core information metabolism and comprise a surprisingly large component in bacterial gene regulation. A common theme with these types of mostly small RNAs is their reliance of conserved secondary structures. Large scale sequencing projects, on the other hand, have profoundly changed our understanding of eukaryotic genomes. Pervasively transcribed, they give rise to a plethora of large and evolutionarily extremely flexible noncoding RNAs that exert a vastly diverse array of molecule functions. In this chapter we provide a-necessarily incomplete-overview of the current state of comparative analysis of noncoding RNAs, emphasizing computational approaches as a means to gain a global picture of the modern RNA world.
Bleitner A, Goeppert J, Lotze N, Keller M, Manoli Y
Comparison and Optimization of the Minimum Supply Voltage of Schmitt Trigger Gates versus CMOS Gates under Process Variations
2018 GMM-Fb. 91: ANALOG 2018, Seiten: 111 - 116
Valle G, Petrini FM, Strauss I, Iberite F, D'Anna E, Granata G, Controzzi M, Cipriani C, Stieglitz T, Rossini PM, Mazzoni A, Raspopovic S, Micera S
Comparison of linear frequency and amplitude modulation for intraneural sensory feedback in bidirectional hand prostheses.
2018 Sci Rep-uk, Band: 8, Nummer: 1, Seite: 16666
KurzfassungRecent studies have shown that direct nerve stimulation can be used to provide sensory feedback to hand amputees. The intensity of the elicited sensations can be modulated using the amplitude or frequency of the injected stimuli. However, a comprehensive comparison of the effects of these two encoding strategies on the amputees’ ability to control a prosthesis has not been performed. In this paper, we assessed the performance of two trans-radial amputees controlling a myoelectric hand prosthesis while receiving grip force sensory feedback encoded using either linear modulation of amplitude (LAM) or linear modulation of frequency (LFM) of direct nerve stimulation (namely, bidirectional prostheses). Both subjects achieved similar and significantly above-chance performance when they were asked to exploit LAM or LFM in different tasks. The feedbacks allowed them to discriminate, during manipulation through the robotic hand, objects of different compliances and shapes or different placements on the prosthesis. Similar high performances were obtained when they were asked to apply different levels of force in a random order on a dynamometer using LAM or LFM. In contrast, only the LAM strategy allowed the subjects to continuously modulate the grip pressure on the dynamometer. Furthermore, when long-lasting trains of stimulation were delivered, LFM strategy generated a very fast adaptation phenomenon in the subjects, which caused them to stop perceiving the restored sensations. Both encoding approaches were perceived as very different from the touch feelings of the healthy limb (natural). These results suggest that the choice of specific sensory feedback encodings can have an effect on user performance while grasping. In addition, our results invite the development of new approaches to provide more natural sensory feelings to the users, which could be addressed by a more biomimetic strategy in the future.
Linseis Vincent, Hassan Zeinab, Reith Heiko, Garcia Javier, Nielsch Kornelius, Baumgart Helmut, Redel Engelbert, Woias Peter
Complete Thermoelectric Characterization of PEDOT:PSS Thin Films with a Novel ZT Test Chip Platform
2018 Physica Status Solidi A: Applications and Materials Science, Band: 215, Nummer: 7, Seite: 1700930
KurzfassungFor the first time, a complete thermoelectric characterization of PEDOT:PSS thin films is performed with a novel lab‐on‐a‐chip measurement platform, which Is developed for the nearly simultaneous in‐plane ZT characterization. The electrical conductivity, the Seebeck coefficient, the thermal conductivity, and consequently the power factor and ZT values as a function of temperature in a single measurement run is experimentally determined. A clear correlation is found between the film thickness of PEDOT:PSS and the thermoelectric properties. While the electrical conductivity increases with decreasing thickness, the thermal conductivity shows a contrary behavior. Both parameters increase monotonically with increasing temperature between 173 and 373 K. The Seebeck coefficient exhibits the same temperature dependency but, in contrast to the previous two parameters, is almost independent of the PEDOT:PSS film thickness. Furthermore, it is demonstrated that a ZT chip, with a complete set of thermoelectric test structures, can be successfully used for a full thermoelectric characterization of conductive organic thin films. This translates into a major testing time advantage for the screening and optimization of promising organic materials during the R&D phase, which can serve as potential candidates for future thermoelectric applications and devices.
VL Deringer, MA Caro, R Jana, A Aarva, SR Elliott, T Laurila, G Csányi, L Pastewka
Computational surface chemistry of tetrahedral amorphous Carbon by combining machine learning and DFT
2018 Chem Mater
KurzfassungTetrahedral amorphous carbon (ta-C) is widely used for coatings due to its superior mechanical properties and has been suggested as an electrode material for detecting biomolecules. Despite extensive research, however, the complex atomic-scale structures and chemical reactivity of ta-C surfaces are incompletely understood. Here, we combine machine learning, density-functional tight-binding, and density-functional theory simulations to shed new light on this long-standing problem. We make atomistic models of ta-C surfaces, characterize them by local structural fingerprints, and provide a library of structures at different system sizes. We then move beyond the pure element and exemplify how chemical reactivity (hydrogenation and oxidation) can be modeled at the surfaces. Our work opens up new perspectives for modeling the surfaces and interfaces of amorphous solids, which will advance studies of ta-C and other functional materials.
Subbiah N, Bruckner G, Beltran Ramirez K, Wilde J
Concept and Implementation of High-Temperature Pressure Sensor Package up to 500 °C
2018 19th ITG/GMA-Symposium, Sensors and Measuring Systems (SENSOR), Nürnberg, Seiten: 55 - 60
Subbiah N, Beltran Ramirez K, Wilde J
Concept and Implementation of High-Temperature Pressure Sensor Package up to 500 °C
2018 Sensoren und Messsysteme, 26. - 27.Juni 2018 in Nürnberg , Seiten: 55 - 60
A Klemenz, A Gola, M Moseler, L Pastewka
Contact mechanics of graphene-covered metal surfaces
2018 Appl Phys Lett, Band: 112, Seite: 061601
KurzfassungWe carry out molecular statics simulations of the indentation of bare and graphene-covered Pt (111) surfaces with smooth and rough indenters of radius 1.5 to 10 nm. Our simulations show that the plastic yield of bare surfaces strongly depends on atomic-scale indenter roughness such as terraces or amorphous disorder. Covering surfaces with graphene regularizes this response to the results obtained for ideally smooth indenters. Our results suggest that graphene monolayers and other 2D materials mitigate the effect of roughness, which could be exploited to improve the fidelity of experiments that probe the mechanical properties of interfaces.
Jia Y, Hanka K, Zawilski K, Schunemann P, Buse K, Breunig I
Continuous-wave whispering-gallery optical parametric oscillator based on CdSiP₂
2018 Opt Express, Band: 26, Nummer: 8, Seiten: 10833 - 10841
KurzfassungContinuous-wave (cw) optical parametric oscillators (OPOs) are ideally suited for applications, for example high-resolution spectroscopy, that need coherent sources combining narrow-linewidth emission with good wavelength tunability. Here, we demonstrate for the first time cw OPOs based on a millimeter-sized whispering gallery resonator (WGR) made of cadmium silicon phosphide (CdSiP₂). By employing a compact laser diode at 1.57-μm wavelength for pumping, a cw OPO with wavelength tunability from 2.3 μm to 5.1 μm is realized based on such a resonator. The oscillation thresholds are in the milliwatt range. The maximum total power conversion efficiency reaches more than 15%. The intrinsic quality factor at 1.57 μm is determined to be 3.5 × 10⁶. This work suggests that CdSiP₂ is a very promising alternative for constructing mid-infrared parametric devices.
Voglstätter C, Weidlich A, Fischer D, Schmidinger J
Control algorithms for electrolyzers - Hydrogen from green electricity
2018 BKW, Band: 70, Nummer: 7/8, Seiten: 36 - 39
KurzfassungIn 2017, the share of renewables in power generation in Germany was around 33 %. By 2030, according to the will of the federal government, it should be as high as 65 %. A large proportion of electricity from wind and solar energy will in future require electricity storage. Particularly promising is the conversion to hydrogen. Research, industry and the energy sector are currently driving forward the development and use of water electrolysers. The Fraunhofer Institute for Solar Energy Systems ISE and the University of Applied Sciences Offenburg, in cooperation with the energy provider badenova and the gas network operator bnNetz have developed operating management algorithms for electrolyzers and tested them at research facilities. Within the project, the integration of hydrogen into municipal gas and electricity grids and into a local energy grid could be tested taking into account the current regulations and economic constraints. Thereby, the partners have laid important foundations for the use of the energy carrier hydrogen.
Werner C, Sturman B, Podivilov E, Kini Manjeshwar S, Buse K, Breunig I
Control of mode anticrossings in whispering gallery microresonators
2018 Opt Express, Band: 26, Nummer: 2, Seiten: 762 - 771
KurzfassungOptical microresonators attract strong interest because of exciting effects and applications ranging from sensing of single atoms and molecules to quantum and nonlinear optics. For all this, control and tuning of the discrete resonances are vital. In resonators made of anisotropic materials that are beneficial for nonlinear-optical applications, anticrossings of ordinarily (o) and extraordinarily (e) polarized modes occur regularly. This effect is badly understood and harmful for mode control and tuning. We show that the anticrossings are inherent in the o- and e-modes because of the vectorial properties of Maxwell’s equations. Within a novel pertubative approach employing a strong localization of the modes near the resonator rim, we have quantified the anticrossings. The values of avoidance gaps strongly exceeding the linewidths and selection rules for the interacting modes are predicted. The inferred values of the avoidance gaps are confirmed experimentally in resonators made of lithium niobate. Furthermore, based on theory, we have eliminated the anticrossings completely by spatially-controlled introduction of defects. This paves the way for unperturbed tuning of anisotropic microresonators.
Jan Wülfing, Sreedhar Saseendran Kumar, Joschka Boedecker, Martin Riedmiller, Ulrich Egert
Controlling Biological Neural Networks with Deep Reinforcement Learning
2018 European Symposium on Artificial Neural Networks, Computational Intelligence and Machine Learning

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Wülfing J, Kumar S S, Boedecker J, Riedmiller M, Egert U
Controlling Biological Neural Networks with Deep Reinforcement Learning
2018 i6doc.com publ., Seiten: 355 - 360
K. Mitsakakis, S. Hin, P. Müller, N. Wipf, E. Thomsen, M. Coleman, R. Zengerle, J. Vontas, K. Mavridis
Converging Human and Malaria Vector Diagnostics with Data Management towards an Integrated Holistic One Health Approach
2018 International Journal of Environmental Research and Public Health, Band: 15, Nummer: 2, Seite: E259
KurzfassungMonitoring malaria prevalence in humans, as well as vector populations, for the presence of Plasmodium, is an integral component of effective malaria control, and eventually, elimination. In the field of human diagnostics, a major challenge is the ability to define, precisely, the causative agent of fever, thereby differentiating among several candidate (also non-malaria) febrile diseases. This requires genetic-based pathogen identification and multiplexed analysis, which, in combination, are hardly provided by the current gold standard diagnostic tools. In the field of vectors, an essential component of control programs is the detection of Plasmodium species within its mosquito vectors, particularly in the salivary glands, where the infective sporozoites reside. In addition, the identification of species composition and insecticide resistance alleles within vector populations is a primary task in routine monitoring activities, aiming to support control efforts. In this context, the use of converging diagnostics is highly desirable for providing comprehensive information, including differential fever diagnosis in humans, and mosquito species composition, infection status, and resistance to insecticides of vectors. Nevertheless, the two fields of human diagnostics and vector control are rarely combined, both at the diagnostic and at the data management end, resulting in fragmented data and mis- or non-communication between various stakeholders. To this direction, molecular technologies, their integration in automated platforms, and the co-assessment of data from multiple diagnostic sources through information and communication technologies are possible pathways towards a unified human vector approach.
Lima F, Mescheder U, Müller C, Reinecke H
Copper electrodeposition on silicon electrodes
2018 Int J Surf Sci Eng, Band: 12, Nummer: 2
Schlachtberger D, Brown T, Schäfer M, Schramm S, Greiner M
Cost optimal scenarios of a future highly renewable European electricity system: Exploring the influence of weather data, cost parameters and policy constraints
2018 Energy, Band: 163, Seiten: 100 - 114
KurzfassungCost optimal scenarios derived from models of a highly renewable electricity system depend on the specific input data, cost assumptions and system constraints. Here this influence is studied using a techno-economic optimisation model for a networked system of 30 European countries, taking into account the capacity investment and operation of wind, solar, hydroelectricity, natural gas power gen- eration, transmission, and different storage options. A considerable robustness of total system costs to the input weather data and to moderate changes in the cost assumptions is observed. Flat directions in the optimisation landscape around cost-optimal configurations often allow system planners to choose between different technology options without a significant increase in total costs, for instance by replacing onshore with offshore wind power capacity in case of public acceptance issues. Exploring a range of carbon dioxide emission limits shows that for scenarios with moderate transmission expansion, a reduction of around 57% compared to 1990 levels is already cost optimal. For stricter carbon dioxide limits, power generated from gas turbines is at first replaced by generation from increasing renewable capacities. Non-hydro storage capacities are only built for low-emission scenarios, in order to provide the necessary flexibility to meet peaks in the residual load.

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Schierle Stefan, Straub Nils, Woias Peter, Goldschmidtboeing Frank
Creep Compensation in an Electrostatic PDMS-Membrane Actuator with Flexible Silver Nanowire Electrodes
2018 Proceedings, Band: 2, Nummer: 13, Seite: 1088
L. Minkova,, S. Gregory,, R. Scahill,, Ahmed Abdulkadir,, C. Kaller,, J. Peter,, J. Long,, J. Stout,, R. Reilmann,, R. Roos, A. Durr, B. Leavit, S. Tabrizi, S. Kloeppel
Cross-sectional and longitudinal voxel-based grey matter asymmetries in Huntingtons disease
2018 Neuroimage, Band: 17, Seiten: 312 - 324
Franz Henriette, Villarreal Alejandro, Heidrich Stefanie, Videm Pavankumar, Kilpert Fabian, Mestres Ivan, Calegari Federico, Backofen Rolf, Manke Thomas, Vogel Tanja
DOT1L promotes progenitor proliferation and primes neuronal layer identity in the developing cerebral cortex
2018 Nucleic Acids Research, Band: 47, Nummer: 1, Seiten: 168 - 183
KurzfassungCortical development is controlled by transcriptional programs, which are orchestrated by transcription factors. Yet, stable inheritance of spatio-temporal activity of factors influencing cell fate and localization in different layers is only partly understood. Here we find that deletion of Dot1l in the murine telencephalon leads to cortical layering defects, indicating DOT1L activity and chromatin methylation at H3K79 impact on the cell cycle, and influence transcriptional programs conferring upper layer identity in early progenitors. Specifically, DOT1L prevents premature differentiation by increasing expression of genes that regulate asymmetric cell division (Vangl2, Cenpj). Loss of DOT1L results in reduced numbers of progenitors expressing genes including SoxB1 gene family members. Loss of DOT1L also leads to altered cortical distribution of deep layer neurons that express either TBR1, CTIP2 or SOX5, and less activation of transcriptional programs that are characteristic for upper layer neurons (Satb2, Pou3f3, Cux2, SoxC family members). Data from three different mouse models suggest that DOT1L balances transcriptional programs necessary for proper neuronal composition and distribution in the six cortical layers. Furthermore, because loss of DOT1L in the pre-neurogenic phase of development impairs specifically generation of SATB2-expressing upper layer neurons, our data suggest that DOT1L primes upper layer identity in cortical progenitors.
M Azhar, S Shakil, A Greiner, D Kauzlaric, JG Korvink
DPD enables mesoscopic MRI simulation of slow flow
2018 Microfluid Nanofluid, Band: 22, Nummer: 5, Seite: 55
KurzfassungWe present a novel method to simulate magnetic resonance imaging (MRI) for the assessment of slow flow at Reynolds number Re≈0.02. We couple Bloch equations with dissipative particle dynamics (DPD) to study the effect of flow dynamics at the mesoscopic level on acquired MR images. The Bloch equations are used to propagate the evolution of the magnetization of particles while their trajectories are being computed simultaneously based on DPD interaction forces. The magnetic resonance assessment of fluid velocities is performed using a phase-contrast MRI technique, implemented by a spin echo single-sided bipolar gradient sequence. The computational cost for simulating the fluid flow is successfully reduced by an efficient implementation of a vectorized isochromat algorithm. We demonstrate successful simulation of laminar flow, flow with diffusion effects, and flow around an obstacle. The method can be used to simulate convective and diffusive flow MRI experiments at the mesoscopic level.
M Azhar, S Shakil, A Greiner, D Kauzlaric, JG Korvink
DPD of diffusion-weighted MRI
2018 Comput Fluids, Band: 172, Seiten: 467 - 473
KurzfassungDiffusion weighted magnetic resonance imaging (DW-MRI) experiments can be simulated by coupling dissipative particle dynamics (DPD) with Bloch equations. DPD gives hydrodynamics with thermal fluctuations at a well-defined temperature by introducing momentum conserving particle interaction forces and a fluctuation dissipation theorem. The Bloch equations are a set of differential equations that describe the evolution of nuclear magnetization as a function of time. Here we successfully simulate DW-MRI by using the solution of Bloch equations for each DPD particle while computing its trajectories through DPD forces. To this end, a spin echo sequence combined with different diffusion-weighting gradients was implemented and tested for the diffusion of a fluid bound by different diffusion regimes. Fluid confinement was easily incorporated, which enabled investigating different diffusion regimes and the performance of different pulse sequences. The three different sequences applied were: spin echo single-sided bipolar gradient, spin echo two-sided bipolar gradient and spin echo uni-polar gradient; and the three imaged diffusion regimes of interest were: free diffusion, localization and motional narrowing.
Gabriel Leivas Oliveira,, W. Burgard,, Thomas Brox
DPDB-Net: Exploiting Dense Connections for Convolutional Encoders
2018 IEEE

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A. Middleton,, C. Dal Bosco,, P. Chlap,, Robert Bensch,, H. Harz,, F. Ren,, S. Bergmann,, S. Wend,, W. Weber,, K. Hayashi,, M. Zurbriggen,, R. Uhl,, Olaf Ronneberger,, K. Palme,, C. Fleck,, A. Dovzhenko
Data-Driven Modeling of Intracellular Auxin Fluxes Indicates a Dominant Role of the ER in Controlling Nuclear Auxin Uptake
2018 Cell Rep, Band: 22, Nummer: 11, Seiten: 3044 - 3057
Christoph Scholl, Ralf Wimmer
Dependency Quantified Boolean Formulas: An Overview of Solution Methods and Applications
2018 13th International Conference on Theory and Applications of Satisfiability Testing (SAT), Springer-Verlag, Nummer: 10929, Seiten: 3 - 16
KurzfassungDependency quantified Boolean formulas (DQBFs) as a generalization of quantified Boolean formulas (QBFs) have received considerable attention in research during the last years. Here we give an overview of the solution methods developed for DQBF so far. The exposition is complemented with the discussion of various applications that can be handled with DQBF solving.
Christoph Scholl, Ralf Wimmer
Dependency Quantified Boolean Formulas: An Overview of Solution Methods and Applications
2018 Oxford, UK Proceedings of the 21st Int'l Conf. on Theory and Applications of Satisfiability Testing (SAT), Olaf Beyersdorff, Christoph M. Wintersteiger, Band: 10929, Seiten: 3 - 16
KurzfassungDependency quantified Boolean formulas (DQBFs) as a generalization of quantified Boolean formulas (QBFs) have received considerable attention in research during the last years. Here we give an overview of the solution methods developed for DQBF so far. The exposition is complemented with the discussion of various applications that can be handled with DQBF solving.
Pascal Raiola, Michael A. Kochte, Ahmed Atteya, Laura Rodríguez Gómez, Hans-Joachim Wunderlich, Bernd Becker, Matthias Sauer
Design of Reconfigurable Scan Networks for Secure Data Transmission
2018 GI/ITG Workshop “Testmethoden und Zuverlässigkeit von Schaltungen und Systemen”
Cojocaru Ludmila, Wienands Karl, Kim Tae, Uchida Satoshi, Bett Alexander, Rafizadeh Saeid, Goldschmidt Jan, Glunz Stefan
Detailed Investigation of Evaporated Perovskite Absorbers with High Crystal Quality on Different Substrates
2018 ACS applied materials & interfaces
KurzfassungDual-source vapor-phase deposition enables low-temperature fabrication of high-performance planar structure perovskite (CH3NH3PbI3) solar cells (PSCs), applicable in tandem devices or for industrial production with high homogeneity. Herein, we report low-temperature fabrication of high-efficiency PSCs by dual-source vapor-phase deposition and significance of TiO2 surface modification with [6,6]-phenyl C61 butyric acid methyl ester (PCBM) on cell performance. Co-evaporation of PbI2 and CH3NH3I, as confirmed by X-ray diffraction and high-resolution transmission electron microscopy analyses, results in CH3NH3PbI3 layers with a well-crystallized tetragonal phase formed on both TiO2 and TiO2/PCBM electron-transport layers (ETLs). The devices with PCBM interlayer between TiO2 and CH3NH3PbI3 showed remarkably higher performance than those with TiO2 only, which was attributed to enhance charge extraction and reduced recombination at the TiO2/PCBM/CH3NH3PbI3 interface. The devices composed of evaporated CH3NH3PbI3 on top of the TiO2/PCBM and [2,2',7,7'-tetrakis( N, N-di- p-methoxyphenyl-amine)-9,9'-spirobifluorene] (Spiro-OMeTAD) as hole-transport material demonstrated power conversion efficiencies of 17.1% (reverse scan) and 13.4% (forward scan) with stabilized efficiency of over 16%, which is, to the best of our knowledge, the highest efficiency reported for evaporated perovskite solar cells using low-temperature fabrication method involving compact TiO2 layer as ETL. Furthermore, we show that this process can be used to deposit a CH3NH3PbI3 layer on top of a textured silicon substrate, which is the first step for preparing perovskite-silicon tandem devices with enhanced antireflection and light-trapping properties.
Bosh N., Mozaffari-Jovein H., Müller C
Determination of Triaxial Residual Stress in Plasma-Sprayed Hydroxyapatite (HAp) Deposited on Titanium Substrate by X-ray Diffraction
2018 J Therm Spray Techn, Band: 27, Nummer: 130, Seiten: 1 - 13
KurzfassungMeasurement of residual stress in plasma-sprayed coating is of key importance to optimize their microstructure and mechanical properties. In this study, the x-ray diffraction analysis was carried out using the sin2ψ method to evaluate the residual stress distribution of hydroxyapatite (HAp) coatings produced on titanium substrate by atmospheric plasma spraying (APS) and vacuum plasma spraying (VPS). The sin2ψ method measured strains at different tilt ψ and rotating φ angles around the specimen surface normal. A non-uniform and inhomogeneous stress distribution was present in the both coatings. The measured strain εψφ is plotted versus sin2ψ, showing a nonlinear (elliptical) behavior, which indicates the presence of inhomogeneous triaxial stress distributions within coating, due to the crystalline anisotropy, inhomogeneous cooling rate or solidification of the molten particles. The normal stress values within both HAp coatings produced were found to be tensile in nature, but the values of tensile stresses are significantly higher in APS coating than those values obtained for VPS coating.
S. H. Moosavi, M. Kroener, M. Frei, F. Frick, S. Kerzenmacher, P. Woias
Development of a TEM Compatible Nanowire Characterization Platform With Self-forming Contacts
2018 Ieee T Semiconduct M, Band: 31, Nummer: 1, Seiten: 1 - 10
KurzfassungA nanowire characterization platform is designed and fabricated in MEMS-technology for the thermoelectric and structural characterization of single nanowires. The latter is achieved by making the chip compatible to TEM holder, by restricting its thickness to less than 160μm and its diagonal dimensions to less than 3mm. Two different fabrication technologies are presented for the realization of such platform, based on a design reproducing the functional requirements. Our first fabrication technique is based on ICP etching, using (100)-silicon wafers, and a subsequent rear grinding. However, as the design includes a vertical wall trench structures, ICP etching of such deep recesses is time-consuming and expensive. Therefore, a second fabrication process is developed, making use of wet-etched (110)-silicon. With these substrates a challenge arises from the intersection of inclined {111} facets. To solve this natural limitation, we introduce a novel fabrication process. Our technique relies on damaging the intersecting {111} planes, to make them etchable again and to produce deeper trenches with vertical walls in a wet-chemical etching process. Additionally, the electrical contacts at the platform are made from porous metal to increase the surface-to-volume ratio, to increase the possibility of a spontaneous electrical contact between the electrodes and nanowires.
Moosavi, Hoda S., Kröner, Michael, Frei, Maxi, Frick, Fabian, Kerzenmacher, Sven, Woias, Peter
Development of a TEM Compatible Nanowire Characterization Platform With Self-Forming Contacts
2018 IEEE Transactions on Semiconductor Manufacturing, Band: 31, Nummer: 1, Seite: 22–31
N. Wipf, K. Mavridis, S. Hin, K. Mitsakakis, M. Specht, S. Medves, B. Carman, P. Müller, J. Vontas
Development of multiplex TaqMan assays for the LabDisk – an automated diagnostic platform for malaria vectors
2018 7th MIM Pan African Malaria Conference - Dakar, 18.04.2018
Hoch K, Pothof F, Becker F, Paul O, Ruther P
Development, Modeling, Fabrication, and Characterization of a Magnetic, Micro-Spring-Suspended System for the Safe Electrical Interconnection of Neural Implants
2018 Micromachines-basel, Band: 9, Nummer: 9, Ergänzungsband: 424, Seiten: 1 - 19
K. Mitsakakis / V. D’Acremont, S. Hin, F. von Stetten, R. Zengerle
Diagnostic tools for tackling febrile illness and enhancing patient management
2018 Microelectron Eng, Band: 201, Seiten: 26 - 59
KurzfassungMost patients with acute infectious diseases develop fever, which is frequently a reason to visit health facilities in resource-limited settings. The symptomatic overlap between febrile diseases impedes their diagnosis on clinical grounds. Therefore, the World Health Organization promotes an integrated management of febrile illness. Along this line, we present an overview of endemic and epidemic etiologies of fever and state-of-the-art diagnostic tools used in the field. It becomes evident that there is an urgent need for the development of novel technologies to fulfill end-users’ requirements. This need can be met with Point-of-Care and near-patient diagnostic platforms, as well as e-Health clinical algorithms, which co-assess test results with key clinical elements and biosensors, assisting clinicians in patient triage and management, thus enhancing disease surveillance and outbreak alerts. This review gives an overview of diagnostic technologies featuring a platform based approach: (i) assay (nucleic acid amplification technologies are examined); (ii) cartridge (microfluidic technologies are presented); (iii) instrument (various detection technologies are discussed); and at the end proposes a way that such technologies can be interfaced with electronic clinical decision-making algorithms towards a broad and complete diagnostic ecosystem.
S. Hin, B. Lopez-Jimena, M.A. Bakheit, V. Klein, S. Stack, C. Fall, A.A. Sall, K. Enan, S. Frischmann, L. Gillies, M. Weidmann, S. Goethel, V. Rusu, O. Strohmeier, N. Paust, R. Zengerle, K. Mitsakakis
Differential diagnosis of fever in West- and East-Africa
2018 WHO Geneva Health Forum, 10. – 12.04.2018, Genf / Schweiz
C.H. Tsai, X. Wu, D.H. Kuan, S. Zimmermann, R. Zengerle, P. Koltay
Digital hydraulic drive for microfluidics and miniaturized cell culture devices based on shape memory alloy actuators
2018 J Micromech Microeng, Band: 28, Seite: 084001
KurzfassungIn order to culture and analyze individual living cells, microfluidic cell culture and manipulation of cells becomes an increasingly important topic. Such microfluidic systems allow for exploring the phenotypic differences between thousands of genetically identical cells or pharmacological tests in parallel, which is impossible to achieve by traditional macroscopic cell culture methods. Therefore, plenty of microfluidic devices have been developed for cell biological studies like cell culture, cell sorting, and cell lysis in the past. However, these devices are still limited by the external pressure sources which most of the time are large in size and have to be connected by fluidic tubing leading to complex and delicate systems. In order to provide a miniaturized, more robust actuation system a novel, compact and low power consumption Digital Hydraulic Drive (DHD) has been developed that is intended for use in portable and automated systems for microfluidic applications. The DHD consists of a shape memory alloy (SMA) actuator and a pneumatic cylinder. The switching time of the digital modes (pressure ON vs. OFF) can be adjusted from 1 second to minutes. Thus, the DHDs might have many applications for driving microfluidic devices. In this work different implementations of DHDs are presented and their performance is characterized by experiments. In particular, it will be shown that DHDs can be used for microfluidic large-scale integration (mLSI) valve control (256 valves in parallel) as well as potentially for droplet-based microfluidic systems. As further application example high-throughput mixing of cell cultures (96 wells in parallel) are demonstrated employing the DHD and a so called "functional lid" (FL) approach, to enable a miniaturized microbioreactor in a regular 96-well micro well plate.
Lausecker R, Bollgruen P, Gleißner U, Wallrabe U
Digital lithography based on renewable materials as a tool for environmentally benign microfabrication
2018 J Clean Prod, Band: 172, Seiten: 3092 - 3101
R. Lausecker, P. Bollgruen, U. Gleißner, U. Wallrabe
Digital lithography based, on renewable materials as a tool for environmentally benign microfabrication
2018 J Clean Prod, Band: 172, Seiten: 3092 - 3101
Dongyang C, Behrmann O, Hufert F, Dame G, Urban G
Direct DNA and RNA detection from large volumes of whole human blood
2018 Sci Rep-uk, Band: 8, Seite: 3410
KurzfassungPCR inhibitors in clinical specimens negatively affect the sensitivity of diagnostic PCR and RT-PCR or may even cause false-negative results. To overcome PCR inhibition, increase the sensitivity of the assays and simplify the detection protocols, simple methods based on quantitative nested real-time PCR and RT-PCR were developed to detect exogenous DNA and RNA directly from large volumes of whole human blood (WHB). Thermus thermophilus (Tth) polymerase is resistant to several common PCR inhibitors and exhibits reverse transcriptase activity in the presence of manganese ions. In combination with optimized concentrations of magnesium ions and manganese ions, Tth polymerase enabled efficient detection of DNA and RNA from large volumes of WHB treated with various anticoagulants. The applicability of these methods was further demonstrated by examining WHB specimens collected from different healthy individuals and those stored under a variety of conditions. The detection limit of these methods was determined by detecting exogenous DNA, RNA, and bacteria spiked in WHB. To the best of our knowledge, direct RNA detection from large volumes of WHB has not been reported. The results of the developed methods can be obtained within 4 hours, making them possible for rapid and accurate detection of disease-causing agents from WHB.

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Z. Shu, B. Gerdes, M. Fechtig, L. Riegger, R. Zengerle, P. Koltay
Direct Printing of Conductive Metal Lines from Molten Solder Jets via StarJet Technology on Thin, Flexible Polymer Substrates
2018 NIP & Digital Fabrication Conference, Printing for Fabrication 2018, Dresden, 23. – 27.09.2018
Z. Shu, B. Gerdes, M. Fechtig, L. Riegger, R. Zengerle, P. Koltay
Direct Printing of Conductive Metal Lines from Molten Solder Jets via StarJet Technology on Thin, Flexible Polymer Substrates
2018 NIP & Digital Fabrication Conference, Printing for Fabrication 2018 Society for Imaging Science and Technology, Band: 4, Seiten: 72 - 75
KurzfassungWe present the direct printing of thin (linewidth of 70 μm) conductive lines from molten solder on thin, flexible substrates. The lines are generated via the so-called StarJet technology that enables the printing of micro jets from molten metal. In this work, metal lines are printed for the first time on flexible substrates, possibly enabling applications in the field of printed electronics. The printed lines are evaluated regarding their mechanical and electrical properties. To the knowledge of the authors, this is the first time that direct printing of a functional metallization, requiring no further treatment, on a flexible polymer substrate was demonstrated. The lines exhibit a low ohmic resistance and can endure shear forces of up to 3.5 N on polyethylene terephthalate (PET) substrates.
Dongyang C, Yi Q, Shen C, Lan Y, Urban G, Du W
Direct enrichment of pathogens from physiological samples of high conductivity and viscosity using H-filter and positive dielectrophoresis
2018 Biomicrofluidics, Band: 12, Nummer: 1, Seite: 014109
KurzfassungThe full potential of microfluidic techniques as rapid and accurate methods for the detection of disease-causing agents and foodborne pathogens is critically limited by the complex sample preparation process, which commonly comprises the enrichment of bacterial cells to detectable levels. In this manuscript, we describe a microfluidic device which integrates H-filter desalination with positive dielectrophoresis (pDEP) for direct enrichment of bacterial cells from physiological samples of high conductivity and viscosity, such as cow's milk and whole human blood. The device contained a winding channel in which electrolytes in the samples continuously diffused into deionized (DI) water (desalination), while the bacterial cells remained in the samples. The length of the main channel was optimized by numerical simulation and experimentally evaluated by the diffusion of fluorescein into DI water. The effects of another three factors on H-filter desalination were also investigated, including (a) the flow rate ratio between the sample and DI water, (b) sample viscosity, and (c) non-Newtonian fluids. After H-filter desalination, the samples were withdrawn into the dielectrophoresis chamber in which the bacterial cells were captured by pDEP. The feasibility of the device was demonstrated by the direct capture of the bacterial cells in 1× PBS buffer, cow's milk, and whole human blood after H-filter desalination, with the capture efficiencies of 70.7%, 90.0%, and 80.2%, respectively. We believe that this simple method can be easily integrated into portable microfluidic diagnosis devices for rapid and accurate detection of disease-causing agents and foodborne pathogens.
B. Gerdes, R. Zengerle, P. Koltay, L. Riegger
Direct printing of miniscule aluminum alloy droplets and 3D structures by StarJet technology
2018 J Micromech Microeng, Band: 28, Seite: 074003
KurzfassungDrop-on demand printing of molten metal droplets could be used for prototyping of 3D objects as promising alternative to laser melting technologies. However, up to date only few printheads were investigated for this purpose using only a limited range of materials. The pneumatically actuated StarJet technology presented previously enables the direct and non-contact printing of molten metal microdroplets from metal melts at high temperatures. Printheads according to the StarJet technology utilize nozzle chips featuring a star-shaped orifice geometry that leads to a formation of the droplets inside the nozzle with high precision. In this paper we present a novel StarJet printhead for printing aluminum alloys featuring a hybrid design with a ceramic reservoir for the molten metal and an outer shell fabricated from stainless steel. The micro machined nozzle chip is made from silicon carbide (SiC). This printhead can be operated at up to 950 °C and is capable of printing high melting metals like aluminum (Al) alloys in standard laboratory conditions. In this work, an aluminum-silicon alloy that features 12 % silicon (AlSi12) is printed. The printhead, the nozzle and the peripheral actuation system have been optimized for stable generation of AlSi12 droplets with high monodispersity, low angular deviation and miniaturized droplet diameters. As main result, a stable drop-on-demand printing of droplets exhibiting diameters of ddroplet = 702 µm +/- 1 % was demonstrated at 5 Hz with a low angular deviation of 0.3°, when a nozzle chip with 500 µm orifice diameter was used. Further, AlSi12 droplets featuring ddroplet = 176 µm ± 7 % were printed when using a nozzle chip with an orifice diameter of 130 µm. Moreover, we present directly printed objects from molten aluminum alloy droplets such as high aspect ratio, free-standing walls (aspect ratio 12:1) and directly printed, flexible springs to demonstrate the principle of 3D printing with molten metal droplets.
Gilsbach Ralf, Schwaderer Martin, Preissl Sebastian, Gruning Bjorn, Kranzhofer David, Schneider Pedro, Nuhrenberg Thomas, Mulero-Navarro Sonia, Weichenhan Dieter, Braun Christian, Dressen Martina, Jacobs Adam, Lahm Harald, Doenst Torsten, Backofen Rolf, Krane Markus, Gelb Bruce, Hein Lutz
Distinct epigenetic programs regulate cardiac myocyte development and disease in the human heart in vivo
2018 Nat Commun, Band: 9, Nummer: 1
KurzfassungEpigenetic mechanisms and transcription factor networks essential for differentiation of cardiac myocytes have been uncovered. However, reshaping of the epigenome of these terminally differentiated cells during fetal development, postnatal maturation, and in disease remains unknown. Here, we investigate the dynamics of the cardiac myocyte epigenome during development and in chronic heart failure. We find that prenatal development and postnatal maturation are characterized by a cooperation of active CpG methylation and histone marks at cis-regulatory and genic regions to shape the cardiac myocyte transcriptome. In contrast, pathological gene expression in terminal heart failure is accompanied by changes in active histone marks without major alterations in CpG methylation and repressive chromatin marks. Notably, cis-regulatory regions in cardiac myocytes are significantly enriched for cardiovascular disease-associated variants. This study uncovers distinct layers of epigenetic regulation not only during prenatal development and postnatal maturation but also in diseased human cardiac myocytes.
C. Van Pham, B. Britton, T. Böhm, S. Holdcroft, S. Thiele
Doped, Defect-Enriched Carbon Nanotubes as an Efﬁcient Oxygen Reduction Catalyst for Anion Exchange Membrane Fuel Cells
2018 Adv Mater Interfaces, Seite: 1800184
KurzfassungBond polarization of doped atoms and carbon and lattice defects are con- sidered important aspects in the catalytic mechanisms of oxygen reduction reaction (ORR) on heteroatom-doped carbon catalysts. Previous work on metal-free catalysts has focused either on bond polarization or lattice defects. Here multi-heteroatom doped defect-enriched carbon nanotubes (MH-DCNTs) that combine both effects to enhance ORR activity are designed. Lattice defects in MH-DCNTs are enriched by unzipping and length-shortening of carbon nanotubes, and also by creating carbon vacancies via decomposition of doped F atoms. Electrochemical analysis using rotating disc electrode voltam- metry shows that the ORR kinetic current density of MH-DCNT increases with lattice-defect density, the latter of which is veriﬁed by Raman spectroscopy, while the onset potential increases with annealing temperatures. An optimized MH-DCNT ORR catalyst exhibits a half-wave potential of 0.81 V versus revers- ible hydrogen electrode and limiting current density of 5.0 mA cm −2 at an electrode rotation speed of 1600 rpm in 0.1 M KOH. Further, it is demonstrated that MH-DCNT, as a cathode catalyst layer in an anion exchange membrane fuel cell (AEMFC), delivers a peak power density of 250 mW cm −2 , which is ≈70% the performance of an AEMFC using a conventional Pt/C catalyst.
K. Tröndle
Drop-on-Demand Bioprinting Process for Single-Spheroid Deposition and Immobilization
2018 International Conference on Biofabrication, Würzburg, 28. – 31.10.2018
Tobias Paxian, Sven Reimer, Bernd Becker
Dynamic Polynomial Watchdog Encoding for Solving Weighted MaxSAT
2018 International Conference on Theory and Applications of Satisfiability Testing, Springer, Band: 10929, Seiten: 37 - 53
KurzfassungIn this paper we present a novel pseudo-Boolean (PB) constraint encoding for solving the weighted MaxSAT problem with iterative SAT-based methods based on the Polynomial Watchdog (PW) CNF encoding. The watchdog of the PW encoding indicates whether the bound of the PB constraint holds. In our approach, we lift this static watchdog concept to a dynamic one allowing an incremental convergence to the optimal result. Consequently, we formulate and implement a SAT-based algorithm for our new Dynamic Polynomial Watchdog (DPW) encoding which can be applied for solving the MaxSAT problem. Furthermore, we introduce three fundamental optimizations of the PW encoding also suited for the original version leading to significantly less encoding size. Our experimental results show that our encoding and algorithm is competitive with state-of-the-art encodings as utilized in QMaxSAT (2nd place in last MaxSAT Evaluation 2017). Our encoding dominates two of the QMaxSAT encodings, and at the same time is able to solve unique instances. We integrated our new encoding into QMaxSAT and adapt the heuristic to choose between the only remaining encoding of QMaxSAT and our approach. This combined version solves 19 (4%) more instances in overall 30\% less run time on the benchmark set of the MaxSAT Evaluation 2017. Compared to each encoding of QMaxSAT used in the evaluation, our encoding leads to an algorithm that is on average at least 2X faster.
Timotius IK, Canneva F, Minakaki G, Pasluosta C, Moceri S, Casadei N, Riess O, Winkler J, Klucken J, von Horsten S, Eskofier B
Dynamic footprints of alpha-synucleinopathic mice recorded by CatWalk gait analysis.
2018 Data in Brief, Band: 17, Seiten: 189 - 193
KurzfassungCharacterizing gait is important in the study of movement disorders, also in clinical mouse models. Gait data are therefore necessary for the development of gait analysis methods and the study of diseases. This article presents gait data of two α-synucleinopathic transgenic mouse models and their non-transgenic littermate, backcrossed into the C57BL/6N genetic background. The animal gait was recorded using CatWalk system, which provides the information for each run about the paw positions, paw print sizes, and paw intensities as a function of time or video frame. A total of 90 run data files are provided in this article.
Roth J, Koch M D, Rohrbach A
Dynamics of a Protein Chain Motor Driving Helical Bacteria under Stress
2018 Biophys J, Band: 114, Nummer: 8, Seiten: 1955 - 1969

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Mokhtarifar, Naser, Goldschmidtboeing, Frank, Woias, Peter
EGFET Differential Pair with ITO as the Extended-Gate Membrane for pH-Sensing
2018 2018 IEEE 13th Annual International Conference on Nano/Micro Engineered and Molecular Systems (NEMS), Singapore 2018 IEEE 13th Annual International Conference on Nano/Micro Engineered and Molecular Systems (NEMS), Seiten: 60 - 63
Maria Hügle, Simon Heller, Manuel Watter, Manuel Blum, Farrokh Manzouri, Matthias Dümpelmann, Andreas Schulze-Bonhage, Peter Woias, Joschka Boedecker
Early Seizure Detection with an Energy-Efficient Convolutional Neural Network on an Implantable Microcontroller
2018 International Joint Conference on Neural Networks
Hugle, Maria, Heller, Simon, Watter, Manuel, Blum, Manuel, Manzouri, Farrokh, Dumpelmann, Matthias, Schulze-Bonhage, Andreas, Woias, Peter, Boedecker, Joschka
Early Seizure Detection with an Energy-Efficient Convolutional Neural Network on an Implantable Microcontroller
2018 2018 International Joint Conference on Neural Networks (IJCNN), Rio de Janeiro, July 8-13, 2018 2018 International Joint Conference on Neural Networks (IJCNN), Seiten: 1 - 7
López-Vidrier J, Gutsch S, Blázquez O, Valenta J, Hiller D, Laube J, Blanco-Portals J, López-Conesa L, Estradé S, Peiró F, Garrido B, Hernández S, Zacharias M
Effect of Si3N4-Mediated Inversion Layer on the Electroluminescence Properties of Silicon Nanocrystal Superlattices
2018 Adv Electron Mater, Band: 4, Nummer: 1700666
Laessig, Torsten, May, Michael, Heisserer, Ulrich, Riedel, Werner, Bagusat, Frank, Werff, Harm van der, Hiermaier, Stefan
Effect of consolidation pressure on the impact behavior of UHMWPE composites
2018 Compos Part B-eng, Band: 147, Seiten: 47 - 55
KurzfassungFor the first time, the influence of the manufacturing process on the dynamic performance of ultra-high molecular weight polyethylene (UHMWPE, Dyneema® HB26) composites is investigated. The material is significantly influenced by the hot-pressing parameters temperature and pressure. The ballistic resistance and shock wave behavior was characterized for the UHMWPE composite consolidated with three different pressures. In the case of UHMWPE composites, higher consolidation pressures result in a better ballistic performance. The shock wave behavior converges to high-density polyethylene (HDPE). Based on these observations, an analytical approach is proposed describing the equation of state as a function of consolidation pressure.
M. Kokko, S. Epple, J. Gescher, S. Kerzenmacher
Effects of wastewater constituents and operational conditions on the composition and dynamics of anodic microbial communities in bioelectrochemical systems
2018 Bioresource Technology, Band: 258, Seiten: 376 - 389
KurzfassungOver the last decade, there has been an ever-growing interest in bioelectrochemical systems (BES) as a sustainable technology enabling simultaneous wastewater treatment and biological production of, e.g. electricity, hydrogen, and further commodities. A key component of any BES degrading organic matter is the anode where electric current is biologically generated from the oxidation of organic compounds. The performance of BES depends on the interactions of the anodic microbial communities. To optimize the operational parameters and process design of BES a better comprehension of the microbial community dynamics and interactions at the anode is required. This paper reviews the abundance of different microorganisms in anodic biofilms and discusses their roles and possible side reactions with respect to their implications on the performance of BES utilizing wastewaters. The most important operational parameters affecting anodic microbial communities grown with wastewaters are highlighted and guidelines for controlling the composition of microbial communities are given.
Rafizadeh Saeid, Wienands Karl, Schulze Patricia, Bett Alexander, Andreani Lucio, Hermle Martin, Glunz Stefan, Goldschmidt Jan
Efficiency Enhancement and Hysteresis Mitigation by Manipulation of Grain Growth Conditions in Hybrid Evaporated-Spincoated Perovskite Solar Cells
2018 ACS applied materials & interfaces
KurzfassungPerovskite solar cells became a game changer in the field of photovoltaics by reaching power conversion efficiencies (PCE) beyond 23%. To achieve even higher efficiencies it is necessary to increase the understanding of crystallization, grain formation and layer ripening. In this study, by a systematic variation of the MAI concentrations we changed the stoichiometry and thereupon the crystal growth conditions in MAPbI3 perovskite solar cells, prepared by a two-step hybrid evaporation-spincoating deposition method. Utilizing X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force miscroscopy (AFM), photoluminescence (PL) and current-voltage (J-V) characterization, we found that a relatively lower concentration of MAI or in other words higher content of remnant and unconverted PbI2 correlates with smaller and stronger interconnected grains, as well as with an improved optoelectronic performance of the solar cells and mitigation of hysteresis. Possible explanations are grain and interface passivation by the excess PbI2 and a positive contribution of the grain boundaries to current extraction.
Eggensperger K, Lindauer M, Hoos H, Hutter F, Leyton-Brown K
Efficient Benchmarking of Algorithm Configurators via Model-Based Surrogates
2018 Machine Learning, Band: 107, Seiten: 15 - 41
Elsken Thomas, Metzen Jan, Hutter Frank
Efficient Multi-objective Neural Architecture Search via Lamarckian Evolution
2018 ArXiv e-prints, Band: 1804.09081
Leicht J, Amayreh M, Cai Y, Goeppert J, Hagedorn F, Hehn T, Lotze N, Moranz C, Rossbach D, Sanchez D, Schillinger D, Manoli Y
Effiziente Schaltungen und Systeme für Energy Harvesting Anwendungen
2018 20. Workshop Analogschaltungen
Szabados J, Kini Manjeshwar S, Breunig I, Buse K
Electro-optic tuning of potassium tantalate-niobate whispering gallery resonators
2018 Laser Resonators, Microresonators, and Beam Control XX, San Francisco, CA, United States Proceedings of SPIE, Band: 10518, Seite: 1051802
KurzfassungMost centrosymmetric materials exhibit a neglectable electro-optic response; the Pockels coefficients are zero, while the DC-Kerr coefficients are typically small. For a standard material such as silica they are on the order of 10−22 m2/V2 . 1 Thus, refractive index tuning is achieved by thermal or mechanical means. Potassium tantalateniobate (KTa1−xNbxO3 with 0 < x < 1, KTN) is a rare exception. It offers outstandingly high DC-Kerr coefficients in the 10−15 m2/V2 range.2 In this contribution, the first-ever KTN whispering gallery resonators (WGR) are demonstrated with quality factors Q > 107 and electro-optic eigenfrequency tuning of more than 100 GHz at λ = 1040 nm for moderate field strengths of 250 V/mm. These results potentially pave the way for applications such as electro-optically tunable Kerr frequency combs.
Boehler C, Kleber C, Oberueber F, Asplund M
Electroactive coatings as a strategy to improve the longevity of neuroelectronic devices.
2018 Gordon Research Conference on Neuroelectronic Interfaces, 25.-30.03.2018, Galveston, TX, USA
Matylitskaya V, Kasemann S, Urban G, Dincer C, Partel S
Electrochemical Characterization of Nanogap Interdigitated Electrode Arrays for Lab-on-a-Chip Applications
2018 J Electrochem Soc, Band: 165, Nummer: 3, Seiten: B127 - B134
KurzfassungIn this work we present recent results on electrochemical characterization of the fabricated nanogap interdigitated electrode arrays (nIDAs) for Lab-on-a-Chip applications (LoC). The advantages of the presented nIDAs and their potential for application in bioelectrochemistry were studied using different electrochemical methods. Chronoamperometry is applied to achieve reversible redox processes which lead to an amplification of the measured current compared to a single electrode configuration and as a result, an increase in signal-to-noise ratio. For the electrochemical characterization of the created nIDAs ferrocenemethanol (FcMeOH) and p-aminophenol (pAP) were selected as redox couples. An amplification factor above 160 compared to a single electrode configuration was obtained with FcMeOH for the nIDAs with 100 nm gap. An inverse correlation between gap size and amplification was proven. In addition, the formation of a polymer film during redox cycling could be verified to cause the lower amplification factor observed in pAP measurements. Furthermore, different electrode cleaning procedures were demonstrated by combination of O2 plasma and cyclic voltammetry. The nIDAs presented here offer many advantages including low-cost fabrication, high amplification and collection factors and thus are highly suitable for biosensor applications.

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Pfau J, Ganatra D, Weltin A, Urban G, Kieninger J, Stieglitz T
Electrochemical Stability of Thin-Film Platinum as Suitable Material for Neural Stimulation Electrodes
2018 BMT 2018, Aachen, Germany Biomed Eng-biomed Te, Band: 63, Ergänzungsband: 1, Seite: S121
Urban S, Weltin A, Flamm H, Kieninger J, Deschner BJ, Kraut M, Dittmeyer R, Urban G
Electrochemical multisensor system for monitoring hydrogen peroxide, hydrogen and oxygen in direct synthesis microreactors
2018 Sensor Actuat B-chem, Band: 273, Seiten: 973 - 982
KurzfassungWe present an electrochemical microsensor system for the monitoring of hydrogen peroxide, dissolved hydrogen and dissolved oxygen inside a direct synthesis microreactor. The setup allows the online, in situ measurement of high reactant concentrations by amperometric detection of all three reactants in aqueous solution using chronoamperometric protocols. Hydrogen peroxide is a key chemical for industrial oxidation applications, and its catalyzed direct synthesis is an attractive process route. For the first time, we integrated an electrochemical cell into a high pressure stainless steel microreactor environment (pressures up to 100  bar, pH of 3-4 and presence of bromide) by fabricating sensor plugs with 300  µm platinum microelectrodes encapsulated into a robust epoxy housing. The first microfabricated silver/silver bromide pseudo-reference electrode, integrated by electrodeposition, allowed to obtain a stable measurement potential directly from the electrolyte containing bromide. The investigation of platinum electrochemistry in the presence of bromide by cyclic voltammetry led to the development of chronoamperometric protocols for the stable, precise and reproducible measurement in this environment. Hydrogen peroxide was detected under reaction conditions showing linear behaviour up to 20  mM with high sensitivity of 55  μA  cm⁻²  mM⁻¹ and excellent stability by application of a diffusion limiting hydrogel layer to the electrode surface. This linear range surpasses most micro- and nanostructured platinum approaches. Oxygen and hydrogen were both measured at elevated pressures up to 70  bar and high dissolved concentrations up to 52  mM and 40  mM with measured sensitivities of 26  μA  cm⁻²  mM⁻¹ and 356  μA  cm⁻²  mM⁻¹, respectively. We have successfully shown the application of electrochemical sensors for online, in situ monitoring of analyte concentrations under conditions found in direct synthesis microreactors.
Vomero M, Castagnola E, Ordonez JS, Carli S, Zucchini E, Maggiolini E, Gueli C, Goshi N, Ciarpella F, Cea C, Fadiga L, Ricci D, Kassegne S, Stieglitz T
Electrocorticography Arrays: Incorporation of Silicon Carbide and Diamond-Like Carbon as Adhesion Promoters Improves In Vitro and In Vivo Stability of Thin-Film Glassy Carbon Electrocorticography Arrays
2018 Advanced Biosystems, Band: 2, Nummer: 1
KurzfassungThin-film neural devices are an appealing alternative to traditional implants, although their chronic stability remains matter of investigation. In this study, a chronically stable class of thin-film devices for electrocorticography is manufactured incorporating silicon carbide and diamond-like carbon as adhesion promoters between glassy carbon (GC) electrodes and polyimide and between GC and platinum traces. The devices are aged in three solutions—phosphate-buffered saline (PBS), 30 × 10−3 and 150 × 10−3m H2O2/PBS—and stressed using cyclic voltammetry (2500 cycles) and 20 million biphasic pulses. Electrochemical impedance spectroscopy (EIS) and image analysis are performed to detect eventual changes of the electrodes morphology. Results demonstrate that the devices are able to undergo chemically induced oxidative stress and electrical stimulation without failing but actually improving their electrical performance until a steady state is reached. Additionally, cell viability tests are carried out to verify the noncytotoxicity of the materials, before chronically implanting them into rat models. The behavior of the GC electrodes in vivo is monitored through EIS and sensorimotor evoked potential recordings which confirm that, with GC being activated, impedance lowers and quality of recorded signal improves. Histological analysis of the brain tissue is performed and shows no sign of severe immune reaction to the implant.

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Neelisetty KK, Gutsch S, von Seggern F, Molinari A, Vahl A, Mu X, Scherer T, Chakravadhanula K, Kübel C
Electron Beam Effects on Silicon Oxide Films–Structure and Electrical Properties
2018 Microsc Microanal, Band: 24, Nummer: S1, Seiten: 1810 - 1811
Reichel Christian, Würfel Uli, Winkler Kristina, Schleiermacher Hans-Frieder, Kohlstädt Markus, Unmüssig Moritz, Messmer Christoph, Hermle Martin, Glunz Stefan
Electron-selective contacts via ultra-thin organic interface dipoles for silicon organic heterojunction solar cells
2018 Journal of Applied Physics, Band: 123, Nummer: 2, Seite: 024505
KurzfassungIn the last years, novel materials for the formation of electron-selective contacts on n-type crystalline silicon (c-Si) heterojunction solar cells were explored as an interfacial layer between the metal electrode and the c-Si wafer. Besides inorganic materials like transition metal oxides or alkali metal fluorides, also interfacial layers based on organic molecules with a permanent dipole moment are promising candidates to improve the contact properties. Here, the dipole effect plays an essential role in the modification of the interface and effective work function of the contact. The amino acids L-histidine, L-tryptophan, L-phenylalanine, glycine, and sarcosine, the nucleobase adenine, and the heterocycle 4-hydroxypyridine were investigated as dipole materials for an electronselective contact on the back of p- and n-type c-Si with a metal electrode based on aluminum (Al). Furthermore, the effect of an added fluorosurfactant on the resulting contact properties was examined. The performance of n-type c-Si solar cells with a boron diffusion on the front was significantly increased when L-histidine and/or the fluorosurfactant was applied as a full-area back surface field. This improvement was attributed to the modification of the interface and the effective work function of the contact by the dipole material which was corroborated by numerical device simulations. For these solar cells, conversion efficiencies of 17.5% were obtained with open-circuit voltages (Voc) of 625mV and fill factors of 76.3%, showing the potential of organic interface dipoles for silicon organic heterojunction solar cells due to their simple formation by solution processing and their low thermal budget requirements.
Keller M, Goeppert J, Manoli Y, Savelli G, Colonna J, Faucherand P, Collin L, Fréchette L
Embedded Thermal Energy Harvesting – Challenges & Opportunities
2018 Presentation, 24th International Workshop on Thermal Investigations of ICs and Systems (THERMINIC)
A Gola, L Pastewka
Embedded atom method potential for studying mechanical properties of binary Cu-Au alloys
2018 Model Simul Mater Sc, Band: 26, Seite: 055006
KurzfassungWe present an embedded atom method (EAM) potential for the binary Cu–Au system. The unary phases are described by two well-tested unary EAM potentials for Cu and Au. We fitted the interaction between Cu and Au to experimental properties of the binary intermetallic phases Cu3Au, CuAu and CuAu3. Particular attention has been paid to reproducing stacking fault energies in order to obtain a potential suitable for studying deformation in this binary system. The resulting energies, lattice constant, elastic properties and melting points are in good agreement with available experimental data. We use nested sampling to show that our potential reproduces the phase boundaries between intermetallic phases and the disordered face-centered cubic solid solution. We benchmark our potential against four popular Cu–Au EAM parameterizations and density-functional theory calculations.
S Palzer, V Sandfort, J Goldschmidt, J Woellenstein
Enhancement Techniques to improve Raman spectroscopy of gases
2018 Sensoren und Messsysteme - 19. ITG/GMA-Fachtagung, Nürnberg, Deutschland
KurzfassungThe reliable chemical analysis of gas mixtures is a challenging task that is often approached by employing optical technologies because of their high reliability, sensitivity, and selectivity as well as the possibility of contactless measurement. When monitoring single or a few components of industrial or natural processes, absorption spectroscopy methods are frequently used. However, this approach becomes tedious when many gas species have to be identified and quantified. In this scenario Raman spectroscopy may offer a viable alternative for multi-gas analysis. In particular, spontaneous Raman scattering offers the possibility to qualitatively and quantitatively detect most molecules with a single laser source. Large-scale use of the technique currently fails due to the little amount of Raman-scattered light, which is a result of the small Raman-scattering cross-section. To mitigate this disadvantage, a number of approaches are currently being researched with the goal to obtain larger scattering intensities. To this effect currently popular methods aim to increase the effective amount of light via the use of optical resonators or photonic hollow fibres. In this article, both approaches are presented and the results achieved in natural gas analysis and food chain management are presented.
Kaiser, A.
Estudios de género y producción del género por las neurociencias.
2018 In C. Mora, A. Kottow, M. Ceballos, V. Osses (Eds.), Investigación, Políticas y Programas de Género., Seiten: 37 - 50
R Pohle, T Pohl, C Pannek, K Tarantik, ML Bauersfeld, J Wöllenstein, S Raible, F Seiler
Evaluation of a Colorimetric Sensor System for Early Fire Detection
2018 Eurosensors 2018, Graz, Austria , Band: 2, Nummer: 13, Seite: 966
KurzfassungThe use of colorimetric reactions as a sensitive, selective and low-cost method for the detection of fire related gases is evaluated in this work. As the most relevant fire gas carbon monoxide CO is addressed in the first place. A rhodium-based metal-organic complex has been selected, which a colorimetric material sensitive for CO. For the optical readout a compact setup has been developed which provides the option for spectroscopy in transmission and attenuated total reflection in parallel. The detection of CO in concentrations relevant for fire detection has been demonstrated in synthetic gas mixtures as well as in real fire gas.
Wilson Dennis, Rodrigues Silvio, Segura Carlos, Loshchilov Ilya, Hutter Frank, Buenfil Guillermo, Kheiri Ahmed, Keedwell Ed, Ocampo-Pineda Mario, Özcan Ender, Peña Sergio, Goldman Brian, Rionda Salvador, Hernández-Aguirre Arturo, Veeramachaneni Kalyan, Cussat-Blanc Sylvain
Evolutionary computation for wind farm layout optimization
2018 Renewable Energy, Band: 126, Seiten: 681 - 691
Bürger JC, Gutsch S, Zacharias M
Extended View on the Vapor–Liquid–Solid Mechanism for Oxide Compound Nanowires: The Role of Oxygen, Solubility, and Carbothermal Reaction
2018 J Phys Chem C, Band: 122, Nummer: 42, Seiten: 24407 - 24414
KurzfassungThe Si nanowire growth can be well explained by the classical vapor–liquid–solid (VLS) process taking into account the respective Au–Si phase diagram. For oxide-based compound materials, no phase diagram with gold exists because of the insolubility of these materials into the Au catalyst material. Hence, it is not correct to claim a simple VLS mechanism for the respective growth. In this study, a more complex model for the growth of oxide nanowires (NWs) is proposed by analyzing the influence of oxygen concentration and timing of oxygen inflow into the furnace while growing SnO2 NWs by a carbothermal chemical vapor deposition process. It is shown that a controlled amount of oxygen is mandatory to grow the SnO2 NWs. However, either too low or too high oxygen concentration strongly suppresses the nanowire growth.
Weise Stefan, Arumugam Ganeshkumar, Villarreal Alejandro, Videm Pavankumar, Heidrich Stefanie, Nebel Nils, Dumit Verónica, Sananbenesi Farahnaz, Reimann Viktoria, Craske Madeline, Schilling Oliver, Hess Wolfgang, Fischer Andre, Backofen Rolf, Vogel Tanja
FOXG1 Regulates PRKAR2B Transcriptionally and Posttranscriptionally via miR200 in the Adult Hippocampus
2018 Molecular Neurobiology
KurzfassungRett syndrome is a complex neurodevelopmental disorder that is mainly caused by mutations in MECP2. However, mutations in FOXG1 cause a less frequent form of atypical Rett syndrome, called FOXG1 syndrome. FOXG1 is a key transcription factor crucial for forebrain development, where it maintains the balance between progenitor proliferation and neuronal differentiation. Using genome-wide small RNA sequencing and quantitative proteomics, we identified that FOXG1 affects the biogenesis of miR200b/a/429 and interacts with the ATP-dependent RNA helicase, DDX5/p68. Both FOXG1 and DDX5 associate with the microprocessor complex, whereby DDX5 recruits FOXG1 to DROSHA. RNA-Seq analyses of Foxg1cre/+ hippocampi and N2a cells overexpressing miR200 family members identified cAMP-dependent protein kinase type II-beta regulatory subunit (PRKAR2B) as a target of miR200 in neural cells. PRKAR2B inhibits postsynaptic functions by attenuating protein kinase A (PKA) activity; thus, increased PRKAR2B levels may contribute to neuronal dysfunctions in FOXG1 syndrome. Our data suggest that FOXG1 regulates PRKAR2B expression both on transcriptional and posttranscriptional levels.
B.P. Bruno, R. Grunwald, U. Wallrabe
Fabrication of an adaptive micro Fresnel-mirror array
2018 ISOT 2018 Int. Symposium of Optomechatronics Technology, Cancún, Mexico Springer Proceedings in Physics, Band: 233, Seiten: 29 - 35
Eltermann F, Wilde J
Fertigungsgerechte Primerprozesse für das mediendichte Umspritzen großer mechatronischer Komponenten - Prozesstechnologieentwicklung und Zuverlässigkeit
2018 Abschlussbericht zum IGF-Vorhaben 18734 N (FVA-Nr. 746 I „PRIME“), FVA-Heft Nr. 1287, Herausgabedatum: 30.04.2018
Tucher Nico, Habtamu T. Gebrewold, Bläsi Benedikt
Field stitching approach for the wave optical modeling of black solicon structures
2018 Opt Express, Band: 26, Nummer: 22, Seite: A937
KurzfassungThe interest in black silicon structures as an anti-reflective interface at the front side of silicon solar cells increased strongly with the rise of diamond wire sawing. The application of optical modeling in order to predict optimal structure parameters could be highly valuable. However, due to the random nature of the structure as well as dimensions in the range of the wavelengths of interest, optical modeling is still a challenge. Within this work, the stitching method of rigorously calculated fields is extended and applied to a black silicon structure. A Fourier transform is used to determine the angular intensity distribution in the far field. In combination with the OPTOS formalism, this allows modeling of silicon substrates with black silicon front side and shows a reasonably good agreement with optical measurement results. Implementing the investigated structure into a solar cell configuration reveals not only a low reflectance but also a very good light trapping performance close to that of a Lambertian scatterer

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Sebastian Junges, Nils Jansen, Ralf Wimmer, Tim Quatmann, Leonore Winterer, Joost-Pieter Katoen, Bernd Becker
Finite-State Controllers of POMDPs via Parameter Synthesis
2018 Proceedings of the 34th Conference on Uncertainty in Artificial Intelligence (UAI), AUAI Press, Seiten: 519 - 529
Kurzfassunge study finite-state controllers (FSCs) for partially observable Markov decision processes (POMDPs) that are provably correct with respect to given specifications. The key insight is that computing (randomised) FSCs on POMDPs is equivalent to (and computationally as hard as) synthesis for parametric Markov chains (pMCs). This correspondence enables using black-box techniques to compute correct-by-construction FSCs for POMDPs for a wide range of properties. Our experimental evaluation on typical POMDP problems shows that we are competitive to state-of-the-art POMDP solvers.

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Subbiah N, Feng Q, Beltran Ramirez K, Wilde J
Flip-chip Die Attachment for High-temperature Pressure Sensor Packages up to 500 °C
2018
Hörsch J, Schäfer M, Becker S, Schramm S, Greiner M
Flow tracing as a tool set for the analysis of networked large-scale renewable electricity systems
2018 Int J Elec Power, Band: 96, Seiten: 390 - 397
KurzfassungThe method of flow tracing follows the power flow from net-generating sources through the network to the net-consuming sinks, which allows to assign the usage of the underlying transmission infrastructure to the system participants. This article presents a reformulation that is applicable to arbitrary compositions of inflow appearing naturally in models of large-scale electricity systems with a high share of renewable power generation. We propose an application which allows to associate power flows on the grid to specific regions or generation technologies, and emphasizes the capability of this technique to disentangle the spatio-temporal patterns of physical imports and exports occurring in such systems. The analytical potential of this method is showcased for a scenario based on the IEEE 118 bus network.
Tranberg B, Schäfer M, Brown T, Hörsch J, Greiner M
Flow-based analysis of storage usage in a low-carbon European electricity scenario
2018 15th International Conference on the European Energy Market (EEM), 2018

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Tranberg B, Schwenk-Nebbe LJ, Schäfer M, Hörsch J, Greiner M
Flow-based nodal cost allocation in a heterogeneous highly renewable European electricity network
2018 Energy, Band: 150, Seiten: 122 - 133
KurzfassungFor a cost efficient design of a future renewable European electricity system, the placement of renewable generation capacity will seek to exploit locations with good resource quality, that is for instance onshore wind in countries bordering the North Sea and solar PV in South European countries. Regions with less favorable renewable generation conditions benefit from this remote capacity by importing the respective electricity as power flows through the transmission grid. The resulting intricate pattern of imports and exports represents a challenge for the analysis of system costs on the level of individual countries. Using a tracing technique, we introduce flow-based nodal levelized costs of electricity (LCOE) which allow to incorporate capital and operational costs associated with the usage of generation capacity located outside the respective country under consideration. This concept and a complementary allocation of transmission infrastructure costs is applied to a simplified model of an interconnected highly renewable European electricity system. We observe that cooperation between the European countries in a heterogeneous system layout does not only reduce the system-wide LCOE, but also the flow-based nodal LCOEs for every country individually.
Zappe H
Fluidic micro-imaging systems (Keynote talk).
2018 13th IEEE International Conference on Nano/Micro Engineered and Molecular Systems (NEMS 2018), Singapore
M. Lehnert, E. Kipf, F. Schlenker, N. Borst, R. Zengerle, F. von Stetten
Fluorescence signal-to-noise optimisation for real-time PCR using universal reporter oligonucleotides
2018 Anal Methods-uk
KurzfassungIn this study we optimised the fluorescence signal generation of contact quenched universal reporter oligonucleotides. These are used as secondary probes in real-time Mediator Probe PCR to detect the sequence-specific cleavage of label-free primary mediator probes. Since the fluorescence signal generation of a universal reporter is not influenced by the target DNA sequence, optimisation of the fluorescence signal-to-noise ratio will improve the performance of all Mediator Probe PCRs that are based on this type of universal reporter. To determine the critical factors influencing signal-to-noise optimisation, we systematically analysed four parameters. These parameters were type of fluorophore, type of quencher molecule, intramolecular orientation of both residuals, and the number of quencher labels. In total, more than 30 different fluorogenic universal reporter structures were analysed, covering the whole fluorescence spectrum from green to crimson. From our results, we deduced a novel set of guidelines for signal-to-noise optimisation in the design of contact quenched, fluorogenic universal reporter oligonucleotides. We confirmed these guidelines in a different thermocycler, and by designing a second set of universal reporters, which were used for multiplex real-time PCR quantification of acute lymphoblastic leukaemia marker sequences. This optimised biplex Mediator Probe PCR showed an improved performance under clinical conditions, with a 10 times higher resolution regarding the limit of quantification. In addition to Mediator Probe PCR, these guidelines may also prove useful in signal-to-noise optimisation of other fluorescence-based assays where contact quenched oligonucleotides or secondary reporter molecules are used.
L. Becherer, M. Bakheit, S. Frischmann, S. Stinco, N. Borst, R. Zengerle, F. von Stetten
Fluorogenic real-time detection of loop-mediated isothermal amplification by novel mediator displacement probes demonstrated for HIV-1 and HTLV-1
2018 International Biotech Innovation Days, 23 - 25 May 2018 / Senftenberg, Germany
Diaz-Maue L, Schwaerzle M, Ruther P, Luther S, Richter C
Follow the Light - From Low-Energy Defibrillation to Multi-Site Photostimulation
2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), Honolulu, HI, USA , Seiten: 4832 - 4835
KurzfassungOne major cause of death in the industrialized world is sudden cardiac death, which so far can be reliably treated only by applying strong electrical shocks. Developing improved methods, aiming at lowering shock intensity and associated side effects potentially has significant clinical implications. Thus, optogenetic stimulation using structured illumination has been introduced as a promising experimental tool to investigate mechanisms underlying multi-site pacing and to optimize potential low-energy approaches. Furthermore, an objective of this work is to strengthen the application of optogenetic tools for cardiac arrhythmia research, which in turn is expected to improve applicable technologies towards tissue-protective defibrillation.
Diaz-Maue L, Schwärzle M, Ruther P, Luther S, Richter C
Follow the light - from low-energy defibrillation to multi-site photostimulation
2018 EMBC 2018 Conference, Hawaii, USA
Raden Martin, Ali Syed, Alkhnbashi Omer, Busch Anke, Costa Fabrizio, Davis Jason, Eggenhofer Florian, Gelhausen Rick, Georg Jens, Heyne Steffen, Hiller Michael, Kundu Kousik, Kleinkauf Robert, Lott Steffen, Mohamed Mostafa, Mattheis Alexander, Miladi Milad, Richter Andreas, Will Sebastian, Wolff Joachim, Wright Patrick, Backofen Rolf
Freiburg RNA tools: a central online resource for RNA-focused research and teaching
2018 Nucleic Acids Research, Band: 46, Nummer: W1, Seiten: W25 - W29
KurzfassungThe Freiburg RNA tools webserver is a well established online resource for RNA-focused research. It provides a unified user interface and comprehensive result visualization for efficient command line tools. The webserver includes RNA-RNA interaction prediction (IntaRNA, CopraRNA, metaMIR), sRNA homology search (GLASSgo), sequence-structure alignments (LocARNA, MARNA, CARNA, ExpaRNA), CRISPR repeat classification (CRISPRmap), sequence design (antaRNA, INFO-RNA, SECISDesign), structure aberration evaluation of point mutations (RaSE), and RNA/protein-family models visualization (CMV), and other methods. Open education resources offer interactive visualizations of RNA structure and RNA-RNA interaction prediction as well as basic and advanced sequence alignment algorithms. The services are freely available at http://rna.informatik.uni-freiburg.de.
Herr S, Brasch V, Szabados J, Obrzud E, Jia Y, Lecomte S, Buse K, Breunig I, Herr T
Frequency comb up- and down-conversion in synchronously driven χ(2) optical microresonators
2018 Opt Lett, Band: 43, Seite: 5745
KurzfassungOptical frequency combs are key to optical precision measurements. While most frequency combs operate in the near-infrared (NIR) regime, many applications require combs at mid-infrared (MIR), visible (VIS), or even ultra-violet (UV) wavelengths. Frequency combs can be transferred to other wavelengths via nonlinear optical processes; however, this becomes exceedingly challenging for high-repetition-rate frequency combs. Here it is demonstrated that a synchronously driven high- microresonator with a second-order optical nonlinearity can efficiently convert high-repetition-rate NIR frequency combs to VIS, UV, and MIR wavelengths, providing new opportunities for microresonator and electro-optic combs in applications including molecular sensing, astronomy, and quantum optics
M. Schulz, N. Borst, M. Specht, S. Calabrese, F. von Stetten, R. Zengerle, N. Paust
From nasal swab to digital answer: unit operations for antibiotic resistance screening on a single cell level
2018 MicroTAS 2018, 11. -15. November 2018, Kaohsiung / Taiwan
B. Gerdes, M. Jehle, N. Lass, L. Riegger, A. Spribille, M. Linse, F. Clement, R. Zengerle, P. Koltay
Front side metallization of silicon solar cells by direct printing of molten metal
2018 Solar Energy Materials and Solar Cells, Band: 180, Seiten: 83 - 90
KurzfassungIn this work, a new approach for the front side metallization of silicon solar cells is presented. Molten solder (Sn96Ag3Cu) is directly printed in a non-contact manner on solar cell precursors via StarJet technology. The StarJet technology features a pneumatically driven, heatable printhead with a reservoir of molten metal and a star-shaped silicon nozzle chip. Using this printhead, a jet of molten metal with 55 μm ± 5 μm diameter is generated and used to apply busbars as well as contact fingers on prefabricated electroplated seed layers. After deposition via StarJet, printed fingers have a minimum width of 70 μm and a mean aspect ratio of 0.94. The printed metallization is evaluated optically and electrically. Aluminum back surface field silicon solar cells with front side electroplated NiAg seed layers and StarJet metallization (busbars and fingers) show efficiencies of up to 18.1% after degradation. Solder is about 30–40 times cheaper than silver and therefore may allow costefficient solar cell metallization. The StarJet metallization on electroplated NiAg seed layers is fully functional and requires no additional post-processing steps. Only 6 mg of Ag per cell are consumed for the seed layer. As a proof-of-principle, a module is demonstrated, which consists of four solar cells that are metallized via StarJet.
De Dorigo D, Moranz C, Graf H, Marx M, Wendler D, Shui B, Herbawi A, Kuhl M, Ruther P, Paul O, Manoli Y
Fully Immersible Subcortical Neural Probes with Modular Architecture and a Delta-Sigma ADC Integrated under each Electrode for Parallel Readout of 144 Recording Sites
2018 IEEE Journal Solid-State Circuits (JSSC), Band: 53, Nummer: 11, Seiten: 3111 - 3125
De Dorigo D, Manoli Y
Fully Integrated Active Neural Probes for Deep Brain Monitoring Applications
2018 IEEE Brain Initiative Workshop on Advanced NeuroTechnologies
Khatri B, Lappe K, Habedank M, Müller T, Megnin C, Hanemann T
Fused Deposition Modeling of ABS-Barium Titanate Composites: A Simple Route towards Tailored Dielectric Devices
2018 Materials, Band: 10, Nummer: 6, Seite: 666
KurzfassungA process for the development, characterization and correlation of composite materials for 3D printing is presented, alongside the processing of a polymer-ceramic functional composite using fused deposition modeling (FDM). The composite was developed using acrylonitrile butadiene styrene (ABS) as the matrix material filled with barium titanate (BT) micro-powder up to 35 vol % (74.2 wt %). The ABS-BT composites exhibited a shear thinning behavior with increasing ceramic content. The composite was 3D printed into structural and functional test samples using FDM by adapting and optimizing the print parameters. Structural characterization revealed increasingly brittle behavior at higher filler ratios, with the ultimate tensile strength falling from 25.5 MPa for pure ABS to 13.7 MPa for the ABS-35 vol % BT composite. Four-point flexural tests showed a similar decrease in flexural strength with increasing ceramic content. Functional characterization revealed an increase in the relative permittivity at 200 kHz from 3.08 for pure ABS to 11.5 for the composite with 35 vol % BT. These results were correlated with the Maxwell-Garnett and Jayasundere-Smith effective medium models. The process described in this work can be used for other 3D printing processes and provides a framework for the rapid prototyping of functional composites into functional parts with reliable properties. The ABS-BT composite shows promise as a functional dielectric material, with potential applications as capacitors and light-weight passive antennas.
Nötzel D, Eickhoff R, Hanemann T
Fused Filament Fabrication of Small Ceramic Components
2018 Materials, Band: 11, Seite: 1463
KurzfassungWith respect to rapid prototyping of ceramic components, there are known only a few processes (stereo lithography, binder jetting). In this work, a new process chain is described in detail, showing that ceramics can be printed in a very cost-efficient way. We developed a ceramic–polymer composite as filament material that can be printed on a low-cost fused filament fabrication (FFF) desktop printer, even with very small nozzle sizes enabling very small geometric feature sizes. The thermal post-processing, with debinding and sintering, is very close to the ceramic injection molding (CIM) process chain.

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K. Kraiczek, G. Rozing, R. Zengerle
G-Index: A New Metric to Describe Dynamic Refractive Index Effects in HPLC Absorbance Detection
2018 Talanta, Band: 187, Seiten: 200 - 206
KurzfassungHigh performance liquid chromatography (HPLC) with a solvent gradient and absorbance detection is one of the most widely used methods in analytical chemistry. The observed absorbance baseline is affected by the changes in the refractive index (RI) of the mobile phase. Near the limited of detection, this complicates peak quantitation. The general aspects of these RI-induced apparent absorbance effects are discussed. Two different detectors with fundamentally different optics and flow cell concepts, a variable-wavelength detector equipped with a conventional flow cell and a diode-array detector equipped with a liquid core waveguide flow cell, are compared with respect to their RI behavior. A simple method to separate static – partly unavoidable – RI effects from dynamic RI effects is presented. It is shown that the dynamic RI behavior of an absorbance detector can be well described using a single, relatively easy-to-determine metric called the G-index. The G-index is typically in the order of a few seconds and its sign depends on the optical flow cell concept.
Lott Steffen, Schäfer Richard, Mann Martin, Backofen Rolf, Hess Wolfgang, Voss Björn, Georg Jens
GLASSgo - Automated and reliable detection of sRNA homologs from a single input sequences
2018 Frontiers in Genetics, Band: 9
KurzfassungBacterial small RNAs (sRNAs) are important post-transcriptional regulators of gene expression. The functional and evolutionary characterization of sRNAs requires the identification of homologs, which is frequently challenging due to their heterogeneity, short length and partly, little sequence conservation. We developed the GLobal Automatic Small RNA Search go (GLASSgo) algorithm to identify sRNA homologs in complex genomic databases starting from a single sequence. GLASSgo combines an iterative BLAST strategy with pairwise identity filtering and a graph-based clustering method that utilizes RNA secondary structure information. We tested the specificity, sensitivity and runtime of GLASSgo, BLAST and the combination RNAlien/cmsearch in a typical use case scenario on 40 bacterial sRNA families. The sensitivity of the tested methods was similar, while the specificity of GLASSgo and RNAlien/cmsearch was significantly higher than that of BLAST. GLASSgo was on average about 87 times faster than RNAlien/cmsearch, and only about 7.5 times slower than BLAST, which shows that GLASSgo optimizes the trade-off between speed and accuracy in the task of finding sRNA homologs. GLASSgo is fully automated, whereas BLAST often recovers only parts of homologs and RNAlien/cmsearch requires extensive additional bioinformatic work to get a comprehensive set of homologs. GLASSgo is available as an easy-to-use web server to find homologous sRNAs in large databases.
L Scholz, A O Ortiz Perez, B Bierer, J Wöllenstein, S Palzer
Gas sensors for climate research
2018 Sensoren und Messsysteme - 19. ITG/GMA-Fachtagung, Nürnberg, Deutschland
Kurzfassungn climate research, the availability of datasets providing information on the spatial and temporal characteristics of green-house gases are of high relevance for the development of reliable climate simulations. However, current gas measurement technologies does not lead to data in the quality and the scales needed for multiple reasons. To contribute to the ongoing search for a suitable method, a novel NDIR-type measurement system is presented that can provide high quality data of carbon dioxide (CO2) concentrations under field conditions at a fast measurement rate. Because of its low power requirements and its robust, low-maintenance and low-cost design, it is particularly suitable for the use as a sensor node as part of large-scale in-situ gas sensor networks.
L Scholz, A O Ortiz Perez, B Bierer, J Wöllenstein, S Palzer
Gas sensors for climate research
2018 J. Sens. Sens. Syst, Band: 7, Seiten: 535 - 541
KurzfassungThe availability of datasets providing information on the spatial and temporal evolution of greenhouse gas concentrations is of high relevance for the development of reliable climate simulations. However, current gas detection technologies do not allow for obtaining high-quality data at intermediate spatial scales with high temporal resolution. In this regard the deployment of a wireless gas sensor network equipped with in situ gas analysers may be a suitable approach. Here we present a novel, non-dispersive infrared absorption spectroscopy (NDIR) device that can possibly act as a central building block of a sensor node to provide high-quality data of carbon dioxide (CO2) concentrations under field conditions at a high measurement rate. Employing a gas-based, photoacoustic detector we demonstrate that miniaturized, low-cost, and low-power consuming CO2 sensors may be built. The performance is equal to that of standard NDIR devices but at a much reduced optical path length. Because of the spectral properties of the photoacoustic detector, no cross-sensitivities to humidity exist.
C Pannek, K Tarantik, L Engel, T Vetter, J Wöllenstein
Gasochromic Detection of NO2 on the Example of the Food Additive E141 (ii)
2018 Eurosensors 2018, Graz, Austria , Band: 2, Nummer: 13, Seite: 721
KurzfassungWe present our investigation on the gasochromic reaction of E141 (ii) towards the toxic gas nitrogen dioxide (NO2). E141 (ii) is a chlorophyllin-based food additive, typically used as green coloring for nearly all kinds of sweets. In this presentation we show an alternative approach for using E141 (ii) as optical gas indicator. All solid samples are prepared by multi-layer screen printing on different substrates like paper and PE-foil. Gas measurements are performed using an UV/Vis spectrometer. The influence of the substrate and according layer thickness is shown.
J. M. Stosch, A. Heumüller, C. Niemöller, S. Bleul, M. Rothenberg-Thurley, J. Riba, N. Renz, K. Szarc vel Szic, D. Pfeifer, M. Follo, H. L. Pahl, S. Zimmermann, J. Duyster, J. Wehrle, M. Lübbert, K. H. Metzeler, R. Claus, H. Becker
Gene mutations and clonal architecture in myelodysplastic syndromes and changes upon progression to acute myeloid leukaemia and under treatment
2018 Brit J Haematol, Band: 182, Seiten: 830 - 842
KurzfassungKnowledge of the molecular and clonal characteristics in the myelodysplastic syndromes (MDS) and during progression to acute myeloid leukaemia (AML) is essential to understand the disease dynamics and optimize treatment. Sequencing serial bone marrow samples of eight patients, we observed that MDS featured a median of 3 mutations. Mutations in genes involved in RNA-splicing or epigenetic regulation were most frequent, and exclusively present in the major clone. Minor subclones were distinguishable in three patients. As the MDS progressed, a median of one mutation was gained, leading to clonal outgrowth. No AML developed genetically independent of a pre-existing clone. The gained mutation mostly affected genes encoding signalling proteins. Additional acquisition of genomic aberrations frequently occurred. Upon treatment, emergence of new clones could be observed. As confirmed by single-cell sequencing, multiple mutations in identical genes in different clones were present within individual patients. DNA-methylation profiling in patients without identification of novel mutations in AML revealed methylation changes in individual genes. In conclusion, our data complement previous observations on the mutational and clonal characteristics in MDS and at progression. Moreover, DNA-methylation changes may be associated with progression in single patients. Redundancy of mutated genes in different clones suggests fertile grounds promoting clonal selection or acquisition.
Vomero M, Zucchini E, Delfino E, Gueli C, Mondragon NC, Carli S, Fadiga L, Stieglitz T
Glassy Carbon Electrocorticography Electrodes on Ultra-Thin and Finger-Like Polyimide Substrate: Performance Evaluation Based on Different Electrode Diameters.
2018 Materials, Band: 11, Nummer: 12, Seite: 2486
KurzfassungGlassy carbon (GC) has high potential to serve as a biomaterial in neural applications because it is biocompatible, electrochemically inert and can be incorporated in polyimide-based implantable devices. Miniaturization and applicability of GC is, however, thought to be partially limited by its electrical conductivity. For this study, ultra-conformable polyimide-based electrocorticography (ECoG) devices with different-diameter GC electrodes were fabricated and tested in vitro and in rat models. For achieving conformability to the rat brain, polyimide was patterned in a finger-like shape and its thickness was set to 8 µm. To investigate different electrode sizes, each ECoG device was assigned electrodes with diameters of 50, 100, 200 and 300 µm. They were electrochemically characterized and subjected to 10 million biphasic pulses—for achieving a steady-state—and to X-ray photoelectron spectroscopy, for examining their elemental composition. The electrodes were then implanted epidurally to evaluate the ability of each diameter to detect neural activity. Results show that their performance at low frequencies (up to 300 Hz) depends on the distance from the signal source rather than on the electrode diameter, while at high frequencies (above 200 Hz) small electrodes have higher background noises than large ones, unless they are coated with poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS).
Costa Fabrizio, Grun Dominic, Backofen Rolf
GraphDDP: a graph-embedding approach to detect differentiation pathways in single-cell-data using prior class knowledge
2018 Nat Commun, Band: 9, Nummer: 1
KurzfassungCell types can be characterized by expression profiles derived from single-cell RNA-seq. Subpopulations are identified via clustering, yielding intuitive outcomes that can be validated by marker genes. Clustering, however, implies a discretization that cannot capture the continuous nature of differentiation processes. One could give up the detection of subpopulations and directly estimate the differentiation process from cell profiles. A combination of both types of information, however, is preferable. Crucially, clusters can serve as anchor points of differentiation trajectories. Here we present GraphDDP, which integrates both viewpoints in an intuitive visualization. GraphDDP starts from a user-defined cluster assignment and then uses a force-based graph layout approach on two types of carefully constructed edges: one emphasizing cluster membership, the other, based on density gradients, emphasizing differentiation trajectories. We show on intestinal epithelial cells and myeloid progenitor data that GraphDDP allows the identification of differentiation pathways that cannot be easily detected by other approaches.
Vomero M, Ashouri D, Oliveira A, Eickenscheidt M, Stieglitz T
Graphitic Carbon Electrodes on Flexible Substrate for Neural Applications Entirely Fabricated Using Infrared Nanosecond Laser Technology.
2018 Sci Rep-uk, Band: 8, Nummer: 1, Seite: 14749
KurzfassungNeural interfaces for neuroscientific research are nowadays mainly manufactured using standard microsystems engineering technologies which are incompatible with the integration of carbon as electrode material. In this work, we investigate a new method to fabricate graphitic carbon electrode arrays on flexible substrates. The devices were manufactured using infrared nanosecond laser technology for both patterning all components and carbonizing the electrode sites. Two laser pulse repetition frequencies were used for carbonization with the aim of finding the optimum. Prototypes of the devices were evaluated in vitro in 30 mM hydrogen peroxide to mimic the post-surgery oxidative environment. The electrodes were subjected to 10 million biphasic pulses (39.5 μC/cm2) to measure their stability under electrical stress. Their biosensing capabilities were evaluated in different concentrations of dopamine in phosphate buffered saline solution. Raman spectroscopy and x-ray photoelectron spectroscopy analysis show that the atomic percentage of graphitic carbon in the manufactured electrodes reaches the remarkable value of 75%. Results prove that the infrared nanosecond laser yields activated graphite electrodes that are conductive, non-cytotoxic and electrochemically inert. Their comprehensive assessment indicates that our laser-induced carbon electrodes are suitable for future transfer into in vivo studies, including neural recordings, stimulation and neurotransmitters detection.
L. Becherer, M. Schulz, H. Kuhn, M. Bakheit, S. Frischmann, F. Zitz, N. Borst, R. Zengerle, F. von Stetten
HIV-1 and HTLV-1 multiplex detection by digital mediator displacement LAMP
2018 MicroTAS 2018, 11. -15. November 2018, Kaohsiung / Taiwan
Heller Simon, Hugle Maria, Nematollahi Iman, Manzouri Farrokh, Dumpelmann Matthias, Schulze-Bonhage Andreas, Boedecker Joschka, Woias Peter
Hardware Implementation of a Performance and Energy-optimized Convolutional Neural Network for Seizure Detection
2018 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), Band: 2018, Seiten: 2268 - 2271
KurzfassungWe present for the first time a μW-power convolutional neural network for seizure detection running on a low-power microcontroller. On a dataset of 22 patients a median sensitivity of 100% is achieved. With a false positive rate of 20.7 fp/h and a short detection delay of 3.4 s it is suitable for the application in an implantable closed-loop device.
Laufer, Bernhard, Krueger-Ziolek, Sabine, Moeller, Knut, Docherty, Paul David, Hoeflinger, Fabian, Reindl, Leonhard
Hierarchical Analysis of Thorax Models to Measure Tidal Volume
2018 Current Directions in Biomedical Engineering, Band: 4, Nummer: 1, Seiten: 429 - 432
KurzfassungMotion tracking of thorax kinematics can be used to determine respiration. However, determining a minimal sensor configuration from 64 candidate sensor locations is associated with high computational costs. Hence, a hierarchical optimization method was proposed to determine the optimal combination of sensors. The hierarchical method was assessed by its ability to quickly determine the sensor combination that will yield optimal modelled tidal volume compared to body plethysmograph measurements. This method was able to find the optimal sensor combinations, in approximately 2% of the estimated time required by an exhaustive search.

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Lehmann K, Yurchenko O, Melke J, Fischer A, Urban G
High electrocatalytic activity of metal-free and non-doped hierarchical carbon nanowalls towards oxygen reduction reaction
2018 Electrochim Acta, Band: 269, Seiten: 657 - 667
KurzfassungUnderstanding the influence of synthesis parameters on morphology and electrochemical properties of carbon nanostructure is necessary for the development of application-tailored materials. We report on the synthesis by plasma enhanced chemical vapor deposition, morphology and catalytic activity towards oxygen reduction reaction (ORR) of hierarchical carbon nanowalls (hCNW) at different deposition times. hCNW are an advancement of common CNW possessing an increased surface area while retaining the ideal mass transport characteristics of common CNW. The hCNW structure results from a synthesis using p-xylene as an aromatic precursor. hCNW are non-doped and metal-free with easily accessible graphitic edge sites at the top of the walls and numerous defects sites located within the porous side walls, which are ideal sites for adsorption and electron transfer. hCNW reveal a high amount of different electrochemically active sites that dominate the material character depending on the deposition time. The hCNW exhibit excellent catalytic activity towards ORR with very high ORR onset potential of 830 mV vs RHE in 0.1  mol L⁻¹ KOH solution and selectivity towards a two electron transfer mechanism. Thereby, the onset is higher than that of several nitrogen doped carbons and one of the highest for pure carbon electrodes. In contrast to other pure carbon materials with similar onsets, oxygen doping of hCNW before the experiments could be ruled out. As such, the results of this paper indicate the existence of inner sphere ORR on sp²-carbon. Additionally, the results emphasize the relevance of often overlooked material properties such as surface accessibility as well as electrical conductivity for ORR.
Klein E, Gossler C, Paul O, Ruther P
High-density mLED-based otpical cochlear implant with improved thermomechanical behavior
2018 Front Neurosci-switz, Band: 12, Seiten: 659 - 659
Ruther P
High-density neural probe arrays using CMOS and MEMS technologies
2018 Neuroelectronic Interfaces, Beyond Feasibility - Bridging the Gap in Neuroelectronic Interfaces,Gordon Research Conference, March 25-30, 2018, Galveston,TX, USA
C. Klose, L. Bohn, M. Klingele, M. Breitwieser, S. Vierrath
How engineering the PEM|CL interface influences the performance of PEMFCs
2018 69th Annual Meeting of the International Society of Electrochemistry (ISE), Bologna/Italy, 02. – 07.09.2018
Steven Carr, Nils Jansen, Ralf Wimmer, Jie Fu, Ufuk Topcu
Human-in-the-Loop Synthesis for Partially Observable Markov Decision Processes
2018 Proceedings of the 2018 Annual American Control Conference (ACC), Seiten: 762 - 69
KurzfassungWe study planning problems where autonomous agents operate inside environments that are subject to uncertainties and not fully observable. Partially observable Markov decision processes (POMDPs) are a natural formal model to capture such problems. Because of the potentially huge or even infinite belief space in POMDPs, synthesis with safety guarantees is, in general, computationally intractable. We propose an approach that aims to circumvent this difficulty: in scenarios that can be partially or fully simulated in a virtual environment, we actively integrate a human user to control an agent. While the user repeatedly tries to safely guide the agent in the simulation, we collect data from the human input. Via behavior cloning, we translate the data into a strategy for the POMDP. The strategy resolves all nondeterminism and non-observability of the POMDP, resulting in a discrete-time Markov chain (MC). The efficient verification of this MC gives quantitative insights into the quality of the inferred human strategy by proving or disproving given system specifications. For the case that the quality of the strategy is not sufficient, we propose a refinement method using counterexamples presented to the human. Experiments show that by including humans into the POMDP verification loop we improve the state of the art by orders of magnitude in terms of scalability.
van Rijn J, Hutter F
Hyperparameter Importance Across Datasets
2018
Feurer Matthias, Hutter Frank
Hyperparameter Optimization
In: AutoML: Methods, Sytems, Challenges
2018, Springer, Seiten: 3 - 37,
Cariou Romain, Benick Jan, Feldmann Frank, Höhn Oliver, Hauser Hubert, Beutel Paul, Razek Nasser, Wimplinger Markus, Bläsi Benedikt, Lackner David, Hermle Martin, Siefer Gerald, Glunz Stefan, Bett Andreas, Dimroth Frank
III–V-on-silicon solar cells reaching 33% photoconversion efficiency in two-terminal configuration
2018 Nature Energy, Band: 3, Nummer: 4, Seite: 326–333
KurzfassungSilicon dominates the photovoltaic industry but the conversion efficiency of silicon single-junction solar cells is intrinsically constrained to 29.4%, and practically limited to around 27%. It is possible to overcome this limit by combining silicon with high-bandgap materials, such as III–V semiconductors, in a multi-junction device. Significant challenges associated with this material combination have hindered the development of highly efficient III–V/Si solar cells. Here, we demonstrate a III–V/Si cell reaching similar performances to standard III–V/Ge triple-junction solar cells. This device is fabricated using wafer bonding to permanently join a GaInP/GaAs top cell with a silicon bottom cell. The key issues of III–V/Si interface recombination and silicon's weak absorption are addressed using poly-silicon/SiOx passivating contacts and a novel rear-side diffraction grating for the silicon bottom cell. With these combined features, we demonstrate a two-terminal GaInP/GaAs//Si solar cell reaching a 1-sun AM1.5G conversion efficiency of 33.3%.
Richter Armin, Benick Jan, Fell Andreas, Hermle Martin, Glunz Stefan
Impact of bulk impurity contamination on the performance of high-efficiency n -type silicon solar cells
2018 Prog Photovoltaics, Band: 24, Nummer: 10, Seite: 1319
KurzfassungThe experimental variation of wafer thickness and resistivity at device level combined with a comprehensive device simulation study allows the identification of dominating recombinationinduced power loss mechanisms in high‐efficiency n‐type silicon solar cells (A. Richter et al, Sol. Energy Mater. Sol. Cells 173, p. 96, 2017). Under the assumption of specific Shockley‐Read‐Hall (SRH) recombination parameters, impurity recombination within the silicon bulk was identified as one main source for efficiency losses particularly for solar cells made of high‐resistivity silicon. In this work, we extend that analysis approach focusing on the SRH recombination parameters in order to investigate whether certain properties of these recombination‐active impurities can be identified using this kind of simulation‐based analysis. Reported SRH recombination parameters of various common impurities (eg, Fe, Cr, or Ni) were considered. It was found that a dominating role of certain impurities as Cu, Au, Co, or Zn can be excluded. A general simulation study as a function of the fundamental SRH recombination parameters allowed us to reduce the possible SRH parameters significantly in particular of the capture cross‐section ratio of electrons and holes. These results demonstrate that our analysis approach, which combines an experimental variation of wafer thickness and resistivity with a comprehensive device simulation, can provide deep insights into the solar cells loss mechanisms. In particular, the conclusions regarding SRH recombination are of importance for solar cells made of n‐type silicon as there are no meta‐stable impurity states formed that would allow a direct identification of impurity recombination–related power loss as reported for p‐type Si.
Otte E, Ayub S, Paul O, Ruther P
Implantable Optrode Enabling Electrophysiology and Optogenetic Stimulation
2018 ICAN – International Conference for Advanced Neurotechnology, University of Michigan, Ann Arbor, USA, 7./8. May 2018
Heller, Simon, Allinger, Kim, Pelz, Uwe, Woias, Peter
Implantable Wireless Ultra-low Power Data Logger for Temperature Measurements in Animal Brains
2018 Mikrosystemtechnik-Kongress 2017, Unterschleißheim, Germany, October 23-25, 2017 MikroSystemTechnik 2017 Congress, Seiten: 410 - 413
KurzfassungThis paper reports on the development of an implantable, microcontroller based, ultra-low power data logger for temperature gradient measurements in animal brains. In contrast to commercially available systems the device uses a wireless interface allowing the readout and reprogramming of the data logger after the implantation. To ensure low power consumption, a wake-up receiver is integrated in the system, aside a dedicated power management system, reducing the power consumption to 43 muW at one temperature sample/min/channel.
Subbiah N, Feng Q, Beltran Ramirez K, Wilde J
Implementation of High-Temperture Pressure Sensor Package and Characterization up to 500 °C
2018 2018 20th Electronics Packaging Technology Conference
Pfau J, Leal Ordonez JA, Stieglitz T
In Situ Measurement of Stimulus Induced pH Changes Using Thin- Film Embedded IrOx pH Electrodes.
2018 EMBC 2018 „40th International Engineering in Medicine and Biology Conference of the IEEE Engin. in Medicine and Biology Society“ , 17.07.-21.07.18 in USA Hawaii, USA IEEE, Seiten: 5049 - 5052
KurzfassungThe high complexity of the biological response to implanted materials builds a serious barrier against implanted recording and stimulation electrode arrays to succeed in clini- cally relevant chronic studies. Some of the cell and molecular inte ractions and the ir contribution to inflammation and de vice failure are s till uncle ar. The inte rre late d me chanis ms le ading to tissue damage and electrode array failure during simultaneous faradaic, electrochemical reactions and biological response under electrical stimulation are not understood sufficiently. One variable, with which inflammatory and electrode surface processes can be analyzed and assessed, is the pH change in the immediate environment of the material-tissue interface. Here, the greatest challenges are in the biocompatibility and in-vivo long-term stability of selected sensor materials, the measure- ment of small transient pH oscillations and positioning of the sensor at a defined and nearest possible distance in the mi- crometer range, to the site of activity without the pH sensing being affected by the material-tissue interactions itself. This work represents the in-situ measurement of local and transient pH changes at a pulsed electrode with an embedded in-vivo compatible pH sensor and therein differentiating from current approaches of pH sensing during electrical stimulation.
Sutandy F, Ebersberger Stefanie, Huang Lu, Busch Anke, Bach Maximilian, Kang Hyun-Seo, Fallmann Jorg, Maticzka Daniel, Backofen Rolf, Stadler Peter, Zarnack Kathi, Sattler Michael, Legewie Stefan, Konig Julian
In vitro iCLIP-based modeling uncovers how the splicing factor U2AF2 relies on regulation by cofactors
2018 Genome Res
KurzfassungAlternative splicing generates distinct mRNA isoforms and is crucial for proteome diversity in eukaryotes. The RNA-binding protein (RBP) U2AF2 is central to splicing decisions, as it recognizes 3’ splice sites and recruits the spliceosome. We establish "in vitro iCLIP" experiments, in which recombinant RBPs are incubated with long transcripts, to study how U2AF2 recognizes RNA sequences and how this is modulated by trans-acting RBPs. We measure U2AF2 affinities at hundreds of binding sites and compare in vitro and in vivo binding landscapes by mathematical modeling. We find that trans-acting RBPs extensively regulate U2AF2 binding in vivo, including enhanced recruitment to 3’ splice sites and clearance of introns. Using machine learning, we identify and experimentally validate novel trans-acting RBPs (including FUBP1, CELF6, and PCBP1) that modulate U2AF2 binding and affect splicing outcomes. Our study offers a blueprint for the high-throughput characterization of in vitro mRNP assembly and in vivo splicing regulation.
Urban G, Dincer C, Weltin A, Prenzler N, Schmitt H, Warnecke A, Falk C, Lenarz T
In-vitro and in-vivo sensors for monitoring neuronal restauration
2018 BMT 2018, Aachen, Germany Biomed Eng-biomed Te, Band: 63, Ergänzungsband: 1, Seite: S141
Herr S, Buse K, Breunig I
Incoherently pumped lasing and self-pumped three-wave mixing in laser-active whispering-gallery resonators
2018 Laser Resonators, Microresonators, and Beam Control XX, San Francisco, CA, United States Proceedings of SPIE, Band: 10518, Seite: 105180U
KurzfassungWe report lasing at 1064 nm in an LED-pumped high-Q whispering-gallery resonator (WGR) made from Nd:YVO4. A single LED is sufficient to achieve quasi-cw operation. Furthermore, self-pumped three-wave-mixing is demonstrated in high-Q WGRs made from laser-active lithium niobate. When pumping the resonator with a free-running laser diode without any external frequency stabilization, self-frequency doubling of the 1.08-μm laser line into the green spectral region is observed. With the application of quasi-phase matching techniques, the nonlinear optical processes can be selected at will, which enables compact and versatile self-pumped frequency synthesizers. As a proof-of-principle experiment, self-pumped optical parametric oscillation is demonstrated in a radially poled WGR made from neodymium-doped lithium niobate.
Mokhtarifar Naser, Goldschmidtboeing Frank, Woias Peter
Indium tin oxide coated PET for differential pH-sensing using field-effect transistor based sensor
2018 Micro & Nano Letters, Band: 13, Nummer: 11, Seiten: 1525 - 1530
Quirynen R, Gros S, Diehl M
Inexact Newton-Type Optimization with Iterated Sensitivities
2018 SIAM Journal on Optimization, Band: 28, Nummer: 1, Seiten: 74 - 95
Frederico Goncalves de Cerqueira Lima, Ulrich Mescheder, Gábor Katona, Harald Leiste, Emre Özel, Holger Reinecke, Müller C
Influence of Silicon Doping Type on the Adhesion of Seedless Electrodeposited Copper Layers
2018 Surf Coat Tech, Band: 349, Seiten: 208 - 216
KurzfassungThe influence of silicon doping on the adhesion of copper layers electroplated directly on (100) silicon without a seed layer was investigated in this work. The adhesion of Cu layers on Si(100) was derived from scratch tests where the critical loads and the types of failures of these layers on phosphorous- and boron-doped silicon were obtained. The maximum loads supported until complete layer removals were about twice as large for Cu layers electrodeposited on p-Si(100) than those deposited on n-Si(100). The Cu layers were also visually inspected using images taken with scanning electron microscopes, their topography was obtained by atomic force microscope measurements and crystal orientations by X-ray *Manuscript_Review Click here to view linked References 2 diffraction. Secondary neutral mass spectroscopy measurements and X-ray photoelectron spectroscopy were used to quantitatively determine the atomic Cu concentration at the surface of each sample. Both measurements have detected larger Cu concentrations at the p-Si(100) surface than at n-Si(100). These measurements were used to support a model previously presented by this group to explain the adhesion difference of Cu electroplated directly on p- or n-doped Si.
Barz F, Ruther P, Asplund M
Influence of the Oxygen Flow Rate on the pH Response of Reactively Sputter Deposited Iridium Oxide Films
2018 40th Annual Conference on Engineering in Biology Society IEEE/EMBC, Honolulu, July, 2018
Barz F, Ruther P, Asplund M
Influence of the Oxygen Flow Rate on the pH Response of Reactively Sputter-deposited Iridium Oxide Films
2018 EMBC 2018 Conf., Hawaii, USA
C. Klose, L. Bohn, M. Klingele, M. Breitwieser, S. Vierrath
Influence of the PEM|CL interface on performance and water management
2018 Gordon Research Conference, Bryant University, Douglas Pike in Smithfield, RI, US., 29.07. – 03.08.2018
KurzfassungGordon Research Conference, Bryant University, Douglas Pike in Smithfield, RI, US., 29.07. – 03.08.2018
Eiselt T, Preinfalk J, Bittkau K, Gomard G, Hanemann T, Lemmer U
Inkjet-printed internal light extraction layers for organic light emitting diodes
2018 Flexible and printed electronics, Band: 3, Seite: 015007
KurzfassungWe have developed inkjet-printed scattering layers for enhanced light extraction in organic light emitting diodes (OLEDs). These layers are based on scattering polymer/nanoparticle composites, which are prepared from a solvent-free process and used for the outcoupling of waveguide modes to free propagating modes, thus improving the device efficiencies. Two different monomers are examined and an inkjet-printing process is developed for each of them. We first analyze the inks’ rheological properties, followed by the optical and morphological properties of the resulting layers. Upon integration of these printed layers into an OLED stack, the device efficiencies are increased by up to 40 % with respect to an unpatterned reference device. Furthermore, we show that these internal light extraction layers improve the angular and spectral stability of the devices.
AO Perez, H Gao, X Lyu, J Wöllenstein, V Kallfaß, J Fonollosa, S Palzer
Inkjet-printed, functional heterolayers of ZnO@ CuO for stoma pouch monitoring
2018 Appl Nanosci, Band: 8, Nummer: 8, Seiten: 1907 - 1914
KurzfassungMany bowel cancer patients are in need of an artificial stoma as part of their surgical treatment, and associated post-surgical odours caused by leaking stoma pouches may lead to social isolation, which is why inconspicuous monitoring of this situation is important for affected persons. The integration of micro- and nanotechnology may offer low-cost, low-power consumption and small solutions to this challenge. To this end, we present an inkjet-printed, heterostructured gas sensor that has been built by incorporating nanosized p-type semiconducting CuO in a porous n-type ZnO matrix. The functional layer is fabricated using a combination of a colloidal suspension and sol–gel approach optimized for inkjet printing thus offering an industry-ready method for integration of nanomaterials in microelectromechanical systems (MEMS) structures. Using a thermal modulation scheme we enhance the information content and classify different events. We demonstrate that a simple MEMS device using a novel hetero-nanomaterial may be used to reliably identify situations where stoma pouch content escapes.
Reichel Christian, Reusch Markus, Kotula Stefan, Granek Filip, Richter Armin, Hermle Martin, Glunz Stefan
Insulating and passivating plasma-enhanced atomic layer deposited aluminum oxide thin films for silicon solar cells
2018 Thin Solid Films, Band: 656, Seite: 53–60
KurzfassungPlasma-enhanced atomic layer deposited (PEALD) aluminum oxide (Al2O3) thin film were investigated with respect to their application in silicon solar cells where not only excellent surface passivation but also excellent electrical insulation properties are required. In this study, the insulation properties of about 10 nm to almost 250 nm Al2O3 thin films, deposited at temperatures in the range of 100 °C to 350 °C and annealed in the range of 250 °C to 450 °C, were correlated to various thin film properties, most notably the thin film defect density, i. e. pinhole density, and the thin film stress. Al2O3 thin films provide sufficient electrical insulation after a postdeposition annealing step at 450 °C when deposited at 250 °C with thickness of at least 80 nm which can be attributed to a low defect density and low stress in the thin films, allowing a low leakage current density and a high breakdown voltage that was independent of the type of metals used for the electrode. Al2O3 thin films deposited and annealed at these temperatures enabled a very good surface passivation of silicon. These results indicate that Al2O3 thin films realized by PEALD are a promising candidate for silicon solar cells that rely on passivating as well as insulating thin films.
Savelli G, Colonna J, Faucherand P, Wendler D, Manoli Y, Keller M
Integrated Thermoelectric Sensors for Thermal Monitoring of Integrated Circuits
2018 Presentation, 24th International Workshop on Thermal Investigations of ICs and Systems (THERMINIC)
Rudmann L, Alt MT, Ashouri Vajari D, Stieglitz T
Integrated optoelectronic microprobes
2018 Curr Opin Neurobiol, Band: 50, Nummer: June, Seiten: 72 - 82
KurzfassungAbstract: Optogenetics opened not only new exciting opportunities to interrogate the nervous system but also requires adequate probes to facilitate these wishes. Therefore, a multidisciplinary effort is essential to match these technical opportunities with biological needs in order to establish a stable and functional material-tissue interface. This in turn can address an optical intervention of the genetically modified, light sensitive cells in the nervous system and recording of electrical signals from single cells and neuronal networks that result in behavioral changes. In this review, we present the state of the art of optoelectronic probes and assess advantages and challenges of the different design approaches. At first, we discuss mechanisms and processes at the material-tissue interface that influence the performance of optoelectronic probes in acute and chronic implantations. We classify optoelectronic probes by their property of delivering light to the tissue: by waveguides or by integrated light sources at the sites of intervention. Both approaches are discussed with respect to size, spatial resolution, opportunity to integrate electrodes for electrical recording and potential interactions with the target tissue. At last, we assess translational aspects of the state of the art. Long-term stability of probes and the opportunity to integrate them into fully implantable, wireless systems are a prerequisite for chronic applications and a transfer from fundamental neuroscientific studies into treatment options for diseases and clinical trials. Highlights: - Miniaturization technologies enable multichannel optoelectronic neural probes. - No external laser is needed when light sources are directly integrated on the probes. - Connectors to recording equipment still limit further miniaturization. - Wireless systems with integrated multiplexers and amplifiers can replace connectors. - Longevity of probes is mandatory for chronic implantation.
Kretschmer S, Jäger J, Ataman C, Zappe H
Integration and biocompatible packaging of multi- modal endoscopic imagers using 3D glass micro structuring
2018 Proceedings of SPIE, Band: 10545, Seite: 105450Q
Miladi Milad, Montaseri Soheila, Backofen Rolf, Raden Martin
Integration of accessibility data from structure probing into RNA-RNA interaction prediction
2018 Bioinformatics, Oxford University Press, Band: 35, Nummer: 16, Seiten: 2862 - 2864
KurzfassungExperimental structure probing data has been shown to improve thermodynamics-based RNA secondary structure prediction. To this end, chemical reactivity information (as provided e.g. by SHAPE) is incorporated, which encodes whether or not individual nucleotides are involved in intra-molecular structure. Since inter-molecular RNA-RNA interactions are often confined to unpaired RNA regions, SHAPE data is even more promising to improve interaction prediction. Here we show how such experimental data can be incorporated seamlessly into accessibility-based RNA-RNA interaction prediction approaches, as implemented in IntaRNA. This is possible via the computation and use of unpaired probabilities that incorporate the structure probing information. We show that experimental SHAPE data can significantly improve RNA-RNA interaction prediction. We evaluate our approach by investigating interactions of a spliceosomal U1 snRNA transcript with its target splice sites. When SHAPE data is incorporated, known target sites are predicted with increased precision and specificity. Keywords: RNA-RNA interaction prediction, accessibility, RNA structure probing, RNA secondary structure, chemical footprinting, SHAPE. Availability: https://github.com/BackofenLab/IntaRNA
Ashouri Vajari D, Vomero M, Erhardt JB, Sadr A, Ordonez JS, Coenen VA, Stieglitz T
Integrity Assessment of a Hybrid DBS Probe that Enables Neurotransmitter Detection Simultaneously to Electrical Stimulation and Recording.
2018 Micromachines, Band: 9, Nummer: 10, Seiten: 510 - 524
KurzfassungDeep brain stimulation (DBS) is a successful medical therapy for many treatment resistant neuropsychiatric disorders such as movement disorders; e.g., Parkinson’s disease, Tremor, and dystonia. Moreover, DBS is becoming more and more appealing for a rapidly growing number of patients with other neuropsychiatric diseases such as depression and obsessive compulsive disorder. In spite of the promising outcomes, the current clinical hardware used in DBS does not match the technological standards of other medical applications and as a result could possibly lead to side effects such as high energy consumption and others. By implementing more advanced DBS devices, in fact, many of these limitations could be overcome. For example, a higher channels count and smaller electrode sites could allow more focal and tailored stimulation. In addition, new materials, like carbon for example, could be incorporated into the probes to enable adaptive stimulation protocols by biosensing neurotransmitters in the brain. Updating the current clinical DBS technology adequately requires combining the most recent technological advances in the field of neural engineering. Here, a novel hybrid multimodal DBS probe with glassy carbon microelectrodes on a polyimide thin-film device assembled on a silicon rubber tubing is introduced. The glassy carbon interface enables neurotransmitter detection using fast scan cyclic voltammetry and electrophysiological recordings while simultaneously performing electrical stimulation. Additionally, the presented DBS technology shows no imaging artefacts in magnetic resonance imaging. Thus, we present a promising new tool that might lead to a better fundamental understanding of the underlying mechanism of DBS while simultaneously paving our way towards better treatments.
Raden Martin, Mohamed Mostafa, Ali Syed, Backofen Rolf
Interactive implementations of thermodynamics-based RNA structure and RNA-RNA interaction prediction approaches for example-driven teaching
2018 PLOS Comput. Biol, Band: 14, Nummer: 8
KurzfassungThe investigation of RNA-based regulation of cellular processes is becoming an increasingly important part of biological or medical research. For the analysis of this type of data, RNA-related prediction tools integrated into of many pipelines and workflows. In order to correctly apply and tune these programs, the user has to have a precise understanding of their limitations and concepts. Within this manuscript, we provide the mathematical foundations and extract the algorithmic ideas that are core to state-of-the-art RNA structure and RNA-RNA interaction prediction algorithms. To allow the reader to change and adapt the algorithms or to play with different inputs, we provide an open-source web interface to JavaScript implementations and visualizations of each algorithm. The conceptual, teaching-focused presentation enables a high-level survey of the approaches while providing sufficient details for understanding important concepts. This is boosted by the simple generation and study of examples using the web interface available under http://rna.informatik.uni-freiburg.de/Teaching/. In combination, we provide a valuable resource for teaching, learning and understanding the discussed prediction tools and thus enable a more informed analysis of RNA-related effects.
da Costa CA, Pasluosta CF, Eskofier B, da Silva DB, da Rosa Righi R
Internet of Health Things: Toward intelligent vital signs monitoring in hospital wards.
2018 Artif Intell Med
KurzfassungBackground Large amounts of patient data are routinely manually collected in hospitals by using standalone medical devices, including vital signs. Such data is sometimes stored in spreadsheets, not forming part of patients’ electronic health records, and is therefore difficult for caregivers to combine and analyze. One possible solution to overcome these limitations is the interconnection of medical devices via the Internet using a distributed platform, namely the Internet of Things. This approach allows data from different sources to be combined in order to better diagnose patient health status and identify possible anticipatory actions. Methods This work introduces the concept of the Internet of Health Things (IoHT), focusing on surveying the different approaches that could be applied to gather and combine data on vital signs in hospitals. Common heuristic approaches are considered, such as weighted early warning scoring systems, and the possibility of employing intelligent algorithms is analyzed. Results As a result, this article proposes possible directions for combining patient data in hospital wards to improve efficiency, allow the optimization of resources, and minimize patient health deterioration. Conclusion It is concluded that a patient-centered approach is critical, and that the IoHT paradigm will continue to provide more optimal solutions for patient management in hospital wards. Graphical abstract Download high-res image (133KB)Download full-size image
Chlouba T, Trojánek F, Laube J, Hiller D, Gutsch S, Zacharias M, Malý P
Interplay of bimolecurlar and Auger recombination in photoexcited carrier dynamics in silicon nanocrystal/silicon dioxide superlattices
2018 Sci Rep-uk, Band: 1703
Ayub S, Ruther P, Paul O, Kohl P, Zgierski-Johnston CM
Invasive Optical Pacing in Perfused, Optogenetically Modified Mouse Heart Using Stiff Multi-LED Optical Probes
2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), Honolulu, HI, USA , Seiten: 4836 - 4839
KurzfassungWe present the first invasive use of a stiff, multiLED optical probe for intramural optical stimulation of cardiac tissue. We demonstrate that optical pacing is possible with high spatial and temporal resolution in transgenic mice expressing channelrhodopsin-2. The technical implementation of this study builds on optical probes recently developed and tested ex vivo in cerebral tissue of mice. The probes comprise LEDs integrated on flexible substrates stiffened by silicon-based MEMS structures enabling the successful penetration into the cardiac tissue. The probe technology is extended to allow dual-sided illumination for directional tissue stimulation. Implantation trials affirm the ability to optically pace the isolated perfused heart at stimulation frequencies between 4Hz and 12Hz with experimentally determined emittance levels of 10mW mm-2Rapid activation of two distant LEDs could reliably be used to induce short runs of ventricular fibrillation, while simultaneous activation of all LEDs allowed termination of re-entrant rhythm disturbances (optical defibrillation). Thus, spatially-resolved intramural pacing and rhythm control of the isolated heart is possible using stiff, multi-LED optical probes.
C Pannek, K Tarantik, K Schmitt, J Wöllenstein
Investigation of Gasochromic Rhodium Complexes Towards Their Reactivity to CO and Integration into an Optical Gas Sensor for Fire Gas Detection
2018 Sensors-basel, Band: 18, Nummer: 7, Seite: 1994
KurzfassungThe detection of the toxic gas carbon monoxide (CO) in the low ppm range is required in different applications. We present a study of the reactivity of different gasochromic rhodium complexes towards the toxic gas carbon monoxide (CO). Therefore, variations of binuclear rhodium complexes with different ligands were prepared. They were characterized by FTIR spectroscopy, 1H NMR spectroscopy, and differential scanning calorimetry. All complexes are spectroscopically distinguishable and temperature stable up to at least 187 °C. The gasochromic behavior of all different compounds was tested. Therefore, the compounds were dissolved in toluene and exposed to 100 ppm CO for 10 min to investigate their gas sensitivity and reaction velocity. The changes in the transmission spectra were recorded by UV/vis spectroscopy. Furthermore, a significant influence of the solvent to the color dyes’ gasochromic reaction and behavior was observed. After characterization, one complex was transferred as sensing element into an optical gas sensor. Two different measurement principles (reflection- and waveguide-based) were built up and tested towards their capability as gasochromic CO sensors. Finally, different gas-dependent measurements were carried out.
Otte E, Ayub S, Paul O, Ruther P
LED-based Intracerebral Optrode for Simultaneous Optical Stimulation and Electrophysiological Recording
2018 IEEE MEMS Conf. 2018, Belfast, Ireland , Seiten: 384 - 387
P. Juelg, M. Specht, E. Kipf, M. Lehnert, C. Eckert, N. Paust, R. Zengerle, T. Hutzenlaub
LabDisk for fully automated quantification of two leukemia associated gene targets
2018 MicroTAS 2018, 11. -15. November 2018, Kaohsiung / Taiwan
Reiterer, A., Leidinger, M.
Laserscanner zur Lichtraummessung: Präzise messen, effizient auswerten
2018 EI - Der Eisenbahningenieur, Nummer: Mai 2018, Seiten: 44 - 47
Schautzgy J, Wilde J
Lebensdaueruntersuchungen an vibrationsbelasteten elektrischen Steckverbindungssystemen
2018 Workshop des DVM-Arbeitskreises Zuverlässigkeit mechatronischer und adaptronischer Systeme, München, Seiten: II-1 - II-18
Schindelhauer C, Höflinger F, Bordoy J, Zhang R, Bannoura A, Reindl L, Simon N
Localization System based on Ultra Low-power Radio Landmarks
2018 7th International Conference on Sensor Networks , Seiten: 51 - 59
Fiath R, Hofer K T, Csikos V, Horvath D, Nanasi T, Toth K, Pothof F, Böhler C, Asplund M, Ruther P, Ulbert I
Long-term recording performance and biocompatibility of chronically implanted cylindrically-shaped, polymer-based neural interfaces
2018 Biomed Eng Online, Seiten: 301 - 315
Fiath R, Hofer KT, Csikos V, Horvath D, Nanasi T, Toth K, Pothof F, Bohler C, Asplund M, Ruther P, Ulbert I
Long-term recording performance and biocompatibility of chronically implanted cylindrically-shaped, polymer-based neural interfaces.
2018 Biomedizinische Technik/Biomedical Engineering
KurzfassungStereo-electroencephalography depth electrodes, regularly implanted into drug-resistant patients with focal epilepsy to localize the epileptic focus, have a low channel count (6-12 macro- or microelectrodes), limited spatial resolution (0.5-1 cm) and large contact area of the recording sites (~mm2). Thus, they are not suited for high-density local field potential and multiunit recordings. In this paper, we evaluated the long-term electrophysiological recording performance and histocompatibility of a neural interface consisting of 32 microelectrodes providing a physical shape similar to clinical devices. The cylindrically-shaped depth probes made of polyimide (PI) were chronically implanted for 13 weeks into the brain of rats, while cortical or thalamic activity (local field potentials, single-unit and multi-unit activity) was recorded regularly to monitor the temporal change of several features of the electrophysiological performance. To examine the tissue reaction around the probe, neuron-selective and astroglia-selective immunostaining methods were applied. Stable single-unit and multi-unit activity were recorded for several weeks with the implanted depth probes and a weak or moderate tissue reaction was found around the probe track. Our data on biocompatibility presented here and in vivo experiments in non-human primates provide a strong indication that this type of neural probe can be applied in stereo-electroencephalography recordings of up to 2 weeks in humans targeting the localization of epileptic foci providing an increased spatial resolution and the ability to monitor local field potentials and neuronal spiking activity.
Langenmair M, Martens J, Gierthmuehlen M, Plachta DTT, Stieglitz T
Low temperature approach for high density electrical feedthroughs for neural implants using maskless fabrication techniques.
2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 18.- 21.07.2018, Oahu, Hawaii, USA IEEE, Seiten: 2933 - 2936
KurzfassungImplantable electronic packages for neural implants utilize reliable electrical feedthroughs that connect the inside of a sealed capsule to the components that are exposed to the surrounding body tissue. With the ongoing miniaturization of implants requiring ever higher integration densities of such feedthroughs new technologies have to be investigated. The presented work investigates the sealing of vertical feedthroughs in aluminum-oxide-substrates with gold stud-bumps. The technology enables integration densities of up to 1600/cm 2 while delivering suitable water leak rates for realistic implantation durations of miniaturized packages (feedthrough-count $>50$, package-volume $<2$ cm $^{3})$ of more than 50 years. All manufacturing steps require temperatures below $420 ^{\circ}\mathrm {C}$ and are suitable for maskless rapid prototyping.
Jörg Schube, Leonard Tutsch, Tobias Fellmeth, Martin Bivour, Frank Feldmann, Thibaud Hatt, Florian Maier, Roman Keding, Florian Clement, Stefan W Glunz
Low-Resistivity Screen-Printed Contacts on Indium Tin Oxide Layers for Silicon Solar Cells With Passivating Contacts
2018 IEEE J Photovolt
KurzfassungThe capability for contact formation on indium tin oxide layers of different low-temperature screen printing silver pastes after thermal curing and photonic sintering is evaluated in detail. The 80-nm-thick indium tin oxide layers used in this study are sputtered at three different oxygen gas flows and, consequently, differ by their electrical and optical properties. All pastes are analyzed by means of simultaneous thermogravimetry-differential scanning calorimetry. After printing and contact formation processing, the lateral resistivity of the metal contacts and their contact resistivity to the indium tin oxide layers are determined. Furthermore, the microstructure of the metal electrodes is investigated to gain a deeper understanding of the underlying contact formation mechanisms. Besides low-temperature curing at T curing,low = 180–220 °C, as conventionally applied to silicon heterojunction solar cells, photonic sintering and thermal curing at medium temperatures T curing,mid = 250–350 °C are utilized. The higher curing temperatures in the range of T curing,mid enhance the sintering and densification processes of the different pastes, and thereby, lateral resistivities of 2.4–3.5 μΩ⋅cm and contact resistivities of 1.0–2.5 mΩ⋅cm2 are achieved. The results indicate a promising industry-relevant non-firing-through metallization approach for, e.g., poly-silicon-based structures like tunnel oxide passivating contacts, which allow comparatively high temperatures for contact formation processing. With thermal curing at T curing,low and photonic sintering, both compatible with temperature-sensitive silicon heterojunction solar cells, lateral finger resistivities of 6.5–9.4 μΩ⋅cm and contact resistivities of 1.2–2.5 mΩ⋅cm2 are achieved. Thereby, photonic sintering has the potential of a significantly reduced process time from several minutes down to 1–4 ms.
Mokhtarifar, Naser, Goldschmidtboeing, Frank, Woias, Peter
Low-cost EGFET-based pH-sensor using encapsulated ITO/PET-electrodes
2018 2018 IEEE International Instrumentation and Measurement Technology Conference (I2MTC), Houston, TX, USA 2018 IEEE International Instrumentation and Measurement Technology Conference (I2MTC), Seiten: 1 - 5
KurzfassungThis paper presents a truly low-cost modular sensor using laser-micromachined Indium Tin Oxide (ITO) on Polyethylene Terephthalate (PET) as pH-sensitive material for a differential Extended Gate Field Effect Transistor (EGFET). In this method, the gate terminal of a commercially available MOSFET is connected to ITO/PET-electrodes providing an electrochemical measurement cell in combination with a reference electrode. Hence, a pH-variation of the solution in contact with the ITO/PET-electrode can be sensed by the MOSFET due to a surface potential change at its “liquid gate” terminal. A serial flow cell configuration has been designed to enable differential sensing, in order to overcome long-term drift and common mode disturbances and eliminate the need for a glass reference electrode. A special encapsulation method of the ITO/PET-foil conserves its pH-sensitivity. The whole sensor and its package are realized without any need for expensive cleanroom processes. The combination yields to a true low-cost modular flow-through-sensor with high precision and robustness to sense pH.
Mann Martin, Kahle Hans-Peter, Beck Matthias, Bender Bela, Spiecker Heinrich, Backofen Rolf
MICA: Multiple interval-based curve alignment
2018 SoftwareX, Band: 7, Seiten: 53 - 58
KurzfassungAbstract MICA enables the automatic synchronization of discrete data curves. To this end, characteristic points of the curves’ shapes are identified. These landmarks are used within a heuristic curve registration approach to align profile pairs by mapping similar characteristics onto each other. In combination with a progressive alignment scheme, this enables the computation of multiple curve alignments. Multiple curve alignments are needed to derive meaningful representative consensus data of measured time or data series. MICA was already successfully applied to generate representative profiles of tree growth data based on intra-annual wood density profiles or cell formation data. The MICA package provides a command-line and graphical user interface. The R interface enables the direct embedding of multiple curve alignment computation into larger analyses pipelines. Source code, binaries and documentation are freely available at https://github.com/BackofenLab/MICA
Yuliya Butkova, Ralf Wimmer, Holger Hermanns
Markov Automata on Discount!
2018 19. International GI/ITG Conference on Measurement, Modelling and Evaluation of Computing Systems (MMB), Reinhard German et al., Band: 10740
KurzfassungMarkov automata (MA) are a rich modelling formalism for complex systems combining compositionality with probabilistic choices and continuous stochastic timing. Model checking algorithms for different classes of properties involving probabilities and rewards have been devised for MA, opening up a spectrum of applications in dependability engineering and artificial intelligence, reaching out into economy and finance. In the latter more general contexts, several quantities of considerable importance are based on the idea of discounting reward expectations, so that the near future is more important than the far future. This paper introduces the expected discounted reward value for MA and develops effective iterative algorithms to quantify it, based on value- as well as policy-iteration. To arrive there, we reduce the problem to the computation of expected discounted rewards and expected total rewards in Markov decision processes. This allows us to adapt well-known algorithms to the MA setting. Experimental results clearly show that our algorithms are efficient and scale to MA with hundred thousands of states.
Wilson James, Hutter Frank, Deisenroth Marc
Maximizing acquisition functions for Bayesian optimization
2018 Advances in Neural Information Processing Systems 31, Curran Associates, Inc., Seiten: 9906 - 9917
Gawronski Alexander, Uhl Michael, Zhang Yajia, Lin Yen-Yi, Niknafs Yashar, Ramnarine Varune, Malik Rohit, Feng Felix, Chinnaiyan Arul, Collins Colin, Sahinalp S, Backofen Rolf
MechRNA: prediction of lncRNA mechanisms from RNA-RNA and RNA-protein interactions
2018 Bioinformatics
KurzfassungMotivation: Long non-coding RNAs (lncRNAs) are defined as transcripts longer than 200 nucleotides that do not get translated into proteins. Often these transcripts are processed (spliced, capped, polyadenylated) and some are known to have important biological functions. However, most lncRNAs have unknown or poorly understood functions. Nevertheless, because of their potential role in cancer, lncRNAs are receiving a lot of attention, and the need for computational tools to predict their possible mechanisms of action is more than ever. Fundamentally, most of the known lncRNA mechanisms involve RNA-RNA and/or RNA-protein interactions. Through accurate predictions of each kind of interaction and integration of these predictions, it is possible to elucidate potential mechanisms for a given lncRNA. Approach: Here we introduce MechRNA, a pipeline for corroborating RNA-RNA interaction prediction and protein binding prediction for identifying possible lncRNA mechanisms involving specific targets or on a transcriptome-wide scale. The first stage uses a version of IntaRNA2 with added functionality for efficient prediction of RNA-RNA interactions with very long input sequences, allowing for large-scale analysis of lncRNA interactions with little or no loss of optimality. The second stage integrates protein binding information pre-computed by GraphProt, for both the lncRNA and the target. The final stage involves inferring the most likely mechanism for each lncRNA/target pair. This is achieved by generating candidate mechanisms from the predicted interactions, the relative locations of these interactions and correlation data, followed by selection of the most likely mechanistic explanation using a combined p-value. Results: We applied MechRNA on a number of recently identified cancer-related lncRNAs (PCAT1, PCAT29, ARLnc1) and also on two well-studied lncRNAs (PCA3 and 7SL). This led to the identification of hundreds of high confidence potential targets for each lncRNA and corresponding mechanisms. These predictions include the known competitive mechanism of 7SL with HuR for binding on the tumor suppressor TP53, as well as mechanisms expanding what is known about PCAT1 and ARLn1 and their targets BRCA2 and AR, respectively. For PCAT1-BRCA2, the mechanism involves competitive binding with HuR, which we confirmed using HuR immunoprecipitation assays. Availability: MechRNA is available for download at https://bitbucket.org/compbio/mechrna. Contact: backofen@informatik.uni-freiburg.de, cenksahi@indiana.edu. Supplementary information: Supplementary data are available at Bioinformatics online.
M. Trotter, N. Borst, F. von Stetten
Mediator probes for electrochemical DNA detection: Universal electrode functionalization for specific detection of different targets
2018 9th Euro Biosensors & Bioelectronics Congress November 29-30, 2018 Dublin, Ireland
J. Kokert, T. Beckedahl, L. M. Reindl
Medlay: A Reconfigurable Micro-Power Management to Investigate Self-Powered Systems
2018 Sensors, Band: 18, Nummer: 1, Seite: 259
KurzfassungIn self-powered microsystems, a power management is essential to extract, transfer and regulate power from energy harvesting sources to loads such as sensors. The challenge is to consider all of the different structures and components available and build the optimal power management on a microscale. The purpose of this paper is to streamline the design process by creating a novel reconfigurable testbed called Medlay. First, we propose a uniform interface for management functions e.g., power conversion, energy storing and power routing. This interface results in a clear layout because power and status pins are strictly separated, and inputs and outputs have fixed positions. Medlay is the ready-to-use and open-hardware platform based on the interface. It consists of a base board and small modules incorporating e.g., dc-dc converters, power switches and supercapacitors. Measurements confirm that Medlay represents a system on one circuit board, as parasitic effects of the interconnections are negligible. The versatility regarding different setups on the testbed is determined to over 250,000 combinations by layout graph grammar. Lastly, we underline the applicability by recreating three state-of-the-art systems with the testbed. In conclusion, Medlay facilitates building and testing power management in a very compact, clear and extensible fashion.
S. Hin, M. Loskyll, V. Klein, M. Keller, O. Strohmeier, F. von Stetten, R. Zengerle, K. Mitsakakis
Membrane-based sample inlet for centrifugal microfluidic cartridges
2018 Microelectron Eng, Band: 187-188, Seiten: 78 - 83
KurzfassungCentrifugal microfluidics enables the rapid execution of complex blood sample analyses in a fully automated manner at the point of care. However, during blood sample addition, the cartridge is at rest and centrifugal forces are not present to allocate the sample in a controlled way. We present a versatile approach for the user-friendly, well-controlled and safe sample addition into a centrifugal microfluidic cartridge for use in serology. It features a commercial (plasma separation) membrane stacked into the inlet chamber of the cartridge. This combination of sample inlet and plasma separation in one structural unit brings the advantage of reducing footprint in highly integrated point-of-care testing. By using a pipette the user may add a blood sample (90 μL) to the membrane holding the liquid by capillary forces. Flowing across the membrane, cells separate from blood plasma. The blood plasma releases into the downstream structure upon centrifugation. The mean plasma recovery rate was 57.3 (± 4.7) % and mean plasma purity 99.5 (± 0.6) % from samples of varying hematocrit (36%–59%). Furthermore, the analyte C-reactive protein (CRP) did not significantly adsorb to the membrane. This was concluded, since CRP immunoassay results with plasma from spiked whole blood, obtained from membrane-based plasma separation and from plasma separation on a standard laboratory centrifuge, did not significantly differ. Thus, the suggested approach is promising for simultaneous application as sample inlet holding the sample by capillary forces and as a plasma separation module for centrifugal microfluidics. Potential future applications may include other sample matrices. The use with further blood transfer devices (capillary, directly from fingertip) seems possible, yet requiring further evaluation.
Durr, Nathanael, Sauer, Martin, Hiermaier, Stefan
Mesoscale investigation of dynamic fracture in quartzite and sandstone and homogenization to macroscale
2018 Int J Solids Struct, Band: 144-145, Seiten: 160 - 179
KurzfassungThe work presented here is part of the MEMIN (Multidisciplinary Experimental and Modeling Impact Research Network) project, which is devoted to the experimental and numerical investigation of the effects of meteorite impact on geological materials from laboratory scale to natural scale. In general, high velocity impacts on rock material causes fractures in the target that may lead to spallation of material near surfaces. While spallation effects are of great importance for laboratory scale craters, they are much less significant in natural craters. Therefore, they need to be taken into account when comparing natural craters with laboratory craters, particularly, when scaling laws that provide relationships between laboratory and natural craters shall be developed. This scale bridging requires realistic quantification of spallation effects, which can be done with numerical methods if appropriate material models exist. For this purpose, we investigate dynamic fracture in quartzite and sandstone. We present a new methodology to derive three dimensional macroscale material data from one-dimensional dynamic fracture experiments, namely Hopkinson-Bar experiments in the spallation configuration, using a new mesoscale simulation model. Simulations are conducted with the in-house hydrocode SOPHIA. Mesoscopic material parameters are identified from a parameter study such that simulated macroscopic failure quantities conform to experimentally measured data. The calibrated mesoscale model is then subjected to a set of multiaxial load cases in order to derive macroscopic yield and failure parameters using averaging techniques. The results can be directly used to calibrate macroscale material models for dynamic fracture and will support the predictability of laboratory craters and, in particular, of spallation effects.
Rehberger F, Eickenscheidt M, Stieglitz T
Micro-folded 3D neural electrodes fully integrated in polyimide.
2018 Engineering in Medicine and Biology Conference (EMBC) 2018. 17-21 July 2018 . Honolulu, Hawaii, United States IEEE, Seiten: 4587 - 4590
KurzfassungRecent neural interfaces are characterized by high functionality and good adaptation to the target tissue. Still, the underlying manufacturing process is mainly planar and so are the device and contact surface. Therefore, three-dimensional structures to contact neuronal tissue are desired to gain higher selectivity. In the present study, local bending structures integrated in flexible electrode arrays based on polyimide are investigated. The bending is achieved by the contraction of a second polyimide (Durimide) that is embedded into grooves with a width of a few micrometers. The angle of the bending can be controlled with a high accuracy from 3 to 20 degrees by changing the geometry of the grooves and the imidization temperature These bending structures can be combined to achieve any desired angle for specific applications.
Kutluk H, Bruch R, Meirich M, Partel S, Urban G, Dincer C
Microfluidic biosensor for the electrochemical on-site detection of microRNAs
2018 MicroTAS 2018, Kaohsiung, Taiwan
KurzfassungIn this work we present a novel approach for the electrochemical detection of miRNAs using a microfluidic platform. Herein, a sensitive, versatile and low-cost biosensor is combined with an enzyme-linked assay to detect miRNAs via hybridization in very low sample volumes (560 nl). The applicability of the system is successfully shown by measuring the miRNA hsa-miR-197 with a limit of detection (LOD) of 6.4 nM and an inter-assay coefficient of variation of below 10%. It is shown that the microfluidic biosensor is capable of measuring low miRNA concentrations with high selectivity against non-targeted miRNAs.
Kieninger J, Weltin A, Flamm H, Urban G
Microsensor systems for cell metabolism – from 2D culture to organ-on-chip
2018 Lab Chip, Band: 18, Seiten: 1274 - 1291
KurzfassungMicrosensor systems for cell metabolism are essential tools for investigation and standardization in cell cul- ture. Electrochemical and optical read-out schemes dominate, which enable the marker-free, continuous, online recording of transient effects and deliver information beyond microscopy and end-point tests. There has been much progress in microfluidics and microsensors, but the translation of both into standard cell culture procedures is still limited. Within this critical review, we discuss different cell culture formats ranging from standard culture vessels to dedicated microfluidic platforms. Key aspects are the appropriate supply of cells, mass transport of metabolites to the sensors and generation of stimuli. Microfluidics enable the transition from static to dynamic conditions in culture and measurement. We illustrate the parameters oxy- gen (respiration), pH (acidification), glucose and lactate (energy metabolism) as well as short-lived reactive species (ROS/RNS) from the perspective of microsensor integration in 2D and 3D cell culture. We discuss different sensor principles and types, along with their limitations, microfabrication technologies and mate- rials. The state-of-the-art of microsensor platforms for cell culture is discussed with respect to sensor per- formance, the number of parameters and timescale of application. That includes the advances from 2D culture to the increasingly important 3D approaches, with specific requirements for organotypic micro- tissues, spheroids and solid matrix cultures. We conclude on the current progress, potential, benefits and limitations of cell culture monitoring systems from monolayer culture to organ-on-chip systems.

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Jia Y, Hanka K, Breunig I, Zawilski K.T., Schunemann P.G., Buse K.
Mid-infrared whispering gallery resonators based on non-oxide nonlinear optical crystals
2018 Laser Resonators, Microresonators, and Beam Control XX, San Francisco, CA, United States Proceedings of SPIE, Band: 10518, Seite: 105180X
KurzfassungHigh-quality whispering gallery resonators (WGRs) made of AgGaSe2 and CdSiP2 bulk crystals are fabricated. With femtosecond laser matching and subsequent fine polishing, the intrinsic Q-factors of these resonators are approaching values of 106 to 107 . By adjusting the coupling condition, maximum coupling efficiencies of 60% and 30% for AgGaSe2 and CdSiP2 resonators could be obtained. In addition, thermal effects on the distortion of the mode spectra of these resonators are also investigated. The results in this work reveal great potentials of WGRs made of non-oxide crystals for mid infrared applications.
Bhat Kashekodi A, Meinert T, Michiels R, Rohrbach A
Miniature scanning light-sheet illumination implemented in a conventional microscope
2018 Biomed Opt Express, Band: 9, Nummer: 9, Seiten: 4263 - 4274

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Fell Andreas, Schön Jonas, Müller Matthias, Wöhrle Nico, Schubert Martin, Glunz Stefan
Modeling Edge Recombination in Silicon Solar Cells
2018 IEEE Journal of Photovoltaics, Seite: 1–7
Kirsch M, Böhm T, Joseph K, Asplund M, Hofmann UG, Thiele S, Stieglitz T, Haas CA
Molecular and structural characterization of probe-tissue interactions in the rat brain.
2018 Gordon Research Conference on Neuroelectronic Interfaces, 25.-30.03.2018, Galveston, TX, USA
B Weber, T Suhina, T Junge, L Pastewka, F Brouwer, D Bonn
Molecular probes reveal deviations from Amontons’ law in multi-asperity frictional contacts
2018 Nat Commun, Band: 9, Seite: 888
KurzfassungAmontons’ law defines the friction coefficient as the ratio between friction force and normal force, and assumes that both these forces depend linearly on the real contact area between the two sliding surfaces. However, experimental testing of frictional contact models has proven difficult, because few in situ experiments are able to resolve this real contact area. Here, we present a contact detection method with molecular-level sensitivity. We find that while the friction force is proportional to the real contact area, the real contact area does not increase linearly with normal force. Contact simulations show that this is due to both elastic interactions between asperities on the surface and contact plasticity of the asperities. We reproduce the contact area and fine details of the measured contact geometry by including plastic hardening into the simulations. These new insights will pave the way for a quantitative microscopic understanding of contact mechanics and tribology.
Fischer, Kai, Hiermaier, Stefan, Riedel, Werner, Haering, Ivo
Morphology dependent assessment of resilience for urban areas
2018 Sustainability, Band: 10, Seiten: 1 - 14
KurzfassungThe formation of new threats and the increasing complexity of urban built infrastructures underline the need for more robust and sustainable systems, which are able to cope with adverse events. Achieving sustainability requires the strengthening of resilience. Currently, a comprehensive approach for the quantification of resilience of urban infrastructure is missing. Within this paper, a new generalized mathematical framework is presented. A clear definition of terms and their interaction builds the basis of this resilience assessment scheme. Classical risk-based as well as additional components are aligned along the timeline before, during and after disruptive events, to quantify the susceptibility, the vulnerability and the response and recovery behavior of complex systems for multiple threat scenarios. The approach allows the evaluation of complete urban surroundings and enables a quantitative comparison with other development plans or cities. A comprehensive resilience framework should cover at least preparation, prevention, protection, response and recovery. The presented approach determines respective indicators and provides decision support, which enhancement measures are more effective. Hence, the framework quantifies for instance, if it is better to avoid a hazardous event or to tolerate an event with an increased robustness. An application example is given to assess different urban forms, i.e., morphologies, with consideration of multiple adverse events, like terrorist attacks or earthquakes, and multiple buildings. Each urban object includes a certain number of attributes, like the object use, the construction type, the time-dependent number of persons and the value, to derive different performance targets. The assessment results in the identification of weak spots with respect to single resilience indicators. Based on the generalized mathematical formulation and suitable combination of indicators, this approach can quantify the resilience of urban morphologies, independent of possible single threat types and threat locations.
Pasluosta C, Hannink J, Gassner H, Von Tscharner V, Winkler J, Klucken J, Eskofier BM
Motor output complexity in Parkinson's disease during quiet standing and walking: Analysis of short-term correlations using the entropic half-life.
2018 Hum Movement Sci, Band: 58, Seiten: 185 - 194
KurzfassungParkinson's disease (PD) is associated with alterations in motor outputs such as center of pressure (CoP) adjustments during quiet standing and foot kinematics during walking. Previous research suggests that the complexity of motor outputs reflects the number of control processes stabilizing a specific movement, providing a measure that is linked to the neurological control of the movement. The Entropic Half Life (EnHL) represents a new method for assessing motor output complexity. We hypothesized that there will be a lack of neuromuscular control pathways for PD patients, resulting in a decrease in motor output complexity. We computed the EnHL of CoP adjustments during quiet standing and foot kinematics during walking of 70 PD patients and 33 age-matched controls. Patients with PD showed longer EnHL values compared to controls, suggesting a tighter motor control. Excluding vision led to a decrease of EnHL of CoP in both groups. EnHL was correlated with spatio-temporal gait parameters. We compared EnHL with the pull test and the timed up-and-go test. No significant differences were present in the pull test, yet motor output complexity was correlated with the timed up-and-go test. The results suggest a reduced complexity in motor outputs of PD patients affecting distinct motor functions.
Kubon M, Hartmann H, Moschallski M, Burkhardt C, Link G, Werner S, Lavalle P, Urban G, Vrana N E, Stelzle M
Multimodal Chemosensor‐Based, Real‐Time Biomaterial/Cell Interface Monitoring
2018 Advanced Biosystems, Seite: 1700236
KurzfassungReal‐time monitoring of the cell/biomaterial interface for biomedical applications can significantly improve the assessment of biomaterials. However, currently there are no multiparametric real‐time monitoring systems for the ex vivo assessment of biomaterials. This study presents a method for monitoring of cell and tissue response to biomaterials based on microsensor read‐outs of pH, O2, and impedance. In vitro, the sensors are compatible with cells implants. For ex vivo measurements, either a biodegradable polymer poly(lactic‐co‐glycolic acid) or a protein‐repellent plasma polymer nanofilm is coated onto sensor arrays and placed on the chorioallantoic membrane of avian embryo ex ovo cultures. Signals related to dissolved oxygen, pH, and electrical impedance are continuously acquired for up to 90 h. Optical observation, immunohistochemical examination of CD45, and Haematoxylin and Eosin (H&E) staining show different unspecific immune responses. Tissue inflammation, capsule formation, and neovascularization are observed. These results correlate well with the type of coating material and the signal patterns acquired by the chemosensors. In addition, tissue death can be inferred from sensor signal patterns. This system is intended to enable continuous monitoring of biomaterials and is envisioned as a prescreening tool to provide real‐time monitoring of cell/biomaterial interface and also to reduce animal testing for biomaterial assessment purposes.
Rognini G, Petrini FM, Raspopovic S, Valle G, Granata G, Strauss I, Solca M, Bello-Ruiz J, Herbelin B, Mange R, D'Anna E, Di Iorio R, Di Pino G, Andreu D, Guiraud D, Stieglitz T, Rossini PM, Serino A, Micera S, Blanke O
Multisensory bionic limb to achieve prosthesis embodiment and reduce distorted phantom limb perceptions.
2018 J Neurol Neurosur Ps
Boehler C, Asplund M
Nanostructured Pt as a high performance coating for neural interfaces
2018 Micro Alliance Workshop 2018, October 4-5, 2018, Freiburg, Germany
Boehler C, Asplund M
Nanostructured platinum as a high performance coating for neural interfaces with excellent stability and biocompatibility.
2018 International Conference on Advanced Neurotechnologies (ICAN), May 6-8, 2018, Ann Arbor, MI, USA
M. Breitwieser, S. Vierrath
Neue Kompositmembranen und Mikrocharakterisierung: Die Gruppe „Elektrochemische Energiesysteme“ an IMTEK und Hahn-Schickard
2018 Brennstoffzellenallianz Duisburg, 26. - 27. Juni 2018
J. Schemberg, M. Specht, M. Karle
Neue Wege in der Krebsdiagnostik - Mikrofluidische Strategien für die Medizin 4.0
2018 GIT-Laborfachzeitschrift, Band: 4, Seite: 16
Eggensperger K, Lindauer M, Hutter F
Neural Networks for Predicting Algorithm Runtime Distributions
2018 Proceedings of the International Joint Conference on Artificial Intelligence (IJCAI’18), Seiten: 1442 - 1448
Gkogkidis CA, Bentler C, Wang X, Gierthmuehlen M, Scheiwe C, Schmitz HC, Haberstroh J, Stieglitz T Ball T
Neurophysiological Evaluation of a Customizable μECoG-based Wireless Brain Implant.
2018 2018 40th AnInternational Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) , 18.-21.07.2018, Oahu, HI, USA IEEE, Seiten: 2953 - 2956
KurzfassungThe number of implantable bidirectional neural interfaces available for neuroscientific research applications is still limited, despite the rapidly increasing number of customized components. We previously reported on how to translate available components into ”ready-to-use” wireless implantable systems utilizing components off-the-shelf (COTS). The aim of the present study was to verify the viability of a micro-electrocorticographic (μECoG) device built by this approach. Functionality for both neural recording and stimulation was evaluated in an ovine animal model using acoustic stimuli and cortical electrical stimulation, respectively. We show that auditory evoked responses were reliably recorded in both time and frequency domain and present data that demonstrates the cortical electrical stimulation functionality. The successful recording of neuronal activity suggests that the device can compete with existing implantable systems as a neurotechnological research tool.
Unmüssig T, Daubinger P, Weltin A, Urban S, Urban G, Kieninger J
Non-enzymatic glucose sensing based on hierarchical platinum micro-/nanostructures
2018 J Electroanal Chem, Band: 816, Seiten: 215 - 222
KurzfassungNon-enzymatic glucose monitoring for biomedical applications asks for long-term stable and selective sensors at neutral pH. A hierarchical platinum micro-/nanostructured electrode along with a novel measurement scheme leads to increased sensitivity, selectivity and stability compared to state-of-the-art. The hierarchical electrode coating was applied by a scalable two-step process, which combined electrochemical deposition and colloidal synthesis to obtain a hierarchical structure with high surface roughness. This three-dimensional structure consists of a cauliflower-like platinum deposition, which is coated by a platinum nanowire network. Amperometric glucose measurements showed a 10,000-fold increase in sensitivity (473  μA  cm⁻²  mM⁻¹) compared to unmodified electrodes and linear behavior in the physiological range. The obtained sensitivities are among the highest values reported for non-enzymatic glucose sensors in neutral pH media. The hierarchical morphology provides a selectivity mechanism depending on the reaction kinetics, improving the selectivity for glucose in the presence of the interferent ascorbic acid 2,000-fold. Selectivity was further enhanced by low-frequency electrochemical impedance spectroscopy (EIS). Chronoamperometric protocols were developed to achieve long-term stability and overcome the loss of sensitivity due to electrode poisoning. Using chronoamperometric protocols for both the amperometry and the EIS measurements improved stability significantly. The presented results make hierarchical platinum micro-/nanostructured electrodes a promising candidate for continuous glucose monitoring.
Zanelli A, Horn G, Frison G, Diehl Moritz
Nonlinear Model Predictive Control of a Human-sized Quadrotor
2018 Proceedings of the European Control Conference (ECC)
H Gao, J Amann, X Lyu, S Palzer
Novel Method for Thermal Characterization of MEMS
2018 J Microelectromech S, Band: 99, Seiten: 1 - 8
KurzfassungThe use of thermal modulation techniques provides powerful tools to enhance and influence the selectivity and sensitivity of metal oxide based functional layers in gas sensing applications. However, when using micromachined, low-power consuming, so-called hotplate devices, the determination of the absolute temperature of the sensitive layer still presents a challenge. In this contribution, a novel method based on a phase transition in thermally sensitive materials is applied to determine the absolute temperature with high accuracy. The technique relies on depositing small, well-defined amounts of various materials with high spatial resolution using an inkjet printer and then establishing the relation between the heater's resistivity and the absolute temperature when the phase transition occurs. With this approach, the spatial distribution of the absolute temperature of microelectromechanical systems can be achieved. Due to the flexibility of inkjet printing, the presented method may be applied to a wide range of scenarios.
Meßmer Christoph, Bivour Martin, Schon Jonas, Glunz Stefan, Hermle Martin
Numerical Simulation of Silicon Heterojunction Solar Cells Featuring Metal Oxides as Carrier-Selective Contacts
2018 IEEE Journal of Photovoltaics, Band: 8, Nummer: 2, Seite: 456–464
KurzfassungThe applicability of different high (low) work function contact materials for the formation of alternative passivating and hole (electron) selective contacts is currently re-explored for silicon solar cells. To assist the engineering of those contacts, which is still in its infancy, numerical device simulations are used to improve knowledge regarding relevant heterojunction and thin film properties with the focus on metal oxide based hole contacts. The importance of 1) a high metal oxide work function for the induced c-Si pn-junction is shown. It is elucidated that for an efficient hole transport from this induced c-Si junction into the external electrode, via the buffer and the metal oxide, 2) the metal oxide’s conduction band must be below the valence band of the buffer (or c-Si absorber) for direct band-to-band tunneling, or 3) bulk traps near the valence band edge of the buffer (or c-Si absorber) are needed for trap-assisted tunneling.
T Kling, D Vogler, L Pastewka, F Amann, P Blum
Numerical simulations and validation of contact mechanics in a granodiorite fracture
2018 Rock Mech Rock Eng, Band: 51, Nummer: 9, Seiten: 2805 - 2824
KurzfassungNumerous rock engineering applications require a reliable estimation of fracture permeabilities to predict fluid flow and transport processes. Since measurements of fracture properties at great depth are extremely elaborate, representative fracture geometries typically are obtained from outcrops or core drillings. Thus, physically valid numerical approaches are required to compute the actual fracture geometries under in situ stress conditions. Hence, the objective of this study is the validation of a fast Fourier transform (FFT)-based numerical approach for a circular granodiorite fracture considering stress-dependent normal closure. The numerical approach employs both purely elastic and elastic–plastic contact deformation models, which are based on high-resolution fracture scans and representative mechanical properties, which were measured in laboratory experiments. The numerical approaches are validated by comparing the simulated results with uniaxial laboratory tests. The normal stresses applied in the axial direction of the cylindrical specimen vary between 0.25 and 10 MPa. The simulations indicate the best performance for the elastic–plastic model, which fits well with experimentally derived normal closure data (root-mean-squared error=9 µm). The validity of the elastic–plastic model is emphasized by a more realistic reproduction of aperture distributions, local stresses and contact areas along the fracture. Although there are differences in simulated closure for the elastic and elastic–plastic models, only slight differences in the resulting aperture distributions are observed. In contrast to alternative interpenetration models or analytical models such as the Barton–Bandis models and the “exponential repulsion model”, the numerical simulations reproduce heterogeneous local closure as well as low contact areas (<2%) even at high normal stresses (10 MPa), which coincides with findings of former experimental studies. Additionally, a relative hardness value of 0.14 for granitic rocks, which defines the general resistance to non-elastic deformation of the contacts, is introduced and successfully applied for the elastic–plastic model.
Ayasli R, Wilde J
Nutzung AVT-bezogener Merkmale zur Absicherung elektronischer Bauteile gegen Fälschung
2018 DVS Berichte, Elektronische Baugruppen und Leiterplatten EBL 2018, Band: 340, Seiten: 319 - 323
Tran Dinh, Navarin Nicolò, Sperduti Alessandro
On filter size in graph convolutional networks
2018 2018 IEEE Symposium Series on Computational Intelligence (SSCI), IEEE, Seiten: 1534 - 1541
KurzfassungRecently, many researchers have been focusing on the definition of neural networks for graphs. The basic component for many of these approaches remains the graph convolution idea proposed almost a decade ago. In this paper, we extend this basic component, following an intuition derived from the well-known convolutional filters over multi-dimensional tensors. In particular, we derive a simple, efficient and effective way to introduce a hyper-parameter on graph convolutions that influences the filter size, i.e., its receptive field over the considered graph. We show with experimental results on real-world graph datasets that the proposed graph convolutional filter improves the predictive performance of Deep Graph Convolutional Networks.
de la Oliva N, Mueller M, Stieglitz T, Navarro X, Del Valle J
On the use of Parylene C polymer as substrate for peripheral nerve electrodes.
2018 Sci Rep-uk, Band: 8, Nummer: 1, Seiten: 5965 - 5965
Marzioch J, Kieninger J, Weltin A, Flamm H, Aravindalochanan K, Sandvik J A, Pettersen E O, Peng Q, Urban G
On-Chip Photodynamic Therapy – Monitoring Cell Metabolism by Electrochemical Microsensors
2018 Lab Chip, Band: 18, Seiten: 3353 - 3360
KurzfassungWe introduce a new system which combines metabolic monitoring by electrochemical microsensors with photodynamic therapy on-chip for the first time. Oxygen consumption of T-47D breast cancer cells was measured during therapy with protoporphyrin IX. We determined the efficacy of therapy and revealed recovery effects, which underlines the high relevance of continuous monitoring.
M Jaegle, HF Pernau, M Pfützner, M Benkendorf, X Li, M Bartel, S Drost, J Wöllenstein
On-Chip Temperature Compensation for Thermal Impedance Sensors
2018 Eurosensors 2018, Graz, Austria , Band: 2, Nummer: 13, Seite: 1053
KurzfassungElectrical impedance spectroscopy is a widespread characterization method for solids or fluids in industrial applications. We here report on its thermal equivalent, the “thermal impedance spectroscopy”, improved by using a temperature compensation method for temperature dependent thermal measurements using an on-chip reference resistor.
Grether E, Bruch R, Kutluk H, Moser I, Jobst G, Goymann W, Gahr M, Urban G, Dincer C
On-site hormone monitoring using an electrochemical microfluidic biosensor for lab-on-a-bird applications
2018 MicroTAS 2018, Kaohsiung, Taiwan
KurzfassungIn this work, we introduce a microfluidic electrochemical platform to measure hormone levels of birds on-site. Herein, a low-cost and easy-to-handle biosensor is combined with a single-step competitive enzyme linked immunoassay. It enables to work with very low sample volumes (less than 600 nanoliters) along with a short sample-to-result time (about one hour). The feasibility of the system for future lab-on-a-bird applications is successfully demonstrated by measuring different testosterone concentrations in whole blood samples of zebra finches, reproducibly.
V Sandfort, J Goldschmidt, j Wöllenstein, S Palzer
One quantum sensor for all gases: cavity-enhanced Raman spectroscopy for food-chain monitoring
2018 Quantum Sensing and Nano Electronics and Photonics XV, San Francisco, California, United States , Band: 10540, Seite: 105400Z
KurzfassungThe comprehensive monitoring of the food chain, i.e. from growth to consumer, without gaps is of outstanding importance to consumer health and the food industry alike. Yet, due to the lack of suitable sensing technologies at adequate costs, only selective, critical spots can currently be monitored. While the particular food to be monitored may take any shape or form during processing, gases are always present and their composition is uniquely suited to learn about the state of the system. In this contribution, a universal quantum sensor concept to identify and quantify the components of complex gas matrices is presented. The sensing approach is based on detecting Raman scattered photons from inside a gas sample filled optical cavity. Because of the typically small Raman scattering cross-sections on the order of 10-30 cm2 a Fabry-Perot cavity with a Finesse of about 2,000 is used to enhance the available laser power of an extended cavity diode laser running at 780 nm. The scattered light is funneled onto a spectrometer after Rayleigh scattered photons have been suppressed using a notch filter. To allow in-situ determination of arbitrary gas matrices, the sensor concept relies on the diffusion of ambient air into the cavity. The setup is currently able to simultaneously detect gases with Raman spectra up to 3000 cm-1, which includes important indicators for food packaging, including nitrogen, oxygen, and carbon dioxide.
Hanemann T, Honnef K
Optical and Thermomechanical Properties of Doped Polyfunctional Acrylate Copolymers
2018 Polymers-basel, Band: 10, Nummer: 337, Seiten: 1 - 14
KurzfassungThree different polyfunctional acrylate monomers—trimethylolpropantriacrylate (TMPTA), pentaerythritol triacrylate (PETA) and di(trimethylolpropane) tetraacrylate (DTTA)—have been used as comonomers in combination with a reactive resin consisting of poly(methylmethacrylate), dissolved in its monomer methylmethacrylate. Phenanthrene has been added to form a guest–host system. The level of phenanthrene present may be adjusted to tailor the refractive index in the system. Prior to curing, the shear rate and temperature-dependent viscosity as a function of the composition were measured. It could be demonstrated that, with respect to different shaping methods, a tailor-made flow behaviour can be adjusted. After thermally-induced polymerization, the resulting optical (refractive index, optical transmittance) and thermomechanical (glass transition behavior, Vickers hardness) properties were characterized. A significant refractive index increase—up to a value close to 1.56 (@589 nm)—under the retention of good optical transmittance was able to be obtained. In addition, the photopolymerization behaviour was investigated to overcome the undesirable oxygen inhibition effect during the light-induced radical polymerization of acrylates. The level of acrylate units in the copolymer can compensate for the plasticizing effect of the dopant phenanthrene, enabling higher concentrations of the dopant in the guest–host system and therefore larger refractive index values suitable for polymer waveguide fabrication.

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Tucher Nico, Höhn Oliver, Goldschmidt Jan Christoph, Bläsi Benedikt
Optical modeling of structured silicon-based tandem solar cells and module stacks
2018 Opt Express, Band: 26, Nummer: 18, Seiten: A761 - A768

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De Schutter J, Leuthold R, Diehl M
Optimal Control of a Rigid-Wing Rotary Kite System for Airborne Wind Energy
2018 Proceedings of the European Control Conference (ECC)
Beh H, Hiller D, Zacharias M
Optimization of ALD-ZnO Thin Films Toward Higher Conductivity
2018 Phys Status Solidi A, Band: 1700880
M. Gorostiaga, M.C. Wapler, U. Wallrabe
Optimizing piezoelectric receivers for acoustic power transfer applications.
2018 Smart Material Structures, Band: 27, Nummer: 075024, Seite: 10pp
Rajaeipour P, Banerjee K, Ataman C, Zappe H
Optofluidic adaptive optics
2018 Appl Optics, Band: 57, Nummer: 22, Seiten: 6338 - 6344
Kilias A, Canales A, Froriep UP, Park S, Egert U, Anikeeva P
Optogenetic entrainment of neural oscillations with hybrid fiber probes.
2018 J Neural Eng, Band: 15, Nummer: 5, Seiten: 056006 - 056006
Kermani H, Rohrbach A
Orientation-control of two plasmonically-coupled nanoparticles in an optical trap
2018 Acs Photonics, Band: 5, Nummer: 11, Seiten: 4660 - 4667

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Boehler C, Asplund M
PEDOT as a high charge injection material for low-frequency stimulation.
2018 40th International Conference of the IEEE Engineering in Medicine and Biology Society, 17.-21.07.2018, Oahu, Hawaii, USA IEEE
KurzfassungAlternating current stimulation (ACS) provides a versatile tool for modulating brain activity and presents a promising strategy for the treatment of neurological disorders like Parkinson’s disease or epilepsy. Stimulation of neural tissue at low-frequency however poses new challenges on conventional electrode materials which support limited charge transfer in the desired frequency range, from less than 0.1 Hz to several tens of Hz. In our study we address this challenge by investigating the charge transfer properties of PEDOT/PSS coatings for low-frequency applications, focusing on the impact of the polymer bulk. PEDOT films of various thicknesses were exposed to low-frequency as well as DC stimulation in vitro and compared to Pt and IrOx electrodes as controls. The charge injection performance of the metallic substrates could be substantially improved already by a thin PEDOT coating. Additionally a linear dependency between charge injection and polymer thickness suggests that PEDOT coatings are promising as materials for future ACS applications.
Paxian Tobias, Reimer Sven, Becker Bernd
Pacose: An Iterative SAT-based MaxSAT Solver
2018 MaxSAT Evaluation 2018
Pasluosta C, Kiele P, Stieglitz T
Paradigms for restoration of somatosensory feedback via stimulation of the peripheral nervous system.
2018 Clin Neurophysiol, Band: 129, Nummer: 4, Seiten: 851 - 862
KurzfassungThe somatosensory system contributes substantially to the integration of multiple sensor modalities into perception. Tactile sensations, proprioception and even temperature perception are integrated to perceive embodiment of our limbs. Damage of somatosensory networks can severely affect the execution of daily life activities. Peripheral injuries are optimally corrected via direct interfacing of the peripheral nerves. Recent advances in implantable devices, stimulation paradigms, and biomimetic sensors enabled the restoration of natural sensations after amputation of the limb. The refinement of stimulation patterns to deliver natural feedback that can be interpreted intuitively such to prescind from long-learning sessions is crucial to function restoration. For this review, we collected state-of-the-art knowledge on the evolution of stimulation paradigms from single fiber stimulation to the eliciting of multisensory sensations. Data from the literature are structured into six sections: (a) physiology of the somatosensory system; (b) stimulation of single fibers; (c) restoral of multisensory percepts; (d) closure of the control loop in hand prostheses; (e) sensory restoration and the sense of embodiment, and (f) methodologies to assess stimulation outcomes. Full functional recovery demands further research on multisensory integration and brain plasticity, which will bring new paradigms for intuitive sensory feedback in the next generation of limb prostheses.
Vomero M, Zuchini E, Gueli C, Delfino E, Ashouri D, Carli S, Fadiga L, Stieglitz T
Performance Evaluation of Glassy Carbon Electrodes for Neural Applications Based on Different Diameters.
2018 Gordon Research Conference on Neuroelectronic Interfaces, 25.-30.03.2018, Galveston, TX, USA
Granata G, Di Iorio R, Romanello R, Iodice F, Raspopovic S, Petrini F, Strauss I, Valle G, Stieglitz T, Cvancara P, Andreu D, Divoux JL, Giraud D, Wauters L, Hiairrassary A, Jensen W, Micera S, Rossini PM
Phantom somatosensory evoked potentials following selective intraneural electrical stimulation in two amputees.
2018 Clin Neurophysiol, Band: 129, Nummer: 6, Seiten: 1117 - 1120
KurzfassungObjective The aim of the paper is to objectively demonstrate that amputees implanted with intraneural interfaces are truly able to feel a sensation in the phantom hand by recording “phantom” somatosensory evoked potentials from the corresponding brain areas. Methods We implanted four transverse intrafascicular multichannel electrodes, available with percutaneous connections to a multichannel electrical stimulator, in the median and ulnar nerves of two left trans-radial amputees. Two channels of the implants that were able to elicit sensations during intraneural nerve stimulation were chosen, in both patients, for recording somatosensory evoked potentials. Results We recorded reproducible evoked responses by stimulating the median and the ulnar nerves in both cases. Latencies were in accordance with the arrival of somatosensory information to the primary somatosensory cortex. Conclusion Our results provide evidence that sensations generated by intraneural stimulation are truly perceived by amputees and located in the phantom hand. Moreover, our results strongly suggest that sensations perceived in different parts of the phantom hand result in different evoked responses. Significance Somatosensory evoked potentials obtained by selective intraneural electrical stimulation in amputee patients are a useful tool to provide an objective demonstration of somatosensory feedback in new generation bidirectional prostheses.
S Knobelspies, B Bierer, A Daus, A Takabayashi, GA Salvatore, G Cantarella,, AO Perez, J Wöllenstein, S Palzer, G Tröster
Photo-Induced Room-Temperature Gas Sensing with a-IGZO Based Thin-Film Transistors Fabricated on Flexible Plastic Foil
2018 Sensors-basel, Band: 18, Nummer: 2, Seite: 358
KurzfassungWe present a gas sensitive thin-film transistor (TFT) based on an amorphous Indium–Gallium–Zinc–Oxide (a-IGZO) semiconductor as the sensing layer, which is fabricated on a free-standing flexible polyimide foil. The photo-induced sensor response to NO2 gas at room temperature and the cross-sensitivity to humidity are investigated. We combine the advantages of a transistor based sensor with flexible electronics technology to demonstrate the first flexible a-IGZO based gas sensitive TFT. Since flexible plastic substrates prohibit the use of high operating temperatures, the charge generation is promoted with the help of UV-light absorption, which ultimately triggers the reversible chemical reaction with the trace gas. Furthermore, the device fabrication process flow can be directly implemented in standard TFT technology, allowing for the parallel integration of the sensor and analog or logical circuits.
M El-Safoury, C Weber, K Schmitt, HF Pernau, B Willing, J Woellenstein
Photoacoustic gas detector for the monitoring of sulfur dioxide content in ship emissions
2018 Sensoren und Messsysteme - 19. ITG/GMA-Fachtagung, Nürnberg, Deutschland
KurzfassungShip emissions heavily pollute marine ecosystems and are extremely detrimental to the health of humans in harbour areas. From 2020 on, the International Maritime Organization (IMO) is imposing tighter limits on global sulphur emissions. Although shipping companies can continue using heavy fuel oils, they are then obligated by international maritime law to install gas scrubbers for the purification of the exhaust gas. In addition, special exhaust gas measuring technology must be installed subsequent to the gas scrubber to detect the actually emitted SO2. We present the development of a low-cost, resonant photoacoustic (PA) gas detector for the monitoring of SO2 in marine vessels. A UV LED at 285 nm is used as light source in combination with a microphone as acoustic detector. In first experiments, we used acetone gas as a substitution for the harmful SO2 for sensor characterization. The results of the experiments show that SO2 concentrations between 0 and 111 ppm should be detectable with 2 ppm accuracy.
Beh H, Hiller D, Salava J, Trojánek F, Zacharias M, Malý P, Valenta J
Photoluminescence Dynamics and Quantum Yield of Intrinsically Conductive ZnO from Atomic Layer Deposition
2018 J Lumin, Band: 201, Nummer: 85
Bläsi Benedikt, Höhn Oliver, Hauser Hubert, Cariou Romain, Benick Jan, Feldmann Frank, Beutel Paul, Lackner David, Hermle Martin, Siefer Gerald, Glunz Stefan, Bett Andreas, Dimroth Frank, Tucher Nico, Wehrspohn Ralf, Sprafke Alexander
Photonic structures for III-V//Si multijunction solar cells with efficiency >33%
In: Photonics for Solar Energy Systems VII
2018, SPIE, Seite: 2, SPIE, ISBN: 9781510619029
KurzfassungSilicon based multi-junction solar cells are a promising option to overcome the theoretical efficiency limit of a silicon solar cell (29.4%). With III-V semiconductors, high bandgap materials applicable for top cells are available. For the application of such silicon based multi-junction devices, a full integration of all solar cell layers in one 2-terminal device is of great advantage. We realized a triple-junction device by wafer-bonding two III-V-based top cells onto the silicon bottom cell. However, in such a series connected solar cell system, the currents of all sub-cells need to be matched in order to achieve highest efficiencies. To fulfil the current matching condition and maximise the power output, photonic structures were investigated. The reference system without photonic structures, a triple-junction cell with identical GaInP/GaAs top cells, suffered from a current limitation by the weakly absorbing indirect semiconductor silicon bottom cell. Therefore rear side diffraction gratings manufactured by nanoimprint lithography were implemented to trap the infrared light and boost the solar cell current by more than 1 mA/cm2. Since planar passivated surfaces with an additional photonic structure (i.e. electrically planar but optically structured) were used, the optical gain could be realized without deterioration of the electrical cell properties, leading to a strong efficiency increase of 1.9% absolute. With this technology, an efficiency of 33.3% could be achieved.
F. Lemke, P.M. Weber, U. Wallrabe, M.C. Wapler
Piezo actuated adaptive prisms for optical scanning
2018 ISOT 2018, Int. Symposium of Optomechatronics Technology, Cancún.Mexico, 2018 Springer Proceedings in Physics, Band: 233, Seiten: 85 - 91
Zappe H
Polymer optics for tunable and printable optical systems (Invited talk)
2018 Advanced Fabrication Technologies for Micro/Nano Optics and Photonics XI at SPIE Photonics West, San Francisco, CA, USA
M. Buehler, F. Hegge, P. Holzapfel, S. Thiele
Porous Transport Electrodes – The Influence of Depositing Electrodes on Porous Transport Layers on the Polarization Behaviour of PEM Water Electrolyzers
2018 69th Annual Meeting of the International Society of Electrochemistry (ISE), Bologna/Italy, 02. – 07.09. 2018
Kurzfassung69th Annual Meeting of the International Society of Electrochemistry (ISE), Bologna/Italy, 02. – 07.09. 2018
Janz P, Hauser P, Heining K, Nestel S, Kirsch M, Egert U, Haas CA
Position- and Time-Dependent Arc Expression Links Neuronal Activity to Synaptic Plasticity During Epileptogenesis.
2018 Front Cell Neurosci, Band: 12, Seiten: 244 - 244
Feißt M, Schätzle P, Wilde J
Power Chip Interconnections Based on TLP and Sintering of CTE- Matched Conductors
2018 10th International Conference on Integrated Power Electronics Systems (CIPS), Stuttgart, Seiten: 331 - 336
Schiffmacher A, Litzenberger L, Wilde J, Polezhaev V, Huesgen T
Power Electronic Assemblies on Printed Wiring Boards Mounted by Silver Sintering
2018 7th Electronics System-Integration Technology Conference (ESTC), Dresden
M. Frei, J. Martin, S. Kindler, G. Cristiano, R. Zengerle, S. Kerzenmacher
Power supply for electronic contact lenses: Abiotic glucose fuel cells vs. Mg/air batteries
2018 J Power Sources, Band: 401, Seiten: 403 - 414
KurzfassungElectronic contact lenses are a promising platform for medical sensors. With these devices a variety of vital signs and medical parameters can be monitored noninvasively and without the risk of foreign body response. However, one current limitation of this technology is the need for an external power supply, resulting in bulky, multi component devices. In this paper, we for the first time investigate and compare the application of abiotic glucose fuel cells and Mg/air batteries as alternative power supply technologies for electronic contact lenses. While abiotic glucose fuel cells harvest energy from metabolites present in tear fluid, Mg/air batteries provide electricity by the oxidation of a sacrificial anode. Considering the space available on standard contact lenses, our results indicate that approx. 40 μW and 2 μW can be generated by Mg/air batteries and glucose fuel cells for a period of at least 24 h, respectively. However, coating galvanic cells with the commonly used contact lens material pHEMA, results in drastically reduced performance, presumably due to hindered mass transport. Nevertheless, even under those circumstances a Mg/air battery can still provide about 7 μW for 24 h, which would already be sufficient for many electronic contact lens applications.
Feurer M, Eggensperger K, Falkner S, Lindauer M, Hutter F
Practical Automated Machine Learning for the AutoML Challenge 2018
2018 ICML 2018 AutoML Workshop
Kluge F, Hannink J, Pasluosta C, Klucken J, Gassner H, Gelse K, Eskofier BM, Krinner S
Pre-operative sensor-based gait parameters predict functional outcome after total knee arthroplasty.
2018 Gait Posture, Band: 66, Seiten: 194 - 200
KurzfassungBackground Despite the general success of total knee arthroplasty (TKA) regarding patient-reported outcome measures, studies investigating gait function have shown diverse functional outcomes. Mobile sensor-based systems have recently been employed for accurate clinical gait assessments, as they allow a better integration of gait analysis into clinical routines as compared to laboratory based systems. Research question In this study, we sought to examine whether an accurate assessment of gait function of knee osteoarthritis patients with respect to surgery outcome evaluation after TKA using a mobile sensor-based gait analysis system is possible. Methods A foot-worn sensor-based system was used to assess spatio-temporal gait parameters of 24 knee osteoarthritis patients one day before and one year after TKA, and in comparison to matched control participants. Patients were clustered into positive and negative responder groups using a heuristic approach regarding improvements in gait function. Machine learning was used to predict surgery outcome based on pre-operative gait parameters. Results Gait function differed significantly between controls and patients. Patient-reported outcome measures improved significantly after surgery, but no significant global gait parameter difference was observed between pre- and post-operative status. However, the responder groups could be correctly predicted with an accuracy of up to 89% using pre-operative gait parameters. Patients exhibiting high pre-operative gait function were more likely to experience a functional decrease after surgery. Important gait parameters for the discrimination were stride time and stride length. Significance The early identification of post-surgical functional outcomes of patients is of great importance to better inform patients pre-operatively regarding surgery success and to improve post-surgical management.
F. Lemke, M. Stürmer, U. Wallrabe, M.C. Wapler
Pre-stressed Piezo Bending-buckling Actuators for Adaptive Lenses
2018 ACTUATOR 2018, 16th Int. Conference on New Actuators, Bremen, Germany , Seiten: 450 - 453
F. Lemke, Y. Frey, U. Wallrabe, M.C. Wapler
Pre-stressed piezo bending-buckling actuators for adaptive lenses
2018 ACTUATOR 2018, 16th Int. Conference on New Actuators, Bremen, 2018 , Seiten: 450 - 453
Ranjit Jhala, Andreas Podelski, Andrey Rybalchenko
Predicate Abstraction for Program Verification
In: Handbook of Model Checking 2018
2018, Springer,
Hofmann F, Schäfer M, Brown T, Hörsch J, Schramm S, Greiner M
Principal Flow Patterns across renewable electricity networks
Epl-europhys Lett, Band: 124, Seite: 18005, 2018
M. Frei, C. Köhler, L. Dietel, J. Martin, F. Wiedenmann, R. Zengerle, S. Kerzenmacher
Pulsed electro-deposition of highly porous Pt-alloys for the use in methanol, formic acid, and glucose fuel cells
2018 Chemelectrochem, Seiten: 1013 - 1023
KurzfassungWe demonstrate an electro-deposition process for the fabrication of highly porous PtCu-alloy anodes. In the fabrication process, Pt and different amounts of a second noble metal (Pd, Ru, Au) are repeatedly co-deposited with Cu from an aqueous electrolyte, followed by selective dealloying of Cu. This way, highly porous PtCu alloys with roughness factors ranging from 400 to 4000 can be obtained. In all cases both noble metal partners are present on the electrode surface, whereas the majority of copper is likely buried underneath. In addition, we can show that H-desorption and COstripping yield substantially different roughness factors, even when applied to PtCu anodes. Hence, when using or comparing results from different stripping methods a calibration is required. Compared to PtCu anodes, small additions of Ru (~3 at% Ru) lead to significantly enhanced catalytic activity for the electro-oxidation of formic acid and methanol, whereas Au-rich PtCu-Au alloys (~75 at% Au) exhibit significantly improved electro-catalytic activity for glucose oxidation. In some cases, large variations impede the identification of significant differences in electro-catalytic activity. To reduce process variability and to increase the specific surface area further optimization of the fabrication process is required. Similarly, the deposition of defined alloy compositions will require further investigation since the composition of electrolyte and deposited alloy do not directly correspond.
Jia Y, Winkler M, Cheng C, Chen F, Kirste L, Cimalla V, Zukauskaite A, Szabados J, Breunig I, Buse K
Pulsed laser deposition of ferroelectric potassium tantalate-niobate optical waveguiding thin films
2018 Opt Mater Express, Band: 8, Nummer: 3, Seiten: 541 - 548
KurzfassungWe present the epitaxial growth of ferroelectric potassium tantalate-niobate (KTN) thin films by pulsed laser deposition. As a result of the optimization of the deposition and the surface finishing processes, a c-axis oriented KTa₀.₅Nb₀.₅O₃ thin film with homogeneous polarization phase grown on KTaO₃ and an efficient KTa₀.₅Nb₀.₅O₃ waveguiding thin film grown on MgO are demonstrated. The highly improved crystalline and optical quality of KTN layers grown in this work reveal the great potential of such films for integrated nonlinear optics.
M. Abdo, E. Förster, P. Bohnert, V. Badilita, R. Brunner, U. Wallrabe, J.G. Korvink
Pushbroom hyperspectral imaging: from passive to active systems components
2018 Rev Sci Instrum, Band: 89, Nummer: 8, Ergänzungsband: 083113, Seite: 11pp
Rauer Michael, Schmiga Christian, Glatthaar Markus, Glunz Stefan
Quantitative theoretical and experimental analysis of alloying from screen-printed aluminum pastes on silicon surfaces
2018 Solar Energy Materials and Solar Cells, Band: 176, Seite: 295–301
KurzfassungIn this study, we present detailed theoretical and experimental investigations on full-area alloying from screenprinted aluminum pastes on silicon surfaces for solar cell applications. We introduce a simple analytical model for the description of the alloying process derived from existing models for evaporated Al layers, which we adapt to printed Al pastes. Thereby, we particularly account for the recrystallization of Si within the paste particles, which we refer to as parasitic Si recrystallization. Applying our model, we demonstrate good accordance of calculated with measured eutectic layer thicknesses. We show that the model can be versatilely used to investigate screen-printed Al-alloyed contacts in detail: We demonstrate that the latent heat of the Al paste significantly influences the alloying process. Thus, the effective peak temperature of the alloying process can be several 100 °C below the set peak temperature of the firing furnace. By combining calculations of the effective peak temperature with measurements of the Al doping concentration, we determine a parameterization of the solid solubility of Al in Si down to the eutectic temperature of 577 °C. Our investigations therefore provide improved understanding of alloying from printed Al pastes and enable the specific optimization of Al-alloyed contacts.
Wolf R, Jia Y, Bonaus S, Werner C, Herr S, Breunig I, Buse K, Zappe H
Quasi-phase-matched nonlinear optical frequency conversion in on-chip whispering galleries
2018 Optica, Band: 5, Seite: 872
KurzfassungChip-integrated whispering-gallery resonators (WGRs) enable compact and wavelength-agile nonlinear optical frequency synthesizers. So far, the most flexible phase-matching technique, i.e., quasi-phase matching, has not been applied in this configuration. The reason is the lack of suitable thin films with alternating crystal structure on a low-refractive-index substrate. Here, we demonstrate an innovative method of realizing thin film substrates suitable for quasi-phase matching by field-assisted domain engineering of lithium niobate, and subsequent direct bonding and polishing. We are able to fabricate high- on-chip WGRs with these substrates by using standard semiconductor manufacturing techniques. The -factors of the resonators are up to one million, which allows us to demonstrate quasi-phase-matched second-harmonic generation in on-chip WGRs for the first time, to the best of our knowledge. The normalized conversion efficiency is 9×10−4 mW−1. This method can also be transferred to other material systems.
Herr S, Werner C, Buse K, Breunig I
Quasi-phase-matched self-pumped optical parametric oscillation in a micro-resonator
2018 Opt Express, Band: 26, Nummer: 8, Seiten: 10813 - 10819
KurzfassungLasing and self-pumped optical parametric oscillation (self-OPO) are achieved in a high-Q whispering-gallery-mode micro-resonator, made of neodymium-doped lithium niobate. A laser process providing 5 mW output power at 1.08 μm wavelength is sufficient to pump a self-OPO process within the same high-Q cavity. At 6 mW lasing output power, the sum of signal and idler output powers exceeds 1.2 mW. The wavelength of the generated light ranges from 1.5 to 3.8 μm. Phase matching is provided by a radial quasi-phase-matching structure, which is generated by a current-controlled calligraphic poling technique. To the best of our knowledge, this is the first demonstration of a quasi-phase-matched self-pumped nonlinear optical process in a micro-resonator, as well as the first self-OPO in a micro-resonator. The concept bears the potential for a highly integrated and wavelength-tunable coherent light source at low cost.
J. Schmitt, A. Meier, U. Wallrabe, F. Völklein
RIE (CF4/Ar) and IBE etching of various glasses for diffractive optical element fabrication.
2018 Int J Appl Glass Sci, Band: 9, Nummer: 4, Seiten: 499 - 509
Podelski, Andreas, Bogomolov, Sergiy, Forets, Marcelo, Frehse, Goran, Viry, Frédéric, Schilling, Christian
Reach set approximation through decomposition with low- dimentional sets and high-dimentional matrices
In: HSSC 2018
2018, ACM,
B Bierer, H-J Nägele, A Ortiz Perez, J Wöllenstein, Ph Kress, A Lemmer, S Palzer
Real‐Time Gas Quality Data for On‐Demand Production of Biogas
2018 Chemical Engineering Technology, Band: 41, Nummer: 4, Seiten: 696 - 701
KurzfassungThe flexible production of biogas makes it a promising candidate to become the first renewable, on‐demand energy source. One appealing possibility to achieve an on‐demand supply of methane is to adjust the output of the biogas plant itself. As a consequence, the biological process will be partially overloaded and might fail. Hence, a prerequisite to avoid cost‐intensive failure is a fast, reliable, and cost‐efficient analytical technology for quickly determining the biogas quality. A low‐cost, robust, in‐situ online measurement system for the real‐time determination of carbon dioxide and methane concentrations is presented. The approach makes use of photoacoustic detectors, allowing for the development of gas sensors with reduced size that do not show cross‐sensitivities towards water vapor. The system's readings may be used as input for a novel type of control system that enables an active, demand‐driven control of actuators, such as feeding machinery or mixers.
B Bierer, HJ Nägele, AO Perez, J Wöllenstein, P Kress, A Lemmer, S Palzer
Real‐Time Gas Quality Data for On‐Demand Production of Biogas
2018 Chem Eng Technol, Band: 41, Nummer: 4, Seiten: 696 - 701
KurzfassungThe flexible production of biogas makes it a promising candidate to become the first renewable, on‐demand energy source. One appealing possibility to achieve an on‐demand supply of methane is to adjust the output of the biogas plant itself. As a consequence, the biological process will be partially overloaded and might fail. Hence, a prerequisite to avoid cost‐intensive failure is a fast, reliable, and cost‐efficient analytical technology for quickly determining the biogas quality. A low‐cost, robust, in‐situ online measurement system for the real‐time determination of carbon dioxide and methane concentrations is presented. The approach makes use of photoacoustic detectors, allowing for the development of gas sensors with reduced size that do not show cross‐sensitivities towards water vapor. The system's readings may be used as input for a novel type of control system that enables an active, demand‐driven control of actuators, such as feeding machinery or mixers.
Meßmer Christoph, Bivour Martin, Schön Jonas, Hermle Martin
Requirements for efficient hole extraction in transition metal oxide-based silicon heterojunction solar cells
2018 J Appl Phys, Nummer: 124, Seiten: 085702-1 - 085702-8

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C Weber, J Kapp, K Schmitt, HF Pernau, J Wöllenstein
Resonant Photoacoustic Detection of NO2 with an LED Based Sensor
2018 Eurosensors 2018, Graz, Austria , Band: 2, Nummer: 13, Seite: 1036
KurzfassungIn times of steadily increasing air pollution especially in urban areas, the monitoring of nitrogen dioxide (NO 2) has gained in importance and with it the search for compact, low-cost sensors. We present a novel approach to measure NO 2 in sub-ppm concentrations with a photoacoustic sensor utilizing a T-shaped resonance cell. An inexpensive single LED with a peak wavelength of 410 nm was used as radiation source and the acoustic detection was done with a commercial MEMS microphone. For optimal coupling of the divergent LED light into the cell, the T-shaped resonator was developed and fabricated with rapid prototyping methods. The resonator shows a acoustic Q-factor> 10 while having nearly no zero gas signal.
M El-Safoury, M Dufner, C Weber, K Schmitt, HF Pernau, B Willing, J Wöllenstein
Resonant Photoacoustic Gas Monitoring of Combustion Emissions
2018 Eurosensors 2018, Graz, Austria , Band: 2, Nummer: 13, Seite: 962
KurzfassungSince the entrance into the industrial era and the increasing demand for energy due to global economic growth and development, the amount of energy-related emissions have continuously grown every year to significantly high levels. Greenhouse gases like carbon dioxide, nitrous oxide or methane cause an increase in the earth’s temperature. Toxic gases like nitrous oxides, Sulphur dioxide and carbon monoxide are extremely detrimental to the health of all living beings. Over the past few years, global organizations are imposing tighter limits by international laws for flue-gas emissions from fossil-fuel combustion. Emission-limiting techniques like filter and scrubber systems have to be installed for waste gas treatment in the exhaust gas streams. In addition, exhaust gas measuring technologies detect the actual emission values of the respective target gases. We present the development of a low-cost and highly sensitive photoacoustic gas detector for the monitoring of emitted combustion gases. First tests were carried out with the toxic Sulphur dioxide (SO 2) in secure lab conditions, where a sensitivity below 1 part per million (ppm) was achieved during continuous flow of the gas.
Feurer Matthias, Letham Benjamin, Bakshy Eytan
Scalable Meta-Learning for Bayesian Optimization using Ranking-Weighted Gaussian Process Ensembles
2018 ICML 2018 AutoML Workshop
Wolf R, Breunig I, Zappe H, Buse K
Scattering-loss reduction of ridge waveguides by sidewall polishing
2018 Opt Express, Band: 26, Seite: 19815
KurzfassungRidge waveguides provide a large refractive index contrast and thus strong mode confinement, making them highly attractive for building compact photonic integrated circuits. However, ridge waveguides suffer from scattering losses. We demonstrate scattering-loss reduction of ridge waveguides made of lithium-niobate-on-insulator (LNOI) substrates by more than one order of magnitude. This is achieved by gently polishing of the ridge’s sidewalls and simultaneous protection of the top surfaces by a metal layer. Whispering-gallery-resonator loss measurements reveal ultra-low losses down to 0.04 dB/cm of the processed waveguides. Our approach pushes ridge waveguides further towards their fundamental absorption-loss limit, enabling highly efficient integrated devices.
Wilmers J, Leicht J, Stoecklin S, Reindl L, Manoli Y
Schaltung fuer die wirkungsgradoptimierte drahtlose Energieversorgung von biomedizinischen Implantaten
2018 Kleinheubacher Tagung
Kieninger J, Tamari Y, Enderle B, Jobst G, Sandvik JA, Pettersen EO, Urban G
Sensor Access to the Cellular Microenvironment Using the Sensing Cell Culture Flask
2018 Biosensors, Band: 8, Nummer: 2, Seite: 44
KurzfassungThe Sensing Cell Culture Flask (SCCF) is a cell culture monitoring system accessing the cellular microenvironment in 2D cell culture using electrochemical microsensors. The system is based on microfabricated sensor chips embedded in standard cell culture flasks. Ideally, the sensor chips could be equipped with any electrochemical sensor. Its transparency allows optical inspection of the cells during measurement. The surface of the sensor chip is in-plane with the flask surface allowing undisturbed cell growth on the sensor chip. A custom developed rack system allows easy usage of multiple flasks in parallel within an incubator. The presented data demonstrates the application of the SCCF with brain tumor (T98G) and breast cancer (T-47D) cells. Amperometric oxygen sensors were used to monitor cellular respiration with different incubation conditions. Cellular acidification was accessed with potentiometric pH sensors using electrodeposited iridium oxide films. The system itself provides the foundation for electrochemical monitoring systems in 3D cell culture.

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S. Klöppel,, M. Kotschi,, J. Peter,, K. Egger,, L. Hausner,, L. Frölich,, A. Förster,, B.Heimbach,, C. Normann,, W. Vach,, H. Urbach,, Ahmed Abdulkadir
Separating Symptomatic Alzheimers Disease from Depression based on Structural MRI
2018 J Alzheimers Dis, Band: 63, Nummer: 1
G Moras, A Klemenz, T Reichenbach, A Gola, H Uetsuka, M Moseler, L Pastewka
Shear melting of silicon and diamond and the disappearance of the polyamorphic transition under shear
2018 Phys Rev Mater, Band: 2, Seite: 083601
KurzfassungMolecular dynamics simulations of diamond-cubic silicon and carbon under combined shear and compression show the formation of an amorphous solid with liquidlike structure at room temperature. Consistent with the opposite density changes of the two crystals upon melting, the amorphous material is denser than the crystal in silicon and less dense than the crystal in carbon. As a result, its rate of formation is enhanced by pressure in silicon but suppressed in carbon. These results are particularly unexpected for silicon, whose amorphous structure is supposed to be liquidlike only when hydrostatically compressed above the polyamorphic transition pressure (∼14 GPa). Below this pressure, amorphous silicon is expected to have a low-density structure with density close to that of the diamond-cubic crystal. Our simulations show that this polyamorphic transition disappears under shear and high-density, liquidlike amorphous silicon with metallic ductility forms even at low pressure. These results are potentially transferable to other diamond-cubic crystals, like germanium and ice Ih, and provide insights into nonequilibrium materials transformations that govern friction and wear in tribological systems.
Erhardt J, Fuhrer E, Gruschke OG, Leupold J, Wapler MC, Hennig J, Stieglitz T, Korvink JG
Should patients with brain implants undergo MRI?
2018 J Neural Eng
KurzfassungPatients suffering from neuronal degenerative diseases are increasingly being equipped with neural implants to treat symptoms or restore functions and increase their quality of life. Magnetic resonance imaging (MRI) would be the modality of choice for diagnosis and compulsory post-operative monitoring of such patients. However, interactions between the MR environment and implants pose severe health risks to the patient. Nevertheless, neural implant recipients regularly underwent MRI examinations, and adverse events were reported rarely. This should not imply that the procedures are safe. More than 300.000 cochlear implant recipients are excluded from MRI unless the indication outweighs excruciating pain. For 75.000 DBS recipients quite the opposite holds: MRI is considered essential part of the implantation procedure and some medical centres deliberately exceed safety regulations which they referred to as crucially impractical. MRI related permanent neurological dysfunctions in DBS recipients have occurred in the past when manufacturer recommendations were exceeded. Within the last decades extensive effort has been invested to identify, characterise, and quantify the occurring interactions. Today we are far from a satisfying solution to achieve a safe and beneficial MR procedure for all implant recipients. To contribute, we intend to raise awareness of a growing concern and want to summon the community to stop absurdities and instead improve the situation for the increasing number of patients. Therefore, we review implant safety in the MRI literature from an engineering point of view, with a focus on cochlear and DBS implants as success stories in clinical practice. We briefly explain fundamental phenomena which can lead to patient harm, and point out breakthroughs and errors made. We end with conclusions and strategies to avoid future implants from being contraindicated to MR examinations. We believe that implant recipients should enter MRI, but before doing so, we should make sure that the procedure is reasonable.
Glunz Stefan, Feldmann Frank
SiO 2 surface passivation layers – a key technology for silicon solar cells
2018 Solar Energy Materials and Solar Cells, Band: 185, Seite: 260–269
KurzfassungHigh-efficiency silicon solar cells strongly rely on an effective reduction of charge carrier recombination at their surfaces, i.e. surface passivation. Today's industrial silicon solar cells often utilize dielectric surface passivation layers such as SiNx and Al2O3. However, a passivation layer well-known from the microelectronic industry, SiO2, had and has a strong impact on silicon photovoltaics. It allowed to develop the first 20% efficient silicon solar cells in the past and currently experiences a renaissance as the interfacial oxide for silicon-based passivating contacts, thus enabling the next generation of silicon solar cells. This article reviews the properties of SiO2 passivation layers and their strong impact on the historical and current development of silicon solar cells.
L. Becherer, M. Bakheit, S. Frischmann, S. Stinco, N. Borst, R. Zengerle, F. von Stetten
Simplified real-time multiplex detection of loop-mediated isothermal amplification (LAMP) using novel mediator displacement probes with universal reporters
2018 Anal Chem, Band: 90, Seiten: 4741 - 4748
KurzfassungA variety of real-time detection techniques for LAMP based on the change in fluorescence intensity during DNA amplification enable simultaneous detection of multiple targets. However these techniques depend on fluorogenic probes containing target-specific sequences. That complicates the adaption to different targets leading to time-consuming assay optimization. Here, we present the first universal real-time detection technique for multiplex LAMP. The novel approach allows simple assay design and is easy to implement for various targets. The innovation features a mediator displacement probe and a universal reporter. During amplification of target DNA the mediator is displaced from the mediator displacement probe. Then it hybridizes to the reporter generating a fluorescence signal. The novel Mediator Displacement (MD) detection was validated against state-of-the-art molecular beacon (MB) detection by means of a HIV-1 RT-LAMP: MD surpassed MB detection by accelerated probe design (MD: 10 min, MB: 3-4 h), shorter times to positive (MD 4.1±0.1 min shorter than MB, n = 36), improved signal to noise fluorescence ratio (MD: 5.9±0.4, MB: 2.7±0.4; n = 15) and showed equally good or better analytical performance parameters. The usability of one universal mediator-reporter set in different multiplex assays was successfully demonstrated for a biplex RT-LAMP of HIV-1 & HTLV-1 and a biplex LAMP of Haemophilus ducreyi & Treponema pallidum, both showing good correlation between target concentration and time to positive. Due to its simple implementation it is suggested to extend the use of the universal mediator-reporter sets to the detection of various other diagnostic panels.
L. Becherer, N. Borst, R. Zengerle, F. von Stetten
Simultaneous detection of HIV and HTLV by mediator displacement loop-mediated isothermal amplification
2018 6th World Congress on Control and Prevention of HIV/AIDS, STDs & STIs, Zürich/Switzerland, 27. – 28.08.2018
Kurzfassung6th World Congress on Control and Prevention of HIV/AIDS, STDs & STIs, Zürich/Switzerland, 27. – 28.08.2018
J. Madjarov, A. Götze, R. Zengerle, S. Kerzenmacher
Simultaneous use of a crossflow filtration membrane as microbial fuel cell anode – permeate flow leads to 4-fold increased current densities
2018 Bioresource Technol, Band: 257, Seiten: 274 - 280
KurzfassungA new concept for the combination of membrane bioreactors and microbial fuel cells is introduced, that aims at the production of electricity for reducing the overall energy consumption of wastewater treatment. In contrast to previous approaches, the anode is integrated as microfiltration membrane in sidestream crossflow configuration. Using a stainless steel filtration membrane with G. sulfurreducens and an acetatebased synthetic medium, up to 4-fold higher current densities are achieved. In a standard setup without filtration, a membrane of filter grade 1 μm shows current densities of 5.8 A m-2 ± 0.5 A m-2 compared to >11 A m-2 when it is used simultaneously as membrane filter. With smaller pore sizes of filter grade 0.5 μm 4.4 A m-2 ± 0.5 A m-2 in a standard setup and >15 A m-2 in a filtration setup are achieved. The permeate flow was identified as the main parameter leading to increased current densities.
Petrini FM, Valle G, Strauss I, Granata G, Di Iorio R, D'Anna E, Cvancara P, Mueller M, Carpaneto J, Clemente F, Controzzi M, Bisoni L, Carboni C, Barbaro M, Iodice F, Andreu D, Hiairrassary A, Divoux JL, Cipriani C, Guiraud D, Raffo L, Fernandez E, Stieglitz T, Raspopovic S, Rossini PM, Micera S
Six-Month Assessment of a Hand Prosthesis with Intraneural Tactile Feedback.
2018 Ann Neurol
KurzfassungObjective Hand amputation is a highly disabling event, which significantly affects quality of life. An effective hand replacement can be achieved if the user, in addition to motor functions, is provided with the sensations that are naturally perceived while grasping and moving. Intraneural peripheral electrodes have shown promising results toward the restoration of the sense of touch. However, the long‐term usability and clinical relevance of intraneural sensory feedback have not yet been clearly demonstrated. Methods To this aim, we performed a 6‐month clinical study with 3 transradial amputees who received implants of transverse intrafascicular multichannel electrodes (TIMEs) in their median and ulnar nerves. After calibration, electrical stimulation was delivered through the TIMEs connected to artificial sensors in the digits of a prosthesis to generate sensory feedback, which was then used by the subjects while performing different grasping tasks. Results All subjects, notwithstanding their important clinical differences, reported stimulation‐induced sensations from the phantom hand for the whole duration of the trial. They also successfully integrated the sensory feedback into their motor control strategies while performing experimental tests simulating tasks of real life (with and without the support of vision). Finally, they reported a decrement of their phantom limb pain and a general improvement in mood state. Interpretation The promising results achieved with all subjects show the feasibility of the use of intraneural stimulation in clinical settings. Ann Neurol 2018; 1–18
Cobry Keith, Mokhtarifar Naser, Talebi Mohammadmahdi, Woias Peter
Spatial sensitivity analysis of fluid mixing in a plate-and-frame microreactor channel via electric impedance spectroscopy with switchable working electrodes
2018 Flow Measurement and Instrumentation, Band: 64, Seiten: 194 - 203
Abdulrahman S, Brazdil P, van Rijn J, Vanschoren J
Speeding up algorithm selection using average ranking and active testing by introducing runtime
2018 Machine Learning, Band: 107, Seiten: 79 - 108
Stieglitz T, Müller M, Boretius T, Micera S, Granata G, Rossini PM, Cvancara P
Stability of miniaturized neural interfaces.
2018 Gordon Research Conference on Neuroelectronic Interfaces, 25.-30.03.2018, Galveston, TX, USA
Seifaei M, De Dorigo D, Fleig D, Kuhl M, Zschieschang U, Klauk H, Manoli Y
Stable, Self-Biased and High-Gain Organic Amplifiers with Reduced Parameter Variation Effect
2018 Proceedings of the IEEE Asian Solid-State Circuits Conference (A-SSCC), Seiten: 119 - 122
Springer
Static Analysis- 25th International Symposium SAS 2018
ISBN: 9783319997247
Podelski, Andreas
KurzfassungThis book constitutes the refereed proceedings of the 25th International Static Analysis Symposium, SAS 2018, held in Freiburg, Germany, in August 2018. The 18 papers presented in this volume were carefully reviewed and selected from 37 submissions. The contributions cover a variety of multi-disciplinary topics in abstract domains: program verication, bug detection, compiler optimization, program understanding, and software maintenance.
F. Balle, T. Beck, D. Eifler, J.H. Fitschen, S. Schuff, G. Steidl
Strain analysis by a total generalized variation regularized optical flow model
2018 Inverse Probl Sci En

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Jünger F, Rohrbach A
Strong cytoskeleton activity on millisecond timescales during particle binding and uptake revealed by ROCS microscopy
2018 Cytoskeleton, Band: 75, Seiten: 410 - 424

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Wright Patrick, Mann Martin, Backofen Rolf
Structure and interaction prediction in prokaryotic RNA biology
2018 Microbiol Spectrum, Band: 6, Nummer: 2
KurzfassungMany years of research in RNA biology have soundly established the importance of RNA based regulation far beyond most early traditional presumptions. Importantly, the advances in "wet" laboratory techniques have produced unprecedented amounts of data that require efficient and precise computational analysis schemes and algorithms. Hence, many in silico methods that attempt topological and functional classification of novel putative RNA based regulators are available. In this review we technically outline thermodynamics-based standard RNA secondary structure and RNA-RNA interaction prediction approaches that have proven valuable to the RNA research community in the past and present. For these, we highlight their usability with a special focus on prokaryotic organisms and also briefly mention recent advances in whole genome interactomics and how this may influence the field of predictive RNA research.
A Gola, L Pastewka
Structure of Interfaces in Cu|Au Nanolaminates
In: NIC Symposium 2018 - Proceedings
2018, Forschungszentrum Jülich, Seiten: 247 - 254, ISBN: 978-3-95806-285-6
KurzfassungWe used molecular dynamics calculations to study the influence of interdiffusion on the bicrystal interface of Cu|Au nanolaminates. Starting from an ideal bicrystal of 50 nm thickness with a {111} semi-coherent interface, we created a diffusive interface region and annealed the system at 1000K. We report the resulting interfacial crystallographic defects as a function of interface width. Our results show an increase of dislocation spacing as the interface becomes more diffuse. The most diffuse interfaces of ~10 nm width studied here form stacking fault tetrahedra.
Schierle, S., Straub, N., Woias, P., Goldschmidtboing, F.
Sub Kilovolt Electrostatic Elastomer Actuator with Silver Nanowire Electrodes
2018 2018 IEEE 18th International Conference on Nanotechnology (IEEE-NANO), Cork, Ireland 2018 IEEE 18th International Conference on Nanotechnology (IEEE-NANO), Seiten: 420 - 425
KurzfassungSilver nanowires are used as a flexible electrode material on the elastic PDMS membrane of an electrostatic membrane actuator. The actuator system is designed in a modular way to promote a facile investigation of the influence of varying design parameters. Parameter simulations have been performed to achieve a high membrane center displacement at low applied voltages, compared to literature. The design properties were tested and verified in first experiments showing a membrane center displacement of over 100 μm at voltages above 4 kV [7].
Widyaya T., Riga E. K., Müller C, Lienkamp K.
Submicrometer-Sized, 3D Surface-Attached Polymer Networks by Microcontact Printing: Using UV-Cross-Linking Efficiency To Tune Structure Height
2018 Macromolecules, Band: 51, Seiten: 1409 - 1417
Boehler C, Schopf A, LealOrdonez J, Asplund M
Super-Capacitive Conducting Polymer Electrodes Can Control Cell Migration Via DC Stimulation.
2018 ”, 40th International Conference of the IEEE Engineering in Medicine and Biology Society, 17.-21.07.2018, Oahu, Hawaii, USA
Ruh D, Mutschler J, Michelbach M, Rohrbach A
Superior contrast and resolution by image formation in rotating coherent scattering (ROCS) microscopy
2018 Optica, Band: 5, Nummer: 11, Seiten: 1371 - 1381

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Bockhorst T, Pieper F, Engler G, Stieglitz T, Galindo-Leon E, Engel AK
Synchrony surfacing: Epicortical recording of correlated action potentials.
2018 Eur J Neurosci, Band: 48, Nummer: 12, Seiten: 3583 - 3596
KurzfassungSynchronous spiking of multiple neurons is a key phenomenon in normal brain function and pathologies. Recently, approaches to record spikes from the intact cortical surface using small high-density arrays of microelectrodes have been reported. It remained unaddressed how epicortical spiking relates to intracortical unit activity. We introduced a mesoscale approach using an array of 64 electrodes with intermediate diameter (250 μm) and combined large-coverage epicortical recordings in ferrets with intracortical recordings via laminar probes. Empirical data and modelling strongly suggest that our epicortical electrodes selectively captured synchronized spiking of neurons in the cortex beneath. As a result, responses to sensory stimulation were more robust and less noisy compared to intracortical activity, and receptive field properties were well preserved in epicortical recordings. This should promote insights into assembly-coding beyond the informative value of subdural EEG or single-unit spiking, and be advantageous to real-time applications in brain-machine interfacing.
Bosh N, Deggelmann L, Blattert C, Mozaffari Jovein H, Müller C
Synthesis and characterization of Halar® polymer coating deposited on titanium substrate by electrophoretic deposition process Corresponding
2018 Surf Coat Tech, Band: 347, Seiten: 369 - 378
Leicht J, Rossbach D, Stoecklin S, Sherif M, Hafner J, Ruther P, Paul O, Reindl L, Kuhl M, Manoli Y
System zur kabellosen Daten- und Leistungsuebertragung fuer biomedizinische Implantate
2018 9. GMM Fachtagung Energieautarke Sensorik
E. Kipf, J. Erben, R. Zengerle, J. Gescher, S. Kerzenmacher
Systematic investigation of anode materials for microbial fuel cells with the model organism G. sulfurreducens
2018 Bioresource Technology Reports, Band: 2, Seiten: 29 - 37
KurzfassungDifferent carbon and metal-based anode materials for microbial fuel cells were systematically investigated with a pure culture of the model organism G. sulfurreducens. The highest limiting current density of 756 ± 15 μA cm-2 at -0.253 ± 0.037 V vs. SCE was achieved with graphite foil using a step-wise galvanostatic technique. But also the application of completely different anode materials such as activated carbon cloth, stainless steel and graphite felt led to similar high limiting current densities, suggesting that G. sulfurreducens is able to use a large range of substantially different anode materials as external electron acceptor. Additionally, we could show that a step-wise galvanostatic technique to record polarization curves yields similar current densities as potentiostatic control at -0.400 V vs. SCE with the investigated carbon-based materials. In case of stainless steel these techniques yield slightly different results, presumably due to an effect related to the material’s surface properties.
T. A. Kohl, M. Beutler, M. Merker, T. Paprotka, K. Rönsch, M. Schmitt, W. Grasse, C. Metzger-Boddien, K. Dormanns, J. Lüddecke, N. Paust, J. Schlanderer, L. Delamotte, J. Schickedanz, M. Steinwand, S. Niemann, H. Hoffmann
TB-SeqDisK: A microfluidics platform in combination with next generation sequencing for ultra-fast notification of Mycobacterium tuberculosis and its resistance pattern
2018 39th Annual Congress of European Society of Mycobacteriology, Dresden, 01. – 04.07.2018
, Artemij Amiranashvili,, A. Dosovitskiy,, V. Koltun,, Thomas Brox
TD or not TD: Analyzing the Role of Temporal Differencing in Deep Reinforcement Learning
2018
Castellini C, Kõiva R, Pasluosta C, Viegas C, Eskofier BM
Tactile Myography: An Off-Line Assessment of Able-Bodied Subjects and One Upper-Limb Amputee
2018 Technologies, Band: 66, Nummer: 2
KurzfassungHuman-machine interfaces to control prosthetic devices still suffer from scarce dexterity and low reliability; for this reason, the community of assistive robotics is exploring novel solutions to the problem of myocontrol. In this work, we present experimental results pointing in the direction that one such method, namely Tactile Myography (TMG), can improve the situation. In particular, we use a shape-conformable high-resolution tactile bracelet wrapped around the forearm/residual limb to discriminate several wrist and finger activations performed by able-bodied subjects and a trans-radial amputee. Several combinations of features/classifiers were tested to discriminate among the activations. The balanced accuracy obtained by the best classifier/feature combination was on average 89.15% (able-bodied subjects) and 88.72% (amputated subject); when considering wrist activations only, the results were on average 98.44% for the able-bodied subjects and 98.72% for the amputee. The results obtained from the amputee were comparable to those obtained by the able-bodied subjects. This suggests that TMG is a viable technique for myoprosthetic control, either as a replacement of or as a companion to traditional surface electromyography.
S. Vierrath, M. Klingele, S. Thiele, R. Zengerle, M. Breitwieser
Tailoring the membrane│electrode interface: a review and perspective of novel engineering approaches
2018 69th Annual Meeting of the International Society of Electrochemistry (ISE), Bologna/Italy, 02. – 07.09.2018
Kurzfassung69th Annual Meeting of the International Society of Electrochemistry (ISE), Bologna/Italy, 02. – 07.09.2018
Maxim Tatarchenko, J. Park, V., Koltun, Q. Zhou
Tangent Convolutions for Dense Prediction in 3D
2018 IEEE
Sileo L, Bitzenhofer S H, Spagnolo B, Pöpplau J A, Holzhammer T, Pisanello M, Pisano F, Bellistri E, Maglie E, De Vittorio M, Ruther P, Hanganu-Opatz I L, Pisanello F
Tapered fibers combined with a multi-electrode array for optogenetics in mouse medial prefrontal cortex
2018 Front Neurosci-switz, Band: 12, Ergänzungsband: e771
J. Riba, S. Zimmermann, P. Koltay
Technologies for Automated Single Cell Isolation
In: Handbook of Single Cell Technologies
2018, Springer Nature, T. S. Santra, F.-G. Tseng, T. S. Santra, F.-G. Tseng, ISBN: 978-981-10-4857-9
KurzfassungThe isolation of individual cells has gained tremendous importance with the advent of new methods for highly parallel single-cell analysis. A prerequisite for effective clonal cultivation or single-cell analysis is the efficient isolation of individual cells from liquid cell suspensions. This review provides an overview of technologies that are used to automate the isolation of single cells for subsequent cultivation or analysis. First, currently available technologies are classified based on their major technical characteristics. Then, the most prominent technologies such as limiting dilution, FACS, single-cell printing, hydrodynamic trapping, droplet microfluidics, and cell manipulation by external forces are described in detail. Furthermore, the individual features of each technology with focus on throughput, isolation efficiency, level of automation, flexibility in terms of cell types, and their suitability for specific downstream processing and analysis methods are discussed. In contrast to previous works, this review provides a classification approach for single-cell isolation technologies according to performance requirements, makes specific reference to methods for the isolation of microbial cells, and discusses sample input requirements, which is an important aspect in particular for diagnostic purposes.
S. Hin, N. Paust, M. Keller, M. Rombach, O. Strohmeier, R. Zengerle, K. Mitsakakis
Temperature change rate actuated bubble mixing for homogeneous rehydration of dry pre-stored reagents in centrifugal microfluidics
2018 Lab Chip, Band: 18, Seiten: 362 - 370
KurzfassungIn centrifugal microfluidics, dead volumes in valves downstream of mixing chambers can hardly be avoided. These dead volumes are excluded from mixing processes and hence cause a concentration gradient. Here we present a new bubble mixing concept which avoids such dead volumes. The mixing concept employs heating to create a temperature change rate (TCR) induced overpressure in the air volume downstream of mixing chambers. The main feature is an air vent with a high fluidic resistance, representing a low pass filter with respect to pressure changes. Fast temperature increase causes rapid pressure increase in downstream structures pushing the liquid from downstream channels into the mixing chamber. As air further penetrates into the mixing chamber, bubbles form, ascend due to buoyancy and mix the liquid. Slow temperature/ pressure changes equilibrate through the high fluidic resistance air vent enabling sequential heating/cooling cycles to repeat the mixing process. After mixing, a complete transfer of the reaction volume into the downstream fluidic structure is possible by a rapid cooling step triggering TCR actuated valving. The new mixing concept is applied to rehydrate reagents for loop-mediated isothermal amplification (LAMP). After mixing, the reaction mix is aliquoted into several reaction chambers for geometric multiplexing. As a measure for mixing efficiency, the mean coefficient of variation (C —— V, n = 4 LabDisks) of the time to positivity (tp) of the LAMP reactions (n = 11 replicates per LabDisk) is taken. The C —— V of the tp is reduced from 18.5% (when using standard shake mode mixing) to 3.3% (when applying TCR actuated bubble mixing). The bubble mixer has been implemented in a monolithic fashion without the need for any additional actuation besides rotation and temperature control, which are needed anyhow for the assay workflow.
Li P, Sherman S, Rezem M, Honnef K, Zappe H
Temperature-dependence of polymer grating couplers for single mode waveguides
2018 Proceedings of SPIE, Band: 10535, Seite: 105351R
Padon, Oded, Hoenicke, Jochen, McMillan, Kenneth L., Podelski, Andreas, Sagiv, Mooly, Shoham, Sharon
Temporal Prophecy for Proving Temporal Properties of Infinite-State Systems
In: Formal methods in Computer Aided Design
2018, IEEE,
Feißt M, Möller E, Wilde J
Testchips für die Stressmessung beim Power-Cycling
2018 DVS Berichte, Elektronische Baugruppen und Leiterplatten EBL 2018, Band: 340, Seiten: 113 - 117
Lindauer M, van Rijn J, Kotthoff L
The Algorithm Selection Competitions 2015 and 2017
2018 Artificial Intelligence, Seiten: 1 - 35
Moosavi S., Kojda Danny, Kockert Maximilian, Fischer Saskia, Kroener Michael, Woias Peter
The Effect of the MEMS Measurement Platform Design on the Seebeck Coefficient Measurement of a Single Nanowire
2018 Nanomaterials-basel, Band: 8, Nummer: 4, Seite: 219
KurzfassungIn order to study the thermoelectric properties of individual nanowires, a thermoelectric nanowire characterization platform (TNCP) has been previously developed and used in our chair. Here, we report on a redesigned platform aiming to optimize performance, mechanical stability and usability. We compare both platforms for electrical conductivity and the Seebeck coefficient for an individual Ag nanowire of the previously-used batch and for comparable measurement conditions. By this, the measurement performance of both designs can be investigated. As a result, whereas the electrical conductivity is comparable, the Seebeck coefficient shows a 50% deviation with respect to the previous studies. We discuss the possible effects of the platform design on the thermoelectric measurements. One reason for the deviation of the Seebeck coefficient is the design of the platform leading to temperature gradients along the bond pads. We further analyze the effect of bonding materials Au and Pt, as well as the effect of temperature distributions along the bond pads used for the thermovoltage acquisition. Another major reason for the variation of the measurement results is the non-homogeneous temperature distribution along the thermometer. We conclude that for the measurement of small Seebeck coefficients, an isothermal positioning of voltage-probing bond pads, as well as a constant temperature profile at the measurement zone are essential.
Rehfeld Frederick, Maticzka Daniel, Grosser Sabine, Knauff Pina, Eravci Murat, Vida Imre, Backofen Rolf, Wulczyn F
The RNA-binding protein ARPP21 controls dendritic branching by functionally opposing the miRNA it hosts
2018 Nat Commun, Band: 9, Nummer: 1
KurzfassungAbout half of mammalian miRNA genes lie within introns of protein-coding genes, yet little is known about functional interactions between miRNAs and their host genes. The intronic miRNA miR-128 regulates neuronal excitability and dendritic morphology of principal neurons during mouse cerebral cortex development. Its conserved host genes, R3hdm1 and Arpp21, are predicted RNA-binding proteins. Here we use iCLIP to characterize ARPP21 recognition of uridine-rich sequences with high specificity for 3’UTRs. ARPP21 antagonizes miR-128 activity by co-regulating a subset of miR-128 target mRNAs enriched for neurodevelopmental functions. Protein-protein interaction data and functional assays suggest that ARPP21 acts as a positive post-transcriptional regulator by interacting with the translation initiation complex eIF4F. This molecular antagonism is reflected in inverse activities during dendritogenesis: miR-128 overexpression or knockdown of ARPP21 reduces dendritic complexity; ectopic ARPP21 leads to an increase. Thus, we describe a unique example of convergent function by two products of a single gene.
Lehman J, Clune J, Misevic D, Adami C, Beaulieu J, Bentley P, Bernard S, Beslon G, Bryson D, Chrabaszcz P, Cheney N, Cully A, Doncieux S, Dyer F, Ellefsen K, Feldt R, Fischer S, Forrest S, Frénoy A, Gagné C, Goff L, Grabowski L, Hodjat B, Hutter F, Keller L, Knibbe C, Krcah P, Lenski R, Lipson H, MacCurdy R, Maestre C, Miikkulainen R, Mitri S, Moriarty D, Mouret J.-B., Nguyen A, Ofria C, Parizeau M, Parsons D, Pennock R, Punch W, Ray T, Schoenauer M, Shulte E, Sims K, Stanley K, Taddei F, Tarapore D, Thibault S, Weimer W, Watson R, Yosinksi J
The Surprising Creativity of Digital Evolution: A Collection of Anecdotes from the Evolutionary Computation and Artificial Life Research Communities
2018 CoRR, Band: abs/1803.03453
Podelski, Andreas, Heizmann, Matthias, Hoenicke, Jochen, Nutz, Alexander
The map equality domain
In: VSTTE 2018
2018, Springer,
Maier Lisa-Katharina, Stachler Aris-Edda, Brendel Jutta, Stoll Britta, Fischer Susan, Haas Karina, Schwarz Thandi, Alkhnbashi Omer, Sharma Kundan, Urlaub Henning, Backofen Rolf, Gophna Uri, Marchfelder Anita
The nuts and bolts of the Haloferax CRISPR-Cas system I-B
2018 RNA Biol, Seiten: 1 - 39
KurzfassungInvading genetic elements pose a constant threat to prokaryotic survival, requiring an effective defence. Eleven years ago, the arsenal of known defence mechanisms was expanded by the discovery of the CRISPR-Cas system. Although CRISPR-Cas is present in the majority of archaea, research often focuses on bacterial models. Here, we provide a perspective based on insights gained studying CRISPR-Cas system I-B of the archaeon Haloferax volcanii. The system relies on more than 50 different crRNAs, whose stability and maintenance critically depend on the proteins Cas5 and Cas7, which bind the crRNA and form the Cascade complex. The interference activity requires a seed sequence and can interact with multiple PAM sequences. H. volcanii stands out as the first example of an organism that can tolerate autoimmunity via the CRISPR-Cas system while maintaining a constitutively active system. In addition, the H. volcanii system was successfully developed into a tool for gene regulation.
van Rijn J, Holmes G, Pfahringer B, Vanschoren J
The online performance estimation framework: heterogeneous ensemble learning for data streams
2018 Machine Learning, Band: 107, Seiten: 149 - 176
C Greiner, Z Liu, R Schneider, L Pastewka, P Gumbsch
The origin of surface microstructure evolution in sliding friction
2018 Scripta Mater, Band: 153, Seiten: 63 - 67
KurzfassungA typical tribologically induced microstructure displays a discontinuity parallel to the surface separating the near-surface layer from the bulk. Despite its ubiquitous observation, the origin of this layer underneath the surface remains elusive. Here, we show that already after the first loading pass a localized dislocation structure is found at a depth of 100–150 nm. This structure is linked to the inhomogeneous stress field under the moving indenter, where dislocations are trapped when the stress drops below the material's yield stress. Control of the initial tribological loading could therefore be exploited to design surfaces and materials with superior tribological properties.
Höhn Oliver, Tucher Nico, Bläsi Benedikt
Theoretical study of pyramid sizes and scattering effects in silicon photovoltaic module stacks
2018 Opt Express, Band: 26, Nummer: 6, Seiten: A320 - A330
KurzfassungFront side pyramids are the industrial standard for wafer based monocrystalline silicon solar cells. These pyramids fulfill two tasks: They act as anti-reflective structure on the one hand and as a light-trapping structure on the other hand. In recent development smaller pyramids with sizes below 1 μm attract more and more interest. In this paper an optical analysis of periodically arranged front side pyramids is performed. The impact on the reflectance as well as on the useful absorption within the solar cell is investigated depending on the pyramids size, the amount of additional scattering in the system and the quality of the rear side reflector. In contrast to other investigations not only the solar cell, but the full photovoltaic (PV) module stack is considered. This can strongly influence results, as we show in this paper. The results indicate that in a PV module stack with realistic assumptions for the amount of scattering as well as for the rear side reflectance only small differences for pyramids with sizes above 600 nm occur. Preliminary conclusions for random pyramids deduced from these results for periodically arranged pyramids indicate that these differences could become even smaller.

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L. Becherer
Therapiebegleitende HIV- und HTLV-Diagnostik am Point-of-Care
2018 microTEC Südwest Clusterkonferenz 2018, 16. – 17.04.2018, Freiburg
Kilias A, Haussler U, Heining K, Froriep UP, Haas CA, Egert U
Theta frequency decreases throughout the hippocampal formation in a focal epilepsy model.
2018 Hippocampus, Band: 28, Nummer: 6, Seiten: 375 - 391
Linseis V., Völklein F., Reith H., Hühne R., Schnatmann L., Nielsch K., Woias P.
Thickness and temperature dependent thermoelectric properties of Bi 87 Sb 13 nanofilms measured with a novel measurement platform
2018 Semiconductor Science and Technology, Band: 33, Nummer: 8, Seite: 085014
KurzfassungThe temperature and thickness dependent thermoelectric properties of Bi87Sb13 nano-films with a thickness from 84 nm to 282 nm have been studied in a temperature range from 110 K up to 450 K. The films have been prepared by thermal evaporation of the raw material from an Al2O3 coated tungsten boat under vacuum conditions of at least 10−6 mbar. The measurements have been performed using a novel measurement platform, which allows the nearly simultaneous characterization of the thermal conductivity, electrical conductivity, the Seebeck coefficient and the Hall coefficient. All properties are measured in the in-plane direction at the same sample within one measurement run, avoiding many sources of uncertainties and allowing the calculation of the direction dependent, in-plane thermoelectric figure of Merit ZT with high precision. The maximum ZT value of 0.28 has been obtained for the thickest sample at a temperature of 265 K. All comparative measurements have been performed after an initial thermal annealing step, as the heat treatment shows a strong impact on the thermoelectric performance of the films.
Heller S., Nematollahi I., Koeble S., Woias P.
Three channel high dynamic current measurement system for low power systems
2018 PowerMEMS 2017, Kanazawa, Japan November 14-17, 2017 Journal of Physics: Conference Series, Band: 1052, Seite: 012059
KurzfassungThe measurement of the dynamic power consumption is a very important task for the characterization and optimization of an energy-autonomous system. In this paper a measurement system is presented that allows the simultaneous measurement of three current ranges from 1 µA to 30 mA at a sample rate of 1 MHz with a selectable supply voltage in the range of 1.8 V to 3.3 V. With this system the full range of low to high power consumption is covered with a high resolution in time, as it is present in a wireless sensor node during data acquisition and wireless communication, respectively.
F. Hegge, R. Moroni, P. Trinke, B. Bensmann, R. Hanke-Rauschenbach, S. Thiele, S. Vierrath
Three-dimensional microstructure analysis of a polymer electrolyte membrane water electrolyzer anode
2018 J Power Sources, Band: 393, Seiten: 62 - 66
KurzfassungThe anode catalyst layer of a PEM water electrolyzer is reconstructed using a combination of FIB-SEM tomography and ionomer modeling. The pore space is infiltrated with silicone, enabling good discrimination between pores and IrRuOx catalyst material, while the ionomer cannot be imaged. The reconstructed volume of 29 μm × 24 μm x 7 μm contains catalyst particles with a median size of 0.5 μm and has a porosity of 55%. By modeling different ionomer contents inside the pore space, the impact on microstructural and transport parameters is investigated. At an ionomer content of 40–50% of the pore volume, all transport parameters are in a reasonable range, confirming experimental results from literature. At an ionomer content of 48% the catalyst layer has a porosity of 29%, a median pore size of 0.94 μm, a permeability of the pore space of and a mean ionomer film thickness of . The tortuosities of the ionomer and the pore space are calculated to 3.5 and 6.7 at the corresponding phase fractions of 26% and 29% respectively. The electrochemically active surface area estimated from the tomography () is considerably lower than literature values, indicating a roughness below FIB-SEM resolution.
D. Kainz, S. Früh, T. Hutzenlaub, R. Zengerle, N. Paust
Total flow control for lateral flow tests with centrifugal microfluidics
2018 MicroTAS 2018, 11. -15. November 2018, Kaohsiung / Taiwan
N. P. Kocatürk-Schumacher, J. Madjarov, P. Viwatthanasittiphong, S. Kerzenmacher
Toward an Energy Efficient Wastewater Treatment: Combining a Microbial Fuel Cell/Electrolysis Cell Anode With an Anaerobic Membrane Bioreactor
2018 Frontiers in Energy Research, Band: 6, Seite: 95
KurzfassungRecently, it has been shown that combining a bioelectrochemical system (BES) with an anaerobic membrane bioreactor (AnMBR) to produce electricity can reduce the overall energy consumption of wastewater treatment. In this study, we tested the recently proposed concept that integrates a microbial anode into an AnMBR, under application relevant conditions, for the treatment of synthetic brewery wastewater. We developed two system configurations: a filtering anode with stainless steel filter plate; and a hybrid anode, in which a polymeric membrane is combined with stainless steel mesh. As fouling is problematic in AnMBRs, we investigated the effect of two fouling mitigation methods, namely electrochemical cleaning and application of a turbulence promotor, on the permeate fluxes and current densities.We also investigated the effect of cathode (counter electrode) position on the permeate fluxes and current densities in filtering and hybrid anode. Our results revealed that permeate fluxes were influenced by the membrane pore size; and dropped below 5 L m−2 hr−1 on day 3 with filter grade 0.5μm; whereas similar values of permeate flux were observed after 5 days of operation with the membrane with filter grade 0.1μm. COD removal across the membrane reached up to 644mg L−1 indicating improvement in energy efficiency and effluent quality of the AnMBR. The location of cathode did not influence permeate fluxes and current densities, but permeate pH was largely affected. Electrochemical cleaning improved permeate fluxes more than 2-fold (18.9 L m−2 hr−1 after 7 days of operation) compared to the operation of the 0.1μm membrane without a cleaning procedure. Application of a turbulence promotor increased permeate fluxes and current densities in filtering anode. The hybrid anode resulted in similar current densities, but higher permeate fluxes as compared to the filtering anode, which dropped below 20 L m−2 hr−1 only after 8 days of operation. The Kocatürk-Schumacher et al. Microbial Anode Combined With AnMBR hybrid anode configuration is an attractive option that combines high permeate fluxes on conventional non-conductive filters with current generation on an inexpensive conductive material. In summary, our results demonstrate that combining BES with AnMBR is a promising approach toward an energy efficient wastewater treatment.
Zela Arber, Klein Aaron, Falkner Stefan, Hutter Frank
Towards Automated Deep Learning: Efficient Joint Neural Architecture and Hyperparameter Search
2018 ICML 2018 AutoML Workshop
Mendoza Hector, Klein Aaron, Feurer Matthias, Springenberg Jost, Urban Matthias, Burkart Michael, Dippel Max, Lindauer Marius, Hutter Frank
Towards Automatically-Tuned Deep Neural Networks
In: AutoML: Methods, Sytems, Challenges
2018, Springer, Seiten: 141 - 156,
Feurer M, Hutter F
Towards Further Automation in AutoML
2018 ICML 2018 AutoML Workshop
P. Juelg, M. Specht, E. Kipf, M. Lehnert, C. Eckert, N. Paust, F. von Stetten, R. Zengerle, T. Hutzenlaub
Towards Standardization of Molecular Diagnostic Workflows: Centrifugal Microfluidic Automation of qPCR for Cancer Monitoring
2018 6th International Molecular Diagnostics Europe, Lissabon / Portugal, 22. - 24. 05.2018
P. Koltay
Towards a generic 3D-Bioprinting Platform
2018 International Conference on Biofabrication, Würzburg, 28. – 31.10.2018
Kurzfassung; “”, (2018), International Conference on Biofabrication, Würzburg, 28. – 31.10.2018
T Graunke, K Schmitt, S Busch, S Raible, J Wöllenstein
Towards an Empirical Model for the Prediction of the Selectivity of Polymer Membranes
2018 Eurosensors 2018, Graz, Austria , Band: 2, Nummer: 13, Seite: 979
KurzfassungPolymer membranes are often used in combination with gas sensors for selectivity enhancement, especially with metal-oxide sensors (MOX). We report on the development of an empirical model to predict the gas separation properties of polymer membranes. This model is based on the two parameters sorption and diffusion, represented by the polar fraction of the free surface energy (SFE), and the water absorption combined with the molecule diameter based on Lennard-Jones. We measured the surface tension for a number of common fluoropolymers and used the results to determine their SFE using the graphical method developed by van Oss—Chaudhury—Good, compared them with literature data and further optimized the model. With the optimized model, combined with the information on functional groups in the polymers, we are able to predict the selectivity of polymer membranes.
M. Mu’min Solihul, T. Böhm, S. Thiele, M. Breitwieser
Towards more hydrophilic proton exchange membranes: adjusting the wetting properties by electrospinning PVDF-HFP/PVP blends
2018 ELEN Electrospinning for Energy, Montpellier / Fracne, 13. - 15.06.2018
Florian Schindler, Andreas Fell, Ralph Müller, Jan Benick, Armin Richter, Frank Feldmann, Patricia Krenckel, Stephan Riepe, Martin C Schubert, Stefan W Glunz
Towards the efficiency limits of multicrystalline silicon solar cells
2018 Sol Energ Mat Sol C, Band: 185, Seiten: 198 - 204
KurzfassungIn this contribution, we present our recent results for high efficiency multicrystalline silicon solar cells. Based on n-type high-performance multicrystalline silicon substrates in combination with the TOPCon solar cell concept featuring a full area passivating back contact and a boron-diffused emitter as well as a plasma-etched black-silicon texture at the front side, a certified conversion efficiency of 22.3% has been achieved, which is currently the world record efficiency for multicrystalline silicon solar cells. A detailed loss analysis of the record solar cell batch discloses the nature of the remaining loss mechanisms, revealing the route for further improvements. We observe an efficiency gap between the multicrystalline and the FZ reference solar cells of ~1%abs. Compared to the FZ reference cells, the mc-Si cells also feature a significantly larger scattering in Voc and Jsc as well as a fill factor loss of ~1.5%abs. We show that the scattering in Jsc correlates with the area fraction of recombination-active structural crystal defects and the scattering in Voc additionally with lateral emitter-induced inhomogeneities. The fill factor loss is attributed to the general presence of strongly recombination-active grain boundaries. A detailed loss analysis of the record mc-Si solar cell shows that the major electrical losses are due to recombination at grain boundaries (0.7%abs) and recombination in the emitter (0.6%abs). By reducing these electrical loss channels, e.g. by an improved crystallization process together with a hydrogenation of the bulk and application of an adapted emitter, we expect to reach efficiencies for mc-Si solar cells in the range of 23%.
Schindler Florian, Fell Andreas, Müller Ralph, Benick Jan, Richter Armin, Feldmann Frank, Krenckel Patricia, Riepe Stephan, Schubert Martin, Glunz Stefan
Towards the efficiency limits of multicrystalline silicon solar cells
2018 Solar Energy Materials and Solar Cells, Band: 185, Seite: 198–204
KurzfassungIn this contribution, we present our recent results for high efficiency multicrystalline silicon solar cells. Based on n-type high-performance multicrystalline silicon substrates in combination with the TOPCon solar cell concept featuring a full area passivating back contact and a boron-diffused emitter as well as a plasma-etched blacksilicon texture at the front side, a certified conversion efficiency of 22.3% has been achieved, which is currently the world record efficiency for multicrystalline silicon solar cells. A detailed loss analysis of the record solar cell batch discloses the nature of the remaining loss mechanisms, revealing the route for further improvements. We observe an efficiency gap between the multicrystalline and the FZ reference solar cells of ~1%abs. Compared to the FZ reference cells, the mc-Si cells also feature a significantly larger scattering in Voc and Jsc as well as a fill factor loss of ~1.5%abs. We show that the scattering in Jsc correlates with the area fraction of recombinationactive structural crystal defects and the scattering in Voc additionally with lateral emitter-induced inhomogeneities. The fill factor loss is attributed to the general presence of strongly recombination-active grain boundaries. A detailed loss analysis of the record mc-Si solar cell shows that the major electrical losses are due to recombination at grain boundaries (0.7%abs) and recombination in the emitter (0.6%abs). By reducing these electrical loss channels, e.g. by an improved crystallization process together with a hydrogenation of the bulk and application of an adapted emitter, we expect to reach efficiencies for mc-Si solar cells in the range of 23%.
Schirrmeister R, Chrabąszcz P, Hutter F, Ball T
Training Generative Reversible Networks
2018 ICML 2018 workshop on Theoretical Foundations and Applications of Deep Generative Models
Feißt M, Yu J, Wilde J
Transient Liquid Phase Bonding Using AgSn-Alloys for Stress Reduced Sensor Mounting
2018 IEEE 68th Electronic Components & Technology Conference (ECTC), San Diego, Ca, Seiten: 293 - 300
Feißt M, Wilde J
Transient-Liquid-Phase Bonding (TLP) mit AgSn-Schichtsystemen für die Montage von Mikrosystemen
2018 IMAPS Herbstkonferenz 2018, München
Wang Z, Folwill Y, Cu Nguyen P, Zappe H
Tunable bandpass filter for mid-infrared wavelengths using liquid crystal elastomer actuators
2018 Proceedings of SPIE, Band: 10545, Seite: 105450D
Heizmann, Matthias, Chen, Yu-Fang, Dietsch, Daniel, Greitschus, Marius, Hoenicke, Jochen, Li, Yong, Nutz, Alexander, Musa, Betim, Schilling, Christian, Schindler, Tanja, Podelski, Andreas
Ultimate Automizer and the Search for Perfect Interpolants
In: TACAS (2) 2018
2018, Springer,
KurzfassungUltimate Automizer is a software verifier that generalizes proofs for traces to proofs for larger parts for the program. In recent years the portfolio of proof producers that are available to Ultimate has grown continuously. This is not only because more trace analysis algorithms have been implemented in Ultimate but also due to the continuous progress in the SMT community. In this paper we explain how Ultimate Automizer dynamically selects trace analysis algorithms and how the tool decides when proofs for traces are “good” enough for using them in the abstraction refinement.
Dietsch, Daniel,, Greitschus, Marius, Heizmann, Matthias, Hoenicke, Jochen, Nutz, Alexander, Podelski, Andreas, Schilling, Christian, Schindler, Thomas
Ultimate Taipan with Dynamic Block Enconding (Competition Contributing)
In: TACAS (2) 2018
2018, Springer,
F. Lionetto, C. Mele, P. Leo, S. D'Ostuni, F. Balle, A. Maffezzoli
Ultrasonic spot welding of carbon fiber reinforced epoxy composites to aluminum: mechanical and electrochemical characterization
2018 Compos Part B-eng, Band: 144, Seiten: 134 - 142
Ilg Eddy, Cicek Oezguen, Galesso Silvio, Klein Aaron, Makansi Osama, Hutter Frank, Brox Thomas
Uncertainty Estimates for Optical Flow with Multi-Hypotheses Networks
2018
Schindelhauer C, Gavrikov P, Verboket P, Ungan T, Muller M, Lai M, Reindl L, Wendt T
Using Bluetooth Low Energy to trigger an ultra-low power FSK wake-up receiver
2018 25th International Conference on Electronics, Circuits and Systems , Seiten: 781 - 784
Williams M, Jervell A, Hiller D, Zacharias M
Using HCl to Control Silver Dissolution in Metal‐Assisted Chemical Etching of Silicon
2018 Phys Status Solidi A, Band: 215, Nummer: 13, Seite: 1800135
Haering, Ivo, Ramin, Malte vo, Stottmeister, Alexander, Schaefer, Johannes, Vogelbacher, Georg, Brombacher, Bernd, Pfeiffer, Mercy, Restayn, Elena-Maria, Ross, Katharina, Schneider, Johannes, Hiermaier, Stefan
Validated 3D spatial stepwise quantitative hazard, risk and resilience analysis and management of explosive events in urban areas
2018 European Journal of security research, Band: Online First, Seiten: 1 - 37
KurzfassungUrban physical security and resilience with respect to accidental and intentional explosive events are an increasing issue regarding civil safety and security of modern societies and their citizens. Examples include industrial on-site explosions, gas explosions or terrorist attacks. In particular, multiple, simultaneous and maliciously time-coordinated events are an increasing event type such as complex attack events consisting of targeted combinations of improvised explosive devices. The paper presents a comprehensive, tailorable and stepwise process. This includes methodologies for scenario, hazard, damage, exposure, event frequency, risk and resilience analysis that have been developed, refined and praxis-tested over decades. The focus is on a summarizing description of the modern best practice approach, the validation efforts undertaken for each step as well as two detailed case studies for exemplary presentation and overall validation. In a comprehensive table, the present approach is compared with other state-of-the-art approaches. The paper shows a refined process how to systematically improve resilience when using the tool, in particular through barriers at explosive sites and at exposed sites of various geometries. Furthermore, along the presentation a set of quality requirements regarding explosive event risk and resilience analyses are provided as collected over the years from the in-field, user group and engineering science perspective as well as a broad outlook on extension options for the future.
C. Siber, F. Stumpf, J. Schöndube, S. Zimmermann, P. Koltay, L. Lautscham
Velocity field analysis of acoustophoretic focusing in a single-cell printing system
2018 Acoustofluidics, Lille/France, 29. – 31.08.2018
F. Balle, D. Backe
Very High Cycle Fatigue of Carbon Fiber Reinforced Polyphenylene Sulfide at Ultrasonic Frequencies
In: Fatigue of Materials at Very High Numbers of Loading Cycles
2018, Springer Spektrum, H.-J. Christ, Seiten: 441 - 461, H.-J. Christ,
Lindauer M, Hutter F
Warmstarting of Model-based Algorithm Configuration
2018 Proceedings of the AAAI conference, Seiten: 1355 - 1362
Nikolaus Mayer,, Eddy Ilg,, Philipp Fischer,, C. Hazirbas,, D. Cremers,, Alexey, Dosovitskiy,, Thomas Brox
What Makes Good Synthetic Training Data for Learning Disparity and Optical Flow Estimation?
2018 Int J Comput Vision
Breunig I, Hanka K, Jia Y, Zawilski K.T., Schunemann P.G., Buse K.
Whispering gallery optical parametric oscillators for the mid-infrared spectral range
2018 Nonlinear Frequency Generation and Conversion: Materials and Devices XVII, San Francisco, CA, United States Proceedings of SPIE, Band: 10516, Seite: 105160E
KurzfassungThe tunability of cw optical parametric oscillators can be extended in the mid-infrared spectral range by using whispering gallery resonators (WGRs) made of non-oxide crystals. We demonstrate the fabrication of WGRs from silver gallium selenide, cadmium silicon phosphide and orientation-patterned gallium phosphide with quality factors above 106 . The resonators made of the first two provide optical parametric oscillation in the mid-infrared pumped by a compact laser diode at 1.57 μm wavelength. The wavelength tunability of the device based on silver gallium selenide provides a tuning range beyond 8 μm wavelength. These achievements are considered as the first steps of cw optical parametric oscillators into this important spectral region.
Dimitriadis G, Neto J P, Aarts A, Alexandru A, Ballini M, Battaglia F, Calcaterra L, David F, Fiath R, Frazao J, Geerts J, Gentet L J, Van Helleputte N, Holzhammer T, van Hoof C, Horvath D, Lopes G, Maris E, Marques-Smith A, Marton G, Meszena D, Mitra S, Musa S, Neves H, Nogueira J, Orban G A, Pothof F, Putzeys J, Raducanu B, Ruther P, Schroeder T, Singer W, Tiesinga P, Ulbert I, Wang S, Welkenhuysen M, Kampff A R
Why not record from every channel with a CMOS scanning probe?
2018 bioRxiv
Kaiser A.
Wie sich Geschlechtlichkeit in den Neurowissenschaften manifestiert und wie Geschlecht in das Gehirn kommt. Kritische Überlegungen.
2018 In M. Koreuber, & B. Assmann (Eds.), Das Geschlecht in der Biologie. Aufforderung zu einem Perspektivwechsel. (Series Schriften zur interdisziplinären Frauen- und Geschlechterforschung), Band: 12, Seiten: 133 - 150
Wright Patrick, Georg Jens
Workflow for a Computational Analysis of an sRNA Candidate in Bacteria
2018 Methods Mol Biol, Band: 1737, Seiten: 3 - 30
KurzfassungComputational methods can often facilitate the functional characterization of individual sRNAs and furthermore allow high-throughput analysis on large numbers of sRNA candidates. This chapter outlines a potential workflow for computational sRNA analyses and describes in detail methods for homolog detection, target prediction, and functional characterization based on enrichment analysis. The cyanobacterial sRNA IsaR1 is used as a specific example. All methods are available as webservers and easily accessible for nonexpert users.
Böhm T, Joseph K, Kirsch M, Moroni R, Hilger A, Manke I, Johnston M, Asplund M, Vomero M, Hofmann UG, Stieglitz T, Haas CA, Thiele S
X-ray tomographic 3D reconstruction of the brain-probe-interface in rat cortex.
2018 Gordon Research Conference on Neuroelectronic Interfaces, 25.-30.03.2018, Galveston, TX, USA
Tanvir N, Yurchenko O, Laubender E, Pohlec R, Sicard O v, Urban G
Zinc peroxide combustion promoter in preparation of CuO layers for conductometric CO₂ sensing
2018 Sensor Actuat B-chem, Band: 257, Seiten: 1027 - 1034
KurzfassungThe detection of CO₂ has applications for both industrial and domestic use due to its high exposure effects on the human health. Conductivity sensors on the other hand, present a cost-effective approach that can be successfully utilized for the detection of CO₂. However, the integration of metal oxide based nanoparticles layers for conducometric sensing is complicated and requires improvement in the layer quality to achieve effective and stable gas sensing properties. Addressing this challenge, we present in this work, p-type semiconducting CuO nanoparticles as a CO₂ gas sensitive material and introduce a combination of organic binder and peroxide such as ZnO₂ for improved gas sensitive layer quality. The addition of ZnO₂ to CuO nanoparticles enables the layers annealing at 300 °C which makes the preparation method compatible to silicon based gas sensing devices. For the characterization of layers, X-ray diffraction, scanning electron microscopy, thermogravimetric analysis and Fourier transform infrared measurements are employed. The CO₂ gas sensing measurements show a reversible change in resistance suggesting hybrid nanoparticles layers as an efficient gas sensitive material. The measurements performed at different humidity levels for CuO-ZnO₂ (10:1) layer indicate different sensing mechanism for dry conditions in comparison to the measurements performed under humid atmosphere. The Lewis acid-base reaction between oxide oxygen and CO₂ has been proposed as sensing mechanism for the measurements in dry air, whereas the formation of surface barriers between nano-grains due to the reaction with CO₂ has been suggested for the CO₂ response under humid conditions.
Briese Michael, Saal-Bauernschubert Lena, Ji Changhe, Moradi Mehri, Ghanawi Hanaa, Uhl Michael, Appenzeller Silke, Backofen Rolf, Sendtner Michael
hnRNP R and its main interactor, the noncoding RNA 7SK, coregulate the axonal transcriptome of motoneurons
2018 Proc Natl Acad Sci USA, Band: 115, Nummer: 12, Seiten: E2859 - E2868
KurzfassungDisturbed RNA processing and subcellular transport contribute to the pathomechanisms of motoneuron diseases such as amyotrophic lateral sclerosis and spinal muscular atrophy. RNA-binding proteins are involved in these processes, but the mechanisms by which they regulate the subcellular diversity of transcriptomes, particularly in axons, are not understood. Heterogeneous nuclear ribonucleoprotein R (hnRNP R) interacts with several proteins involved in motoneuron diseases. It is located in axons of developing motoneurons, and its depletion causes defects in axon growth. Here, we used individual nucleotide-resolution cross-linking and immunoprecipitation (iCLIP) to determine the RNA interactome of hnRNP R in motoneurons. We identified approximately 3,500 RNA targets, predominantly with functions in synaptic transmission and axon guidance. Among the RNA targets identified by iCLIP, the noncoding RNA 7SK was the top interactor of hnRNP R. We detected 7SK in the nucleus and also in the cytosol of motoneurons. In axons, 7SK localized in close proximity to hnRNP R, and depletion of hnRNP R reduced axonal 7SK. Furthermore, suppression of 7SK led to defective axon growth that was accompanied by axonal transcriptome alterations similar to those caused by hnRNP R depletion. Using a series of 7SK-deletion mutants, we show that the function of 7SK in axon elongation depends on its interaction with hnRNP R but not with the PTEF-B complex involved in transcriptional regulation. These results propose a role for