Current publications of the Faculty of Engineering

2021

 back to the year overview

• Wendler D, De Dorigo D, Amayreh M, Bleitner A, Marx M, Manoli Y
  A 0.00378mm2 Scalable Neural Recording Front-End for Fully Immersible Neural Probes Based on a Two-Step Incremental Delta-Sigma Converter with Extended Counting and Hardware Reuse
  2021 accepted for publication and presentation in the IEEE International Solid-State Circuits Conference (ISSCC)
• Lukas Mentel, Karsten Scheibler, Felix Winterer, Bernd Becker, Tino Teige
  Benchmarking SMT Solvers on Automotive Code
  2021 GI/ITG/GMM Workshop “Methoden und Beschreibungssprachen zur Modellierung und Verifikation von Schaltungen und Systemen”
  » show abstract« hide abstract
  Abstract

  Using embedded systems in safety-critical environments requires a rigorous testing of the components these systems are composed of. For example, the software running on such a system has to be evaluated regarding its code coverage – in particular, unreachable code fragments have to be avoided according to the ISO 26262 standard. Software model checking allows to detect such dead code automatically. While the recent case study [1] compares several academic software model checkers with the commercial test and verification tool BTC EmbeddedPlatform R (BTC EP), we want to focus on a lower level – i.e. the back-end solvers within BTC EP. Therefore, we evaluate the performance of off-the-shelf SMT solvers supporting the theory of floating-point as well as the theory of bitvectors on floating-point dominated benchmark instances originating from the automotive domain. Furthermore, we compare these off-the-shelf SMT solvers with the back-end solvers used by BTC EP.
• Karsten Scheibler, Felix Winterer, Tobias Seufert, Tino Teige, Christoph Scholl, Bernd Becker
  ICP and IC3
  2021 Conference on Design, Automation and Test in Europe Conference (DATE)
  » show abstract« hide abstract
  Abstract

  If embedded systems are used in safety-critical environments, they need to meet several standards. For example, in the automotive domain the ISO 26262 standard requires that the software running on such systems does not contain unreachable code. Software model checking is one effective approach to automatically detect such dead code. Being used in a commercial product, iSAT3 already performs very well in this context. In this paper we integrate IC3 into iSAT3 in order to improve its dead code detection capabilities even further.
• Karsten Scheibler, Felix Winterer, Tobias Seufert, Tino Teige, Christoph Scholl, Bernd Becker
  ICP and IC3
  2021 DATE, IEEE
  » show abstract« hide abstract
  Abstract

  If embedded systems are used in safety-critical environments,they need to meet several standards. For example, in the automotive domain the ISO 26262 standard requires that the software running on such systems does not contain unreachable code. Software model checking is one effective approach to automatically detect such dead code. Being used in a commercial product, iSAT3 already performs very well in this context. In this paper we integrate IC3 into iSAT3 in order to improve its dead code detection capabilities even further.
• Felix Winterer, Tobias Seufert, Karsten Scheibler, Tino Teige, Christoph Scholl, Bernd Becker
  ICP and IC3 with Stronger Generalization
  2021 GI/ITG/GMM Workshop “Methoden und Beschreibungssprachen zur Modellierung und Verifikation von Schaltungen und Systemen”
  » show abstract« hide abstract
  Abstract

  Most recently, IC3 was integrated into the SMT solver iSAT3. Thus, iSAT3+IC3 introduces the first IC3 variant based on interval abstraction and Interval Constraint Propagation (ICP). As strong generalization is one of the key aspects for the IC3 algorithm to be successful, we integrate two additional generalization schemes from literature into iSAT3+IC3: Inductive Generalization and Counterexamples To Generalization (CTG). Furthermore, we evaluate the benefits and the drawbacks of different variants of these methods in the context of interval abstraction and ICP.
• Felix Winterer, Tobias Seufert, Karsten Scheibler, Tino Teige, Christoph Scholl, Bernd Becker
  ICP and IC3 with Stronger Generalization
  2021 MBMV
  » show abstract« hide abstract
  Abstract

  Most recently, IC3 was integrated into the SMT solver iSAT3. Thus, iSAT3+IC3 introduces the first IC3 variant based on interval abstraction and Interval Constraint Propagation (ICP). As strong generalization is one of the key aspects for the IC3 algorithm to be successful, we integrate two additional generalization schemes from literature into iSAT3+IC3: Inductive Generalization and Counterexamples To Generalization (CTG). Furthermore, we evaluate the benefits and the drawbacks of different variants of these methods in the context of interval abstraction and ICP.
• Tobias Paxian, Pascal Raiola, Bernd Becker
  On Preprocessing for Weighted MaxSAT
  2021 VMCAI - 22nd International Conference on Verification, Model Checking, and Abstract Interpretation, Springer, volume: 12597, pages: 556 - 577
  » show abstract« hide abstract
  Abstract

  Modern competitive solvers employ various preprocessing techniques to efficiently tackle complex problems. This work introduces two preprocessing techniques to improve solving weighted partial MaxSAT problems: Generalized Boolean Multilevel Optimization (GBMO) and Trimming MaxSAT (TrimMaxSAT). GBMO refines and extends Boolean Multilevel Optimization (BMO), thereby splitting instances due to their distribution of weights into multiple less complex subproblems, which are solved one after the other to obtain the overall solution. The second technique, TrimMaxSAT, finds unsatisfiable soft clauses and removes them from the instance. This reduces the complexity of the MaxSAT instance and works especially well in combination with GBMO. The proposed algorithm works incrementally in a binary search fashion, testing the satisfiability of every soft clause. Furthermore, as a by-product, typically an initial weight close to the maximum is found, which is in turn advantageous w.r.t. the size of e.g. the Dynamic Polynomial Watchdog (DPW) encoding. Both techniques can be used by all MaxSAT solvers, though our focus lies on Pseudo Boolean constraint based MaxSAT solvers. Experimental results show the effectiveness of both techniques on a large set of benchmarks from a hardware security application and from the 2019 MaxSAT Evaluation. In particular for the hardest of the application benchmarks, the solver Pacose with GBMO and TrimMaxSAT performs best compared to the MaxSAT Evaluation solvers of 2019. For the benchmarks of the 2019 MaxSAT Evaluation, we show that with the proposed techniques the top solver combination solves significantly more instances.
• Marc Pfeifer, Benjamin Völker, Sebastian Böttcher, Sven Köhler, Philipp M Scholl
  Teaching Embedded Systems by Constructing an Escape Room
  2021 In Proceedings of the 52nd ACM Technical Symposium on Computer Science Education (SIGCSE ’21), Virtual Event, New York, USA ACM
  » show abstract« hide abstract
  Abstract

  Embedded systems form the basis of many of today's consumer products and industrial applications - and they are increasingly connected. To teach this topic, we created a course with the overarching goal of designing and constructing an automated escape room. This provided the motivation for the students to learn the engineering and soft skills required for building networked embedded systems. The game was open for faculty members and friends of the students after course completion. By splitting the building process into multiple tasks, such as individual puzzles, the presented concept encourages inter- and intra-group work, including conceptualizing, designing and developing reliable, connected embedded systems. In this paper we first present the motivation, context, and pedagogical approach of the course. We then describe the course structure and conclude with experiences from constructing an escape room as a group.
  
  
   
  Download file
• Christoph Scholl, Alexander Konrad, Alireza Mahzoon, Daniel Große, Rolf Drechsler
  Verifying Dividers Using Symbolic Computer Algebra and Don’t Care Optimization
  2021 DATE, IEEE
  » show abstract« hide abstract
  Abstract

  In this paper we build on methods based on Symbolic Computer Algebra that have been applied successfully to multiplier verification and more recently to divider verification as well. We show that existing methods are not sufficient to verify optimized non-restoring dividers and we enhance those methods by a novel optimization method for polynomials w. r. t. satisfiability don’t cares. The optimization is reduced to Integer Linear Programming (ILP). Our experimental results show that this method is the key for enabling the verification of large and optimized non-restoring dividers (with bit widths up to 512).

2020

 back to the year overview

• Bast H, Brosi P, Näther M
  Similarity Classification of Public Transit Stations
  2020 arXiv
  » show abstract« hide abstract
  Abstract

  We study the following problem: given two public transit station identifiers and , each with a label and a geographic coordinate, decide whether and describe the same station. For example, for "St Pancras International" at (51.5306, −0.1253) and "London St Pancras" at (51.5319, −0.1269), the answer would be "Yes". This problem frequently arises in areas where public transit data is used, for example in geographic information systems, schedule merging, route planning, or map matching. We consider several baseline methods based on geographic distance and simple string similarity measures.We also experiment with more elaborate string similarity measures and manually created normalization rules. Our experiments show that these baseline methods produce good, but not fully satisfactory results. We therefore develop an approach based on a random forest classifier which is trained on matching trigrams between two stations, their distance, and their position on an interwoven grid. All approaches are evaluated on extensive ground truth datasets we generated from OpenStreetMap (OSM) data: (1) The union of Great Britain and Ireland and (2) the union of Germany, Switzerland, and Austria. On all datasets, our learning based approach achieves an F1 score of over 99%, while even the most elaborate baseline approach (based on TFIDF scores and the geographic distance) achieves an F1 score of at most 94%, and a naive approach of using a geographical distance threshold achieves an F1 score of only 75%. Both our training and testing datasets are publicly available1.
  
  
   
  Download file as PDF
• Bast H, Brosi P, Näther M
  staty: Quality Assurance for Public Transit Stations in OpenStreetMap
  2020 Sigspatial
  » show abstract« hide abstract
  Abstract

  We present staty, a browser-based tool for quality assurance of public transit station tagging in OpenStreetMap (OSM). Building on the results of a similarity classifier for these stations, our tool visualizes name tag errors as well as incorrect and/or missing station group relations. Detailed edit suggestions are provided for individual objects. This is done intrinsically without an external ground truth. Instead, the underlying classifier is trained on the OSM data itself. We describe how our tool derives errors and suggestions from station tag similarities and provide experimental results on the OSM data of the United Kingdom, the United States, and a dataset consisting of Germany, Switzerland, and Austria. Our tool can be accessed under https://staty.cs.uni-freiburg.de.
• Bast H, Hertel M, Mostafa M
  Tokenization Repair in the Presence of Spelling Errors
  2020 arXiv
  » show abstract« hide abstract
  Abstract

  We consider the following tokenization repair problem: Given a natural language text with any combination of missing or spurious spaces,correct these. Spelling errors can be present,but it’s not part of the problem to correct them. For example, given: “Tispa per is about tokenizaion repair”, compute “Tis paper is about tokenizaion repair”.It is tempting to think of this problem as a special case of spelling correction or to treat the two problems together. We make a case that tokenization repair and spelling correction should and can be treated as separate problems.We investigate a variety of neural models as well as a number of strong baselines. We identify three main ingredients to high-quality tokenization repair: deep language models with a bidirectional component, training the models on text with spelling errors, and making use of the space information already present.Our best methods can repair all tokenization errors on 97.5% of the correctly spelled test sentences and on 96.0% of the misspelled test sentences. With all spaces removed from the given text (the scenario from previous work),the accuracy falls to 94.5% and 90.1%, respectively. We conduct a detailed error analysis.
  
  
   
  Download file
• Merkle, Dominik, Schmitt, Annette, Reiterer, Alexander
  Concept of an autonomous mobile robotic system for bridge inspection
  2020 Conference "Remote Sensing Technologies and Applications in Urban Environments" <5, 2020 SPIE, SPIE, 2020 (Proceedings of SPIE 11535) Paper 115350A
  » show abstract« hide abstract
  Abstract

  Fraunhofer-Gesellschaft Concept of an autonomous mobile robotic system for bridge inspection Autor(en): Merkle, Dominik; Schmitt, Annette; Reiterer, Alexander Zugang: Postprint urn:nbn:de:0011-n-6032527 (17 MByte PDF) MD5 Fingerprint: 5cbbff9ccf7e32d405c888142f2850d4 Copyright Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited. Erstellt am: 9.10.2020 DOI: 10.1117/12.2570633 [Titel anhand dieser DOI in Citavi-Projekt übernehmen] Quelle Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.: Remote Sensing Technologies and Applications in Urban Environments V : 21-25 September 2020, Online Only Bellingham, WA: SPIE, 2020 (Proceedings of SPIE 11535) Paper 115350A, 16 S. Konferenz Conference "Remote Sensing Technologies and Applications in Urban Environments" <5, 2020, Online> Sprache Englisch Dokumentart Konferenzbeitrag, Elektronische Publikation Fraunhofer Institut Fraunhofer IPM (Institutshomepage) Schlagwörter mobile mapping; LiDAR; bridge inspection; sensor system; mobile robot Abstract In the next decade, many old bridges will be exposed to increasing traffic loads and destructive environmental conditions. Measurement methods like laser scanning, infrared thermography, photogrammetry, ground penetrating radar, or ultrasonic scanning are used on single robotic systems to partially support the inspectors. However, time-consuming manual inspections for crack detection, measurement, and documentation are still necessary. This paper describes the concept of an autonomous mobile robotic bridge inspection system. The proposed concept for an unmanned ground vehicle (UGV) is achieved by a trade-off of different mobile platforms, sensor systems for mapping, localization and inspection, and fist tests assessing the feasibility. We use a small concrete bridge in Freiburg (Germany) with various cracks for testing the sensors, the UGV concept, and initial tests of the mobile platform. This results in the choice of selecting the weatherproof version of the mobile robotic platform Husky from Clearpath Robotics. It is equipped with Swift Navigation's Duro real-time kinematic (RTK) system, a heading system, an inertial measurement unit (IMU), a base station, and software for semi-autonomous navigation. In the next step, we compare different sensor systems. For mapping and localization, we decide to use the 360 spherical camera Ladybug 5+ from FLIR Systems and a Velodyne VLP-16 light detection and ranging (LiDAR). High-resolution cameras allow recording damages on the bridge's surface. We perform first tests using monochrome and colour cameras. After evaluating different sensor integration concepts, we present a preliminary design of the UGV including integrated sensors.
  
  
   
  Download file
• Magnús M. Halldórsson, Fabian Kuhn, Yannic Maus, Alexandre Nolin
  Coloring Fast Without Learning Your Neighbors' Colors.
  2020 34rd International Symposium on Distributed Computing (DISC)
  » show abstract« hide abstract
  Abstract

  We give an improved randomized CONGEST algorithm for distance-2 coloring that uses Δ²+1 colors and runs in O(log n) rounds, improving the recent O(log Δ ⋅ log n)-round algorithm in [Halldórsson, Kuhn, Maus; PODC '20]. We then improve the time complexity to O(log Δ) + 2^{O(√{log log n})}.
• Fabian Kuhn, Philipp Schneider
  Computing Shortest Paths and Diameter in the Hybrid Network Model.
  2020 39th ACM Symposium on Principles of Distributed Computing (PODC)
  » show abstract« hide abstract
  Abstract

  The HYBRID model, introduced in [Augustine et al., SODA '20], provides a theoretical foundation for networks that allow multiple communication modes. The model follows the principles of synchronous message passing, whereas nodes are allowed to use two fundamentally different communication modes. First, a local mode where nodes may exchange arbitrary information per round over edges of a local communication graph G (akin to the LOCAL model). Second, a global mode where every node may exchange O(log n) messages of size O(log n) bits per round with arbitrary nodes in the network. The HYBRID model intends to reflect the conditions of many real hybrid networks, where high-bandwidth but inherently local communication is combined with highly flexible global communication with restricted bandwidth. We continue to explore the power and limitations of the HYBRID model by investigating the complexity of computing shortest paths and diameter of the local communication graph G. We show that the all pair shortest paths problem can be solved exactly in [EQUATION] rounds, which improves on the previous Õ(n2/3) round algorithm and closes the gap to the known [EQUATION] lower bound (up to polylog n factors). Furthermore, we give constant approximations for the k-source shortest paths problem (k-SSP) with runtime [EQUATION], provided that k is sufficiently large. As k-SSP has a lower bound of [EQUATION] even for large approximation ratios, our k-SSP algorithms are almost tight for large enough k. In the case of a single source we give an exact Õ(n2/5)-round algorithm, improving on the known [EQUATION]-round algorithm for graphs with large diameter D. For the diameter problem we provide algorithms with complexities Õ(n1/3/ε) and Õ(n0.397/ε) and approximation factors (3/2 + ε) and (1 + ε), respectively. On the negative side, we demonstrate that the classical 2-party set-disjointness framework can be adapted for the HYBRID model to prove a lower bound of [EQUATION] rounds for computing the diameter exactly. For the weighted diameter problem the same holds for computing (2 − ε)-approximations for any ε > 0.
• Magnús M. Halldórsson, Fabian Kuhn, Yannic Maus
  Distance-2 Coloring in the CONGEST Model.
  2020 39th ACM Symposium on Principles of Distributed Computing (PODC)
  » show abstract« hide abstract
  Abstract

  We give efficient randomized and deterministic distributed algorithms for computing a distance-2 vertex coloring of a graph G in the CONGEST model. In particular, if Δ is the maximum degree of G, we show that there is a randomized CONGEST model algorithm to compute a distance-2 coloring of G with Δ2 + 1 colors in O(log Δ · log n) rounds. Further if the number of colors is slightly increased to (1 + ∈)Δ2 for some ∈ > 1/polylog n, we show that it is even possible to compute a distance-2 coloring deterministically in polylog n time in the CONGEST model. Finally, we give a O(Δ2 + log* n)-round deterministic CONGEST algorithm to compute distance-2 coloring with Δ2 + 1 colors.
• Alkida Balliu, Fabian Kuhn, Dennis Olivetti
  Distributed Edge Coloring in Time Quasi-Polylogarithmic in Delta.
  2020 39th ACM Symposium on Principles of Distributed Computing (PODC)
  » show abstract« hide abstract
  Abstract

  The problem of coloring the edges of an n-node graph of maximum degree Δ with 2Δ − 1 colors is one of the key symmetry breaking problems in the area of distributed graph algorithms. While there has been a lot of progress towards the understanding of this problem, the dependency of the running time on Δ has been a longstanding open question. Very recently, Kuhn [SODA '20] showed that the problem can be solved in time [EQUATION]. In this paper, we study the edge coloring problem in the distributed LOCAL model. We show that the (degree + 1)-list edge coloring problem, and thus also the (2Δ − 1)-edge coloring problem, can be solved deterministically in time 2O(log2 log Δ)+O(log*n). This is a significant improvement over the result of Kuhn [SODA '20].
• Mohamad Ahmadi, Fabian Kuhn
  Distributed Maximum Matching Verification in CONGEST.
  2020 34rd International Symposium on Distributed Computing (DISC)
  » show abstract« hide abstract
  Abstract

  We study the maximum cardinality matching problem in a standard distributed setting, where the nodes V of a given n-node network graph G = (V,E) communicate over the edges E in synchronous rounds. More specifically, we consider the distributed CONGEST model, where in each round, each node of G can send an O(log n)-bit message to each of its neighbors. We show that for every graph G and a matching M of G, there is a randomized CONGEST algorithm to verify M being a maximum matching of G in time O(|M|) and disprove it in time O(D + ), where D is the diameter of G and is the length of a shortest augmenting path. We hope that our algorithm constitutes a significant step towards developing a CONGEST algorithm to compute a maximum matching in time Õ(s^*), where s^* is the size of a maximum matching.
• Philipp Bamberger, Fabian Kuhn, Yannic Maus
  Efficient Deterministic Distributed Coloring with Small Bandwidth.
  2020 39th ACM Symposium on Principles of Distributed Computing (PODC)
  » show abstract« hide abstract
  Abstract

  We show that the (degree + 1)-list coloring problem can be solved deterministically in O(D · log n · log2 Δ) rounds in the CONGEST model, where D is the diameter of the graph, n the number of nodes, and Δ the maximum degree. Using the recent polylogarithmic-time deterministic network decomposition algorithm by Rozhoň and Ghaffari [49], this implies the first efficient (i.e., poly log n-time) deterministic CONGEST algorithm for the (Δ + 1)-coloring and the (degree + 1)-list coloring problem. Previously the best known algorithm required [EQUATION] rounds and was not based on network decompositions. Our techniques also lead to deterministic (degree + 1)-list coloring algorithms for the congested clique and the massively parallel computation (MPC) model. For the congested clique, we obtain an algorithm with time complexity O(log Δ · log log Δ), for the MPC model, we obtain algorithms with round complexity O(log2 Δ) for the linear-memory regime and O(log2 Δ + log n) for the sublinear memory regime.
• D. Merkle;, A. Schmitt;, A. Reiterer
  SENSOR EVALUATION FOR CRACK DETECTION IN CONCRETE BRIDGES
  2020 Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci., pages: 1107 - 1114
  » show abstract« hide abstract
  Abstract

  Bridges are one of the most critical traffic infrastructure objects, therefore it is necessary to monitor them at regular intervals. Nowadays, this monitoring is made manually by visual inspection. In recent projects, the authors are developing automated crack detection systems to support the inspector. In this pre-study, different sensors, like different camera systems for photogrammetry, a laser scanner, and a laser triangulation system are evaluated for crack detection based on a defined required minimum crack width of 0.2 mm. The used test object is a blasted concrete plate, sized 70 cm × 70 cm × 5 cm and placed in an outdoor environment. The results of the data acquisition with the different sensors are point clouds, which make the results comparable. The point cloud from the chosen laser scanner is not sufficient for the required crack width even at a low speed of 1 m/s. The RGB or intensity information of the photogrammetric point clouds, even based on a low-cost smartphone camera, contain the targeted cracks. The authors advise against using only the 3D information of the photogrammetric point clouds for crack detection due to noise. The laser triangulation system delivers the best results in both intensity and 3D information. The low weight of camera systems makes photogrammetry to the preferred method for an unmanned aerial vehicle (UAV). In the future, the authors aim for crack detection based on the 2D images, automated by using machine learning, and crack localisation by using structure from motion (SfM) or a positioning system.
  
  
   
  Download file
• Bast H, Brosi P, Storandt S
  Metro Maps on Octilinear Grid Graphs
  2020 EuroVis Eurographics Conference on Visualization, volume: 39, issue: 3
  » show abstract« hide abstract
  Abstract

  Schematic transit maps (often called "metro maps" in the literature) are important to produce comprehensible visualizations ofcomplex public transit networks. In this work, we investigate the problem of automatically drawing such maps on an octilineargrid with an arbitrary (but optimal) number of edge bends. Our approach can naturally deal with obstacles that should berespected in the final drawing (points of interest, rivers, coastlines) and can prefer grid edges near the real-world course of aline. This allows our drawings to be combined with existing maps, for example as overlays in map services. We formulate aninteger linear program which can be used to solve the problem exactly. We also provide a fast approximation algorithm whichgreedily calculates shortest paths between node candidates on the underlying octilinear grid graph. Previous work used localsearch techniques to update node positions until a local optimum was found, but without guaranteeing octilinearity. We canthus calculate nearly optimal metro maps in a fraction of a second even for complex networks, enabling the interactive use ofour method in map editors
• Ruther P
  LED-based optogenetic tools - Thin-film LEDs vs LED chips
  2020 Bionics Institute Melbourne, Melbourbe, Australia; Remote seminar talk
• Ruther P, Ayub S, Klein E, Sharma K, Paul O
  LED-Based Optogenetic Tools - Are Smallest LEDs Always Requested and Reasonable?
  2020 ICAN Workshop 2./3.3.2020, College of Health and Life Sciences at Hamad Bin Khalifa University, Doha, Qatar
  
   
  Download file as PDF
• Vilches S, Ataman C, Zappe H
  Non-contact endoscopic temperature measurement
  2020 Proceedings of SPIE, volume: 11233
• Feißt M, Wilde J
  Niedertemperatur-Verbindungstechnik für MEMS-Sensorbauelemente
  2020 Elektronische Baugruppen und Leiterplatten EBL 2020, Fellbach, ISBN 978-3-8007-5185-3, VDE VERLAG GMBH, volume: 94, pages: 199 - 203
• Kohler F, Wilde J
  Untersuchung der Einflussfaktoren zur Industrialisierung der Prozesse beim mediendichten Umspritzen von mechatronischen Komponenten
  2020 Elektronische Baugruppen und Leiterplatten EBL 2020, Fellbach, ISBN 978-3-8007-5185-3, VDE VERLAG GMBH, volume: 94, pages: 114 - 118
• Stieglitz T, Cvancara P, Mueller M, Ordonez JS
  Minaturized neural implants: towards longevity of compound systems.
  2020 Wissenschaftliches Symposium zur Einweihung des 3000. FIB/SEM Gerätes der Firma TESCAN am IMTEK , 11.02.2020, Freiburg (2020).
• Stieglitz T, Cvancara P, Mueller M, Liljemalm R, Erhardt J, Boehler C, Pfau J, Fiedler E, Ashouri Vajari D, Vomero M, Oliveira A, Kan S, Kiele P, Langenmair M, Pasluoasta C, Eickenscheidt M, Asplund M, Ordonez JS
  Miniaturized neural implants for interfacing with the brain
  2020 6th CiNet Conference: Brain-Machine Interface - Medical Engineering based on Neuroscience, Feb. 5-7, 2020, Osaka , Japan (2020). -
• Ruther P, Ayub S, Klein E, Sharma K, Paul O
  MEMS tools based on integrated light sources for optogenetics
  2020 beim Physikalisches Kolloquium, Institut für Physik, Universität Chemnitz
  
   
  Download file as PDF
• Stieglitz T
  Advanced Testing for future active implants.
  2020 Themenforum “Additive Medicine 4.0, Advanced Testing & Big Data” am Fraunhofer ITEM, 22.01.2020, Hannover (2020).
• Negassi M.,, Parupalli U.,, Suarez-Ibarrola R.,, Schmitt A.,, Hein S.,, Miernik A.,, Reiterer A.
  3D-Reconstruction and Semantic Segmentation of Cystoscopic Images
  2020 MICAD2020; Oxford, UK
  
   
  Download file
• Ruther P, Ayub S, Klein E, Sharma K, Paul O
  Optical MEMS tools based on light-emitting diodes for optogenetics
  2020 Max Planck Institute for Biological Cybernetics, Max-Planck-Ring 8, D-72076 Tübingen
• Fabian Kuhn
  Faster Deterministic Distributed Coloring Through Recursive List Coloring
  2020 31st ACM-SIAM Symp. on Discrete Algorithms (SODA)
  » show abstract« hide abstract
  Abstract

  We provide novel deterministic distributed vertex coloring algorithms. As our main result, we give a deterministic distributed algorithm to compute a (Δ + 1)-coloring of an n-node graph with maximum degree rounds. For graphs with arboricity a, we obtain a deterministic distributed algorithm to compute a (2 + o(1))a-coloring in time . Further, for graphs with bounded neighborhood independence, we show that a (Δ + 1)-coloring can be computed more efficiently in time . This in particular implies that also a (2Δ – 1)-edge coloring can be computed deterministically in rounds, which improves the best known time bound for small values of Δ. All results even hold for the list coloring variants of the problems. As a consequence, we also obtain an improved deterministic n-round algorithm for Δ-coloring non-complete graphs with maximum degree Δ ≥ 3. Most of our algorithms only require messages of O(log n) bits (including the (Δ + 1)-vertex coloring algorithms). Our main technical contribution is a recursive deterministic distributed list coloring algorithm to solve list coloring problems with lists of size Δ1+o(1). Given some list coloring problem and an orientation of the edges, we show how to recursively divide the global color space into smaller subspaces, assign one of the subspaces to each node of the graph, and compute a new edge orientation such that for each node, the list size to out-degree ratio degrades at most by a constant factor on each recursion level.
  
  
   
  Download file as PDF
• John Augustine, Kristian Hinnenthal, Fabian Kuhn, Christian Scheideler, Philipp Schneider
  Shortest Paths in a Hybrid Network Model
  2020 31st ACM-SIAM Symp. on Discrete Algorithms (SODA)
  » show abstract« hide abstract
  Abstract

  We introduce a communication model for hybrid networks, where nodes have access to two different communication modes: a local mode where (like in traditional networks) communication is only possible between specific pairs of nodes, and a global mode where (like in overlay networks) communication between any pair of nodes is possible. Typically, communication over short-range connections is cheaper and can be done at a much higher rate than communication via the overlay network. Therefore, we are focusing on the LOCAL model for the local connections where nodes can exchange an unbounded amount of information per round. For the global communication we assume the so-called nodecapacitated clique model, where in each round every node can exchange O(log n)-bit messages with O(log n) arbitrary nodes. We explore the impact of hybrid communication on the complexity of distributed algorithms by studying the problem of computing shortest paths in the graph given by the local connections. We present the following results. For the all-pairs shortest paths problem, we show that an exact solution can be computed in time Õ (n2/3), and that approximate solutions can be computed in time but not faster. For the single-source shortest paths problem an exact solution can be computed in time , where SPD denotes the shortest path diameter. Furthermore, a (l + o(1))-approximate solution can be computed in time . Finally, we show that for every constant ε > 0, it is possible to compute an O(1)-approximate solution in time.
  
  
   
  Download file as PDF
• L Nitzsche, J Goldschmidt, J Kießling, S Wolf, F Kühnemann, J Wöllenstein
  A Mid-Infrared Dual-Comb Spectrometer for High Sensitivity Multi-Component Trace Gas Detection
  2020 Frontiers in Optics, Washington, DC, United States, 14–17 September; Verlag: Optical Society of America, page: FW7B. 2
  » show abstract« hide abstract
  Abstract

  A dual-comb spectrometer with flexibility in spectral coverage, resolution and central wavelength where all affect sensitivity is optimized to simultaneously determine atmospheric concentration levels of CO 2 and N 2 O from spectra taken at 4470 nm.
• A. Brunauer, B. Breiner, S. Hennig, D. Kainz, R. Verboket, B. Johannsen, D. Baumgartner, K. Mitsakakis, L. Gutzweiler, Z. Shu, P. Koltay, T. Hutzenlaub, N. Paust, R. Zengerle, F. von Stetten, S. M. Früh
  Actuation principles for bioanalytical platforms to combat infectious diseases
  2020 Virtual EMBL Conference: Microfluidics: Designing the Next Wave of Biological Inquiry 2020, 13.-15.07.2020
• Murmann B, Verhelst M, Manoli Y
  Analog-to-Information Conversion
  In: NANO-CHIPS 2030 - On-Chip AI for an Efficient Data-Driven World
  2020, Springer, pages: 275 - 292, ISBN: 978-3-030-18338-7
• Benjamin Völker, Marc Pfeifer, Philipp M Scholl, Bernd Becker
  Annoticity: A Smart Annotation Tool and Data Browser for Electricity Datasets
  2020 5th International Workshop on Non-Intrusive Load Monitoring ACM
  » show abstract« hide abstract
  Abstract

  The growing request for eco-feedback and smart living concepts accelerated the development of Non-Intrusive Load Monitoring (NILM) algorithms during the last decade. Comparing and evaluating these algorithms still remains challenging due to the absence of a common benchmark datasets, and missing best practises for their application. Despite the fact that multiple datasets were recorded for the purpose of comparing NILM algorithms, many researchers still have to record their own dataset in order to meet the requirements of their specific application. Adding ground truth labels to these datasets is a cumbersome and time consuming process as it requires an expert to visually inspect all the data manually. Therefore, we propose the Annoticity inspection and labeling tool which simplifies the process of visualizing and labeling of electricity data. We use an event detector based on the log likelihood ratio test which achieved an F1 score of 90.07% in our experiments. Preliminary results indicate that the effort of generating event labels is reduced by 80.35% using our tool.
  
  
   
  Download file
• Kohler F, Wilde J
  Assembly Technologies for Piezoelectric Sensors up to 1000 °C
  2020 2020 IEEE 70th Electronic Components and Technology Conference (ECTC), Orlando, FL
• Post Regina, Niewelt Tim, Kwapil Wolfram, Schubert Martin C.
  Assessment of Influencing Factors on Lifetime-Based Defect Analysis
  2020 37th EU PVSEC , pages: 332 - 335
  » show abstract« hide abstract
  Abstract

  Since most detection methods are not sensitive enough to detect and characterize recombination active defects in silicon lifetime spectroscopy is an important method in silicon photovoltaics. It is a powerful tool, that can determine the defect parameters Et and k via the analysis of defect parameter solution surfaces. But despite being a crucial method there is no convention for the assessment of uncertainties. This work lines out a possible way to characterize the uncertainty of the method by a simulation of statistical noise onto lifetime curves following the Shockley-Read-Hall-statistics. The uncertainty analysis is done for one exemplary set of defect parameters. It outlines how prone to wrongful parametrization this method can be, if not conducted with great care. Thereby the suggested approach can act as a tool to decrease the uncertainty of the method by understanding, which influences are most crucial to control.
• J. F. Hess, M. Kotrová, S. Calabrese, T. Hutzenlaub, R. Zengerle, M. Brüggemann, N. Paust
  Automated library preparation for next generation sequencing of immunoglobulin gene rearrangements by centrifugal microfluidics
  2020 MicroTAS 2020, 04.-09.10.2020, virtual
• Farahani H, Wagiran R, Urban G
  Capacitive Properties of Ceramic Humidity Sensors Made from Porous Perovskite Films
  2020 IEEE SENSORS 2020
  » show abstract« hide abstract
  Abstract

  In this research, ceramic-based capacitive humidity sensors based on the barium strontium titanate perovskite nanocomposite and doped with the various concentrations of magnesia nanoparticles were fabricated and investigated. The particle size of the sensing elements is varied from 56 nm to 35 nm per dopant surcharges. The interaction between bulk perovskites (pellet) and water vapor was studied by impedance spectroscopy. Presence of the ionic transport even at low RH values is observed from the bulk frequency-capacitance spectra. The EIS results of the bulk sample confirm that the proton transfer operates only by charge transfer kinetics and not diffusion process to metals (up to 90% RH). Among all the proposed sensors, the device contains of 3 mol% magnesia exhibits the most capacitance change (21 pF – 25200 pF) with the sensitivity of 335 pF/RH% in the range of 20–95% RH, and a maximum hysteresis of 5.2% RH at 60% RH. The impact of rest of dopant values on the main perovskite is negative.
• F. Schlenker, E. Kipf, N. Borst, T. Hutzenlaub, N. Paust, R. Zengerle, F. von Stetten, P. Juelg
  Centrifugal microfluidic 4 Plex digital droplet PCR for quantification of circulating tumor DNA
  2020 MicroTAS 2020, 04.-09.10.2020, virtual
• F. Lombeck, F. Hegge, M. von Holst, C. Klose, S. Vierrath, M. Breitwieser
  Ceramic Nanofibers: A versatile material class to improve Electrochemical Energy Applications
  2020 71st International Society of Electrochemistry, Belgrad, Serbia (Online), 30.08. – 04.09.2020
• Hampson K, Cui J, Wincott M, Lane R, Hussain S, Banerjee K, Rajaeipour P, Zappe H, Ataman C, Booth M
  Closed-loop multiconjugate adaptive optics for microscopy
  2020 Adaptive Optics and Wavefront Control for Biological Systems VI
• Subbiah N, Schiffmacher A, Song X, Wilde J
  Comparison of Silver Sintered Assemblies on Non-DCB Substrates
  2020 CIPS 2020; 11th International Conference on Integrated Power Electronics Systems, Berlin, Germany, pp. 1-7.
  
   
  Download file
• Weber T, Zgierski-Johnston C, Klein E, Ayub S, Paul O, Kohl P, Ruther P
  Concentric MEMS-based Opto-electro-mechanical Pacer for Multimodal Cardiac Tissue Excitation
  2020 2020 IEEE 33rd International Conference on Micro Electro Mechanical Systems (MEMS), Vancouver, Canada
  » show abstract« hide abstract
  Abstract

  This paper reports on the fabrication, assembly, characterization and validation of a novel opto-electrical cardiac stimulator designed to augment a mechanical pacing device. The integration of miniaturized electrodes and blue light-emitting diode (LED) chips on the pacer tip with a diameter of 1 mm enables the application of multimodal stimuli in one location on the surface of isolated murine hearts. The opto-electrical stimulator is based on two separate polyimide (PI) substrates each with a thickness of 10 μm combined into a functional unit based on dedicated assembly and encapsulation processes using silicone rubber. The experimental validation in isolated, whole hearts compares electrical, optical and mechanical stimuli exerted at frequencies of up to 8 Hz on Langen-dorff-perfused hearts expressing channelrhodopsin-2. The integrated iridium oxide electrodes implemented above the LED chips enable simultaneous electrical recordings of local cardiac electrical activity.
• M. Liebmann, A. Treffer, M. Bock, U. Wallrabe, R. Grunwald
  Controlling the spectral rotation of ultra-short vortex pulses
  2020 SPIE OPTO 2020, San Francisco, CA, USA , volume: 112970W
• Uwe Wagschal, Thomas Metz, Thomas Waldvogel, Bernd Becker, Linus Feiten, Samuel Weishaupt
  Das »Debat-O-Meter« als neues Tool in der E-Partizipation
  In: Demokratie im 21. Jahrhundert
  2020, Nomos, pages: 341 - 368, ISBN: 978-3-7489-2150-9
• Schiffmacher A, Qelibari A, Rudzki R, Osterwald F, Wilde J
  Deformation Measurements during Active Operation of Power Modules with Novel Assembly and Packaging Technology
  2020 CIPS 2020; 11th International Conference on Integrated Power Electronics Systems, Berlin, Germany
  
   
  Download file
• Luderer C., Tutsch L., Messmer M., Bivour M., Hermle M.
  Doping Variation at the TCO/a-Si(p) Hole Contact
  In: 37th EU PVSEC
  2020, Proceedings of the 37th European Photovoltaic Solar Energy Conference and Exhibition, page: 493–496,
  » show abstract« hide abstract
  Abstract

  Resistive losses arise at the transport barriers at the interfaces between the different semiconductor materials in the TCO/a-Si/c-Si stack and limit the power output of silicon heterojunction (SHJ) solar cells. A key element is the unisotype recombination junction at the TCO/a-Si(p) interface. We identify sufficient doping on both sides of this junction to be crucial for low contact resistance ( c). For a-Si this is achieved by using a sufficient but not too high doping gas concentration during deposition. On the TCO side high oxygen (O2) gas concentrations during deposition have to be avoided. To combine high transparency of O2-rich TCOs with low c and Rsheet of O2-poor TCOs, we utilize a TCO layer stack. We show that a low O2 content in the vicinity of the TCO/a-Si(p) interface is mandatory to provide efficient tunnelling transport and to avoid resistive losses at the TCO/a-Si(p) interface.
• Luderer, C., Tutsch, L., Messmer, M., Bivour, M., Hermle, M.
  Doping Variation at the TCO/a-Si(p) Hole Contact
  2020 37th EU PVSEC , pages: 493 - 496
  » show abstract« hide abstract
  Abstract

  Resistive losses arise at the transport barriers at the interfaces between the different semiconductor materials in the TCO/a-Si/c-Si stack and limit the power output of silicon heterojunction (SHJ) solar cells. A key element is the unisotype recombination junction at the TCO/a-Si(p) interface. We identify sufficient doping on both sides of this junction to be crucial for low contact resistance ( c). For a-Si this is achieved by using a sufficient but not too high doping gas concentration during deposition. On the TCO side high oxygen (O2) gas concentrations during deposition have to be avoided. To combine high transparency of O2-rich TCOs with low c and Rsheet of O2-poor TCOs, we utilize a TCO layer stack. We show that a low O2 content in the vicinity of the TCO/a-Si(p) interface is mandatory to provide efficient tunnelling transport and to avoid resistive losses at the TCO/a-Si(p) interface.
• Minet Y, Breunig I, Buse K
  Electro-optic based adiabatic frequency conversion in a non-centrosymmetric microresonator
  2020 Laser Resonators, Microresonators, and Beam Control XXII, San Francisco, CA, United States Proceedings of SPIE, volume: 11266, page: 1126606
  » show abstract« hide abstract
  Abstract

  A rather unknown method to perform optical frequency tuning is the adiabatic frequency conversion. But this method has some appealing advantages compared to conventional frequency conversion schemes, i. e. nonlinear- optical based ones: The internal conversion efficiency can reach unity even on a single-photon level. No threshold and no phase-matching conditions need to be fulfilled. Previous realizations of adiabatic frequency conversion suffer from short photon lifetimes, limited tuning range and challenging experimental setups. Here, we employ the Pockels effect for adiabatic frequency conversion (AFC) in a non-centrosymmetric ultrahigh-Q microresonator made out of lithium niobate. With a 70-μm-thick resonator we observe frequency shifts of more than 5 GHz by applying a moderate voltage of 20V. In contrast to former schemes our setup is considerably simplified and provides a linear electric-to-optical link that enables us to generate also arbitrary waveforms of frequency shifts. Furthermore, our presented conversion scheme is well-suited for on-chip fabrication. Volume fabrication and application of larger electric fields for reasonable voltages become possible. By doing this, it is feasible to achieve tuning on the order of hundreds of GHz.
• M. Trotter, N. Borst, R. Thewes, F. von Stetten
  Electrochemical DNA sensing – Principles, commercial systems, and applications
  2020 Biosens Bioelectron, volume: 154, page: 112069
  » show abstract« hide abstract
  Abstract

  Driven by the vision of robust and portable, yet sensitive DNA detection systems for point-of-need applications, the development of electrochemical DNA sensing principles has been of high interest. Many different principles have been developed and these are regularly reviewed. However, the maturity of electrochemical principles and their ability to produce competitive real-world applications is rarely assessed. In this review, general electrochemical DNA sensing principles are briefly introduced and categorized into heterogeneous vs. homogeneous approaches, and then the subcategories label-free vs. labeled and reagent-less vs. reagent-dependent principles. We then focus on reviewing the electrochemical sensing principles implemented in DNA detection systems, which are commercially available or close to market entry, considering the complete analysis process, automation and the field of application. This allows us to outline and discuss which principles have proved suitable for which kinds of applications, as well as the stage of integration and automation. Examples from all the identified categories of electrochemical DNA sensing principles have found application in commercial detection systems or advanced prototypes. Various applications have already been demonstrated, ranging from on-site skin care testing, to food safety to the most frequent in vitro diagnostic tests, partially conducted in automated sample-to-answer devices. Our review is intended to enable researchers in areas related to electrochemistry, biochemistry or microfluidics to assess the commercial state of the art of electrochemical nucleic acid testing, and the interdisciplinary challenges for further improvements.
• Hehn T, Bleitner A, Goeppert J, Hoffmann D, Schillinger D, Sanchez D, Manoli Y
  Energy-Harvesting Applications and Efficient Power Processing
  In: NANO-CHIPS 2030 - On-Chip AI for an Efficient Data-Driven World
  2020, Springer, pages: 405 - 442, ISBN: 978-3-030-18338-7
• Becker, Denise;, Stemmler, Simon;, Reiterer, Alexander
  Entwicklung und Evaluierung eines kompakten Multisensorsystems für den Einsatz auf Drohnen
  In: Ingenieurvermessung 20 Beiträge zum 19. Internationalen Ingenieurvermessungskurs München, 2020
  2020, Wichmann, Thomas A. Wunderlich, pages: 99 - 108, Thomas A. Wunderlich, ISBN: 978-3-87907-672-7
• Benjamin Völker, Marc Pfeifer, Philipp M Scholl, Bernd Becker
  FIRED: A Fully-labeled hIgh-fRequency Electricity Disaggregation Dataset
  2020 The 7th ACM International Conference on Systems for Energy-Efficient Buildings, Cities, and Transportation Virtual Event Japan November, 2020 ACM
  » show abstract« hide abstract
  Abstract

  As more and more homes are equipped with smart electricity meters, home owners gain the ability to monitor their total electricity consumption on a daily or hourly basis. Techniques such as load forecasting, load disaggregation, and activity recognition try to provide even better insights into our electricity consumption, highlight saving potential or improve our daily living. To develop and evaluate these techniques, publicly available datasets are used. We identified a lack of high frequency fully labeled electricity datasets in the residential domain and present the FIRED dataset. It contains 52 of 8kHz aggregated current and voltage readings of the 3-phase supply of a typical residential apartment in Germany. The dataset also contains synchronized ground truth data as 2kHz readings of 21 individual appliances, as well as room temperature readings and fully labeled state changes of the lighting system, resulting in a complete and versatile residential electricity dataset.
• A Eberhardt, C Weber, L Bauersfeld, J Wöllenstein
  FT-IR Coupled Goniometer Setup for Characterization of the Spatial and Spectral Emission of IR-Sources
  2020 SMSI Sensors and Instrumentation (did not take place because of Covid-19 virus pandemic) Chapter: C4.5; AMA, pages: 177 - 178
  » show abstract« hide abstract
  Abstract

  We present a FT-IR coupled goniometer setup, which allows the simultaneous spatial and spectral characterization of optical components used in non-dispersive infrared gas sensor systems. The per-formance of the laboratory setup is demonstrated by comparing reflector and Fresnel lens equipped thermal infrared radiation sources. We show that even the simplest binary Fresnel lenses, when opti-mally designed, can achieve a thinner emission angle than parabolic mirrors at comparable radiation intensities.
• K. Tröndle, A. Itani, F. Koch, R. Zengerle, S. Zimmermann, P. Koltay
  Fabrication and fluidic integration of self-assembled cellular microtubules for nephron-on-chip applications
  2020 MicroTAS 2020, 04.-09.10.2020, virtual
• Szabados J, Breunig I, Buse K
  Frequency comb generation in non-centrosymmetric optical microresonators
  2020 Laser Resonators, Microresonators, and Beam Control XXII, San Francisco, CA, United States Proceedings of SPIE, volume: 11266, page: 112660G
  » show abstract« hide abstract
  Abstract

  Optical frequency combs are a key technology for precision measurements. In the past years, microresonatorbased frequency combs based on third-order χ (3) (Kerr) nonlinearities have attracted significant attention thanks to their small footprint and their wide-ranging applications in fields such as telecommunications, molecular spectroscopy or ultrafast distance measurements. In this contribution, we present a frequency comb generated in a microresonator made of 5% MgO-doped congruent lithium niobate, a non-centrosymmetric crystalline material, employing the generally much stronger second-order χ (2)-nonlinearities of such a material via a scheme of cascaded nonlinear processes. This approach paves the way towards reduced pump thresholds for comb generation and comes with intrinsic suitability for self-referencing.
• H. Nguyen, P. Heizmann, F. Lombeck, A. Belletti, B. Britton, S. Vierrath, M. Breitwieser
  Improving the Performance of All-Hydrocarbon PEM Fuel Cells Based on Pemion™ Ionomer
  2020 71st International Society of Electrochemistry, Belgrad, Serbia (Online), 30.08. – 04.09.2020
• R Bernhardsgrütter, C Hepp, M Jägle, H Pernau, K Schmitt, J Wöllenstein
  Inline Quality Monitoring of Diesel Exhaust Fluid (AdBlue) by Using the 3w-Method
  2020 SMSI Sensors and Instrumentation (did not take place because of Covid-19 virus pandemic) Chapter: A5.2; AMA, pages: 79 - 80
  » show abstract« hide abstract
  Abstract

  Quality monitoring of diesel exhaust fluid is crucial for optimal selective catalytic reduction in diesel combustion processes. This article presents a platinum thin film sensor using the 3ω-method to char-acterize the diesel exhaust fluid. The results show that this sensor can determine the urea content with in 1% by weight. An inline measurement is well applicable because the same structure can be used for both concentration and flow measurement.
• H. C. Ates, A. Brunauer, F. von Stetten, G. A. Urban, F. Güder, A. Merkoçi, S. M. Früh, C. Dincer
  Integrated Devices for Non‐Invasive Diagnostics
  2020 Advanced Functional Materials, volume: 2020, page: 2010388
  » show abstract« hide abstract
  Abstract

  “Sample‐in‐answer‐out” type integrated diagnostic devices have been widely recognized as the ultimate solution to simplify testing across healthcare systems. Such systems are equipped with advanced fluidic, mechanical, chemical, biological, and electronic components to handle patient samples without any manual steps therefore have the potential to accelerate intervention and improve patient outcomes. In this regard, the combination of integrated devices and non‐invasive sampling has gained a substantial interest to further improve the comfort and safety of patients. In this Review, the pioneering developments in integrated diagnostics are covered and their potential in non‐invasive sampling is discussed. The key properties of possible sample types are highlighted by addressing their relevance for the clinical practice. Last, the factors affecting the transition of integrated devices from academia to the market are identified by analyzing the technology readiness levels of selected examples and alternative remedies are explored to increase the rate of survival during this transition.
• A. Brunauer, H. Ceren Ates, C. Dincer, S. M. Früh
  Integrated paper-based sensing devices for diagnostic applications
  In: Comprehensive Analytical Chemistry
  2020, Elsevier,
  » show abstract« hide abstract
  Abstract

  Paper-based sensing platforms are one of the most powerful tools for point-of-care diagnostics. The ease of use while ensuring low production costs of such devices is the key for paper-based technologies to find their way to a successful commercialization. Thus, all steps in the analytical process chain from sample interface, sample preparation, signal amplification to signal transduction and data analysis have to be integrated in a single diagnostic platform. In this chapter, we provide a comprehensive and critical overview on recent developments towards integrated paper-based platforms in academia and industry. Herein, innovative solutions are discussed with respect to their sampling methods such as invasive and non-invasive approaches. We also address the requirements and challenges for the sampling and analysis of the different body fluids. Finally, we present our views about the future perspectives, challenges, and opportunities of the integrated paper-based devices.
• Breunig I, Buse K
  Juggling with light: powerful second-order nonlinear optical effects in whispering gallery resonators
  2020 Laser Resonators, Microresonators, and Beam Control XXII, San Francisco, CA, United States Proceedings of SPIE, volume: 11266, page: 1126609
  » show abstract« hide abstract
  Abstract

  Whispering gallery resonators made out of crystalline materials exhibiting second-order nonlinearities enable frequency mixing such as optical parametric oscillation with high efficiency at low optical input powers and are ideally suited to realize versatile and compact optical frequency converters. Recent achievements stimulate this field further: Frequency conversion not only at a single wavelength or with few wavelengths is possible, entire frequency combs can be transferred into different spectral domains, e.g., allowing the realization of frequency combs in spectral regions that are suitable for multicomponent analytics like the mid-infrared region. Furthermore, these resonators are also supposed to be the ideal host for cascaded nonlinearities allowing the build-up of frequency combs based on second-order nonlinearities. All this comes with new and better schemes to tune whispering gallery resonators, providing advanced opportunities to modulate the laser wavelengths with nanosecond speed employing the Pockels effect. Juggling with light: We will summarize in the presentation these recent achievements, demonstrating that in the field of whispering gallery resonators still many discoveries are ahead of us.
• Kwapil W., Dalke J., Niewelt T., Schubert M.
  LeTID- and (Extended) BO-Related Degradation and Regeneration in B- and Ga-Doped Monocrystalline Silicon during Dark and Illuminated Anneals
  In: 37th EU PVSEC
  2020, , page: 152–155,
  » show abstract« hide abstract
  Abstract

  We study the degradation effects of boron-oxygen related light-induced degradation (LID) and light- and elevated temperature-induced degradation (LeTID) on both B- and Ga-doped Cz-Si wafers from the same industrial producer. The wafers of the two doping types were subjected to the same sample processing and degradation conditions. The studied conditions include dark anneal (DA) at 175°C and illuminated anneals at 75°C and either 1 or 0.1 sun eq. illumination intensity, which allow a good direct comparison of the influence of the dopant elements on the degradation effects. We find an atypical injection dependence of LeTID in the Ga-doped samples compared to the “standard” behavior in B-doped silicon. The Ga-doped samples degrade strongly only when the carrier injection is low. Degradation of Ga-doped samples during DA is only observed on long timescales, resulting in an injection-dependent lifetime dissimilar to LeTID-degraded Ga-doped samples and B-doped samples after both DA and LeTID. The results indicate that the dopants have a strong influence on the degradation behavior.
• Kwapil W., Dalke J., Niewelt T., Schubert M.
  LeTID- and (Extended) BO-Related Degradation and Regeneration in B- and Ga-Doped Monocrystalline Silicon during Dark and Illuminated Anneals
  In: 37th EU PVSEC
  2020, , page: 152–155,
  » show abstract« hide abstract
  Abstract

  We study the degradation effects of boron-oxygen related light-induced degradation (LID) and light- and elevated temperature-induced degradation (LeTID) on both B- and Ga-doped Cz-Si wafers from the same industrial producer. The wafers of the two doping types were subjected to the same sample processing and degradation conditions. The studied conditions include dark anneal (DA) at 175°C and illuminated anneals at 75°C and either 1 or 0.1 sun eq. illumination intensity, which allow a good direct comparison of the influence of the dopant elements on the degradation effects. We find an atypical injection dependence of LeTID in the Ga-doped samples compared to the “standard” behavior in B-doped silicon. The Ga-doped samples degrade strongly only when the carrier injection is low. Degradation of Ga-doped samples during DA is only observed on long timescales, resulting in an injection-dependent lifetime dissimilar to LeTID-degraded Ga-doped samples and B-doped samples after both DA and LeTID. The results indicate that the dopants have a strong influence on the degradation behavior.
• Kwapil W., Dalke J., Niewelt T., Schubert M.
  LeTID- and (Extended) BO-Related Degradation and Regeneration in B- and Ga-Doped Monocrystalline Silicon during Dark and Illuminated Anneals
  In: 37th EU PVSEC
  2020, , page: 152–155,
  » show abstract« hide abstract
  Abstract

  We study the degradation effects of boron-oxygen related light-induced degradation (LID) and light- and elevated temperature-induced degradation (LeTID) on both B- and Ga-doped Cz-Si wafers from the same industrial producer. The wafers of the two doping types were subjected to the same sample processing and degradation conditions. The studied conditions include dark anneal (DA) at 175°C and illuminated anneals at 75°C and either 1 or 0.1 sun eq. illumination intensity, which allow a good direct comparison of the influence of the dopant elements on the degradation effects. We find an atypical injection dependence of LeTID in the Ga-doped samples compared to the “standard” behavior in B-doped silicon. The Ga-doped samples degrade strongly only when the carrier injection is low. Degradation of Ga-doped samples during DA is only observed on long timescales, resulting in an injection-dependent lifetime dissimilar to LeTID-degraded Ga-doped samples and B-doped samples after both DA and LeTID. The results indicate that the dopants have a strong influence on the degradation behavior.
• Kwapil W, Niewelt T, Schubert M, Dalke, J
  LeTID- and (Extended) BO-Related Degradation and Regeneration in B- and Ga-Doped Monocrystalline Silicon during Dark and Illuminated Anneals
  In: 37th EU PVSEC
  2020, Dalke et al., page: 152–155,
  » show abstract« hide abstract
  Abstract

  We study the degradation effects of boron-oxygen related light-induced degradation (LID) and light- and elevated temperature-induced degradation (LeTID) on both B- and Ga-doped Cz-Si wafers from the same industrial producer. The wafers of the two doping types were subjected to the same sample processing and degradation conditions. The studied conditions include dark anneal (DA) at 175°C and illuminated anneals at 75°C and either 1 or 0.1 sun eq. illumination intensity, which allow a good direct comparison of the influence of the dopant elements on the degradation effects. We find an atypical injection dependence of LeTID in the Ga-doped samples compared to the “standard” behavior in B-doped silicon. The Ga-doped samples degrade strongly only when the carrier injection is low. Degradation of Ga-doped samples during DA is only observed on long timescales, resulting in an injection-dependent lifetime dissimilar to LeTID-degraded Ga-doped samples and B-doped samples after both DA and LeTID. The results indicate that the dopants have a strong influence on the degradation behavior.
• Kwapil W., Dalke J., Niewelt T., Schubert M.
  LeTID- and (Extended) BO-Related Degradation and Regeneration in B- and Ga-Doped Monocrystalline Silicon during Dark and Illuminated Anneals
  In: 37th EU PVSEC
  2020, , page: 152–155,
  » show abstract« hide abstract
  Abstract

  We study the degradation effects of boron-oxygen related light-induced degradation (LID) and light- and elevated temperature-induced degradation (LeTID) on both B- and Ga-doped Cz-Si wafers from the same industrial producer. The wafers of the two doping types were subjected to the same sample processing and degradation conditions. The studied conditions include dark anneal (DA) at 175°C and illuminated anneals at 75°C and either 1 or 0.1 sun eq. illumination intensity, which allow a good direct comparison of the influence of the dopant elements on the degradation effects. We find an atypical injection dependence of LeTID in the Ga-doped samples compared to the “standard” behavior in B-doped silicon. The Ga-doped samples degrade strongly only when the carrier injection is low. Degradation of Ga-doped samples during DA is only observed on long timescales, resulting in an injection-dependent lifetime dissimilar to LeTID-degraded Ga-doped samples and B-doped samples after both DA and LeTID. The results indicate that the dopants have a strong influence on the degradation behavior.
• J. F. Hess, T.A. Kohl, M. Kotrová, K. Roensch, T. Paprotka, V. Mohr, T. Hutzenlaub, M. Brüggemann, R. Zengerle, S. Niemann, N. Paust
  Library preparation for next generation sequencing: A review of automation strategies
  2020 Biotechnol Adv, page: 107537
  » show abstract« hide abstract
  Abstract

  Next generation sequencing is in the process of evolving from a technology used for research purposes to one which is applied in clinical diagnostics. Recently introduced high throughput and benchtop instruments offer fully automated sequencing runs at a lower cost per base and faster assay times. In turn, the complex and cumbersome library preparation, starting with isolated nucleic acids and resulting in amplified and barcoded DNA with sequencing adapters, has been identified as a significant bottleneck. Library preparation protocols usually consist of a multistep process and require costly reagents and substantial hands-on-time. Considerable emphasis will need to be placed on standardisation to ensure robustness and reproducibility. This review presents an overview of the current state of automation of library preparation for next generation sequencing. Major challenges associated with library preparation are outlined and different automation strategies are classified according to their functional principle. Pipetting workstations allow high-throughput processing yet offer limited flexibility, whereas microfluidic solutions offer great potential due to miniaturisation and decreased investment costs. For the emerging field of single cell transcriptomics for example, microfluidics enable singularisation of tens of thousands of cells in nanolitre droplets and barcoding of the RNA to assign each nucleic acid sequence to its cell of origin. Finally, two applications, the characterisation of bacterial pathogens and the sequencing within human immunogenetics, are outlined and benefits of automation are discussed.
• Gaiser P., Klingler M, Wilde J
  Lifetime model for the fatigue fracture in Cu/Al2O3/Cu composites: experimental validation of a substantial lifetime enhancement by Cu step etching
  2020 Journal of Electronic Packaging
• Hafner J, Moazenzadeh A, Heinen F, Rodriguez M, Wallrabe U, Paul O
  Long-range telemetric smart orthodontic bracket with CMOS-integrated 3D wirebonder-fabricated microcoils
  2020 IEEE 33rd International Conference on Micro Electro Mechanical Systems (MEMS), Vancouver, Canada , pages: 1266 - 1269
  » show abstract« hide abstract
  Abstract

  This paper reports a novel telemetric smart bracket (TSB) for in vivo force/moment measurements during clinical orthodontic applications. The prototype implements a novel microcoil design resulting in a significant increase of the transmission distance compared to the previous state-of-the-art TSB. Using an automatic wirebonder, the microcoil is wound around an SU-8 post attached to the CMOS sensor wafer. For the first time, thus, 3D wirebonder-fabricated microcoils were integrated on a CMOS substrate, without compromising CMOS functionality. The augmented CMOS system serves here as a force/moment measurement device with six-degree-of-freedom (fx, fy, fz, mx, my, mz) functionality. The achieved transmission distance, i.e. coil-to-coil distance, was thereby increased by 80% compared to the best previous design to 5 mm, without the need for the system to exceed the severe size constraints of 2×2.8×1 mm 3 defined by the bracket dimensions. The increased transmission distance allows uncritical contactless system powering and readout.
• F. Schlenker, E. Kipf, M. Deuter, I. Hoeffkes, N. Borst, T. Hutzenlaub, R. Zengerle, F. von Stetten, N. von Bubnoff, P. Juelg
  Low optimization effort for highly sensitive assays for point mutation quantification in CTDNA: the Mediator Probe digital PCR
  2020 Liquid Biopsy Symposium, 30.10.2020, virtuell
• P Nitzsche, C Dinc, J Wöllenstein, K Schmitt
  Measurement of 13C and 18O Ratio in CO2 using Quantum Cascade Laser based Tunable Absorption Spectroscopy
  2020 SMSI Sensors and Instrumentation (did not take place because of Covid-19 virus pandemic) Chapter: C4; AMA, pages: 175 - 176
  » show abstract« hide abstract
  Abstract

  We present a spectroscopic approach for measurements of 13C and 18O isotopic ratio in carbon dioxide (CO2) gas using a quantum cascade laser (QCL). A narrow linewidth mid-infrared QCL is continuously scanned across three absorption lines of CO2 near 2310 cm-1 including 12C16O2, 13C16O2 and 16O12C18O isotopes. The simultaneous detection of three spectral lines permits the determination of simple concentration ratios (R13 and R18) in atmospheric CO2. With an averaging time of about 10 s both R13 and R18 reach a precision of 0.2‰ and 0.1‰, respectively.
• González G, Stein P, Kretschmer S, Bauer C, Sandic D, Ataman C, Zappe H
  Micro-structured glass probe for endoscopic Optical Coherence Tomography
  2020 SPIE Photonics Europe, 2020, France , volume: 11359
• P. Koch, O. Barth, M. Meyer, R. Streller, R. Zengerle, M. Rombach, M. Jehle
  Microthermoforming: Enhancing blister technology to introduce microstructures in functional packaging
  2020 12. European Thermoforming Conference, Geneva, Switzerland, 18.-20.03.2020
• C Weber, E El-Safoury, C Pannek, L Engel, A Eberhardt, M Bauersfeld, J Wöllenstein
  Multispectral Readout System for Detecting Tiny Color Changes of Gas Sensitive Colorimetric Dyes
  2020 SMSI (did not take place because of Covid-19 virus pandemic) ECS - The Electrochemical Society, pages: 205 - 206
  » show abstract« hide abstract
  Abstract

  The detection of flammable gases is necessary to avoid explosive atmospheres. For this reason, low-cost pellistors are frequently used sensors, although they suffer from high operation temperatures and high power consumption. Within the scope of our work, we present a novel wireless low-power catalytic gas sensor system for flammable gases. The combination of a MEMS-based sensor and low power radio system provide the opportunity to monitor complex infrastructures without using the grid for power supply.
• M. Breitwieser, S. Vierrath
  One for all or one for each application? Recent advances in membrane & ionomer development for electrochemical energy converters
  2020 E3C Electrochemical Cell Concepts Colloquium Fraunhofer UMSICHT, 14.05.2020
• Folwill Y, Zappe H
  Optics and Photonics for Advanced Dimensional Metrology
  2020 Photonics Europe, 2020, France SPIE Digital Library, volume: 11352U
• Tobias Paxian, Bernd Becker
  Pacose: an iterative SAT-based MaxSAT solver
  2020 MaxSAT Evaluation 2020: Solver and Benchmark Descriptions, volume: 16, pages: 12 - 12
• Brunauer A, Ates H, Dincer C, Früh S
  Paper Based Sensors, Volume 89
  In: Integrated paper-based sensing devices for diagnostic applications
  2020, Elsevier B.V., pages: 1 - 54, ISBN: 9780444643452
  » show abstract« hide abstract
  Abstract

  Paper-based sensing platforms are one of the most powerful tools for point-of-care diagnostics. The ease of use while ensuring low production costs of such devices is the key for paper-based technologies to find their way to a successful commercialization. Thus, all steps in the analytical process chain from sample interface, sample preparation, signal amplification to signal transduction and data analysis have to be integrated in a single diagnostic platform. In this chapter, we provide a comprehensive and critical overview on recent developments towards integrated paper-based platforms in academia and industry. Herein, innovative solutions are discussed with respect to their sampling methods such as invasive and non-invasive approaches. We also address the requirements and challenges for the sampling and analysis of the different body fluids. Finally, we present our views about the future perspectives, challenges, and opportunities of the integrated paper-based devices.
• Pascal Raiola, Tobias Paxian, Bernd Becker
  Partial (un-) weighted MaxSAT benchmarks: minimizing witnesses for security weaknesses in reconfigurable scan networks
  2020 MaxSAT Evaluation 2020, volume: 14, pages: 44 - 44
• E. Cruz Ortiz, F. Hegge, M. Breitwieser, S. Vierrath
  Performance Improvement of PEM Water Electrolyzer Anodes via a Bi-Functional Binder Polymer Blends for Ionic and Electrical Conduction
  2020 71st International Society of Electrochemistry, Belgrad, Serbia (Online), 30.08. – 04.09.2020
• S Wolf, T Trendle, N Catalan, J Kießling, J Wöllenstein, F Kühnemann
  Photothermal Common-Path Interferometry for Trace Gas Detection
  2020 Laser Applications to Chemical, Security and Environmental Analysis, DC, United States, 22-26 June; Verlag: Optical Society of America, page: LTu3C.3
  » show abstract« hide abstract
  Abstract

  Photothemal common-path interferometty is used for sensitive infrared gas spectroscopy. Numerical modeling of the effect is validated by experimental results. The method enables compact sensor systems that operate largely independent of the achral excitation wavelength.
• Schäfer M, Tranberg B, Greiner M
  Power flows in complex renewable energy networks
  In: Discoveries at the Frontiers of Science
  2020, Springer, pages: 239 - 251,
• M. Rombach, S. Hin, M. Specht, B. Johannsen, J. Lüddecke, N. Paust, R. Zengerle, K. Mitsakakis
  RespiDisk: A Point-of-Care platform for fully automated detection of respiratory tract infection pathogens in clinical samples
  2020 MicroTAS 2020, 04.-09.10.2020, virtual
• Tobias Paxian, Mael Gay, Devanshi Upadhyaya, Bernd Becker, Ilia Polian
  SAT Benchmarks of AutoFault Attacking AES, LED and PRESENT
  2020 SAT COMPETITION 2020, volume: 20, pages: 79 - 79
• Behrmann O, Bachmann I, Hufert F, Dame G
  Schnellnachweis von SARS-CoV-2 mit recombinase polymerase amplification
  BIOSpektrum, 2020
• Heimsath A, Sutardhio C, Schöttl P, Nitz P
  Soiling of Solar Mirrors - Impact of Incidence Angles on CSP Plant Performance
  2020 25th Solar Power And Chemical Energy Systems International Symposium SolarPACES 2019 25th Solar Power And Chemical Energy Systems International Symposium SolarPACES, volume: 1
• Christoph Scholl, Alexander Konrad
  Symbolic Computer Algebra and SAT Based Information Forwarding for Fully Automatic Divider Verification
  2020 Design Automation Conf., pages: 1 - 6
  » show abstract« hide abstract
  Abstract

  During the last few years Symbolic Computer Algebra (SCA) delivered excellent results in the verification of large integer and finite field multipliers at the gate level. In contrast to those encouraging advances, SCA-based divider verification has been still in its infancy and awaited a major breakthrough. In this paper we analyze the fundamental reasons that prevented the success for SCA-based divider verification so far and present SAT Based Information Forwarding (SBIF). SBIF enhances SCA-based backward rewriting by information propagation in the opposite direction. We successfully apply the method to the fully automatic formal verification of large non-restoring dividers.
• O Yurchenko, H-F Pernau, L Engel, B Bierer, M Jägle, J Wöllenstein
  Systematic Investigations on the Reaction Potential of Catalytic Sensor Materials
  2020 SMSI (did not take place because of Covid-19 virus pandemic) ECS - The Electrochemical Society, pages: 201 - 202
  » show abstract« hide abstract
  Abstract

  We present Simultaneous Thermal Analysis (STA) as a systematic approach for investigation of cata-lytic activity at ideal conditions and for thermal stability. The investigations were performed on different cobalt oxide samples differing in particle size, which is a promising catalyst for methane oxidation. The obtained results demonstrate the reliability of the method for preselection of catalysts for their applica-tion in catalytic gas sensors.
• Schiffmacher A, C. Kempiak, J. Rudzki, F. Osterwald, A. Lindemann, Wilde J.
  Thermomechanical Deformations of Power Modules with Sintered Metal Buffer Layers under Consideration of the Operating Time and Conditions
  2020 IEEE 70th Electronic Components and Technology Conference (ECTC), Orlando, FL, USA, 2020, pp. 561-567
  
   
  Download file
• Alireza Mahzoon, Daniel Große, Christoph Scholl, Rolf Drechsler
  Towards Formal Verification of Optimized and Industrial Multipliers
  2020 Conference on Design, Automation and Test in Europe (DATE), pages: 544 - 549
  » show abstract« hide abstract
  Abstract

  Formal verification methods have made huge progress over the last decades. However, proving the correctness of arithmetic circuits involving integer multipliers still drives the verification techniques to their limits. Recently, Symbolic Computer Algebra (SCA) methods have shown good results in the verification of both large and non-trivial multipliers. Their success is mainly based on (1) reverse engineering and identifying basic building blocks, (2) finding converging gate cones which start from the basic building blocks and (3) early removal of redundant terms (vanishing monomials) to avoid the blow-up during backward rewriting. Despite these important accomplishments, verifying optimized and technology-mapped multipliers is an almost unexplored area. This creates major barriers for industrial use as most of the designs are area and delay optimized. To overcome the barriers, we propose a novel SCA-method which supports the formal verification of a large variety of optimized multipliers. Our method takes advantage of a dynamic substitution ordering to avoid the monomial explosion during backward rewriting. Experimental results confirm the efficiency of our approach in the verification of a wide range of optimized multipliers including industrial benchmarks.
• S. Koch, C. Klose, B. Britton, M. Breitwieser, S. Vierrath
  Towards stable catalyst layers for water electrolysis based on anion-exchange membranes
  2020 71st International Society of Electrochemistry, Belgrad, Serbia (Online), 30.08. – 04.09.2020
• Breunig I, Herr S, Buse K
  Tunable single-frequency lasing in whispering gallery resonators
  2020 Laser Resonators, Microresonators, and Beam Control XXII, San Francisco, CA, United States Proceedings of SPIE, volume: 11266, page: 112660Q
  » show abstract« hide abstract
  Abstract

  Whispering gallery resonators (WGRs) are ideally suited for the realization of miniaturized lasers. Due to their high quality factor and small mode volume, they allow for low-threshold and narrow-linewidth emission from (sub)millimeter-sized cavities made of laser-active materials. However, so far the majority of experimental realizations relies on expensive pump light sources like narrow-linewidth or pulsed laser systems, impeding most applications. We demonstrate two whispering-gallery-based single-frequency lasers pumped by compact spectrally multimode low-cost laser diodes. The spheroidally-shaped millemeter-sized WGRs are made of Pr:LiLuF4 and Nd:YVO4. They provide quality factors beyond 107 at the lasing wavelengths (640 nm and 1064 nm, respectively). The pump light is focused onto the rim of the WGR. We observe single frequency emission at milliwatt output powers. The temporal stability of the output power and of the output frequency are determined to be ±1:5 % and ±30 MHz within 30 min, respectively. By changing the temperature of the cavity, we achieve mode-hop-free tuning exceeding 11 GHz.
• L Nitzsche, J Kießling, S Wolf, F Kühnemann, J Wöllenstein
  Ultra-fast gas spectroscopy with a dual-comb spectrometer
  2020 SMSI Sensors and Instrumentation (did not take place because of Covid-19 virus pandemic) Chapter: B4.4; AMA, pages: 123 - 124
  » show abstract« hide abstract
  Abstract

  Dual-comb spectroscopy has the potential to measure broadband transmission spectra fast and precisely. To employ these features for gas analysis we present a fiber-based dual-comb-spectrometer and compare the spectrum of an HCN filled cell with a simulation using the HITRAN database. Although point-to-point fluctuations across the spectrum show a rms of 4% fit results indicate that absorptions features with (α* L)= 0.01 can be detected within measurement time of 0.5 ms.
• Reiterer, Alexander, Störk, Dominik, Wäschle, Katharina, Leydecker, Achim
  Vollautomatisierte Auswertung von Mobile-Mapping-Daten mithilfe von Machine Learning
  In: Ingenieurvermessung 20 Beiträge zum 19. Internationalen Ingenieurvermessungskurs München, 2020
  2020, Wichmann, Thomas A. Wunderlich, pages: 141 - 147, Thomas A. Wunderlich, ISBN: 978-3-87907-672-7
• B Bierer, J Wöllenstein, O Yurchenko, L Engel, H Pernau, L Reindl, D Grgic
  Wireless low-power warning system for the detection of flammable gases
  2020 SMSI Sensors and Instrumentation (did not take place because of Covid-19 virus pandemic) Chapter: B4.3; AMA, pages: 121 - 122
  » show abstract« hide abstract
  Abstract

  The detection of flammable gases is necessary to avoid explosive atmospheres. For this reason, low-cost pellistors are frequently used sensors, although they suffer from high operation temperatures and high power consumption. Within the scope of our work, we present a novel wireless low-power catalytic gas sensor system for flammable gases. The combination of a MEMS-based sensor and low power radio system provide the opportunity to monitor complex infrastructures without using the grid for power supply.
• Schiffmacher A, Strahringer D, Kempiak C, Rudzki J, Osterwald F, Lindemann A, Wilde J
  Zuverlässigkeitsuntersuchungen von Leistungsmodulen mit neuartiger Aufbau- und Verbindungstechnik
  2020 49. Kolloquium Leistungshalbleiter-Bauelemente und ihre systemtechnische Integration
• B. Johannsen
  id Diagnosis of Respiratory Tract Infections Using a Point-of-Care Platform Incorporating a Clinical Decision Support Algorithm
  2020 pHealth2020, 14. – 16. 09. 2020