@article{PangerlMuellerRuecketal., author = {Pangerl, Jonas and M{\"u}ller, Max and R{\"u}ck, Thomas and Weigl, Stefan and Bierl, Rudolf}, title = {Characterizing a sensitive compact mid-infrared photoacoustic sensor for methane, ethane and acetylene detection considering changing ambient parameters and bulk composition (N2, O2 and H2O)}, series = {Sensors and Actuators B: Chemical}, volume = {352,1}, journal = {Sensors and Actuators B: Chemical}, publisher = {Elsevier}, doi = {10.1016/j.snb.2021.130962}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-25868}, pages = {1 -- 12}, abstract = {We present a sensitive and compact interband cascade laser (ICL) based photoacoustic setup for the detection of gaseous hydrocarbons and discuss its applicability towards trace gas analysis. We investigated the performance of the sensor for trace concentrations of methane, ethane and acetylene diluted in nitrogen. The excitation of methane and ethane was accomplished using one tunable diode laser, covering a range from 3360 to 3372 nm, which was replaced by a separate ICL at 3025 nm for acetylene detection. The influence of ambient parameters such as temperature, flow rate and pressure as well as potential cross-sensitivities towards O2 and H2O have been examined in terms of methane and acetylene detection. A series of simulations proved several of these influences to be attributed to relaxation effects. With a 3σ limit of detection (LoD) of 6.8 parts per billion (ppbV) in case of methane, 2.3 ppbV regarding ethane and 3.6 ppbV in terms of acetylene, the sensor demonstrates a great potential for applications in the field of trace gas analysis.}, language = {en} } @article{MuellerRueckJobstetal., author = {M{\"u}ller, Max and R{\"u}ck, Thomas and Jobst, Simon and Pangerl, Jonas and Weigl, Stefan and Bierl, Rudolf and Matysik, Frank-Michael}, title = {An Algorithmic Approach to Compute the Effect of Non-Radiative Relaxation Processes in Photoacoustic Spectroscopy}, series = {Photoacoustics}, volume = {26}, journal = {Photoacoustics}, publisher = {Elsevier}, doi = {10.1016/j.pacs.2022.100371}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-39935}, abstract = {Successful transfer of photoacoustic gas sensors from laboratory to real-life applications requires knowledge about potential cross-sensitivities towards environmental and gas matrix changes. Multi-dimensional calibration in case of cross-sensitivities can become very complex or even unfeasible. To address this challenge, we present a novel algorithm to compute the collision based non-radiative efficiency and phase lag of energy relaxation on a molecular level (CoNRad) for photoacoustic signal calculation. This algorithmic approach allows to calculate the entire elaxation cascade of arbitrarily complex systems, yielding a theoretical photoacoustic signal. In this work the influence of varying bulk compositions, i.e. nitrogen (N2), oxygen (O2) and water (H2O) on the photoacoustic signal during methane (CH4) detection is demonstrated. The applicability of the algorithm to other photoacoustic setups is shown exemplary by applying it to the relaxational system investigated in [1]. Hayden et al. examined the effect of water on photoacoustic carbon monoxide (CO) detection.}, language = {en} } @inproceedings{MelekhovAbbLechneretal., author = {Melekhov, Evgeny and Abb, Valerius and Lechner, Alfred and Kammler, Martin}, title = {Development of a glass-fiber-based spectrometer for the determination of drug residues in groundwater}, series = {Tagungsband 2. Symposium Elektronik und Systemintegration ESI 2020 "Intelligente Systeme und ihre Komponenten: Forschung und industrielle Anwendung"}, booktitle = {Tagungsband 2. Symposium Elektronik und Systemintegration ESI 2020 "Intelligente Systeme und ihre Komponenten: Forschung und industrielle Anwendung"}, editor = {Ivanov, Artem and Bicker, Marc and Patzelt, Peter}, isbn = {978-3-9818439-4-1}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:860-opus4-2174}, pages = {101 -- 109}, abstract = {Within the scope of this project, a portable measuring device has been developed which enables a cost-effective analysis of organic substances from ppm to sub-ppm range, such as drug residues in groundwater. The measurement is carried out by means of a surface-enhanced Raman scattering effect (SERS effect) and an exchangeable sensor head. The sensor head used is a nanostructured optical glass fiber glued into a fiber cannula. The tip of the fiber has been processed to act as a SERS cell. The fiber cannula is connected to a freely movable patch cable by using an adapter. Para-thiocresol is used to characterize the SERS cells.}, language = {en} } @inproceedings{SchererVitzthumeckerBierl, author = {Scherer, Leo and Vitzthumecker, Thomas and Bierl, Rudolf}, title = {Capacitive PCB sensor for the detection of insects in intelligent traps}, series = {Applied Research Conference 2022 Conference Proceedings: 4th July 2022, University of Applied Sciences Ansbach (Onsite Conference)}, booktitle = {Applied Research Conference 2022 Conference Proceedings: 4th July 2022, University of Applied Sciences Ansbach (Onsite Conference)}, editor = {Uhl, Christian and Walter, Michael and Stiehl, Annika}, publisher = {Hochschule Ansbach}, address = {Ansbach}, doi = {10.25929/qbwt-zf40}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-55837}, pages = {519 -- 523}, abstract = {Reliable and fast detection of pest in the food processing and pharmaceutical industry is crucial to ensure hygienically safe, pure and healthy products. This is why intelligent traps, that are able to detect insects automatically are needed. For this, a capacitive PCB sensor is developed and tested, which could be a simplistic, low power solution to the problem. This includes design, footprint generation and simulation as well as testing different types of capacitve sensing against noise immunity and sensitivity to Blattella germanica, the German cockroach. It is shown that a single specimen can very well and reliably be detected by the developed sensor.}, language = {en} } @article{SerbunBornmannNavitskietal., author = {Serbun, Pavel and Bornmann, Benjamin and Navitski, Aliaksandr and M{\"u}ller, G{\"u}nter and Prommesberger, Christian and Langer, Christoph and Dams, Florian and Schreiner, Rupert}, title = {Stable field emission of single B-doped Si tips and linear current scaling of uniform tip arrays for integrated vacuum microelectronic devices}, series = {Journal of Vacuum Science \& Technology B Nanotechnology and Microelectronics}, volume = {31}, journal = {Journal of Vacuum Science \& Technology B Nanotechnology and Microelectronics}, number = {2}, publisher = {AIP Publishing}, doi = {10.1116/1.4765088}, abstract = {Advanced Si-based semiconductor technology is most suitable to fabricate uniform nanostructures as integrated field emitter arrays for novel vacuum electronic devices. In order to improve the field emission homogeneity and stability of p-type silicon tip arrays for pulsed sensor applications, the authors have systematically studied the influence of the fabrication parameters on the tip shape and on the specific operating conditions. Based on detailed design calculations of the field enhancement, they have fabricated two series of hexagonal arrays of B-doped Si-tips in a triangular arrangement. The first (second) type contains three (four) patches with different number of tips (1, 91, 547 and 1, 19, 1027, 4447 for the first and second type, respectively) of about 1 (2.5) μm height, ∼20 (20) nm apex radius, and 20 (10) μm pitch. The field emission properties of both individual tips and complete arrays were investigated with a field emission scanning microscope at a pressure of 10-9 mbar. The current plateau of these tips typically occurs at about 10 (3) nA and around 65 (25) V/μm field level. In this carrier saturation range, single tips provide the highest current stability (<5\%) and optical current switching ratio (∼2.5). Fairly homogeneous emission of the tip arrays leads to an undershooting of the expected linear scaling of the mean plateau current as well as to a much improved current stability (<1\%).}, language = {en} } @misc{MelekhovAbbWeidaueretal., author = {Melekhov, Evgeny and Abb, Valerius and Weidauer, Tobias and Kammler, Martin and Lechner, Alfred}, title = {Tunable Nanopillars as Surface Enhanced Raman Scattering (SERS) Active Structure for Optical Quartz Glass Fiber}, series = {SMSI 2021 - Sensors and Instrumentation}, journal = {SMSI 2021 - Sensors and Instrumentation}, publisher = {AMA Association for Sensors and Measurement}, isbn = {978-3-9819376-4-0}, doi = {10.5162/SMSI2021/B8.2}, pages = {153 -- 154}, abstract = {In this work, a simple cost effective method to create tunable self-assembled three-dimensional nanostructure array-like nanoantennas on a tip of an optical quartz glass fiber is described. The structures are prepared using lithography-less dry etching. Gold nanoparticles are used as an etching mask using a thin metal-film thermal dewetting technique. The structures are applied as sensor for label-free analysis of organic substances in ppb range, such as drug residues in groundwater. The measurements are carried out by means of a Surface-enhanced Raman scattering (SERS) effect, an exchangeable sensor head, and a portable Raman device. This method allows in situ applications. Parathiocresol is used as a model substance to characterize the SERS cells. For metallization, gold and silver are compared. Reproducible SERS enhancement factors up to 10 7 are evaluated.}, language = {en} } @inproceedings{KhaledBruhnsReichlingetal., author = {Khaled, W. and Bruhns, Otto T. and Reichling, S. and B{\"o}se, Holger and Baumann, Michael and Monkman, Gareth J. and Egersd{\"o}rfer, Stefan and Meier, Alexander and Klein, Dagmar and Freimuth, Herbert and Ermert, Helmut}, title = {A haptic sensor-actuator-system based on ultrasound elastography and electrorheological fluids for virtual reality applications in medicine}, series = {CARS 2003 : computer assisted radiology and surgery ; proceedings of the 17th International Congress and Exhibition London, June 25 - 28, 2003}, booktitle = {CARS 2003 : computer assisted radiology and surgery ; proceedings of the 17th International Congress and Exhibition London, June 25 - 28, 2003}, publisher = {Elsevier}, address = {Amsterdam}, pages = {1354}, abstract = {Mechanical properties of biological tissue represent important diagnostic information and are of histological relevance (hard lesions, "nodes" in organs: tumors; calcifications in vessels: arteriosclerosis). The problem is, that such information is usually obtained by digital palpation only, which is limited with respect to sensitivity. It requires intuitive assessment and does not allow quantitative documentation. A suitable sensor is required for quantitative detection of mechanical tissue properties. On the other hand, there is also some need for a realistic mechanical display of those tissue properties. Suitable actuator arrays with high spatial resolution and real-time capabilities are required operating in a haptic sensor actuator system with different applications. The sensor system uses real time ultrasonic elastography whereas the tactile actuator is based on electrorheological fluids. Due to their small size the actuator array elements have to be manufactured by micro-mechanical production methods. In order to supply the actuator elements with individual high voltages a sophisticated switching and control concept have been designed. This haptic system has the potential of inducing real time substantial forces, using a compact lightweight mechanism which can be applied to numerous areas including intraoperative navigation, telemedicine, teaching, space and telecommunication.}, language = {en} } @article{BeckerRaikherStolbovetal., author = {Becker, Tatiana I. and Raikher, Yuriy L. and Stolbov, Oleg V. and B{\"o}hm, Valter and Zimmermann, Klaus}, title = {Magnetoactive elastomers for magnetically tunable vibrating sensor systems}, series = {Physical Sciences Reviews}, volume = {7}, journal = {Physical Sciences Reviews}, number = {10}, publisher = {de Gruyter}, issn = {2365-659X}, doi = {10.1515/psr-2019-0125}, pages = {1 -- 28}, abstract = {Magnetoactive elastomers (MAEs) are a special type of smart materials consisting of an elastic matrix with embedded microsized particles that are made of ferromagnetic materials with high or low coercivity. Due to their composition, such elastomers possess unique magnetic field-dependent material properties. The present paper compiles the results of investigations on MAEs towards an approach of their potential application as vibrating sensor elements with adaptable sensitivity. Starting with the model-based and experimental studies of the free vibrational behavior displayed by cantilevers made of MAEs, it is shown that the first bending eigenfrequency of the cantilevers depends strongly on the strength of an applied uniform magnetic field. The investigations of the forced vibration response of MAE beams subjected to in-plane kinematic excitation confirm the possibility of active magnetic control of the amplitude-frequency characteristics. With change of the uniform field strength, the MAE beam reveals different steady-state responses for the same excitation, and the resonance may occur at various ranges of the excitation frequency. Nonlinear dependencies of the amplification ratio on the excitation frequency are obtained for different magnitudes of the applied field. Furthermore, it is shown that the steady-state vibrations of MAE beams can be detected based on the magnetic field distortion. The field difference, which is measured simultaneously on the sides of a vibrating MAE beam, provides a signal with the same frequency as the excitation and an amplitude proportional to the amplitude of resulting vibrations. The presented prototype of the MAE-based vibrating unit with the field-controlled "configuration" can be implemented for realization of acceleration sensor systems with adaptable sensitivity. The ongoing research on MAEs is oriented to the use of other geometrical forms along with beams, e.g. two-dimensional structures such as membranes.}, language = {de} } @misc{PremSindersbergerMonkman, author = {Prem, Nina and Sindersberger, Dirk and Monkman, Gareth J.}, title = {Spectroscopic Analysis of Magneto-Active Polymers (MAP) - Poster}, series = {DFG-Tagung, Benediktbeuern, September 2017}, journal = {DFG-Tagung, Benediktbeuern, September 2017}, language = {en} } @misc{HeinrichKetterl, author = {Heinrich, Tobias and Ketterl, Hermann}, title = {AI to quantify biological diversity}, series = {LANDSUPPORT Final Conference and the Save Our Soils Workshop, 27 -28 APRIL 2022, Portici, Italy}, journal = {LANDSUPPORT Final Conference and the Save Our Soils Workshop, 27 -28 APRIL 2022, Portici, Italy}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-50080}, abstract = {The primary consumers of plant exudates - in exact fungi and bacteria, are representative for the soil succession level from bare soil, which is bacterial dominant to old growth forest constitute by fungal dominance. In a specified level of soil succession, a special kind of plant family benefits on the Fungal to Bacteria Ratio. The ability to determine this ratio in situ without complex chemical applications is part of the project Electronical Laboratory for Intelligent Soil Examination (ELISE). Several mechanical and optical tests on soil samples are covered within this Project. To analyze the fungal to bacteria ratio, samples are prepared automatically - in a defined and reproductive procedure - to generate slides for shadowing microscopy. The samples are observed by a camera, which is attached to a transmitted light microscope. The automatic analysis, done with computer vision algorithms, aims to quantify bacterial and fungal biomass in the actual sample view. Moreover, the algorithm can classify organisms according to their color and shape. To get a processable picture, several images from different focal levels must be taken through the sample thickness. Parts of each image, are in focus at the actual layer, are merged to a whole depth of field picture, by focus stacking. This produced picture is used to classify, locate and quantify - in first step filamentous organisms e.g. fungal by image sematic segmentation. The result represents an image sized mask, which indicates the class of fungi with class equivalate values at the pixel positions - covered by the organism. This information is used to calculate the fungal mass per gram soil. To quantify the bacterial biomass two approaches are implemented. For low density of bacterial existence, the individual bacteria is counted for a part of the field of view by an image detection algorithm to be extrapolate afterwards to the mass per gram soil. For high density of bacterial occurrence, specified regions of interest with only bacteria present are chosen. An image classification which has been pretrained by pictures of bacterial density patterns - previously determent by making the sample countable due to preforming sample dilutions, is done. The second option for high density bacterial count is, to automatically preform dilutions until the image detection is confidently countable. To ensure a usable confidence score a statistical approach of many fields of view is taken.}, language = {en} } @misc{KetterlHeinrich, author = {Ketterl, Hermann and Heinrich, Tobias}, title = {Vivid tool for comprehensive biological soil analysis}, series = {LANDSUPPORT Final Conference and the Save Our Soils Workshop, 27 -28 APRIL 2022, Portici, Italy}, journal = {LANDSUPPORT Final Conference and the Save Our Soils Workshop, 27 -28 APRIL 2022, Portici, Italy}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-50078}, abstract = {The sample preparation for shadowing microscopy, to examinate biological soil properties, is time consuming, manual work. The outcome depends on subjective skills of the operator, furthermore the results are mostly not quantitative. The database on biological soil properties is mostly not sufficient for an integrated modelling on an multidisciplinary scale. This project combines three progressive approaches to develop a tool that is easy to use and gives in situ results that can be used for many purposes.}, language = {en} } @misc{vanderWeerdBierlMatysik, author = {van der Weerd, Bastiaan and Bierl, Rudolf and Matysik, Frank-Michael}, title = {A Conductivity Probe for Determination of the Carbon Dioxide Tension at the Oxygenator Exhaust Outlet during Extracorporeal Membrane Oxygenation (ECMO)}, series = {Proceedings of the 9th ISC Modern Analytical Chemistry 2013, Prag}, journal = {Proceedings of the 9th ISC Modern Analytical Chemistry 2013, Prag}, language = {en} } @misc{RueckHofmannBierl, author = {R{\"u}ck, Thomas and Hofmann, Matthias and Bierl, Rudolf}, title = {Development of a miniaturized photoacoustic multigas sensing system for trace gas measurement}, series = {17th International Conference on Photoacoustic and Photothermal Phenomena, Oct. 20-24, 2013, Suzhou China}, journal = {17th International Conference on Photoacoustic and Photothermal Phenomena, Oct. 20-24, 2013, Suzhou China}, language = {en} } @misc{RueckMatysikBierl, author = {R{\"u}ck, Thomas and Matysik, Frank-Michael and Bierl, Rudolf}, title = {Development of a miniaturized photoacoustic multigas sensing system for trace gas measurement}, series = {analytica conference 2014, 1. bis 4. April, M{\"u}nchen}, journal = {analytica conference 2014, 1. bis 4. April, M{\"u}nchen}, language = {en} } @misc{RueckMatysikBierl, author = {R{\"u}ck, Thomas and Matysik, Frank-Michael and Bierl, Rudolf}, title = {Comparison of acoustic detectors for use in miniaturized photoacoustic devices designed for nitrogen dioxide trace gas measurement}, series = {ANAKON, 23.-26.3.2015, Graz}, journal = {ANAKON, 23.-26.3.2015, Graz}, language = {en} } @article{PangerlSukulRuecketal., author = {Pangerl, Jonas and Sukul, Pritam and R{\"u}ck, Thomas and Fuchs, Patricia and Weigl, Stefan and Miekisch, Wolfram and Bierl, Rudolf and Matysik, Frank-Michael}, title = {An inexpensive UV-LED photoacoustic based real-time sensor-system detecting exhaled trace-acetone}, series = {Photoacoustics}, volume = {38}, journal = {Photoacoustics}, publisher = {Elsevier}, issn = {2213-5979}, doi = {10.1016/j.pacs.2024.100604}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-71279}, pages = {12}, abstract = {n this research we present a low-cost system for breath acetone analysis based on UV-LED photoacoustic spectroscopy. We considered the end-tidal phase of exhalation, which represents the systemic concentrations of volatile organic compounds (VOCs) - providing clinically relevant information about the human health. This is achieved via the development of a CO2-triggered breath sampling system, which collected alveolar breath over several minutes in sterile and inert containers. A real-time mass spectrometer is coupled to serve as a reference device for calibration measurements and subsequent breath analysis. The new sensor system provided a 3σ detection limit of 8.3 ppbV and an NNEA of 1.4E-9 Wcm 1Hz 0.5. In terms of the performed breath analysis measurements, 12 out of 13 fell within the error margin of the photoacoustic measurement system, demonstrating the reliability of the measurements in the field.}, language = {en} } @article{EscherRueckJobstetal., author = {Escher, Lukas and R{\"u}ck, Thomas and Jobst, Simon and Pangerl, Jonas and Bierl, Rudolf and Matysik, Frank-Michael}, title = {Photodissociation-Driven Photoacoustic Spectroscopy with UV-LEDs for Ozone Detection}, series = {Photoacoustics}, volume = {43}, journal = {Photoacoustics}, publisher = {Elsevier BV}, issn = {2213-5979}, doi = {10.1016/j.pacs.2025.100718}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-80076}, pages = {16}, abstract = {This study presents the development and evaluation of a UV-LED based photoacoustic (PA) measurement system for ozone (O3) detection to demonstrate its potential for low-cost and accurate sensing while for the first time addressing the importance of photodissociation for PA signal generation for O3 in the UV range. With a detection limit of 7.9 ppbV, the system exhibits a significant advancement over state-of-the-art UV-PA O3 detection and is on par with laser-based setups. Following a novel discussion of the PA signal arising from photodissociation and its products, cross-sensitivity effects due to environmental factors such as temperature and gas composition were systematically analyzed. A digital twin driven compensation for these influences was implemented and evaluated. Despite the challenges associated with modeling the effects of H2O and CO2, the PA system shows considerable potential, though further studies in real world applications must be conducted.}, language = {en} } @article{HauslerHolznerEhrnspergeretal., author = {Hausler, Peter and Holzner, Lukas and Ehrnsperger, Matthias and Bierl, Rudolf}, title = {Evaluation of the creep strength of samples produced by fused deposition modeling}, series = {Open Engineering}, volume = {14}, journal = {Open Engineering}, number = {1}, publisher = {de Gruyter}, doi = {10.1515/eng-2024-0084}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-79760}, pages = {10}, abstract = {Data sheets for 3D printing materials typically include softening temperature, impact strength, tensile strength, and stiffness. However, creep strength, an important parameter for components used over an extended period, is usually not included. Nevertheless, this parameter is of significant importance for components that are used over an extended period of time.This study compares the long-term creep behavior of a selection of materials that are commonly used in fused deposition modeling 3D printing. The materials under investigation are acrylonitrile butadiene styrene, acrylonitrile styrene acrylate, polylactic acid, and polycarbonate. In addition, the influence of fiber reinforcements on these materials is also examined. A simple, reproducible test procedure is proposed for users to determine and compare creep resistance of materials. This enables developers to select materials suitable for their own requirements on creep resistance and allows 3D-printing users to compare different materials. Results suggest that fiber reinforcement generally improves creep stability in 3D-printing materials, with GreenTEC Pro Carbon and add:north PC Blend HT LCF showing the most promise in this study.}, language = {en} } @article{SchelsEdlerHerdletal., author = {Schels, Andreas and Edler, Simon and Herdl, Florian and Hansch, Walter and Bachmann, Michael and Ritter, Daniela and Dudeck, Markus and Duesberg, Felix and Meyer, Manuel and Pahlke, Andreas and Hausladen, Matthias and Buchner, Philipp and Schreiner, Rupert}, title = {In situ quantitative field emission imaging using a low-cost CMOS imaging sensor}, series = {Journal of Vacuum Science \& Technology B}, volume = {40}, journal = {Journal of Vacuum Science \& Technology B}, number = {1}, publisher = {AIP Publishing}, doi = {10.1116/6.0001551}, abstract = {Spatially resolved field emission measurements represent an important factor in further development of existing field emitter concepts. In this work, we present a novel approach that allows quantitative analysis of individual emission spots from integral current-voltage measurements using a low-cost and commercially available CMOS camera. By combining different exposure times to extrapolate oversaturated and underexposed pixels, a near congruence of integral current and image brightness is shown. The extrapolation also allows parallel investigation of all individual tips participating in the total current with currents ranging from a few nanoampere to one microampere per tip. The sensitivity, which is determined by the integral brightness-to-current ratio, remains unchanged within the measurement accuracy even after ten full measurement cycles. Using a point detection algorithm, the proportional current load of each individual tip of the field emitter array is analyzed and compared at different times during the initial measurement cycle. Together with the extracted I-V curves of single emission spots from the integral measurement, the results indicate the effect of premature burnout of particularly sharp tips during conditioning of the emitter.}, language = {en} } @article{EngelhardtMelznerHavelkovaetal., author = {Engelhardt, Lucas and Melzner, Maximilian and Havelkova, Linda and Fiala, Pavel and Christen, Patrik and Dendorfer, Sebastian and Simon, Ulrich}, title = {A new musculoskeletal AnyBodyTM detailed hand model}, series = {Computer Methods in Biomechanics and Biomedical Engineering}, volume = {24}, journal = {Computer Methods in Biomechanics and Biomedical Engineering}, number = {7}, publisher = {Taylor \& Francis}, doi = {10.1080/10255842.2020.1851367}, pages = {777 -- 787}, abstract = {Musculoskeletal research questions regarding the prevention or rehabilitation of the hand can be addressed using inverse dynamics simulations when experiments are not possible. To date, no complete human hand model implemented in a holistic human body model has been fully developed. The aim of this work was to develop, implement, and validate a fully detailed hand model using the AnyBody Modelling System (AMS) (AnyBody, Aalborg, Denmark). To achieve this, a consistent multiple cadaver dataset, including all extrinsic and intrinsic muscles, served as a basis. Various obstacle methods were implemented to obtain with the correct alignment of the muscle paths together with the full range of motion of the fingers. These included tori, cylinders, and spherical ellipsoids. The origin points of the lumbrical muscles within the tendon of the flexor digitorum profundus added a unique feature to the model. Furthermore, the possibility of an entire patient-specific scaling based on the hand length and width were implemented in the model. For model validation, experimental datasets from the literature were used, which included the comparison of numerically calculated moment arms of the wrist, thumb, and index finger muscles. In general, the results displayed good comparability of the model and experimental data. However, the extrinsic muscles showed higher accordance than the intrinsic ones. Nevertheless, the results showed, that the proposed developed inverse dynamics hand model offers opportunities in a broad field of applications, where the muscles and joint forces of the forearm play a crucial role.}, language = {en} } @inproceedings{TschurtschenthalerKrenkelSchreiner, author = {Tschurtschenthaler, Karl and Krenkel, Lars and Schreiner, Rupert}, title = {Mechano-optical micro pillar sensor for biofluidmechanic wall shear stress measurements}, series = {25th Congress of the European Society of Biomechanics (ESB), July 7-10, 2019, Vienna, Austria}, booktitle = {25th Congress of the European Society of Biomechanics (ESB), July 7-10, 2019, Vienna, Austria}, language = {en} } @incollection{Weber, author = {Weber, Karsten}, title = {Alternative Benutzerschnittstellen als M{\"o}glichkeit der Kompensation sensorischer Handicaps}, series = {Barrierefreie Informationssysteme: Zug{\"a}nglichkeit f{\"u}r Menschen mit Behinderung in Theorie und Praxis}, booktitle = {Barrierefreie Informationssysteme: Zug{\"a}nglichkeit f{\"u}r Menschen mit Behinderung in Theorie und Praxis}, editor = {Kerkelmann, Friederike and Lewandowski, Dirk}, publisher = {de Gruyter}, address = {Berlin}, doi = {10.1515/9783110337297-004}, pages = {49 -- 70}, language = {de} } @inproceedings{PrommesbergerLangerSchreiner, author = {Prommesberger, Christian and Langer, Christoph and Schreiner, Rupert}, title = {Stable and low noise field emission from single p-type Si-tips}, series = {International Vacuum Nanoelectronics Conference (IVNC), 31st, 2018, Kyoto, Japan}, booktitle = {International Vacuum Nanoelectronics Conference (IVNC), 31st, 2018, Kyoto, Japan}, publisher = {IEEE}, doi = {10.1109/IVNC.2018.8520018}, pages = {1-2}, abstract = {Single gated p-type Si-tips with two different tip radii were fabricated. An emission current of 2.40 μA was measured for the sharp-edged tip at a voltage of 170 V. In contrast, a stable and reproducible emission behavior was observed with an increased tip radius resulting in a pronounced saturation region between 90 V and 150 V, but merely an emission current of 0.55 μA at 150 V. More remarkable is the stable emission behavior with fluctuation of ± 4 \% during a measurement period of 30 minutes. The integral emission current in a homogeneous tip array (16 emitters) showed nearly the same I-V characteristics compared to the single tip and is therefore, most dominated by only a stable single tip in the array.}, language = {en} } @inproceedings{LindnerBerndtPrommesbergeretal., author = {Lindner, Matthias and Berndt, Dominik and Prommesberger, Christian and Langer, Christoph and Schreiner, Rupert}, title = {Field emission assisted micro plasma discharges at vacuum and atmospheric pressures}, series = {31st International Vacuum Nanoelectronics Conference (IVNC), 2018, Kyoto, Japan}, booktitle = {31st International Vacuum Nanoelectronics Conference (IVNC), 2018, Kyoto, Japan}, doi = {10.1109/IVNC.2018.8520181}, pages = {2}, abstract = {Spatially confined non-equilibrium plasmas at vacuum and atmospheric pressure in the dimensions from a few microns to one millimeter are a promising approach to the generation and maintenance of stable glow discharges. The realization of these micro-discharges or micro-plasmas enable more accurate investigations in the field of micro plasma research. We report on field emission assisted micro plasmas excited by an alternating current with frequencies up to 1 kHz. Due to the field enhancement caused by an array of Si nano-tip structures the ignition voltage of stable plasma discharges can be reduced by 30\%.}, language = {en} } @inproceedings{BerndtLindnerTschurtschenthaleretal., author = {Berndt, Dominik and Lindner, Matthias and Tschurtschenthaler, Karl and Langer, Christoph and Schreiner, Rupert}, title = {Miniaturized Plasma Actuator Flow Measurements by MEMS-Based Thermal Conductivity Sensors}, series = {MDPI Proceedings of Eurosensors 2018, 9-12 September, Graz}, volume = {Vol.13}, booktitle = {MDPI Proceedings of Eurosensors 2018, 9-12 September, Graz}, number = {2}, doi = {10.3390/proceedings2130939}, abstract = {The gasflow created by a minaturized dielectric barrier discharge (DBD) plasma actuator is measured by a MEMS-based thermal conductivity gas sensor giving an indication of flow velocity and flow direction. The possiblity of several sensors in a small area gives a far better accuracy of local flow phenomena compared to conventional sensors. This is important for a better understanding of plasma- induced flow characteristics.}, language = {en} } @inproceedings{SteindlMottokMeieretal., author = {Steindl, Michael and Mottok, J{\"u}rgen and Meier, Hans and Schiller, Frank and Fr{\"u}chtl, M.}, title = {Safeguarded Processing of Sensor Data}, series = {IT-SecurityArea (IT-SA 2009) vom 13.-15. Oktober 2009, N{\"u}rnberg}, booktitle = {IT-SecurityArea (IT-SA 2009) vom 13.-15. Oktober 2009, N{\"u}rnberg}, pages = {8}, abstract = {The spectrum of software tasks no longer includes only rare function controlling tasks for sensor actuator chains in reactive embedded systems. However, more and more responsible challenges like safety-critical scenarios are tackled. Therefore sensor data have to be safeguarded by several mechanism. An obvious and widely used approach is the use of two redundant hardware controllers, but this comes along with an additional cost, space and energy factor. Another way to fulfill certain safety properties is to implement a second diverse software channel in a single micro-controller architecture according the Safely Embedded Software (SES) approach. However, a lack of performance occurs by implementing this diverse channel for complex computations e.g. floating-point operations. This paper gives an approach for transferring the SES into a coprocessor and to migrate SES to a flexible and powerful FPGA architecture.}, language = {en} } @inproceedings{SteindlMottokMeieretal., author = {Steindl, Michael and Mottok, J{\"u}rgen and Meier, Hans and Schiller, Frank and Fr{\"u}chtl, M.}, title = {Safeguarded Processing of Sensor Data}, series = {5th Embedded Real Time Software and Systems Conference (ERTS2 2010), May 2010, Toulouse, France}, booktitle = {5th Embedded Real Time Software and Systems Conference (ERTS2 2010), May 2010, Toulouse, France}, language = {en} } @inproceedings{EdlerHanschPrommesbergeretal., author = {Edler, Simon and Hansch, Walter and Prommesberger, Christian and Schreiner, Rupert}, title = {Influence of adsorbates on the performance of a field emitter array in a high voltage triode setup}, series = {International Vacuum Nanoelectronics Conference (IVNC), 31st, 2018, Kyoto, Japan}, booktitle = {International Vacuum Nanoelectronics Conference (IVNC), 31st, 2018, Kyoto, Japan}, publisher = {IEEE}, doi = {10.1109/IVNC.2018.8520214}, pages = {1-2}, abstract = {The influence of residual gas pressure on the characteristics of black-Silicon field emitter arrays in a high voltage triode setup is investigated. I-Vcharacteristics at different pressure levels show a decrease of emission current with rising pressure. This can be explained by an increase of the work function and charging of the emitter surface due to adsorbates. The initial characteristics can be restored by heating the FEA up to 110 °C during electron emission. This regeneration procedure enables an extension of the lifetime from about 20 h to 440 h at a residual gas pressure of 10 -5 mbar.}, language = {en} } @inproceedings{KaesbauerSchmailzlPrehmetal., author = {K{\"a}sbauer, Johannes and Schmailzl, Anton and Prehm, Jens and Loose, Tobias and Hierl, Stefan}, title = {Simulation of Quasi-Simultaneous Laser Transmission Welding of Plastics}, series = {Procedia CIRP}, volume = {94}, booktitle = {Procedia CIRP}, publisher = {Elsevier}, doi = {10.1016/j.procir.2020.09.136}, pages = {737 -- 741}, abstract = {Thermo-mechanical simulation offers great opportunities to optimize welding processes of plastics. For realistic simulation, the temperature dependent mechanical properties need to be implemented from ambient temperature to temperatures above the flow temperature. Standard test methods are insufficient for characterization in the entire temperature range because close to the flow temperature the material is too soft for tensile tests and too stiff for rheometry. Therefore, an optimization strategy is developed, that determines unknown material parameters by testing in welding simulations. The unknown parameters are iteratively adjusted to minimize the mismatch between computed and measured set-paths. Thus, important process characteristics are calculated realistically, enabling the computer aided assessment of the weld quality.}, subject = {Kunststoffschweißen}, language = {en} } @article{WeiglFeldmeierBierletal., author = {Weigl, Stefan and Feldmeier, Florian and Bierl, Rudolf and Matysik, Frank-Michael}, title = {Photoacoustic detection of acetone in N2 and synthetic air using a high power UV LED}, series = {Sensors Actuators B Chemical}, volume = {316}, journal = {Sensors Actuators B Chemical}, number = {August}, publisher = {Elsevier}, doi = {10.1016/j.snb.2020.128109}, pages = {1 -- 11}, abstract = {The performance of a photoacoustic trace gas sensor for the detection of acetone in N2 and synthetic air is reported. The sensor system utilises an amplitude modulated UV LED. The light source has an emission maximum at 278 nm and a maximum CW output power of 300 mW according to the datasheet. Three different collimating and focusing approaches have been investigated to guide the highly divergent LED light into the acoustic resonator of the photoacoustic measurement cell. A 3D printed aluminium cell was designed to optimize light coupling by simultaneously minimizing the photoacoustic background signal generation. Hence, the diameter of the resonator was set to a comparable large diameter of 10 mm and the inner walls of the resonator were mirror polished. The additive manufacturing procedure allowed for integration of a spirally formed gas channel, enabling gas heating prior to detection. The sensor performance was investigated by measuring acetone in N2 and synthetic air at different concentrations. The UV LED current was set to 86 \% of the maximum value according to the datasheet of the light source in order to increase the lifetime and thermal stability. An Allan-Werle deviation analysis validates a stable sensor performance. The limit of detection (LoD) was determined at a 3σ noise level with a 10 s lock-in amplifier time constant by sampling data points over 20 s with a data acquisition rate of 5 Hz. LoDs of 80.8 ppbV and 19.6 ppbV were obtained for acetone in N2 and synthetic air, respectively.}, language = {en} } @article{BerndtMuggliWittweretal., author = {Berndt, Dominik and Muggli, Josef and Wittwer, Franz and Langer, Christoph and Heinrich, Stephan and Knittel, Thorsten and Schreiner, Rupert}, title = {MEMS-based thermal conductivity sensor for hydrogen gas detection in automotive applications}, series = {Sensors and Actuators A: Physical}, volume = {305}, journal = {Sensors and Actuators A: Physical}, number = {April}, publisher = {Elsevier}, doi = {10.1016/j.sna.2019.111670}, abstract = {Accurate detection of hydrogen gas in vehicle interiors is very important for the future of a fuel cell car. Since this type of gas is highly volatile and flammable, the measurement methods have to be very reliable and precise due to safety reasons. In this paper a thermal conductivity sensor for hydrogen gas detection is presented, exhibiting a lower detection limit of 2000 ppm hydrogen in laboratory air. The sensor element is realized by micro-fabrication techniques on silicon wafers. The heated filament is exposed by a selective wet etching process creating a micro-hotplate on a thin membrane. In order to minimize power consumption, the sensor is operated in pulsed mode. Hydrogen gas detection was carried out using a synthetic gas testbench. Measurements of hydrogen contents ranging from 0\% to 4\% with an increment of 0.5\% were successfully performed for ambient gas temperatures between -15°C and 84°C. Including humidity, high moisture contents have the greatest influence on thermal conductivity. This was predicted in theoretical investigations and confirmed in experiments. For evaluation, both the change in resistance ΔR as well as the time constant τ were taken as sensor output. For both quantities, the previously established theoretical relationship with thermal conductivity could be confirmed.}, language = {en} } @article{WeiglWittmannRuecketal., author = {Weigl, Stefan and Wittmann, Elisabeth and R{\"u}ck, Thomas and Bierl, Rudolf and Matysik, Frank-Michael}, title = {Effects of ambient parameters and cross-sensitivities from O2, CO2 and H2O on the photoacoustic detection of acetone in the UV region}, series = {Sensors Actuators B Chemical}, journal = {Sensors Actuators B Chemical}, number = {328}, publisher = {Elsevier}, issn = {0925-4005}, doi = {10.1016/j.snb.2020.129001}, abstract = {We present a sensitive UV LED photoacoustic setup for the detection of gaseous acetone and discuss its applicability towards breath analysis. We investigated the performance of the sensor for low acetone concentrations down to 0.1 parts per million (ppmV). The influences of temperature, flow, pressure, optical power and LED duty cycle on the measured signal have been examined. To gain a better understanding of the different effects on the photoacoustic signal, correlation analysis was applied and feature importance was determined using a large measured dataset. Furthermore, the cross-sensitivities towards O2, CO2 and H2O have been studied extensively. Finally, the sensor's performance to detect acetone between 0.1-1 ppmV within gas mixtures simulating breath exhale conditions has been investigated, too. With a limit of detection (LoD) of 12.5 parts per billion (ppbV) (3σ) measured under typical breath exhale gas mixture conditions, the sensor demonstrated a high potential for the application of acetone detection in human breath analysis.}, language = {en} } @inproceedings{SchubertSeignDaietal., author = {Schubert, Martin J. W. and Seign, Stefan and Dai, Q. and Hinterseer, Sebastian and Pielmeier, F. and Pietsch, Alexander and Seebauer, C. and Weiß, Josef and Yu, C. and Zenger, Stefan}, title = {Capacitive Sensor Technology for Soil Moisture Monitoring Networks}, series = {24th IEEE International Conference on Electronics, Circuits and Systems (ICECS), 5-8 Dec. 2017, Batumi, Georgia}, booktitle = {24th IEEE International Conference on Electronics, Circuits and Systems (ICECS), 5-8 Dec. 2017, Batumi, Georgia}, doi = {10.1109/ICECS.2017.8292018}, pages = {190 -- 193}, abstract = {A sensor technology for tracking soil-moisture in agricultural fields is presented. A linear measurement method was developed to satisfy the need for cheap sensors with wide range of capacitance change such as factor 30. A combined wired and wireless network transmits data to a server. Various battery aspects are compared with respect to use in agriculture.}, language = {en} } @inproceedings{Schubert, author = {Schubert, Martin J. W.}, title = {System Contemplations for Precision Irrigation in Agriculture}, series = {AIP Conference Proceedings}, volume = {1828}, booktitle = {AIP Conference Proceedings}, number = {1}, isbn = {9780735414969}, doi = {10.1063/1.4979393}, abstract = {This communication contemplates political, biological and technical aspects for efficient and profitable irrigation in sustainable agriculture. A standard for irrigation components is proposed. The need for many, and three-dimensionally distributed, soil measurement points is explained, thus enabling the control of humidity in selected layers of earth. Combined wireless and wired data transmission is proposed. Energy harvesting and storage together with mechanical sensor construction are discussed.}, language = {en} } @inproceedings{LeeSchubertHo, author = {Lee, Wai-Kong and Schubert, Martin J. W. and Ho, Stanley Jian-Qin}, title = {Multi-source energy harvesting and storage for floating wireless-sensor-network nodes}, series = {2016 IEEE Industrial Electronics and Applications Conference (IEACon 2016), 20.-22. Nov. 2016, Kota Kinabalu, Malaysia}, booktitle = {2016 IEEE Industrial Electronics and Applications Conference (IEACon 2016), 20.-22. Nov. 2016, Kota Kinabalu, Malaysia}, isbn = {9781509009268}, language = {en} } @misc{SchubertSeign, author = {Schubert, Martin J. W. and Seign, Stefan}, title = {Arrangement for Measuring Capacitance}, language = {en} } @article{Weber, author = {Weber, Karsten}, title = {Die Macht der Maschinenmoral}, series = {Schweizer Monat}, journal = {Schweizer Monat}, number = {1077 - Juni}, language = {de} } @article{GerhardsWeberBittneretal., author = {Gerhards, Helene and Weber, Karsten and Bittner, Uta and Fangerau, Heiner}, title = {Machine Learning Healthcare Applications (ML-HCAs) Are No Stand-Alone Systems but Part of an Ecosystem - A Broader Ethical and Health Technology Assessment Approach is Needed}, series = {The American Journal of Bioethics - AJOB}, volume = {20}, journal = {The American Journal of Bioethics - AJOB}, number = {11}, doi = {10.1080/15265161.2020.1820104}, pages = {46 -- 48}, language = {de} } @article{StadlerHofmannMotschmannetal., author = {Stadler, Dominik and Hofmann, Matthias J. and Motschmann, Hubert and Shamonin (Chamonine), Mikhail}, title = {Automotived system for measuring the surface dilational modulus of liquid-air interfaces}, series = {Measurement Science and Technology}, volume = {27}, journal = {Measurement Science and Technology}, number = {6}, publisher = {IOP Science}, doi = {10.1088/0957-0233/27/6/065301}, pages = {065301}, abstract = {The surface dilational modulus is a crucial parameter for describing the rheological properties of aqueous surfactant solutions. These properties are important for many technological processes. The present paper describes a fully automated instrument based on the oscillating bubble technique. It works in the frequency range from 1 Hz to 500 Hz, where surfactant exchange dynamics governs the relaxation process. The originality of instrument design is the consistent combination of modern measurement technologies with advanced imaging and signal processing algorithms. Key steps on the way to reliable and precise measurements are the excitation of harmonic oscillation of the bubble, phase sensitive evaluation of the pressure response, adjustment and maintenance of the bubble shape to half sphere geometry for compensation of thermal drifts, contour tracing of the bubbles video images, removal of noise and artefacts within the image for improving the reliability of the measurement, and, in particular, a complex trigger scheme for the measurement of the oscillation amplitude, which may vary with frequency as a result of resonances. The corresponding automation and programming tasks are described in detail. Various programming strategies, such as the use of MATLAB® software and native C++ code are discussed. An advance in the measurement technique is demonstrated by a fully automated measurement. The instrument has the potential to mature into a standard technique in the fields of colloid and interface chemistry and provides a significant extension of the frequency range to established competing techniques and state-of-the-art devices based on the same measurement principle.}, language = {en} } @inproceedings{SilberbauerLindnerSchreiner, author = {Silberbauer, Theodor and Lindner, Matthias and Schreiner, Rupert}, title = {Charakterisierung der dielektrischen Barrierenentladung von Mikroplasmaaktuatoren in Abh{\"a}ngigkeit der Substratdicke}, series = {Intelligente Systeme und ihre Komponenten: Forschung und industrielle Anwendung : Fachbeitr{\"a}ge 2. Symposium Elektronik und Systemintegration ESI 2020}, booktitle = {Intelligente Systeme und ihre Komponenten: Forschung und industrielle Anwendung : Fachbeitr{\"a}ge 2. Symposium Elektronik und Systemintegration ESI 2020}, address = {Landshut}, pages = {64 -- 72}, language = {de} } @article{KrysztofMieraUrbańskietal., author = {Krysztof, Michał and Miera, Paweł and Urbański, Paweł and Grzebyk, Tomasz and Hausladen, Matthias and Schreiner, Rupert}, title = {Integrated silicon electron source for high vacuum microelectromechanical system devices}, series = {Journal of Vacuum Science \& Technology B}, volume = {42}, journal = {Journal of Vacuum Science \& Technology B}, number = {2}, publisher = {AIP Publishing}, issn = {2166-2746}, doi = {10.1116/6.0003385}, abstract = {The article presents the process of developing a silicon electron source designed for high-vacuum microelectromechanical system (HV MEMS) devices, i.e., MEMS electron microscope and MEMS x-ray source. Technological constraints and issues of such an electron source are explained. The transition from emitters made of carbon nanotubes to emitters made of pure silicon is described. Overall, the final electron source consists of a silicon tip emitter and a silicon gate electrode integrated on the same glass substrate. The source generates an electron beam without any carbon nanotube coverage. It generates a high and stable electron current and works after the final bonding process of an HV MEMS device.}, language = {en} } @article{SchreinerNaegeleKoerbletal., author = {Schreiner, Rupert and Naegele, Peter and K{\"o}rbl, M. and Groning, A. and Gentner, Jean-Louis and Schweizer, Heinz C.}, title = {Monolithically integrated tunable laterally coupled distributed-feedback lasers}, series = {Photonics Technology Letters}, volume = {13}, journal = {Photonics Technology Letters}, number = {12}, publisher = {IEEE}, doi = {10.1109/68.969880}, pages = {1277 -- 1279}, abstract = {A new method for fabrication of tunable InGaAsP-InP single-mode lasers without epitaxial overgrowth is reported. These devices show the advantage of a considerably simplified fabrication process compared to conventional tunable laser types. The lasers comprise an active Bragg reflector integrated with an uncorrugated separately pumped gain region. By adjusting the current through the Bragg reflector, the wavelength can be tuned between 1590.8 and 1595.2 nm.}, language = {en} } @unpublished{PangerlSukulRuecketal., author = {Pangerl, Jonas and Sukul, Pritam and R{\"u}ck, Thomas and Fuchs, Patricia and Weigl, Stefan and Miekisch, Wolfram and Bierl, Rudolf and Matysik, Frank-Michael}, title = {An Inexpensive Uv-Led Photoacoustic Based Real-Time Sensor-System Detecting Exhaled Trace-Acetone}, publisher = {Elsevier}, doi = {10.2139/ssrn.4724198}, abstract = {In this research we present a low-cost system for breath acetone analysis based on UV-LED photoacoustic spectroscopy. We considered the end-tidal phase of exhalation, which represents the systemic concentrations of volatile organic compounds (VOCs) - providing clinically relevant information about the human health. This is achieved via the development of a CO2-triggered breath sampling system, which collected alveolar breath over several minutes in sterile and inert containers. A real-time mass spectrometer is coupled to serve as a reference device for calibration measurements and subsequent breath analysis. The new sensor system provided a 3σ detection limit of 6.4 ppbV and an NNEA of 1.1E-9 Wcm-1Hz-0.5. In terms of the performed breath analysis measurements, 12 out of 13 fell within the error margin of the photoacoustic measurement system, demonstrating the reliability of the measurements in the field.}, language = {en} } @inproceedings{BuchnerKaiserHausladenetal., author = {Buchner, Philipp and Kaiser, Alexander and Hausladen, Matthias and Bartl, Mathias and Bachmann, Michael and Schreiner, Rupert}, title = {Silicon Nanowire Field Emitters with Integrated Extraction Gates Using Benzocyclobutene as an Insulator}, series = {37th International Vacuum Nanoelectronics Conference (IVNC), 15-19 July 2024, Brno, Czech Republic}, booktitle = {37th International Vacuum Nanoelectronics Conference (IVNC), 15-19 July 2024, Brno, Czech Republic}, publisher = {IEEE}, doi = {10.1109/IVNC63480.2024.10652314}, pages = {1 -- 2}, abstract = {We are continuously improving the performance of our field emission electron sources. In this work a geometrically optimized design of electron sources with silicon nanowire field emitters on pillars was fabricated. This new design increased the packing density of the emitters by using a hexagonal arrangement of the pillars and a pillar spacing of 40 µm. Benzocyclobutene was used as the insulator material for an integrated (Cr/Ni) extraction gate. A modified fabrication process for the field emitters further improved reproducibility and reliability. An emission current of about 0.4 mA was measured for 30 minutes at an extraction voltage of 250 V and an anode voltage of 500 V. Electron transmission through the gate reached almost 100\%.}, language = {en} } @article{BerndtMuggliHeckeletal., author = {Berndt, Dominik and Muggli, Josef and Heckel, Robert and Rahiman, Mohd Fuad and Lindner, Matthias and Heinrich, Stephan and Pl{\"o}chinger, Heinz and Schreiner, Rupert}, title = {A Robust Miniaturized Gas Sensor for H₂ and CO₂ Detection Based on the 3ω Method}, series = {Sensors}, volume = {22}, journal = {Sensors}, number = {2}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/s22020485}, pages = {1 -- 17}, abstract = {Gas concentration monitoring is essential in industrial or life science areas in order to address safety-relevant or process-related questions. Many of the sensors used in this context are based on the principle of thermal conductivity. The 3ω-method is a very accurate method to determine the thermal properties of materials. It has its origin in the thermal characterization of thin solid films. To date, there have been very few scientific investigations using this method to determine the thermal properties of gases and to apply it to gas measurement technology. In this article, we use two exemplary gases (H2 and CO2) for a systematical investigation of this method in the context of gas analysis. To perform our experiments, we use a robust, reliable sensing element that is already well established in vacuum measurement technology. This helix-shaped thin wire of tungsten exhibits high robustness against chemical and mechanical influences. Our setup features a compact measurement environment, where sensor operation and data acquisition are integrated into a single device. The experimental results show a good agreement with a simplified analytical model and FEM simulations. The sensor exhibits a lower detection limit of 0.62\% in the case of CO2, and only 0.062\% in case the of H2 at an excitation frequency of 1 Hz. This is one of the lowest values reported in literature for thermal conductivity H2 sensors.}, language = {en} } @article{MonkmanSindersbergerPremetal., author = {Monkman, Gareth J. and Sindersberger, Dirk and Prem, Nina and Szecsey, Tamara}, title = {Smart Stiction}, series = {Robotics \& Automation Engineering Journal}, volume = {4}, journal = {Robotics \& Automation Engineering Journal}, number = {4}, publisher = {Juniper Publishers}, doi = {10.19080/RAEJ.2019.04.555641}, abstract = {Soft robotics could loosely be described as the engineering science of expanded dexterity through controllable flexibility. The exploitation of controllable compliance through the judicious choice of soft flexible members, as opposed to a finite number of rigid kinematic joints, can result in greater dexterity without compromising simplicity. One example is the replacement of segmented mechanical legs with simple compliant material eruciform prolegs. To achieve this in robotics, without introducing additional mechanical joints, mobile surfaces with switchable coefficients of friction is essential. This paper explains how, using silicone based smart materials, the rapid alternation between kinematic and static friction (stiction) may be achieved.}, language = {en} } @article{SchreinerKoerblGraebeldingeretal., author = {Schreiner, Rupert and K{\"o}rbl, M. and Gr{\"a}beldinger, H. and Gentner, Jean-Louis and Schweizer, H.}, title = {Laterally gain-coupled 1.57 [micro sign]m DFB lasers with chromium surface grating and self-aligned Ti/Pt/Au ohmic contact}, series = {Electronics Letters}, volume = {36}, journal = {Electronics Letters}, number = {7}, publisher = {The Institution of Engineering and Technology, IET}, issn = {0013-5194}, doi = {10.1049/el:20000500}, pages = {636 -- 637}, abstract = {A simple method for fabricating gain coupled DFB lasers with lateral surface chromium Bragg gratings and self-aligned low capacitance ohmic contacts is reported. These InGaAsP/InP lasers show monomode emission with a sidemode suppression ratio of 40 dB. For 243 µm long devices a continuous wave threshold current of 17 mA was measured at room temperature.}, language = {en} } @article{RueckBierlMatysik, author = {R{\"u}ck, Thomas and Bierl, Rudolf and Matysik, Frank-Michael}, title = {NO2 trace gas monitoring in air using off-beam quartz enhanced photoacoustic spectroscopy (QEPAS) and interference studies towards CO2, H2O and acoustic noise}, series = {Sensors and Actuators B: Chemical}, volume = {255}, journal = {Sensors and Actuators B: Chemical}, number = {Part 3, February}, publisher = {Elsevier}, doi = {10.1016/j.snb.2017.09.039}, pages = {2462 -- 2471}, abstract = {We present the development and characterization as well as comprehensive interference studies of a photoacoustic NO2 trace gas detection system. The system is based on an off-beam quartz enhanced photoacoustic scheme (off-beam QEPAS) and signal generation was initiated by amplitude modulating a low-cost diode laser emitting at 450 nm. The QEPAS sensor element features double-resonant amplification, still it is only ∼ 5 × 5 × 2.5 mm in size. The individual and combined resonance characteristics were investigated and specified to 52 dB amplification, adding up 15 dB acoustic- and 37 dB mechanical-resonance amplification. The linearity of the photoacoustic signal dependency on the analyte concentration was verified from 200 ppbV to 100 ppmV NO2 in synthetic air. The detection limit (3σ) was determined to 1.8 ppbV using a lock-in time constant of 10 s and an averaging time of 20 s. The normalized noise equivalent absorption coefficient was specified to 2.5·10-8 W cm-1 Hz-0.5. The stability of the signal was investigated over time and a slight drift by 1 per mille was observed after 30 min without temperature stabilizing the photoacoustic cell (PAC). Noise analysis was performed by means of Allan deviation and the inverse dependency of response time and precision of the system on the lock-in time constant was outlined. We performed interference analyses towards N2, O2, CO2, H2O and acoustic noise, respectively. Although neither spectral interferences nor losses due to slow NO2 VT-relaxation were observed, O2 was identified to cause a 15\% signal drop due to VVNO2-O2-relaxation. Changing H2O concentrations were found to cause acoustic detuning, which cannot be compensated by adjusting the frequency of modulation, because of the double-resonant feature of the PAC. However, alternative approaches of compensation were discussed. Finally, we carried out heavy traffic noise simulations and determined the QEPAS setup to be 46 times less susceptible towards ambient noise compared to standard microphone-based photoacoustic setups.}, language = {en} } @article{RueckBierlMatysik, author = {R{\"u}ck, Thomas and Bierl, Rudolf and Matysik, Frank-Michael}, title = {Development and characterization of a laboratory setup for photoacoustic NO2 determination based on the excitation of electronic 2B2 and 2B1 states using a low-cost semiconductor laser}, series = {Sensors and Actuators A: Physical}, volume = {258}, journal = {Sensors and Actuators A: Physical}, publisher = {Elsevier}, address = {Amsterdam, Niederlande}, doi = {10.1016/j.sna.2017.03.024}, pages = {193 -- 200}, abstract = {This work gives a detailed characterization of a laboratory setup for photoacoustic NO2 trace gas detection at the ppb level. The signal generation is based on the excitation of electronic 2B2 and 2B1 states using a low-cost semiconductor laser emitting at 450 nm. An acoustic resonator was used for signal amplification and the modulation frequency of the laser was determined to 3395 Hz in order to gain maximum signal amplification. The quality of resonant amplification was determined to 7.9. The gas samples were NO2 calibration gases diluted with pure nitrogen. The signal-to-noise ratio (SNR) dependency on the flow rate Q and the lock-in time constant τLIA was investigated, respectively, and the optimum values were specified to Q = 500 mL/min and τLIA = 2 s. In case of ambient noise, increasing τLIA to 10 s was evaluated as sufficient for SNR preservation. The noise level was measured in the absence of NO2 and it was determined to be composed of 51\% electronic noise and 49\% gas flow noise. With the analyte concentration ranging from 300 ppbV to 100 ppmV, the linear dependency of the photoacoustic amplitude on the NO2 concentration was specified, the sensitivity was determined to 110 μV/ppmV and the maximum measurement error was calculated to ±0.8\%. The detection limit was determined to 2.0 ppbV. Furthermore, the stability of the signal was investigated and a maximum drift of ±1\% was observed within a measuring period of 30 min. The response time τ90 was specified to 58 s. All results considered, this photoacoustic measuring system, which is based on low-cost signal generation and detection units, provides an excellent basis in view of developing a portable device for photoacoustic trace gas detection.}, language = {en} } @article{RueckBierlMatysik, author = {R{\"u}ck, Thomas and Bierl, Rudolf and Matysik, Frank-Michael}, title = {Low-cost photoacoustic NO2 trace gas monitoring at the pptV-level}, series = {Sensors and Actuators A: Physical}, volume = {263}, journal = {Sensors and Actuators A: Physical}, publisher = {Elsevier}, address = {Amsterdam, Niederlande}, doi = {10.1016/j.sna.2017.06.036}, pages = {501 -- 509}, abstract = {We present the development and the characterization of a photoacoustic NO2 trace gas detection system. The system is based on the implementation of low-cost components, i.e. a mass-produced blue diode laser and a standard MEMS microphone which is commonly built into smartphones, for example. An optimized cell design was realized by means of 3D printing. The linearity of the photoacoustic signal dependency on the analyte concentration was verified from 200 ppbV to 100 ppmV NO2. The detection limit (1σ) was determined to 33 pptV and the normalized noise equivalent absorption coefficient was calculated to 7.0 ∙ 10-10 W cm-1 Hz-1/2. The dynamic range of the system was verified to be linear over three magnitudes of order and the sensitivity was calculated to 814 μV/ppmV. The system was characterized in view of optimal operating parameters, i.e. lock-in time constant τLIA and total mass flow rate, optical performance and signal stability. The mass flow dependend response time of the system was specified to 19 s and an idealized step response to a quasi-Heaviside step function was quantified as a function of τLIA. The quality factor of acoustic resonance was determined to 21.9 and an empirical expression regarding acoustic node shifting is provided. The expression takes into account the radius of the resonator pipe and the radius of the hole, which was drilled into the pipe for microphone coupling. Furthermore, we studied the cross-sensitivity of the photoacoustic signal towards H2O and CO2, respectively.}, language = {en} } @misc{WeiglMatysikBierl, author = {Weigl, Stefan and Matysik, Frank-Michael and Bierl, Rudolf}, title = {Development of a sensor system for analysis of human breath exhale}, series = {BayWISS Herbstakademie 2018, Plankstetten}, journal = {BayWISS Herbstakademie 2018, Plankstetten}, abstract = {Atemgasanalyse ist ein junges und vielversprechendes Feld im Bereich der diagnostischen Medizin. Der Ansatz verspricht einfach zug{\"a}ngliche und leicht wiederholbare Probennahme die zum einen non-invasiv ist und zugleich R{\"u}ckschl{\"u}sse auf Vorg{\"a}nge im menschlichen K{\"o}rper und bspw. dessen Gesundheitszustand zul{\"a}sst. Seit Ende des 20. Jahrhunderts gibt es Massenspektrometer die es erm{\"o}glicht haben mehrere Tausend verschiedene Stoffe in der Ausatemluft nachzuweisen. Diese Technologien verbessern sich stetig und erm{\"o}glichen es die Vorg{\"a}nge und Zusammenh{\"a}nge zwischen Zusammensetzung der Ausatemluft und systemischen Prozessen besser zu verstehen. Die bei Studien mit Massenspektrometern ermittelten Biomarker, deren qualitative und quantitative Detektion Gesundheitsdiagnosen erm{\"o}glichen, haben aber noch nicht den Weg in den klinischen Alltag gefunden. Das Problem sind meistens die hohen Anschaffungskosten, komplizierte Datenauswertung und zumeist geringe Verf{\"u}gbarkeit und Immobilit{\"a}t dieser Messger{\"a}te. Die photoakustische Spektroskopie ist eine selektive und hochsensitive Messmethode, die es erm{\"o}glichen soll den Biomarker „Aceton", der grunds{\"a}tzlich die Metabolisierung von Fetten widerspiegelt, schnell und reproduzierbar quantitativ zu detektieren. Dabei m{\"u}ssen Hindernisse wie Querempfindlichkeiten, ausgel{\"o}st durch die komplexe Zusammensetzung der Messmatrix Atemgas, bei gleichzeitig kleine Aceton Konzentrationen (200-800 parts-per-billion) {\"u}berwunden werden. Verschiedene Wellenl{\"a}ngenbereiche mit unterschiedlichen Lichtquellen, akustisch resonante sowie innovative Messzellendesigns und anspruchsvolle Datenauswertung mittels komplexer Algorithmik sind n{\"o}tig um das Ziel, die Entwicklung eines kompakten, g{\"u}nstigen und zuverl{\"a}ssigen Acetonsensors, zu erreichen.}, language = {en} }