TY - JOUR A1 - Pangerl, Jonas A1 - Moser, Elisabeth A1 - Müller, Max A1 - Weigl, Stefan A1 - Jobst, Simon A1 - Rück, Thomas A1 - Bierl, Rudolf A1 - Matysik, Frank-Michael T1 - A sub-ppbv-level Acetone and Ethanol Quantum Cascade Laser Based Photoacoustic Sensor– Characterization and Multi-Component Spectra Recording in Synthetic Breath JF - Photoacoustics N2 - Trace gas analysis in breath is challenging due to the vast number of different components. We present a highly sensitive quantum cascade laser based photoacoustic setup for breath analysis. Scanning the range between 8263 and 8270 nm with a spectral resolution of 48 pm, we are able to quantify acetone and ethanol within a typical breath matrix containing water and CO2. We photoacoustically acquired spectra within this region of mid-infra-red light and prove that those spectra do not suffer from non-spectral interferences. The purely additive behavior of a breath sample spectrum was verified by comparing it with the independently acquired single component spectra using Pearson and Spearman correlation coefficients. A previously presented simulation approach is improved and an error attribution study is presented. With a 3σ detection limit of 6.5 ppbv in terms of ethanol and 250 pptv regarding acetone, our system is among the best performing presented so far. KW - Acetone KW - Breath analysis KW - Photoacoustic spectroscopy KW - Quantum cascade laser KW - Spectral simulation Y1 - 2023 U6 - https://doi.org/10.1016/j.pacs.2023.100473 SN - 2213-5979 N1 - Corresponding author: Jonas Pangerl VL - 30 SP - 1 EP - 12 PB - Elsevier ER - TY - THES A1 - Zhang, Yunjia T1 - Microcontroller Programming of a Contactless Optical Position Measurement Device N2 - This thesis focuses on programming a microcontroller to receive and process data from a waveguide optic distance sensor, and to visualize the measured distance on a display screen. During the measurement process, LED moves above the 3D-printed D-shaped waveguide. The light transmitted through the waveguide is converted into photocurrents by photodiodes located at both ends of the optical waveguide, which are then converted into voltage signals through specific electronic components. By computing the ratio of the optical power detected at each end, the relative position of the LED along the waveguide can be determined. In this project, a microcontroller is used to acquire the voltage data, correct measurement errors, calculate the LED position, and display the result on screen in real time. Compared to manual calculation of photocurrent values, using a microcontroller for automated data processing greatly improves speed and efficiency. At the same time, real-time visualization enhances the system’s practicality and usability, making it more suitable for future applications. Y1 - 2025 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-84647 CY - Regensburg ER - TY - CHAP A1 - Weigl, Stefan A1 - Müller, Max A1 - Pangerl, Jonas A1 - Rück, Thomas T1 - Scopes and Limits of Photoacoustic Spectroscopy in Modern Breath Analysis T2 - Breath Analysis N2 - Photoacoustic spectroscopy is a viable tool for trace gas detection in various application fields. In recent years, this technique has been exploited more and more for modern breath analysis as well. Within this chapter, a holistic overview of photoacoustic spectroscopy is presented, while maintaining the relationship to breath analysis. Therefore, a concise description of the fundamentals of photoacoustic spectroscopy is provided. This is essential for understanding the scopes and limits of this outstanding measurement technique being described within this chapter. In the past several different types of photoacoustic measurement setups for trace gas detection have emerged, including different light sources, modulation techniques, and detection schemes. These are described shortly and advantages as well as disadvantages, especially in relation to breath analysis, are highlighted. Though being a promising sensor principle, measurement devices based on photoacoustic spectroscopy are still rare on the sensor market, especially when it comes to trace gas detection in complex gas matrices, e.g., human breath exhale. One main reason is due to possible molecular interactions influencing the relaxational behavior of the analyte altering the sensor signal. Recent results shedding light on the intricate relaxational processes within complex gas matrices are discussed in detail, providing approaches to overcome this issue. Finally, various applications of photoacoustic spectroscopy in breath analysis are described demonstrating the great potential of this technology. Y1 - 2022 SN - 978-3-031-18526-7 U6 - https://doi.org/10.1007/11663_2022_22 SP - 101 EP - 159 PB - Springer nature ER - TY - PAT A1 - Olbrich, Florian A1 - Pongratz, Christian A1 - Bierl, Rudolf A1 - Ehrlich, Ingo T1 - Method and System for Evaluating a Structural Integrity of an Aerial Vehicle T2 - Europäisches Patentblatt (09.12.2020) zur Anmeldung: OTH Regensburg, Anmeldenummer: 19179054.2, Patentnummer 1001/3748327, Veröffentlichungsnummer: 3 748 327 Y1 - 2020 SP - 395 EP - 396 ER - TY - JOUR A1 - Kleshch, Victor I. A1 - Serbun, Pavel A1 - Lützenkirchen-Hecht, Dirk A1 - Orekhov, Anton A1 - Ivanov, Victor E. A1 - Prommesberger, Christian A1 - Langer, Christoph A1 - Schreiner, Rupert A1 - Obraztsov, Alexander N. T1 - A Comparative Study of Field Emission from Pristine, Ion-treated and Tungsten Nanoparticle-decorated p-type Silicon Tips JF - Physica Status Solidi B N2 - The field electron emission characteristics of individual tips of a silicon field emitter array are analyzed. The array of conical‐shaped tips is fabricated on a p‐type silicon wafer by using reactive ion etching and sharpening oxidation. The tips are decorated with single tungsten nanoparticles at their apexes. Furthermore, the focused ion beam is also used to increase surface conductivity of some of the tips. Comparative measurements of field emission are performed by using the scanning anode probe field emission microscopy technique. All types of tips demonstrated emission activation consisting of a sudden current increase at a certain value of the applied voltage. Compared to the pristine tips, a noticeable reduction of the saturation effect in the current–voltage characteristics and a smaller light sensitivity for the decorated tips is found. For ion‐treated tips, saturation effects and light sensitivity are completely suppressed. Scanning electron microscopy observations reveal the formation of single nanoscale protrusions extending from the metal particles and from the apexes of bare ion‐treated tips after exposure under strong electric fields during the field emission measurements. The influence of protrusions growth on characteristics of silicon field emitter arrays is discussed. Y1 - 2019 U6 - https://doi.org/10.1002/pssb.201800646 VL - 256 IS - 9 PB - Wiley ER - TY - CHAP A1 - Serbun, Pavel A1 - Porshyn, Vitali A1 - Müller, Günter A1 - Lützenkirchen-Hecht, Dirk A1 - Prommesberger, Christian A1 - Langer, Christoph A1 - Ławrowski, Robert Damian A1 - Schreiner, Rupert T1 - Field emission behavior of single n- and p-type black Si pillar structures T2 - International Vacuum Nanoelectronics Conference (IVNC), 31st, 2018, Kyoto, Japan N2 - We have investigated the properties of single n- and p-type black silicon (b-Si) pillars with a height of 20 μ m under strong electric field and halogen lamp or laser illumination. For both type of b-Si pillar structures, I-V measurements revealed strong activation effects, which consisted in sudden current increases during the first up/down voltage sweeps. The maximum reproducible emission current from a single n-type b-Si pillar structure was about 15 μ A. A pronounced saturation region at 240 nA was observed for a single p-type b-Si pillar. The current fluctuation over time showed a standard deviation of 28% and 2.5% for n- and p-type single b-Si pillar structures, respectively. Optical switching under halogen lamp illumination resulted in at least 3 times higher saturation currents and showed a linear dependence of the FE current on the laser power. KW - field emission KW - black silicon KW - photoemission Y1 - 2018 U6 - https://doi.org/10.1109/IVNC.2018.8520292 PB - IEEE ER - TY - CHAP A1 - Serbun, Pavel A1 - Porshyn, Vitali A1 - Lützenkirchen-Hecht, Dirk A1 - Prommesberger, Christian A1 - Langer, Christoph A1 - Ławrowski, Robert Damian A1 - Schreiner, Rupert T1 - Photosensitivity of single silicon high-aspect-ratio tips with different doping levels T2 - International Vacuum Nanoelectronics Conference (IVNC), 31st, 2018, Kyoto, Japan N2 - Photosensitivity of single lightly p-doped, highly p-doped, with an integrated p/n junction and intrinsic high-aspect-ratio (HAR) silicon tips was investigated in an ultra-high vacuum environment. The current-voltage characteristics (I-V) of the lightly doped p-type HAR tips showed a characteristic current saturation at around 10-12 nA, whereas the HAR Si tips with p/n junction showed similar saturation phenomena, however, at much smaller current values starting at ~20-30 pA. Optical switching under a halogen lamp illumination resulted in at least 2-4 times higher saturation currents and showed a linear dependence between the illumination power and the FE current, for both types of structures. In case of the highly p-doped HAR tips optical current switching effects, i. e. current saturation, were observed at rather low current levels 1-2 pA. Intrinsic HAR Si-tips showed relative unstable field emission behavior without a clear evidence of the photosensitivity. KW - field emission KW - Si p/n junction KW - p-type Si KW - photosensitivity Y1 - 2018 U6 - https://doi.org/10.1109/IVNC.2018.8520288 PB - IEEE ER - TY - JOUR A1 - Unterreitmeier, M. A1 - Nagler, Oliver A1 - Pfitzner, L. A1 - Weigel, R. A1 - Holmer, Rainer T1 - An acoustic emission sensor system for thin layer crack detection JF - Microelectronics Reliability N2 - We present a new method for semiconductor layer characterization enabling simultaneous crack generation and detection based on the established acoustic emission testing. In this paper, we explain the test concept and failure mechanism of diamond tip indentation with acoustic wave measurement on oxide layers by analytical modeling and computer-aided simulations. For this purpose, an innovative design of a sensor-indenter system was developed and experimentally verified. In further tests, the new acoustic crack detection method is correlated with proven optical inspection methods and the good reproducibility of the measurement is demonstrated. The high sensitivity and resolution of this method offer new opportunities for thin layer characterization at lower time and cost. The new high-efficient method can be used especially for process qualification for semiconductor wafer test, where oxide cracks can be induced by sharp probes causing electrical failure of the chip. KW - FLAT KW - INDENTATION Y1 - 2018 U6 - https://doi.org/10.1016/j.microrel.2018.07.015 VL - 88-90 IS - September SP - 16 EP - 21 PB - Pergamon-Elsevier ER - TY - JOUR A1 - Zimmermann, Klaus A1 - Chavez Vega, Jhohan Harvey A1 - Becker, Tatiana I. A1 - Witte, Hartmut A1 - Schilling, Cornelius A1 - Köhring, Sebastian A1 - Böhm, Valter A1 - Monkman, Gareth J. A1 - Prem, Nina A1 - Sindersberger, Dirk A1 - Lutz, I. I. A1 - Merker, Lukas T1 - An approach to a form-adaptive compliant gripper element based on magneto-sensitive elastomers with a bioinspired sensorized surface JF - Problems of Mechanics Y1 - 2019 SN - 1512-0740 VL - 75 IS - 2 SP - 23 EP - 38 PB - Georgian Technical University CY - Tbilisi ER - TY - CHAP A1 - Schreiner, Rupert A1 - Langer, Christoph A1 - Prommesberger, Christian A1 - Ławrowski, Robert Damian A1 - Dams, Florian A1 - Bachmann, Michael A1 - Düsberg, F. A1 - Hofmann, Martin A1 - Pahlke, Andreas A1 - Serbun, Pavel A1 - Mingels, Stephan A1 - Müller, Günter T1 - Semiconductor field emission electron sources using a modular system concept for application in sensors and x-ray-sources T2 - 2015 28th International Vacuum Nanoelectronics Conference (IVNC), 13-17 July 2015, Guangzhou, China N2 - Semiconductor field emitters are suitable candidates for applications, which require a very stable field emission (FE) current and a high emission uniformity over the entire emission area. By using different materials and geometries, we are able to vary the FE characteristics within a wide range. Each specific application requires its own optimized design for the cathode as well as for the other parts of the FE electron source. To meet as many of these requirements as possible while using only a limited number of different prefabricated components, we established a modular system concept for our FE electron source. This allows the implementation of almost every cathode material. For first characterizations, we used gated p-type Si cathodes with 16 tips. We obtained stable FE currents of 0.4 μA for a grid-potential of 400 V and a gate potential of 100 V. Almost 100% of the electrons are emitted towards the grid-electrode. Parasitic leakage paths, as well as the electron emission towards the gate-electrode can be neglected. Approximately 10% of the electrons are transmitted through the grid and reach the external anode. This is in good agreement with the optical transmission through the grid-mesh. KW - Anodes KW - CATHODES KW - electron sources KW - GEOMETRY KW - Iron KW - Logic gates KW - semiconductor field emission KW - silicon Y1 - 2015 U6 - https://doi.org/10.1109/IVNC.2015.7225572 SP - 178 EP - 179 PB - IEEE ER - TY - CHAP A1 - Ławrowski, Robert Damian A1 - Langer, Christoph A1 - Prommesberger, Christian A1 - Schreiner, Rupert A1 - Mingels, Stephan A1 - Porshyn, Vitali A1 - Serbun, Pavel A1 - Müller, Günter T1 - Field emission from surface textured GaN with buried double-heterostructures T2 - 2015 28th International Vacuum Nanoelectronics Conference (IVNC), 13-17 July 2015, Guangzhou, China N2 - In this contribution we report on field emission (FE) cathodes based on thin-film LED-technology and surface texturing. The FE cathode can be used both as an n-GaN cathode with an electrical contact at the top side metallization as well as a pn-GaN diode contacting only the p-GaN layer at the bottom side of the structure. The local and integral FE properties of the textured surface of the LED structure were investigated. For n-GaN an integral emission current up to 1.0 μA at an electric field of 19 V/μm was achieved. The pn-GaN diode measurements showed an integral current saturation behavior with two orders of magnitude lower FE currents. Regulated voltage scans obtained by FE scanning microscopy revealed a well-distributed emission over the whole cathode area. Measurements under pulsed tunable laser illumination and moderate electric fields indicated charge carrier generation in the buried double-heterostructures at photon energies below 3.5 eV besides normal photoemission above 4.1 eV. KW - CATHODES KW - Current measurement KW - Electric fields KW - field emission KW - Gallium nitride KW - GaN KW - Iron KW - Light emitting diodes KW - photoemission KW - Surface texture Y1 - 2015 U6 - https://doi.org/10.1109/IVNC.2015.7225548 SP - 106 EP - 107 PB - IEEE ER - TY - CHAP A1 - Mingels, Stephan A1 - Porshyn, Vitali A1 - Serbun, Pavel A1 - Lützenkirchen-Hecht, Dirk A1 - Müller, Günter A1 - Prommesberger, Christian A1 - Langer, Christoph A1 - Schreiner, Rupert A1 - Lutzenkirchen-Hecht, Dirk T1 - Photo-enhanced field emission properties of p-doped black Si arrays T2 - 2016 29th International Vacuum Nanoelectronics Conference (IVNC), 11-15 July 2016, Vancouver, BC, Canada N2 - We have carried out systematic investigations of p-type black Si field emitter arrays under laser illumination. As expected the current-voltage characteristic revealed a strong saturation providing a high photosensitivity, which had a maximum on-off ratio of 43 at a maximum current of 13 μA. The saturation current was stable in the dark as well as under illumination with fluctuations <;0.7%. Results from time-resolved measurements of the photo-sensitivity showed a rather fast response but a long decay time. Electron spectra in the dark and under laser illumination revealed the origin of the emission. KW - black Si KW - Decision support systems KW - photo-enhanced field emission Y1 - 2016 U6 - https://doi.org/10.1109/IVNC.2016.7551447 SP - 1 EP - 2 PB - IEEE ER - TY - CHAP A1 - Hausler, Peter A1 - Fischer, Johannes A1 - Wunderlich, Lukas A1 - Recum, Patrick A1 - Peller, Sebastian A1 - Hirsch, Thomas A1 - Bierl, Rudolf T1 - Miniaturisierte Sensoren basierend auf Oberflächenplasmonenresonanz, Chancen und Herausforderungen T2 - DGaO-Proceedings 2021 N2 - Derzeit gibt es zahlreiche Bereiche, wie Umwelt Monitoring und zivile Infrastruktur in denen geeignete Sensoren für die Überwachung der Systeme fehlen. SPR-basierte Sensoren haben das Potential diese Lücke zu schließen. Um für den Einsatz in der Umwelt tauglich zu werden, müssen die Sensoren noch robuster werden. Hier wird eine mögliche Lösung gezeigt. Y1 - 2021 UR - https://www.dgao-proceedings.de/download/122/122_a21.pdf PB - Dt. Gesellschaft für angewandte Optik CY - Erlangen-Nürnberg ER - TY - CHAP A1 - Al-Falouji, Ghassan A1 - Prestel, Dietmar A1 - Scharfenberg, Georg A1 - Mandl, Roland A1 - Deinzer, Arnulf A1 - Halang, W. A1 - Margraf-Stiksrud, Jutta A1 - Sick, B. A1 - Deinzer, Renate T1 - SMART-iBrush - Individuelle Unterstützung der Zahnreinigung durch Messung von Bewegung und Druck mit einer intelligenten Zahnbürsten T1 - SMART-iBrush - Individuelle Unterstützung der Zahnreinigung durch Messung von Bewegung und Druck mit einer intelligenten Zahnbürste T2 - Transdisziplinäre Konferenz Technische Unterstützungssysteme, die die Menschen wirklich wollen, 1, 2014, Gießen N2 - Der Forschungsansatz der intelligenten Zahnbürste (SMART-iBrush) verfolgt das Ziel, dass Menschen die für sie effektivste Zahnputzmethode unter individueller Anleitung der Zahnbürste interaktiv trainieren können. Hierzu wurde eine Zahnbürste entwickelt, die Bewegung und Druckverlauf erfasst. Daten werden an ein Smart Device übertragen und können dort in Echtzeit visualisiert werden, z.B. in eher spielerischer Form für Jugendliche oder sachlich nüchterner Form für Erwachsene. In einem Feldversuch wurden Daten von 100-Probanden erfasst. Zukünftig soll mit der SMART-iBrush Technologie, bei deren Entwicklung Wissenschaftler in den Bereichen Psychologie, Zahnmedizin, Embedded Systems und Machine Learning kooperieren, auch die Güte des Putzvorgangs bewertet werden, um die Putzenden aktiv anzuleiten. Intelligent toothbrush research (SMART-iBrush) aims to support humans in learning their individual, most effective tooth brushing technique. Therefore, a toothbrush was developed that measures motion and force applied to its tip. Measurements are transferred to a smart device where they can be visualized in real-time, for example in a more playful fashion for children or a-more factual fashion for adults. Field trials were conducted with 100 participants. Future features of SMART-iBrush 'will include interactive guidance and training techniques. To achieve these goals, researchers from the fields of psychology, dentistry, embedded systems, and machine learning cooperate in SMART-iBrush project. KW - Bewegungsmessung KW - Druckverlauf KW - Embedded-System KW - Erwachsener KW - Feldversuch KW - Jugendlicher KW - Kind KW - maschinelles Lernen KW - Psychologie KW - Zahnbürste KW - Zahnmedizin Y1 - 2014 SN - 978-3-86818-073-2 SP - 315 EP - 327 PB - Helmut-Schmidt-Universität, Universität der Bundeswehr CY - Hamburg ER - TY - CHAP A1 - Moser, Elisabeth A1 - Pangerl, Jonas A1 - Jobst, Simon A1 - Weigl, Stefan A1 - Bierl, Rudolf T1 - Modeling the Photoacoustic Spectrum of a Quantum Cascade Laser for Human Breath T2 - Optical Sensors and Sensing Congress 2022 (AIS, LACSEA, Sensors, ES): July 11 - 15, 2022, Vancouver, British Columbia Canada N2 - A modeling approach to create a photoacoustic spectrum from synthetic data is presented and evaluated. The resulting model reaches a MAPE score of 2.7% and can be used to enable data-driven development in future work. KW - Quantenkaskadenlaser KW - Photoakustische Spektrometrie KW - Atemluft Y1 - 2022 SN - 978-1-957171-10-4 U6 - https://doi.org/10.1364/AIS.2022.ATu3G.2 PB - Optica Publishing Group ER - TY - JOUR A1 - Goldschmidt, Jens A1 - Moser, Elisabeth A1 - Nitzsche, Leonard A1 - Bierl, Rudolf A1 - Wöllenstein, Jürgen T1 - Improving the performance of artificial neural networks trained on synthetic data in gas spectroscopy – a study on two sensing approaches JF - tm - Technisches Messen N2 - Artificial neural networks (ANNs) are used in quantitative infrared gas spectroscopy to predict concentrations on multi-component absorption spectra. Training of ANNs requires vast amounts of labelled training data which may be elaborate and time consuming to obtain. Additional data can be gained by the utilization of synthetically generated spectra, but at the cost of systematic deviations to measured data. Here, we present two approaches to train ANNs with a combination of comparatively small, measured data sets and synthetically generated data. For the first approach a neural network is trained hybridly with synthetically generated infrared absorption spectra of mixtures of N2O and CO and measured zero-gas spectra, taken with a mid-infrared dual comb spectrometer. This improves the mean absolute error (MAE) of the network predictions from 0.46 to 0.01 ppmV and 0.24 to 0.01 ppmV for the concentration predictions of N2O and CO respectively for zero-gas measurements which was previously observed for training with purely synthetic data. At the same time a similar performance on spectra from gas mixtures of 0–100 ppmV N2O and 0 to 60 ppmV CO was achieved. For the second approach an ANN pre-trained on synthetic infrared spectra of mixtures of acetone and ethanol is retrained on a small dataset consisting of 26 spectra taken with a mid-infrared photoacoustic spectrometer. In this case the MAE for the concentration predictions of ethanol and acetone are improved by 45 % and 20 % in comparison to purely synthetic training. This shows the capability of using synthetically generated data to train ANNs in combination with small amounts of measured data to further improve neural networks for gas sensing and the transferability between different sensing approaches. N2 - Künstliche neuronale Netze werden in der quantitativen Infrarot-Gasspektroskopie eingesetzt, um Gaskonzentrationen in Multi-Komponenten-Absorptionsspektren vorherzusagen. Das Training von künstlichen neuronalen Netzen benötigt große Mengen an Trainingsdaten, was mit einem hohen Arbeits- und Zeitaufwand verbunden ist. Zusätzliche Trainingsdaten können durch synthetisch generierte Spektren gewonnen werden, sind jedoch mit systematischen Abweichungen zu tatsächlich gemessenen Daten verbunden. In dieser Arbeit werden zwei Ansätze präsentiert, um künstliche neuronale Netze mit einer Kombination aus vergleichsweise kleinen, gemessenen Datensätzen und synthetisch erzeugten Daten zu trainieren. Für den ersten Ansatz wird das neuronale Netz hybrid mit synthetisch erzeugten Infrarot-Absorptionsspektren von Mischungen aus N2O und CO und gemessenen Null-Gas-Spektren trainiert, welche mit einem Doppel-Kamm-Spektrometer im Mittelinfraroten aufgenommen wurden. Dieses Vorgehen verbessert den mittleren, absoluten Fehler der Netzvorhersagen von 0,46 auf 0,01 ppmV und 0,24 auf 0,01 ppmV für N2O bzw. für CO für Null-Gas-Messungen, im Vergleich zu den Vorhersagen des neuronalen Netzes, welches nur mit synthetisch erzeugten Daten trainiert wurde. Gleichzeitig zeigte das hybrid trainierte Netz eine gleichbleibende Performance für Konzentrationsvorhersagen für Spektren aus Gasmischungen von 0 bis 100 ppmV N2O und 0 bis 60 ppmV CO. Für den zweiten Ansatz wird ein neuronales Netz, welches bereits mit synthetischen erzeugten Infrarotspektren von Mischungen aus Aceton und Ethanol trainiert wurde, erneut auf einem kleinen gemessenen Datensatz bestehend aus 26 Spektren trainiert, welche mit einem photoakustischen Spektrometer im mittleren Infrarot aufgenommen wurden. In diesem Fall hat sich der mittlere absolute Fehler der Konzentrationsvorhersage für Ethanol und Aceton um 45 % bzw. 20 % im Vergleich zu einem rein synthetischen Training verbessert. Das zeigt das Potential synthetisch erzeugte Daten für das Training von künstlichen neuronalen Netzen in Kombination mit kleinen gemessenen Datensätzen zu nutzen, um neuronale Netze für den Einsatz im Bereich der Gassensorik zu verbessern und gleichzeitig die Übertragbarkeit der Methodik auf verschiedene Messansätze. Y1 - 2023 U6 - https://doi.org/10.1515/teme-2023-0051 PB - Oldenbourg Wissenschaftsverlag ET - Online veröffentlicht ER - TY - CHAP A1 - Ulreich, Fabian A1 - Moser, Elisabeth A1 - Olbrich, Florian A1 - Ebert, Martin A1 - Bierl, Rudolf A1 - Kaup, André ED - Keil, Rudolf ED - Tschorn, Jan Alexander ED - Tümler, Johannes ED - Altinsoy, Mehmet Ercan T1 - Luminance Simulation in CARLA under Cloud Coverage - Model Validation and Implications T2 - 2023 IEEE International Workshop on Metrology for Automotive (MetroAutomotive), -30 June 2023, Modena, Italy N2 - To decrease the number of kilometers driven during the development of autonomous cars or driving assistance systems, performant simulation tools are necessary. Currently, domain distance effects between simulation and reality are limiting the successful application of rendering engines in data-driven perception tasks. In order to mitigate those domain distance effects, simulation tools have to be as close to reality as possible for the given task. For optical sensors like cameras, the luminance of the scene is essential. We provide within this paper a method to measure the luminance of rendered scenes within CARLA, an often used open-source simulation environment. Thereby, it is possible to validate the environment and weather models by taking real-world measurements with photometric sensors or with the help of open-source weather data, published e.g. by the German federal service for weather data (DWD - "Deutscher Wetterdienst"). Employing our proposed luminance measurement, the domain gap resulting from the simulation can be specified, which makes it possible to evaluate the statements about the safety of the automated driving system determined within the simulation. We show that the ratio between global and diffuse radiation modeled by the default atmosphere models within CARLA are under limited conditions similar to real-world measurements taken by the DWD. Nevertheless, we show, that the ratio’s temporal variability in real-world situations is not modeled by CARLA. KW - Atmospheric measurements KW - Atmospheric modeling KW - Cameras KW - carla KW - Cloud computing KW - cloud coverage KW - Data models KW - luminance KW - meteorology KW - Simulation KW - Soft sensors KW - weather KW - Wind Y1 - 2023 SN - 979-8-3503-2187-6 U6 - https://doi.org/10.1109/MetroAutomotive57488.2023.10219098 SP - 228 EP - 233 PB - IEEE ER - TY - JOUR A1 - Müller, Max A1 - Weigl, Stefan A1 - Müller-Williams, Jennifer A1 - Lindauer, Matthias A1 - Rück, Thomas A1 - Jobst, Simon A1 - Bierl, Rudolf A1 - Matysik, Frank-Michael T1 - Comparison of photoacoustic spectroscopy and cavity ring-down spectroscopy for ambient methane monitoring at Hohenpeißenberg JF - Atmospheric Measurement Techniques N2 - With an atmospheric concentration of approximately 2000 parts per billion (ppbV, 10−9), methane (CH4) is the second most abundant greenhouse gas (GHG) in the atmosphere after carbon dioxide (CO2). The task of long-term and spatially resolved GHG monitoring to verify whether climate policy actions are effective is becoming more crucial as climate change progresses. In this paper we report the CH4 concentration readings of our photoacoustic (PA) sensor over a 5 d period at Hohenpeißenberg, Germany. As a reference device, a calibrated cavity ring-down spectrometer, Picarro G2301, from the meteorological observatory of the German Weather Service (DWD) was employed. Trace gas measurements with photoacoustic instruments promise to provide low detection limits at comparably low costs. However, PA devices are often susceptible to cross-sensitivities related to fluctuating environmental conditions, e.g. ambient humidity. The obtained results show that for PA sensor systems non-radiative relaxation effects induced by varying humidity are a non-negligible factor. Applying algorithm compensation techniques, which are capable of calculating the influence of non-radiative relaxation effects on the photoacoustic signal, increase the accuracy of the photoacoustic sensor significantly. With an average relative deviation of 1.11 % from the G2301, the photoacoustic sensor shows good agreement with the reference instrument. Y1 - 2023 U6 - https://doi.org/10.5194/amt-16-4263-2023 SN - 1867-8548 VL - 16 IS - 18 SP - 4263 EP - 4270 PB - Copernicus Publications ER - TY - JOUR A1 - Pirker, Luka A1 - Ławrowski, Robert Damian A1 - Schreiner, Rupert A1 - Remškar, Maja A1 - Višić, Bojana T1 - MoₓWₓ₋₁S₂ Nanotubes for Advanced Field Emission Application JF - Advanced Functional Materials N2 - Transition metal dichalcogenide (TMDC) nanotubes complement the field of low-dimensional materials with their quasi-1D morphology and a wide set of intriguing properties. By introducing different transition metals into the crystal structure, their properties can be tailored for specific purpose and applications. Herein, the characterization and a subsequent preparation of single-nanotube field emission devices of MoxWx-1S2 nanotubes prepared via the chemical vapor transport reaction is presented. Energy-dispersive X-ray spectroscopy, Raman spectroscopy, and X-ray diffraction indicate that the molybdenum and tungsten atoms are randomly distributed within the crystal structure and that the material is highly crystalline. High resolution transmission electron microscopy and electron diffraction (ED) patterns further corroborate these findings. A detailed analysis of the ED patterns from an eight-layer nanotube reveal that the nanotubes grow in the 2H structure, with each shell consists of one bilayer. The work function of the nanotubes is comparable to that of pure MoS2 and lower of pure WS2 NTs, making them ideal candidates for field emission applications. Two devices with different geometrical setup are prepared and tested as field emitters, showing promising results for single nanotube field emission applications. Y1 - 2023 U6 - https://doi.org/10.1002/adfm.202213869 SN - 1616-3028 N1 - Early View. Online Version of Record before inclusion in an issue SP - 1 EP - 8 PB - Wiley ER - TY - INPR A1 - Pangerl, Jonas A1 - Moser, Elisabeth A1 - Müller, Max A1 - Weigl, Stefan A1 - Jobst, Simon A1 - Rück, Thomas A1 - Bierl, Rudolf A1 - Matysik, Frank-Michael T1 - A Highly Sensitive Acetone and Ethanol Quantum Cascade Laser Based Photoacoustic Sensor: Characterization and Multi-Component Spectra Recording in Synthetic Breath T2 - SSRN Electronic Journal N2 - Trace gas analysis in breath is challenging due to the vast number of different components. We present a highly sensitive quantum cascade laser based photoacoustic setup for breath analysis. Scanning the range between 8260 and 8270 nm with a spectral resolution of 48 pm, we are able to quantify acetone and ethanol within a typical breath matrix containing water and CO2. We photoacoustically acquired spectra within this region of mid-infra-red light and prove that those spectra do not suffer from non-spectral interferences. The purely additive behavior of a breath sample spectrum was verified by comparing it with the independently acquired single component spectra using Pearson and Spearman correlation coefficients. A previously presented simulation approach is improved and an error attribution study is presented. With a 3σ detection limit of 6.5 ppbV in terms of ethanol and 250 pptV regarding acetone, our system is among the best performing presented so far. KW - Photoacoustic spectroscopy KW - quantum cascade laser KW - spectral simulation KW - breath analysis KW - acetone Y1 - 2022 U6 - https://doi.org/10.2139/ssrn.4305376 PB - Elsevier ER - TY - PAT A1 - Olbrich, Florian A1 - Pongratz, Christian A1 - Bierl, Rudolf A1 - Ehrlich, Ingo T1 - Method and System for Evaluating a Structural Integrity of an Aerial Vehicle Y1 - 2024 ER - TY - CHAP A1 - Peller, Sebastian A1 - Zankl, Tobias A1 - Fischer, Christoph A1 - Bierl, Rudolf T1 - Fast sound field characterization of beamforming capable capacitive micromachined ultrasonic transducer (CMUT) arrays by refracto-vibrometry T2 - IEEE IUS 2023, International Ultrasonics Symposium, Montréal, September 3-8, 2023 N2 - We introduce a time-optimized setup based on refracto-vibrometry for the purpose of scanning the sound field of capacitive micromachined ultrasonic transducer (CMUT) arrays primarily for the qualification of their beamforming capability. In comparison to commonly used microphones on a traversing stage the proposed method is substantially faster and consumes only a few minutes of time for a complete two-dimensional sound field containing about 100.000 scan points. T2 - Schnelle Schallfeld-Charakterisierung von CMUT-Arrays mithilfe von Refrakto-Vibrometrie KW - CMUT KW - LDV KW - refracto-vibrometry KW - sound field KW - beamforming Y1 - 2023 SN - 979-8-3503-4645-9 U6 - https://doi.org/10.1109/IUS51837.2023.10308126 SN - 1948-5727 SP - 1 EP - 3 PB - IEEE ER - TY - JOUR A1 - Becker, Tatiana I. A1 - Böhm, Valter A1 - Schale, Florian A1 - Zimmermann, Klaus T1 - Vibrating sensor unit made of a magnetoactive elastomer with field-adjustable characteristics JF - Journal of Magnetism and Magnetic Materials N2 - The present work deals with the investigation of the oscillatory behavior displayed by a vibrating sensor unit made of a magnetoactive elastomer (MAE). Since this type of smart materials consists of an elastic matrix and micro-magnetic particles, it reveals exceptional magnetic-field-dependent material properties. The forced vibration response under the bending of the MAE unit subjected to in-plane harmonic kinematic excitation of the housing is studied. It is found that the amplitude-frequency characteristics of the MAE unit can be changed considerably by means of an external homogeneous magnetic field. With and without applied field, the unit displays different steady-state responses for the same excitation, and the resonance occurs at various ranges of the excitation frequency. The nonlinear phenomenon of the resonance hysteresis is observed depending on whether the excitation frequency increases or decreases. It is shown that the MAE vibrations can be detected based on the magnetic field distortion measurements. The presented prototype of the MAE-based vibrating unit with field-adjustable “configuration” can be potentially implemented for realization of acceleration sensor systems with adaptive sensitivity. Y1 - 2020 U6 - https://doi.org/10.1016/j.jmmm.2019.166196 VL - 498 IS - March PB - Elsevier ER - TY - JOUR A1 - Glavan, Gašper A1 - Belyaeva, Inna A. A1 - Ruwisch, Kevin A1 - Wollschlaeger, Joachim A1 - Shamonin (Chamonine), Mikhail T1 - Magnetoelectric Response of Laminated Cantilevers Comprising a Magnetoactive Elastomer and a Piezoelectric Polymer, in Pulsed Uniform Magnetic Fields JF - Sensors N2 - The voltage response to pulsed uniform magnetic fields and the accompanying bending deformations of laminated cantilever structures are investigated experimentally in detail. The structures comprise a magnetoactive elastomer (MAE) slab and a commercially available piezoelectric polymer multilayer. The magnetic field is applied vertically and the laminated structures are customarily fixed in the horizontal plane or, alternatively, slightly tilted upwards or downwards. Six different MAE compositions incorporating three concentrations of carbonyl iron particles (70 wt%, 75 wt% and 80 wt%) and two elastomer matrices of different stiffness are used. The dependences of the generated voltage and the cantilever's deflection on the composition of the MAE layer and its thickness are obtained. The appearance of the voltage between the electrodes of a piezoelectric material upon application of a magnetic field is considered as a manifestation of the direct magnetoelectric (ME) effect in a composite laminated structure. The ME voltage response increases with the increasing total quantity of the soft-magnetic filler in the MAE layer. The relationship between the generated voltage and the cantilever's deflection is established. The highest observed peak voltage around 5.5 V is about 8.5-fold higher than previously reported values. The quasi-static ME voltage coefficient for this type of ME heterostructures is about 50 V/A in the magnetic field of approximate to 100 kA/m, obtained for the first time. The results could be useful for the development of magnetic field sensors and energy harvesting devices relying on these novel polymer composites. KW - cantilever KW - composites KW - DEMAGNETIZING FACTORS KW - direct magnetoelectric effect KW - laminated structure KW - magnetic field sensor KW - magnetoactive elastomer KW - piezoelectric polymer Y1 - 2021 U6 - https://doi.org/10.3390/s21196390 N1 - Corresponding authors: Gašper Glavan, Mikhail Shamonin VL - 21 IS - 19 SP - 1 EP - 19 PB - MDPI CY - Basel ER - TY - CHAP A1 - Herdl, Florian A1 - Bachmann, Michael A1 - Wohlfartsstätter, Dominik A1 - Düsberg, Felix A1 - Dudeck, Markus A1 - Eder, Magdalena A1 - Meyer, Manuel A1 - Pahlke, Andreas A1 - Edler, Simon A1 - Schels, Andreas A1 - Hansch, Walter A1 - Schreiner, Rupert A1 - Wohlfartsstatter, Dominik A1 - Dusberg, Felix T1 - A novel current dependent field emission performance test T2 - 2021 34th International Vacuum Nanoelectronics Conference (IVNC): 5-9 July 2021, Lyon, France N2 - A current dependent performance test for comparison of different field emitter arrays is introduced. Statistical analysis is enabled due to a short measurement time and as a main feature the electric field shift, comparable to the degradation of the emitter is examined. Significance of the test method is shown by a comparison of field emitter arrays with different doping levels. KW - Current measurement KW - Field emitter arrays KW - Statistical analysis KW - Systematics KW - Time measurement KW - Tools KW - Vacuum systems Y1 - 2021 U6 - https://doi.org/10.1109/IVNC52431.2021.9600695 SP - 1 EP - 2 ER - TY - CHAP A1 - Bieker, Johannes A1 - Roustaie, Farough A1 - Schlaak, Helmut F. A1 - Langer, Christoph A1 - Schreiner, Rupert T1 - Field emission characterization of in-situ deposited metallic nanocones T2 - 2017 30th International Vacuum Nanoelectronics Conference (IVNC), 10-14 July 2017, Regensburg, Germany N2 - An in-situ fabrication technique based on ion track etched template electrodeposition of metallic nanocones was used for the production of field emitter cathodes. Gold nanocones with a height of 24 microns, a base diameter between 3 to 4 microns and a tip diameter below 300 nanometers were deposited on a circular electrode with a diameter of 2.5 mm. The integral field emission (FE) measurements of samples with cone densities of 6 · 104 cones/cm2 (sample A) and 1 · 106 cones/cm2 (sample B) yielded in a maximum current of 37.5 μA at an applied field of 12.5 V/μm for sample A and 29.1 μA at 9.4 V/μm for sample B. The stability of emission current was investigated for over 48 hours and no degradation was observed. KW - CATHODES KW - Current measurement KW - FABRICATION KW - field emission KW - ion track template KW - Ions KW - Iron KW - nanocones KW - Vacuum technology KW - Voltage measurement Y1 - 2017 U6 - https://doi.org/10.1109/IVNC.2017.8051571 SP - 120 EP - 121 PB - IEEE ER - TY - CHAP A1 - Schels, Andreas A1 - Edler, Simon A1 - Hansch, Walter A1 - Bachmann, Michael A1 - Herdl, Florian A1 - Dusberg, F. A1 - Eder, Magdalena A1 - Meyer, Manuel A1 - Dudek, M. A1 - Pahlke, Andreas A1 - Schreiner, Rupert ED - Purcell, Stephen ED - Mazellier, Jean-Paul T1 - Current dependent performance test used on different types of silicon field emitter arrays T2 - 2021 34th International Vacuum Nanoelectronics Conference (IVNC): 5-9 July 2021, Lyon, France N2 - A current dependent performance test is used to investigate the influence of doping and emitter geometry on the lifetime of silicon field emitter arrays. The measurements reveal an improved performance for lower n-type dopant concentrations. Furthermore, two new types of field emitters are introduced by slightly varying the original fabrication process [1]. The comparison shows superiority of tip like emitters over blade like structures. Y1 - 2021 SN - 978-1-6654-2589-6 U6 - https://doi.org/10.1109/IVNC52431.2021.9600787 SP - 1 EP - 2 PB - IEEE CY - Piscataway, NJ ER - TY - CHAP A1 - Roth, Carina A1 - Hausler, Peter A1 - Bierl, Rudolf T1 - Einbindung eines 2D-Photodetektors in einen hochintegrierten SPR-Imaging-Sensor T2 - 7. MikroSystemTechnik Kongress "MEMS, Mikroelektronik, Systeme", 23.-25. Oktober 2017, München N2 - Die Oberflächenplasmonenresonanzspektroskopie (SPR) ist eine hochempfindliche Messmethode, die es erlaubt, Gase und Flüssigkeiten zerstörungs- und markierungsfrei in Echtzeit zu analysieren. Bisher vornehmlich im Labormaßstab in der Bioanalytik und dem Wirkstoffscreening eingesetzt, soll diese Technologie nun miniaturisiert und für weitere Anwendungsgebiete zugänglich gemacht werden. Dazu wird ein kompakter Micro-Opto-Electro-Mechanical Systems Sensor (MOEMS) entwickelt, der mit Hilfe des SPR Imaging Änderungen der chemischen Zusammensetzung verschiedener Flüssigkeiten inline messen kann. N2 - Surface plasmon resonance spectroscopy (SPR) is a highly sensitive measurement method which allows the analysis of gases and liquids in real-time in a non-destructive and marking-free manner. Presently SPR is predominantly used for pharmaceutical screening and biotechnical analysis. Now this technology is to be miniaturized and made accessible for further application areas. For this purpose, a compact micro-opto-electro-mechanical system sensor (MOEMS) is developed, which can measure changes in the chemical composition of different fluids using SPR imaging. T2 - Integration of a 2D-photodetector in a SPR-Imaging-Sensor KW - Bildsensor KW - Bioanalytik KW - chemische Zusammensetzung KW - Fotodetektor KW - Labormaßstab KW - Messmethode KW - mikrooptoelektromechanisches System KW - Oberflächenplasmon KW - Oberflächenplasmonenresonanzspektroskopie KW - pharmazeutisches Screening KW - Spektroskopie KW - Wirkstoff Y1 - 2017 SN - 978-3-8007-4491-6 SP - 848 EP - 850 PB - VDE-Verlag CY - München ER - TY - GEN A1 - Chavez Vega, Jhohan Harvey A1 - Böhm, Valter A1 - Scharff, Moritz A1 - Prem, Nina A1 - Monkman, Gareth J. A1 - Becker, Tatiana I. A1 - Günther, L. A1 - Alencastre, Jorge H. A1 - Grieseler, R. A1 - Zimmermann, Klaus T1 - Magneto-active elastomer as viscoelastic foundation material for artificial tactile sensors with tuneable properties T2 - Book of Abstracts of the 16th German Ferrofluid Workshop, Braunschweig, 18.-20.07.2018 Y1 - 2018 SP - 16 EP - 17 ER - TY - JOUR A1 - Schels, Andreas A1 - Herdl, Florian A1 - Hausladen, Matthias A1 - Wohlfartsstätter, Dominik A1 - Edler, Simon A1 - Bachmann, Michael A1 - Pahlke, Andreas A1 - Schreiner, Rupert A1 - Hansch, Walter T1 - Quantitative Field Emission Imaging for Studying the Doping-Dependent Emission Behavior of Silicon Field Emitter Arrays JF - Micromachines N2 - Field emitter arrays (FEAs) are a promising component for novel vacuum micro- and nanoelectronic devices, such as microwave power amplifiers or fast-switching X-ray sources. However, the interrelated mechanisms responsible for FEA degradation and failure are not fully understood. Therefore, we present a measurement method for quantitative observation of individual emission sites during integral operation using a low-cost, commercially available CMOS imaging sensor. The emission and degradation behavior of three differently doped FEAs is investigated in current-regulated operation. The measurements reveal that the limited current of the p-doped emitters leads to an activation of up to 55% of the individual tips in the array, while the activation of the n-type FEA stopped at around 30%. This enhanced activation results in a more continuous and uniform current distribution for the p-type FEA. An analysis of the individual emitter characteristics before and after a constant current measurement provides novel perspectives on degradation behavior. A burn-in process that trims the emitting tips to an integral current-specific ideal field enhancement factor is observed. In this process, blunt tips are sharpened while sharp tips are dulled, resulting in homogenization within the FEA. The methodology is described in detail, making it easily adaptable for other groups to apply in the further development of promising FEAs. Y1 - 2023 U6 - https://doi.org/10.3390/mi14112008 VL - 14 IS - 11 PB - MDPI ER - TY - CHAP A1 - Schels, Andreas A1 - Herdl, Florian A1 - Hausladen, Matthias A1 - Wohlfartsstätter, Dominik A1 - Bachmann, Michael A1 - Edler, Simon A1 - Düsberg, Felix A1 - Pahlke, Andreas A1 - Buchner, Philipp A1 - Schreiner, Rupert A1 - Hansch, Walter T1 - Beta Factor Mapping of Individual Emitting Tips During Integral Operation of Field Emission Arrays T2 - 2023 IEEE 36th International Vacuum Nanoelectronics Conference (IVNC), 10-13 July 2023, Cambridge, MA, USA N2 - Emission uniformity mappings of field emitter arrays provide important insight into degradation mechanisms, but are often laborious, non-integral, costly, or not quantifiable. Here, a low-cost Raspberry Pi HQ camera is used as an extraction anode to quantify the emission distribution in field emitter arrays. A verification measurement using controlled SEM electron beams proves, that current-voltage characteristics of individual emission sites can be determined by combining the integral electrical data with the image data. The characteristics are used to quantify the field enhancement factors of an 30x30 silicon field emitter array during integral operation. Comparison of the field enhancement factor distributions before and after a one-hour constant current operation at 1 µA shows an increase from 50 actively emitting tips before to 156 after the measurement. It is shown, that the distribution of field enhancement factors shifts towards lower values, due to the increasing degradation for high field enhancement tips, especially above 1500. KW - field emission KW - field emission imaging KW - field emission distribution KW - field enhancement factor KW - CMOS imaging KW - beta factor Y1 - 2023 SN - 979-8-3503-0143-4 U6 - https://doi.org/10.1109/IVNC57695.2023.10188957 SP - 224 EP - 226 PB - IEEE ER - TY - CHAP A1 - Herdl, Florian A1 - Kueddelsmann, Maximillian J. A1 - Schels, Andreas A1 - Bachmann, Michael A1 - Edler, Simon A1 - Wohlfartsstätter, Dominik A1 - Düsberg, Felix A1 - Prugger, Alexander A1 - Dillig, Michael A1 - Dams, Florian A1 - Schreiner, Rupert A1 - Coileáin, Cormac Ó. A1 - Zimmermann, Stefan A1 - Pahlke, Andreas A1 - Duesberg, Georg S. T1 - Characterization and Operation of Graphene-Oxide-Semiconductor Emitters at Atmospheric Pressure Levels T2 - 2023 IEEE 36th International Vacuum Nanoelectronics Conference (IVNC), 10-13 July 2023, Cambridge, MA, USA N2 - In recent years Graphene-Oxide-Semiconductor (GOS) electron emitters have attracted a lot of interest due to their outstanding durability in modest vacuum conditions. However, the performance at ambient pressure remains largely unexplored. In this study GOS-emitters are characterized in nitrogen and air at atmospheric pressure, and compared with their vacuum characteristics. For this purpose, lifetime and IV-characteristics measurements are shown. Furthermore, the GOS-emitter was operated as an ionization source for ion mobility spectrometry (IMS) at ambient conditions. KW - durability KW - graphene compounds KW - ion mobility KW - semiconductor-insulator boundaries Y1 - 2023 SN - 979-8-3503-0143-4 U6 - https://doi.org/10.1109/IVNC57695.2023.10188974 SP - 14 EP - 16 PB - IEEE ER - TY - CHAP A1 - Hausladen, Matthias A1 - Buchner, Philipp A1 - Schels, Andreas A1 - Edler, Simon A1 - Bachmann, Michael A1 - Schreiner, Rupert T1 - An Integrated Field Emission Electron Source on a Chip Fabricated by Laser-Micromachining and Mems Technology T2 - 2023 IEEE 36th International Vacuum Nanoelectronics Conference (IVNC), 10-13 July 2023, Cambridge, MA, USA N2 - A silicon field emission electron source consisting of a cathode and a grid electrode has been fabricated by laser micromachining. The cathode features 21×21 tips on an area of 4×4 mm 2 , With a self-aligning MEMS technology for the aperture grid, a high electron transmission (99 %) was achieved. Onset voltages of 50…70 V were observed for an emission current of 1 nA. A stable emission current of 1 mA ± 1.3 % at an extraction voltage of 250 V was observed during a 30-min operation. KW - Apertures KW - Field Emission KW - Field Emission Array KW - Ions KW - Laser-Micromachining KW - Lasers KW - Micromechanical devices KW - Silicon KW - Silicon Field Emission Array KW - Steady-state KW - Vacuum systems Y1 - 2023 SN - 979-8-3503-0143-4 U6 - https://doi.org/10.1109/IVNC57695.2023.10189001 SP - 115 EP - 116 PB - IEEE ER - TY - CHAP A1 - Buchner, Philipp A1 - Hausladen, Matthias A1 - Schels, Andreas A1 - Herdl, Florian A1 - Edler, Simon A1 - Bachmann, Michael A1 - Schreiner, Rupert T1 - An Integrated Silicon Nanowire Field Emission Electron Source on a Chip with High Electron Transmission T2 - 2023 IEEE 36th International Vacuum Nanoelectronics Conference (IVNC), 10-13 July 2023, Cambridge, MA, USA N2 - Silicon nanowire field emission arrays (50 × 50 pillars) were fabricated on a silicon glass hybrid wafer. The glass acts both as the support for the whole structure and insulator between cathode and extraction grid. The extraction grid matches the emitter structures and is optically aligned and adhered to the emitter chip by a vacuum compatible epoxide adhesive. These chips exhibit an emission current of about 600 μA at an extraction voltage of 300 V. The electron transmission through the grid is above 80 %. 58-hour longtime measurements were conducted showing low degradation of the emission current and high stability of electron transmission. KW - Semiconductor device measurement KW - Stimulated emission KW - Optical device fabrication KW - Glass KW - Power system stability KW - Insulators KW - Electron optics Y1 - 2023 SN - 979-8-3503-0143-4 U6 - https://doi.org/10.1109/IVNC57695.2023.10188878 SP - 6 EP - 8 PB - IEEE ER - TY - CHAP A1 - Hausladen, Matthias A1 - Schels, Andreas A1 - Buchner, Philipp A1 - Bartl, Mathias A1 - Asgharzade, Ali A1 - Edler, Simon A1 - Wohlfartsstätter, Dominik A1 - Bachmann, Michael A1 - Schreiner, Rupert T1 - Improved Method for Determining the Distribution of FEA Currents by Optical CMOS Sensors T2 - 37th International Vacuum Nanoelectronics Conference (IVNC), 15-19 July 2024, Brno, Czech Republic N2 - CMOS image sensors are utilized to determine the time- and spatially-resolved distribution of the electron emission of silicon field emission arrays. During initial experiments, rather low field emission currents already visibly damaged the sensor surface, altering the system accuracy over the measurement time. Therefore, we coated the sensor surface with copper for protection. In contrast to the original insulating surface, the Cu coating provides a conductive surface for incident electrons and improves heat dissipation in addition. This prevents localized surface charges and surface damages which stabilize the system accuracy. Y1 - 2024 U6 - https://doi.org/10.1109/IVNC63480.2024.10652543 SP - 1 EP - 2 PB - IEEE ER - TY - JOUR A1 - Bachmann, Michael A1 - Düsberg, Felix A1 - Pahlke, Andreas A1 - Edler, Simon A1 - Schels, Andreas A1 - Herdl, Florian A1 - Hausladen, Matthias A1 - Buchner, Philipp A1 - Schreiner, Rupert T1 - The “LED‐version” of the electron gun: An electron source for operation in ambient pressure environments based on silicon field emitter arrays JF - Vakuum in Forschung und Praxis N2 - We report on our progress to develop and optimize electron sources for practical applications. A simple fabrication process is introduced based on a wafer dicing saw and a wet chemical etch step without the need for a clean room. Due to the formation of crystal facets the samples show a homogeneous geometry throughout the array. Characterization techniques are developed to systematically compare various arrays. A very defined measurement procedure based on current controlled IV-sweeps as well as lifetime measurements at various currents is proposed. To investigate the current distribution in the array a commercial CMOS detector is used and shows the potential for in depth analysis of the arrays. Finally, a compact hermetically sealed housing is presented enabling electron generation in atmospheric pressure environments. Y1 - 2023 U6 - https://doi.org/10.1002/vipr.202300801 VL - 35 IS - 3 SP - 32 EP - 37 PB - Wiley ER - TY - THES A1 - Zhong, Gantong T1 - Calibration and Performance Evaluation of Contactless Optical Position Sensors Based on 3D Printed Optical Waveguides N2 - This work presents the design, implementation, and performance evaluation of a positionsensing system based on a 3D printed optical waveguide. Building upon the conceptual foundation of D-shaped polymer optical fiber (POF) sensors [1], this study introduces a novel waveguide structure fabricated via multi-material fused filament fabrication (FFF) 3D printing. The waveguide incorporates a square-core geometry with integrated mechanical brackets and selective black cladding layer to enhance optical confinement and minimize boundary-induced nonlinearity. Three successive design iterations were developed and evaluated, with each version refined based on calibration results and structural observations. The final version demonstrated high fabrication stability and improved optical behavior, enabling consistent calibration across multiple samples. Using a center-corrected linear attenuation model, the position of a side-coupled LED was estimated from dual photodiode signals and compared with true light source position. The measurement results for five independently printed waveguides show mean absolute errors below 0.2 mm and standard deviations as low as 0.268 mm. The sensor response was found to be highly linear over the 5–55 mm sensing range, with worst-case errors bounded within ±1.7 mm. Compared with traditional D-shaped POF sensors, where performance is limited by manual polishing variability and nonuniform attenuation, the 3D-printed approach offers superior linearity, submillimeter accuracy, and batch-to-batch reproducibility. These findings prove the feasibility of 3D-printed optical waveguides in scalable and precise position sensing applications, marking a further step toward the batch fabrication and and potential industrialization of contactless optical position sensors. A conclusion of the research findings and suggestions for future improvements were provided at the end of this thesis, offering insights for the further development in this area. Y1 - 2025 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-84668 CY - Regensburg ER - TY - JOUR A1 - Hausladen, Matthias A1 - Schels, Andreas A1 - Buchner, Philipp A1 - Bartl, Mathias A1 - Asgharzade, Ali A1 - Edler, Simon A1 - Wohlfartsstätter, Dominik A1 - Bachmann, Michael A1 - Schreiner, Rupert T1 - Measurement of field emission array current distributions by metal-coated CMOS image sensors JF - Journal of Vacuum Science & Technology B N2 - A CMOS image sensor is utilized to determine the time- and spatially resolved distribution of the total electron emission current of a silicon field emission array. The sensor measures electron emission without the need for phosphorus screens or scintillators as converters. However, in initial experiments, rather low field emission currents of several hundreds of nanoamperes per emitter already damaged the sensor surface, which altered the systems’ signal response over the measurement time. In consequence, we coated the CMOS sensor surface with a Cu layer for surface protection. In contrast to the original insulating surface, Cu is an excellent current- and heat-conductor, which avoids lens charging by providing a conductive path for incident electrons and has an improved heat dissipation capability. Measurements using a segmented field emission cathode with four individually addressable tips demonstrate a consistent correlation between the emission current and the sensor signal of the metal-coated image sensor. Furthermore, the characterization of a field emission array showed that single tip emission currents of up to 12 μA per tip are measurable without discernible damage effects of the sensor’s surface. KW - Bremsstrahlung KW - Laser micromachining KW - Image sensors KW - Field emitter arrays Y1 - 2024 U6 - https://doi.org/10.1116/6.0004074 VL - 42 IS - 6 PB - AIP Publishing ER - TY - JOUR A1 - Schreiner, Rupert A1 - Wiedmann, J. A1 - Coenning, W. A1 - Porsche, J. A1 - Gentner, Jean-Louis A1 - Berroth, Manfred A1 - Scholz, Ferdinand A1 - Schweizer, H. T1 - Fabrication approach for antiphase narrow linewidth complex coupled 1.55 μm DFB lasers JF - Electronics Letters N2 - A new method for fabricating narrow linewidth antiphase complex coupled MQW DFB lasers by periodically etching the active layer and quartemary InGaAsP overgrowth is reported. The minimum linewidth for a 375 µm long ridge waveguide laser is only 250 kHz at an optical output power of 4 mW. KW - etching KW - optical fabrication KW - quantum well lasers KW - ridge waveguides KW - distributed feedback lasers Y1 - 1999 U6 - https://doi.org/10.1049/el:19990132 SN - 0013-5194 VL - 35 IS - 2 SP - 146 EP - 148 PB - The Institution of Engineering and Technology IET ER - TY - JOUR A1 - Hausladen, Matthias A1 - Schels, Andreas A1 - Asgharzade, Ali A1 - Buchner, Philipp A1 - Bartl, Mathias A1 - Wohlfartsstätter, Dominik A1 - Edler, Simon A1 - Bachmann, Michael A1 - Schreiner, Rupert T1 - Investigation of Influencing Factors on the Measurement Signal of a CMOS Image Sensor for Measuring Field Emission Currents JF - Sensors Y1 - 2025 U6 - https://doi.org/10.3390/s25051529 N1 - Corresponding author der OTH Regensburg: Matthias Hausladen VL - 25 IS - 5 PB - MDPI ER - TY - CHAP A1 - Buchner, Philipp A1 - Hausladen, Matthias A1 - Bartl, Mathias A1 - Schreiner, Rupert T1 - Elektronenquellen basierend auf Feldemission aus Silizium T2 - Tagungsband zum 4. Symposium Elektronik und Systemintegration ESI: 17. April 2024, Hochschule Landshut N2 - Der Beitrag gibt einen Überblick über zwei typische Bauformen für Elektronenquellen auf der Basis von Feldemission aus Silizium. Des Weiteren wird eine typische Trioden-Beschaltung solcher Elektronenquellen für hohe Elektronentransmission vorgestellt und dabei auf ihre Leistungsfähigkeit eingegangen. Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:860-opus4-4212 SN - 978-3-9818439-9-6 SP - 46 EP - 53 PB - Hochschule für Angewandte Wissenschaften Landshut CY - Landshut ER - TY - GEN A1 - Eiler, Julian A1 - Weber, Stefan A1 - Gerlesberger, Peter A1 - Plöchinger, Heinz A1 - Schreiner, Rupert T1 - Miniaturized Pirani vacuum sensor with active heat-loss compensation T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft e.V. (DPG), Regensburg, 16. - 21. März 2025 N2 - Pirani sensors measure the thermal conductivity of the residual gas in a vacuum by creating a thermal gradient between a heated sensor element and a heat sink. The heat flux from the sensor element to the heat sink over the residual gas is a measure of the vacuum and can be determined by the electrical power applied. In addition to the heat flux over the gas, there are further energy losses from the heating structure due to radiation and parasitic heat fluxes via the suspensions of the sensor element. These losses reduce the sensitivity of the sensor. For this reason, a Micro-Pirani sensor in the shape of a microhotplate was developed that actively compensates the heat flux via the suspensions. This was achieved by placing additional heating structures on the suspensions, which interrupt the heat flow from the sensor element via the suspensions during operation. This active compensation improves the sensitivity at low pressures, enabling vacuum measurements from atmospheric pressure down to 10e-6 mbar. Y1 - 2025 UR - https://www.dpg-verhandlungen.de/year/2025/conference/regensburg/part/o/session/66/contribution/7 SN - 2751-0522 PB - Deutsche Physikalische Gesellschaft e.V. ER - TY - CHAP A1 - Eiler, Julian A1 - Berndt, Dominik A1 - Schreiner, Rupert T1 - Miniaturisierter Wasserstoffsensor basierend auf der 3-Omega Methode T2 - Tagungsband zum 4. Symposium Elektronik und Systemintegration ESI: 17. April 2024, Hochschule Landshut N2 - Die Arbeit stellt einen thermischen Wasserstoffsensor auf Siliziumbasis vor, der mit der 3-Omega Messmethode betrieben wird. Durch das dynamische Messverfahren, die große Sensoroberfläche bei gleichzeitig geringer thermischer Masse und der Materialkombination wird eine Auflösungsgrenze von 55 ppm Wasserstoff in Stickstoff erreicht. Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:860-opus4-4205 SN - 978-3-9818439-9-6 SP - 38 EP - 45 PB - Hochschule für Angewandte Wissenschaften Landshut CY - Landshut ER - TY - THES A1 - Lindner, Matthias T1 - Miniaturisierte dielektrische Barrierenentladungen und ihre Anwendung für das Anti- bzw. De-Icing von aerodynamischen Oberflächen N2 - Das grundlegende physikalische Verständnis und die kontinuierliche Weiterentwicklung von dielektrischen Oberflächenbarrierenentladungen (SDBDs) sowie der damit erbundenen elektrischen Diagnostik, sind für eine Vielzahl von Niedertemperaturplasmaanwendungen von entscheidender Bedeutung. In Bezug auf die Anwendung dieser Plasmatechnologie in der Luftfahrt liegt neben der bereits umfassend erforschten aktiven Strömungskontrolle zunehmend der Schwerpunkt auf der Vermeidung von Eisablagerungen auf aerodynamischen Komponenten. Die Bildung von Eis auf Oberflächen wie zum Beispiel den Tragflächen kann unter extremen Wetterbedingungen erhebliche Leistungsdefizite hervorrufen und zu ernsthaften Sicherheitsrisiken führen. In Anbetracht der signifikanten Vorteile gegenüber traditionellen Enteisungsmethoden steht die Erforschung von SDBDs im Mittelpunkt des anwendungsorientierten Abschnitts dieser Arbeit. Vorliegende Arbeit untergliedert sich in einen grundlegenden und einen anwendungsbezogenen Teil. Darin werden sowohl die physikalischen Eigenschaften und Prozesse von SDBDs analysiert als auch ihre potenziellen Anwendungen in Bezug auf Flugsicherheit und Effizienz untersucht. Die wissenschaftliche Forschung hat in der Vergangenheit erhebliche Anstrengungen unternommen, um ein umfassendes Verständnis der physikalischen Vorgänge, die im Zusammenhang mit SDBDs stehen, zu erarbeiten. Insbesondere die präzise Bestimmung der räumlichen Ausdehnung der Entladung entlang der dielektrischen Oberfläche - die üblicherweise in direkter Proportionalität zur Amplitude der angelegten Spannung steht - ist hierbei eine herausfordernde Aufgabe. Diese umfangreichen Studien sind essenziell, um die Entladungseigenschaften und die grundlegenden physikalischen Prozesse zu verstehen, was erhebliche Anwendungspotenziale eröffnet. Parallel zu diesen grundlegenden Studien hat sich auch der praktische Einsatz von SDBDs zur Verhinderung der Eisbildung auf aerodynamischen Bauteilen bedeutend weiterentwickelt. Untersuchungen legen nahe, dass Lösungen auf Basis von SDBDs im Vergleich zu konventionellen Enteisungsmethoden, wie beispielsweise chemischen Enteisungsmitteln oder thermischen Systemen, ein höheres Effizienz- und Wirkungspotential besitzen könnten. Allerdings wurden bisherige Entwicklungen von SDBDs hauptsächlich auf Basis der Leiterplattentechnologie realisiert, was bestimmte Begrenzungen in Bezug auf ihre Anwendbarkeit für Anti-Icing- Technologie mit sich bringt. Im ersten Teil dieser Arbeit wurde die sequentielle Ausbreitung der SDBD-Entladung entlang der dielektrischen Al2O3-Oberfläche systematisch analysiert. Die durchgeführten experimentellen Untersuchungen zeigten, dass die Entladungen unmittelbar nach dem Erreichen der Zündspannung einen fest definierten Bereich belegen, der bis zum Erreichen einer kritischen Spannungsamplitude VL stabil bleibt. Anzumerken ist auch, dass das Ausbleiben der Plasmaausbreitung innerhalb dieses Spannungsbereichs zu einer linearen Korrelation zwischen der Entladungsleistung und der angelegten Spannungsamplitude führt. Diese tiefergehenden Einblicke in die Dynamik der Entladung können dazu beitragen, den Einsatz von SDBDs in diversen Anwendungsbereichen effizienter zu gestalten. Im zweiten Teil der Arbeit steht die Entwicklung und Implementierung eines innovativen Ansatzes zur Realisierung von SDBDs im Vordergrund, der auf der Nutzung von Dünnschichtsubstra-Vten und mikroelektromechanischen Systemen (MEMS) basiert. Die Verwendung dieser Technologie erlaubt einen präziseren Design- und Fertigungsprozess von Elektrodenstrukturen, was sich positiv auf die Effizienz der Enteisung auswirken kann. Zur Beurteilung des Anti-Icing-Potenzials der entwickelten MEMS-SDBDs wurde ein direkter Vergleich mit konventionellen PCB-SDBDs durchgeführt. Die Ergebnisse legen nahe, dass die 35 μm dicken Elektroden der PCB-SDBDs eine Oberflächenvereisung fördern, die vorrangig durch die Elektrodenkanten induziert wird. Im Gegensatz dazu wurde dieser Effekt bei den deutlich dünneren, lediglich 0.3 μm dicken, mittels MEMS gefertigten Elektroden nicht festgestellt. Diese Beobachtungen deuten darauf hin, dass SDBDs, die mit MEMS-Technologien gefertigt wurden, einen signifikanten Vorteil in Anti-Icing-Anwendungen aufweisen könnten und stellen somit einen wesentlichen Fortschritt in der Forschung und Anwendung von SDBDs dar. Die in dieser Arbeit vorgelegten Forschungsergebnisse und innovativen Methoden liefern zahlreiche neue Erkenntnisse, die das Potential besitzen, sowohl das Verständnis als auch die Anwendung von SDBDs wesentlich zu erweitern. So bestätigen die Langzeitbelichtungsaufnahmen das neu entdeckte Phänomen einer sequenziellen Ausbreitung des Entladungsplasmas, das bei SDBDs mit dickeren Dielektrika stärker ausgeprägt ist. Eine neu entwickelte Methodik ermöglicht die Anwendung der Ladungs-Spannungs-Charakteristik von SDBDs, um essenzielle Parameter für ein vereinfachtes Ersatzschaltbild abzuleiten. Darüber hinaus wurde eine bemerkenswerte numerische Übereinstimmung zwischen der Ladungs-Spannungs-Charakteristik für den positiven Halbzyklus der Entladung und der aus den optischen Aufnahmen abgeleiteten spannungsabhängigen Reaktorkapazität festgestellt. Diese Erkenntnisse öffnen neueWege für die Optimierung und Anwendung von SDBDs in verschiedenen technischen Bereichen. Weiterhin identifizierte die durchgeführte Erosionsstudie Titan als optimal geeignetes Material für MEMS-Elektroden aufgrund seiner hohen Korrosionsbeständigkeit und ausgezeichneten elektrischen Leitfähigkeit. Es wurden auch Potentiale zur Optimierung von MEMS-SDBDs durch die Auswahl geeigneter dielektrischer Materialien und geeigneter SDBD-Geometrien aufgezeigt. Eine solche Optimierung könnte die Enteisungseffizienz weiter verbessern, indem beispielsweise die dielektrischen Eigenschaften an die spezifischen Anwendungsanforderungen angepasst werden. Innovative Designkonzepte, wie eine gezielte Anordnung der Elektroden oder die Integration von Sensoren zur Überwachung des Enteisungsprozesses, könnten ebenfalls zur Leistungsfähigkeit und Zuverlässigkeit von MEMS-SDBDs beitragen. Ein weiterer bedeutender Aspekt ist die Anwendung von Piezotransformatoren zur Generierung der benötigten Hochspannung für SDBD-Systeme. Dieser innovative Ansatz könnte die Effizienz des auf SDBD-Technologie basierenden Enteisungsverfahrens optimieren und somit zur Verbesserung der Leistungsfähigkeit und Sicherheit von Flugzeugen unter extremen Wetterbedingungen beitragen. Das Forschungsfeld bietet viel Raum für zukünftige Studien, was die Bedeutung und Zukunftsrelevanz der in dieser Arbeit gewonnenen Ergebnisse hervorhebt. N2 - The fundamental physical understanding and continuous development of Surface Dielectric Barrier Discharges (SDBDs) and associated electrical diagnostics are of crucial importance for a wide range of low-temperature plasma applications. Regarding the application of this plasma technology in aviation, the focus is increasingly on the prevention of ice accumulation on aerodynamic components, in addition to the already extensively researched active flow control. The formation of ice on surfaces such as the wings can cause significant performance deficits under extreme weather conditions and lead to serious safety risks. Considering the significant advantages over traditional de-icing methods, the investigation of SDBDs is at the forefront of the application-oriented section of this work. This work is divided into a fundamental and an application-oriented part. Both the physical properties and processes of SDBDs are analyzed and their potential applications in terms of flight safety and efficiency are examined. Past scientific research has made considerable efforts to develop a comprehensive understanding of the physical processes associated with SDBDs. The precise determination of the spatial extension of the discharge along the dielectric surface - which is typically in direct proportion to the amplitude of the applied voltage - is a challenging task. These extensive studies are essential to understand the discharge characteristics and the fundamental physical processes, revealing significant application potential. In parallel to these fundamental studies, the practical use of SDBDs for preventing ice formation on aerodynamic components has also made significant progress. Research suggests that solutions based on SDBDs could have higher efficiency and effect potential compared to conventional de-icing methods such as chemical de-icing agents or thermal systems. However, past developments of SDBDs have been mainly based on printed circuit board technology, which brings certain limitations in terms of their applicability for anti-icing technology. In the first part of this work, the sequential propagation of the SDBD discharge along the dielectric Al2O3 surface was systematically analyzed. The experimental investigations carried out showed that the discharges occupy a fixed area immediately after reaching the ignition voltage, which remains stable until a critical voltage amplitude VL is reached. It should also be noted that the absence of plasma expansion within this voltage range leads to a linear correlation between the discharge power and the applied voltage amplitude. These deeper insights into the dynamics of the discharge can contribute to making the use of SDBDs more efficient in various application areas. In the second part of the work, the development and implementation of an innovative approach to realize SDBDs is in the foreground, based on the use of thin-film substrates and Microelectromechanical Systems (MEMS). Using this technology allows for a more precise design and manufacturing process of electrode structures, which can positively affect the efficiency of deicing. To assess the anti-icing potential of the developed MEMS-SDBDs, a direct comparison with conventional PCB-SDBDs was conducted. The results suggest that the 35 μm thick electrodes of the PCB-SDBDs promote surface icing, primarily induced by the electrode edges. In contrast, this effect was not observed with the much thinner, only 0.3 μm thick, electrodes produced using MEMS. These observations suggest that SDBDs manufactured using MEMS technologies could have a significant advantage in anti-icing applications and thus represent a significant advance in the research and application of SDBDs. The research results and innovative methods presented in this work provide numerous new insights that have the potential to significantly expand both the understanding and application of SDBDs. Long-exposure photographs confirm the newly discovered phenomenon of a stepwise expansion of the discharge plasma, which is more pronounced for SDBDs with thicker dielectrics. A new methodological approach – the bow tie plot - allows the utilization of the charge-voltage relationship in SDBDs to derive crucial parameters from the simplest equivalent circuit model. Furthermore, a remarkable numerical agreement was found between the charge-voltage characteristic for the positive half-cycle of the discharge and the voltage-dependent reactor capacity derived from the optical images. These findings present new opportunities for the enhancement and deployment of SDBDs across various technological sectors. Moreover, the erosion study conducted identified titanium as the optimal material for MEMS electrodes due to its high corrosion resistance and excellent electrical conductivity. There were also potentials for optimizing MEMS-SDBDs by selecting suitable dielectric materials and suitable SDBD geometries. Such optimization could further improve de-icing efficiency, for example by adjusting the dielectric properties to the specific application requirements. Innovative design concepts, such as targeted arrangement of electrodes or integration of sensors for monitoring the de-icing process, could also contribute to the performance and reliability of MEMS-SDBDs. Another significant aspect is the application of piezoelectric transformers to generate the required high voltage for SDBD systems. This innovative approach could optimize the efficiency of the de-icing process based on SDBD technology and thus contribute to improving the performance and safety of aircraft under extreme weather conditions. The field of research offers great potential for future studies, which underscores the significance and future relevance of the results obtained in this work. KW - Kaltes Plasma KW - Barrierenentladung KW - Enteisung KW - Flugzeugaerodynamik KW - MEMS KW - Plasmaentladung KW - Dielektrische Barrierenentladung Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:384-opus4-1118933 UR - https://opus.bibliothek.uni-augsburg.de/opus4/111893 ER - TY - THES A1 - Jonker, Dirk T1 - Advanced nanofabrication techniques for electron emission devices N2 - The goal of this thesis is to develop an electron injection source based on a cold field emission cathode that ultimately functions as an alternative electron source used during the Birch reduction process. The experimental configuration to conduct an alternative Birch reduction involves the combination of various physical domains, including solid-state physics, physics of interfaces, electrochemistry, and fluid dynamics. The body of this thesis discusses the fabrication and characterization of a silicon nanocone array. It also presents a self-aligned method to incorporate an electronic gate structure that may function as an extractor grid. The emission behavior and transport properties of the silicon nanocones are assessed by scanning tunneling microscopy by performing measurements on flat silicon and silicon nanocone surfaces containing different dopant types and doping concentrations. Furthermore, additional experimental work is conducted to replace a thermally grown silicon dioxide layer with platinum silicide and characterize the electrical properties by means of scanning tunneling microscopy. Lastly, the thesis discusses the fabrication of two plasmonic structures and evaluates the plasmonic modes, surface enhancement, and Raman activity. KW - Nanofabrication KW - Scanning tunneling microscopy (STM) KW - Geometric diode KW - surface enhanced Raman scattering KW - silicon nanowires KW - silicon nanocones KW - platinum silicide (PtSi) KW - Plasmonic substrates Y1 - 2023 UR - https://research.utwente.nl/en/publications/advanced-nanofabrication-techniques-for-electron-emission-devices SN - 978-90-365-5632-3 U6 - https://doi.org/10.3990/1.9789036556323 ER - TY - THES A1 - Weigl, Stefan T1 - Development of a sensor system for human breath acetone analysis based on photoacoustic spectroscopy N2 - The breath analysis section of this thesis outlines the potentials but also emphasises the concomitant challenges of human breath analysis. The section further describes the usefulness of a point-of-care (POC) device for breath acetone detection. In addition, it covers various breath analysis related subjects, which can be useful considering further developments of breath analysers. This includes an extensive summary involving the high abundant endogenous as well as the exogenous breath species present in a clinical environment. Subsequently, a detailed discussion about the theoretical aspects of absorption spectra is provided, forming the basis for the spectral interference chapter. Classical absorption spectroscopy (AS) is compared with photoacoustic spectroscopy (PAS) in view of trace gas analysis. Different modulation schemes for signal generation, i.e. amplitude modulation (AM) and wavelength modulation (WM) are part of the comparison, while the advantages and disadvantages of each technique are highlighted. As a result, PAS is considered superior to AS and hence is selected as the method of choice regarding the development of a sensor for breath acetone detection. A detailed mathematical derivation of the photoacoustic signal generation as well as the signal enhancement by means of acoustic resonance amplification is provided. Moreover, several phenomena causing signal attenuation are outlined, including vibrational-translational (VT) relaxation, vibrational-vibrational (VV) energy transfer mechanism, acoustic detuning and photodissociation. Various simulations regarding spectral interferences in the infra-red (IR) and ultraviolet (UV) region are presented, demonstrating the susceptibility towards spectral cross-sensitivities in the IR region, hence, rather suggesting the UV region for acetone detection. However, this simulation can be easily adopted to other target analytes and serves as a basis for multicomponent analysis approaches in the IR region using tuneable light sources. Ultra sensitive acetone detection employing a high power UV LED is presented and a detailed analysis considering the effects of environmental parameters onto the photoacoustic signal, including temperature, pressure, LED duty cycle and flow rate, is provided. In addition, general cross-sensitivities of the photoacoustic signal towards the high abundant species O2, CO2 and H2O have been investigated and discussed. Moreover, several LED and photoacoustic cell (PAC) combinations have been compared in order to evaluate improvement approaches regarding an enhancement of the system’s sensitivity. Finally, photoacoustic sensor setups employing an interband cascade laser (ICL) or a quantum cascade laser (QCL) have been studied and compared to various UV setups in view of different key performance parameters, including the limits of detection (LOD) and the normalised noise equivalent absorption (NNEA) coefficients. The juxtaposition of the different approaches once more emphasises the extraordinary sensitivity of photoacoustic spectroscopy. To the best of the author’s knowledge, the LODs (3σ) of the UV LED based photoacoustic measurement in typical breath conditions (12.5 ppbV) and the LOD of the QCL measurement (0.79 ppbV) provide two world records. First, regarding photoacoustic acetone detection using an UV LED and second, in view of other published results for photoacoustic acetone detection in general. N2 - Zu Beginn der Arbeit werden zum einen die Potentiale der Analyse des menschlichen Ausatemgases aufgezeigt und zum anderen die damit verbundenen Herausforderungen beschrieben. Dabei wird auch die Nützlichkeit eines Point-of-Care (POC) Gerätes zur Bestimmung des Acetongehalts im Ausatemgas hervorgehoben. Darüber hinaus werden verschiedene mit der Atemgasanalyse zusammenhängende Themen behandelt, die hinsichtlich weiterer Entwicklungen von Atemgasanalysegeräten sehr hilfreich sein können. Dazu gehört u.a. eine ausführliche Analyse der Zusammensetzung des menschlichen Ausatemgases, die sowohl die hauptsächlichen endogenen als auch die im klinischen Umfeld verstärkt vorkommenden, exogenen Bestandteile, aufgelistet. Anschließend werden die theoretischen Grundlagen von Absorptionsspektren detailliert behandelt, da sie die Grundlage für das Kapitel über die spektralen Interferenzen bilden. Des Weiteren werden die klassische Absorptionsspektroskopie (AS), als auch die photoakustische Spektroskopie (PAS), hinsichtlich ihrer Eignung für die Spurengasanalytik verglichen. Verschiedene Modulationsschemata für die Signalerzeugung, d.h. Amplitudenmodulation (AM) und Wellenlängenmodulation (WM), sind Teil des Vergleichs, wobei die Vor- und Nachteile jeder Technik hervorgehoben werden. Als Ergebnis wurde die PAS gegenüber der AS als überlegen angesehen und daher als Methode der Wahl bei der Entwicklung eines Sensors zur Bestimmung des Acetongehalts in der Ausatemluft ausgewählt. Eine detaillierte mathematische Herleitung der photoakustischen Signalerzeugung sowie der Signalverstärkung mittels akustischer Resonanzverstärkung ist ebenso in der Arbeit enthalten. Darüber hinaus werden mehrere Phänomene der Signaldämpfung skizziert, dazu zählen u.a. die Schwingungs-Translation Relaxation, der Schwinungs-Schwingungs Energieübertragungsmechanismus, die Photodissoziation und die akustische Resonanzverschiebung. Es werden verschiedene Simulationen bezüglich spektraler Interferenzen im infraroten (IR) und ultraviolleten (UV) Wellenlängenbereich vorgestellt, die die Anfälligkeit gegenüber spektralen Querempfindlichkeiten im IR-Bereich demonstrieren und somit eher den UV-Bereich für die Acetonbestimmung nahelegen. Die Simulationsergebnisse können leicht auf weitere Zielanalyten übertragen werden und dienen somit als Grundlage für Multikomponenten-Analyseansätze im IR-Bereich mittels durchstimmbarer Lichtquellen. Im Ergebnisteil wird u.a. ein hochempfindliches System zur Acetondetektion unter Verwendung einer Hochleistungs-UV LED vorgestellt. Dieses System wurde außerdem einer detaillierten Analyse unter Berücksichtigung der Auswirkungen von Umgebungsparametern auf das photoakustische Signal, einschließlich Temperatur, Druck, LED-Tastverhältnis und Durchfl ussrate, unterzogen. Zusätzlich wurden Querempfi ndlichkeiten des photoakustischen Systems gegenüber den im Ausatemgas hochkonzentrierten Stoffen O2, CO2 und H2O untersucht und die Ergebnisse diskutiert. Darüber hinaus wurden verschiedene Kombinationen von LEDs und photoakustischen Zellen verglichen, um Verbesserungsansätze hinsichtlich der Empfindlichkeit des Systems zu untersuchen. Abschließend wurden photoakustische Sensorsysteme, die einen Interbandkaskadenlaser (ICL) oder einen Quantenkaskadenlaser (QCL) verwenden, untersucht und mit verschiedenen UV LED Systemen im Hinblick auf unterschiedliche Leistungsparameter, einschließlich der Nachweisgrenzen (NWG) und den normierten, rauschäquivalenten Absorptionskoeffizienten, verglichen. Die Gegenüberstellung der verschiedenen Ansätze unterstreicht einmal mehr die außerordentliche Empfindlichkeit der photoakustischen Spektroskopie. Nach bestem Wissen des Autors stellen die NWGs (3σ) der photoakustischen Messung mit einer UV LED in typischer Atemgaszusammensetzung (12.5 ppbV) und die NWG der QCL-Messungen (0.79 ppbV) zwei Weltrekorde dar. Zum einen gibt es keine Veröffentlichung hinsichtlich einer besseren, photoakustisch ermittelten NWG für Aceton mittels einer UV LED und zum anderen stellt die mit dem QCL photoakustisch gemessene NWG im Allgemeinen die beste, je veröffentlichte photoakustische NWG für Aceton dar. KW - Photoacoustic KW - Breath Analysis KW - Acetone Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:355-epub-447768 ER - TY - JOUR A1 - Buchner, Philipp A1 - Hausladen, Matthias A1 - Bartl, Mathias A1 - Bachmann, Michael A1 - Schreiner, Rupert T1 - High current field emission from Si nanowires on pillar structures JF - Journal of Vacuum Science and Technology B: Nanotechnology and Microelectronics N2 - We investigate the influence of the geometry and doping level on the performance of n-type silicon nanowire field emitters on silicon pillar structures. Therefore, multiple cathodes with 50 by 50 pillar arrays (diameter: 5 μm, height: 30 μm, spacing: 50 μm) were fabricated and measured in diode configuration. In the first experiment, we compared two geometry types using the same material. Geometry 1 is black silicon, which is a highly dense surface covering a forest of tightly spaced silicon needles resulting from self-masking during a plasma etching process of single crystal silicon. Geometry 2 are silicon nanowires, which are individual spaced-out nanowires in a crownlike shape resulting from a plasma etching process of single crystal silicon. In the second experiment, we compared two different silicon doping levels [n-type (P), 1–10 and <0.005 Ω cm] for the same geometry. The best performance was achieved with lower doped silicon nanowire samples, emitting 2 mA at an extraction voltage of 1 kV. The geometry/material combination with the best performance was used to assemble an integrated electron source. These electron sources were measured in a triode configuration and reached onset voltages of about 125 V and emission currents of 2.5 mA at extraction voltages of 400 V, while achieving electron transmission rates as high as 85.0%. KW - Doping KW - Electron sources KW - Nanowires KW - Plasma processing KW - Field emitter arrays KW - Triodes KW - Semiconductors Y1 - 2024 U6 - https://doi.org/10.1116/6.0003384 SN - 2166-2754 VL - 42 IS - 2 PB - AIP ER -