TY - JOUR A1 - Eiler, Julian A1 - Weber, Stefan A1 - Gerlesberger, Peter A1 - Plöchinger, Heinz A1 - Schreiner, Rupert T1 - Active heat-loss compensated miniaturized pirani sensor chip JF - IEEE Sensors Letters N2 - Due to the limited measuring range of commercial Pirani sensors in lower pressure regimes, attempts are being made to extend the measuring range of the sensors. Our approach to extend the measuring range toward lower pressures is a micro-electromechanical systems (MEMS) Pirani sensor with active heat compensation on the suspensions. The sensor element has the shape of a microhotplate and consists of a nickel heating meander embedded in two silicon nitride layers. The whole structure is built on a silicon wafer. The sensor element is suspended on all four corners of the substrate. On each of the suspensions, there is an additional heating structure that minimizes the heat flux from the hot sensor element toward the substrate. The sensor is driven at a constant temperature through a self-balancing Wheatstone bridge. A constant voltage is applied to the heating structures on the suspensions. It has been demonstrated that with these additional heaters, the sensitivity of the sensor can be increased in the high-vacuum regime. This enables reliable vacuum measurements down to 10−6 mbar. KW - Temperature measurement KW - Heating systems KW - Temperature sensors KW - Sensitivity KW - Pressure measurement KW - Voltage measurement KW - Heat sinks KW - Semiconductor device measurement KW - Noise measurement KW - Bridge circuits Y1 - 2025 U6 - https://doi.org/10.1109/LSENS.2025.3605747 SN - 2475-1472 VL - 9 IS - 10 PB - Institute of Electrical and Electronics Engineers (IEEE) 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 - CHAP A1 - Bauer, Lukas A1 - Vitzthumecker, Thomas A1 - Bierl, Rudolf A1 - Ehrnsperger, Matthias T1 - Machine-learning-based detection and severity estimation of drought stress in plants using hyperspectral imaging data T2 - Remote Sensing for Agriculture, Ecosystems, and Hydrology XXVII N2 - Growing food demand due to population growth, coupled with increasingly frequent and severe droughts caused by climate change make water increasingly scarce. To address this, accurate assessment of plant water demand is essential for precise drought treatment and water conservation. Hyperspectral imaging (HSI) captures hypercubes, a combination of spectral and spatial data and offers promising capabilities for detection of plant stresses. However, most reported approaches only use selected spectral bands or indices, neglecting the full hypercube information. This is assumed to limit the detection accuracy. To overcome these limitations, we aim to develop a measurement pipeline to generate a comprehensive dataset comprising hypercubes of plants under varying drought stress levels along with selected physiological, environmental, and illumination data. This dataset will be used to train suitable data-driven models that enable improved drought stress detection as well as the non-invasive determination of physiological parameters based on HSI data. Y1 - 2025 U6 - https://doi.org/10.1117/12.3072011 PB - SPIE ER - TY - CHAP A1 - Ehrnsperger, Matthias G. T1 - Enhancing object recognition through camera-radar fusion and micro-doppler signature integration T2 - Emerging Technologies and Materials for Security and Defence 2025 N2 - Object recognition systems based on visual sensors often struggle in degraded environmental conditions such as fog, rain, darkness, or occlusion. Radar, in contrast, offers robust detection capabilities under such conditions but lacks the spatial resolution of optical sensors. This paper presents an ongoing research effort towards a multimodal sensor fusion framework that integrates camera data with radar signals, specifically exploiting micro-Doppler (μD) signatures, with the aim of improving object recognition robustness. The proposed setup uses an Intel RealSense Depth Camera D455 and an Infineon BGT60TR13C radar sensor, deployed on a low-power embedded platform with STM32 microcontrollers. The signal processing pipeline, currently under development, combines time–frequency radar analysis with convolutional neural network-based visual feature extraction for real-time edge AI inference. We describe the system design, preliminary data acquisition setup, and planned evaluation strategy. Y1 - 2025 U6 - https://doi.org/10.1117/12.3071682 PB - SPIE ER - TY - CHAP A1 - Ehrnsperger, Matthias G. T1 - Multimodal sensor fusion for resilient perception: combining radar and imaging for all-weather object tracking T2 - Artificial Intelligence and Image and Signal Processing for Remote Sensing XXXI N2 - This work presents the concept and initial qualitative observations of a multimodal perception system that fuses radar, lidar, and camera data to improve object detection and tracking under adverse environmental conditions. The approach focuses on building weather-impact models for each sensor modality—quantifying performance degradation effects such as color shifts and contrast loss in cameras, range reduction and spurious returns in lidar, and resolution limitations in radar. These models will later inform adaptive sensor fusion strategies deployed on embedded edge-AI hardware, using an Infineon BGT60TR13C FMCW radar, Intel RealSense D455 depth camera, and low-power processors. Preliminary visual inspection of collected datasets indicates that combining complementary sensing modalities can maintain detection continuity under conditions where single modalities fail. Future work will quantitatively evaluate these effects and demonstrate weather-adaptive perception on the embedded platform. Y1 - 2025 U6 - https://doi.org/10.1117/12.3071683 PB - SPIE ER - TY - RPRT A1 - Pfingsten, Andrea A1 - Bredehorst, Maren A1 - Leinweber, Juliane A1 - Richter, Robert A1 - Vogel, Barbara T1 - HVG-Positionspapier für die Therapiewissenschaften : Fachkommission Forschung im Hochschulverbunde Gesundheitsfachberufe (HVG) N2 - Zeitgemäße Therapie ist effektiv, effizient, patient*innen‐ und teilhabeorientiert. Ergotherapie, Logopädie/Sprachtherapie und Physiotherapie (im Folgenden kurz: ELP) sind gesellschaftlich relevant und essenzieller Bestandteil einer nachhaltigen Gesundheitsversorgung. Therapiewissenschaften evaluieren, verbessern und erweitern Möglichkeiten der Prävention und Behandlung von Krankheiten sowie der Beratung und Begleitung von Menschen in gesundheitlicher Hinsicht. Wer, wenn nicht die Therapeut*innen, stellt Forschungsfragen und verfolgt Forschungsinteressen, durch die forschungsbasiertes Wissen zu Therapie entsteht? Dieses Positionspapier der Fachkommission Forschung im HVG wurde entwickelt als Referenz zur Forschungslandschaft der ELP. Es ist als Argumentationshilfe gedacht, um die Voraussetzungen für die Therapiewissenschaften zu verbessern. KW - Allied Health KW - Physiotherapie KW - Wissenschaft Y1 - 2024 U6 - https://doi.org/10.5281/zenodo.14495900 ET - Version 1 (Stand 08.04.2024) ER - TY - JOUR A1 - Pierobon, Chiara A1 - Sharshenova, Aijan T1 - German and Russian Public Diplomacy Efforts in Kyrgyzstan: A Comparative Study of Norm Entrepreneurship JF - Europe-Asia Studies N2 - This article explores Russian and German public diplomacy efforts in Central Asia through the example of Kyrgyzstan. Due to a difficult economic and socio-political situation, Kyrgyzstan remains open to externally funded programmes and projects, including initiatives funded by foreign governments, and thus offers a unique environment for the study of public diplomacy. The article looks at transnational public diplomacy actors such as German political foundations and Russian-sponsored organisations active in the country. Overall, the article offers interesting insights into the nature and substance of the soft power policies pursued by Germany and Russia that are relevant for Kyrgyzstan and beyond. Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-87380 VL - 75 IS - 8 SP - 1384 EP - 1407 PB - Taylor & Francis ER - TY - JOUR A1 - Pierobon, Chiara T1 - European Union, civil society and local ownership in Kyrgyzstan: analysing patterns of adaptation, reinterpretation and contestation in the prevention of violent extremism (PVE) JF - Central Asian Survey N2 - In the last decade, a growing body of literature has investigated the promotion of good governance, rule of law, democracy and human rights in Central Asia through funding from the European Union (EU). Most of this research has taken an EU-centric approach and is concerned with the supply side of external democratization. As a result, little is known about how EU projects are implemented on the ground and what EU-funded civil society organizations consider to be their priorities. This article investigates the agency of such organizations in Kyrgyzstan by focusing on their contribution to one particular EU instrument: the Instrument contributing to Stability and Peace (IcSP), and its programme: Strengthening Resilience to Violence and Extremism (STRIVE). The findings offer new insights into the processes of adaptation, reinterpretation and contestation through which EU-funded organizations exercise ownership while engaging in the prevention of violent extremism (PVE). Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-87378 VL - 41 IS - 4 SP - 752 EP - 769 PB - Taylor & Francis ER - TY - JOUR A1 - Pierobon, Chiara T1 - EU’s support to civil society in Kazakhstan: A pilot evaluation of the social capital generated JF - Evaluation N2 - In the last decade, several studies have been devoted to the analysis of the EU’s support to civil society abroad, but only recently has scholarly attention turned to Central Asia. Most of the research in this field has adopted a macro-level perspective, concerned with the supply side of external democratization, and has examined external assistance to civil society in terms of democratization ideal types and typologies. The main contribution of this study consists of a meso-level analysis of the outcomes of the EU’s support to civil society in terms of production of social capital, conceived as the raw material of civil society itself. More precisely, the article evaluates the first wave of grants awarded to civil society organizations in Kazakhstan as part of two EU funding schemes—the European Instrument for Democracy and Human Rights and the Non-State Actors and Local Authorities in Development. The article sheds new light on the use of social capital and its two dimensions-structural and cognitive-as heuristic tools for evaluating civil society support programs. Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-87394 VL - 25 IS - 2 SP - 207 EP - 223 PB - Sage ER - TY - BOOK A1 - Kriza, Thomas ED - Lerch, Sebastian T1 - Ethische Fragen der Digitalisierung und ihre Thematisierung in Forschung und Lehre an Hochschulen BT - Dimensionen von Transdisziplinarität T3 - Interdisziplinarität in der Hochschullehre N2 - Die Digitalisierung als fortschreitende Durchdringung aller Lebensbereiche durch Informationstechnik geht mit gesellschaftlichen Transformationsprozessen und weitreichenden ethischen Fragen einher. Diese Fragen haben einen transdisziplinären Charakter in dem Sinne, dass sie sich nur durch ein Überschreiten von fachlichen Perspektiven einzelner wissenschaftlicher Disziplinen und durch eine ganzheitliche Bezugnahme auf gesellschaftliche Auswirkungen angemessen adressieren lassen. Anhand der technischen Möglichkeiten von Big Data Analytics lässt sich aufzeigen, wie disziplinübergreifende wissenschaftliche Forschungen zu technischen Anwendungen führen können, die gewichtige, gesellschaftlich relevante Fragen nach ihrer ethischen Vertretbarkeit aufwerfen. Diese können in letzter Konsequenz auch ethische Grundprinzipien und Auffassungen des Menschseins ins Wanken bringen. Besonders prägnant lässt sich dies mit den Studien des Big-Data-Forschers Michal Kosinski und seines Forscherkreises sowie den daraus resultierenden Anwendungen von Unternehmen wie Cambridge Analytica vor Augen führen: Die Analyse von großen Mengen digitaler persönlicher Daten eröffnet umfassende Möglichkeiten zur Verhaltensbeeinflussung und stellt dabei sehr weitreichend auch ethische Grundwerte wie Privatheit in Frage. Universitäten und Hochschulen sind aufgefordert, durch transdisziplinäre Lehre und Forschung die ethischen Fragen der Digitalisierung als bestimmende Themen der Gegenwart direkt zu adressieren. Y1 - 2023 SN - 9783763974610 U6 - https://doi.org/10.3278/9783763974610 SP - 45 EP - 58 PB - wbv Publikation CY - Bielefeld ER - TY - THES A1 - Vokkethur, Rachana T1 - Design, simulation, fabrication, measurement, and analysis of 3D-printed radio frequency conductive structures N2 - Additive manufacturing has emerged as a disruptive technology in the field of electronics, offering new possibilities for the fabrication of complex, lightweight, and customizable components. Conventional PCB manufacturing relies on multi-step processes and is limited to planar geometries, making it less suitable for rapid prototyping or integration into non-standard surfaces. In contrast, Fused Deposition Modelling (FDM) provides a cost-effective and accessible approach to directly fabricate functional electronic structures by combining conductive and dielectric materials within a single printing process. This thesis examines the design, simulation, fabrication, measurement and analysis of 3D-printed conductive transmission lines utilising FDM technology. A conductive filament and a dielectric filament are employed to realise fully integrated microstrip and coaxial structures. Electromagnetic simulations are performed to optimise the geometry for RF performance, and the printed prototypes are experimentally characterised using vector network analyser measurements. The analysis focuses on the transmission coefficients and the reflection coefficients, providing insights into impedance matching, insertion loss, and frequency-dependent behaviour. These findings confirm that FDM-based additive manufacturing can produce functional RF structures with reliable performance, despite material and fabrication limitations. The work demonstrates the potential of 3D printing as a flexible and low-cost method for prototyping radio frequency components, highlighting future directions that include improved material characterisation, connector integration, and the design of more advanced components, such as filters and antennas. Y1 - 2026 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-87809 CY - Regensburg ER - TY - GEN A1 - Krysztof, Michal A1 - Baranowski, Kamil A1 - Zychla, Michal A1 - Hausladen, Matthias A1 - Schreiner, Rupert A1 - Knápek, Aleksandr T1 - MP61 - Detection of Electron Beam in Atmospheric Pressure Using CMOS Image Sensor T2 - EUROSENSORS XXXVII ; 07.09.2025 - 10.09.2025 ; Wroclaw ; Poster I N2 - In the article, a new detection system that enables observation of the electron beam signal passing through a gas layer at atmospheric pressure is presented. An experimental setup consisting of an elec-tron gun (electron emitter, extraction, and focus electrodes), silicon nitride membrane, and a CMOS image sensor is described, as well as first image of the electron beam spot after passing through 400 µm of air at atmospheric pressure is presented. Y1 - 2025 U6 - https://doi.org/10.5162/EUROSENSORS2025/MP61 SP - 325 EP - 326 PB - AMA ER - TY - CHAP A1 - Sadeque, Md. Golam A1 - Ahmmed, Tanvir A1 - Hossain, Md. Aowal A1 - Rahman, Md. Naimur A1 - Sarker, Md Tanjil A1 - Ramasamy, Gobbi T1 - A Novel CWT-CNN Framework for Driver Fatigue Detection from EEG Signals T2 - 2025 Multimedia University Engineering Conference (MECON), 21-23 July 2025, Cyberjaya, Malaysia N2 - Fatigued driving has been a significant contributor to traffic accidents globally, posing serious threats to both human life and economic stability. Machine learning techniques based on electroencephalography (EEG) are showing promise for detecting driver fatigue, excelling other physiological modalities in this regard. However, it requires a lot of exertion, demands domain knowledge, and may not generalize effectively across different datasets to manually extract features from EEG signals. Therefore, investigating innovative deep-learning architectures that can effectively extract discriminative characteristics from unprocessed EEG data is necessary. This paper proposes a novel framework for driver fatigue detection from EEG signals using Continuous Wavelet Transform (CWT) and Convolutional Neural Networks (CNN). Rather than depending on hand-crafted feature extraction, we use CWT to convert EEG data into time-frequency spectrum pictures. After concatenating these spectral images from every channel, a CNN is fed to learn discriminative features for driver normal and fatigued states automatically. An average classification accuracy of 98.3% is obtained by evaluating the proposed CWT-CNN system on a publicly available EEG dataset comprising recordings from twelve subjects. The results obtained indicate that the CWT-CNN framework has enormous potential to create strong driver fatigue detection systems, thereby enhancing road safety. KW - CNN KW - CWT KW - Deep Learning (DL) KW - Driver Fatigue KW - EEG Y1 - 2025 SN - 979-8-3315-5549-8 U6 - https://doi.org/10.1109/MECON67253.2025.11277149 PB - IEEE ER - TY - INPR A1 - Fischer, Johannes A1 - Hirsch, Thomas A1 - Reitmeier, Torsten A1 - Bierl, Rudolf T1 - Real-time hardware-based processing of high-precision detector signals for surface plasmon resonance spectroscopy N2 - Surface plasmon resonance (SPR) is limited by small-signal detectability and drift when subtraction occurs in software after digitization. We introduce an SPR detector that performs on-detector amplification and analog differential readout, eliminating moving parts and software-heavy correction. The hardware-native subtraction boosts the usable ADC range and suppresses illumination and environmental noise. In fixed-angle refractive-index steps (NaCl), the platform resolves Δn_min ≈ 1.8 × 10⁻⁷ RIU compared to 4.6–7.2 × 10⁻⁶ RIU on a commercial comparator and improves small-signal SNR by up to ∼5,000-fold, while remaining competitive at high signal levels. In a model IgG–BSA assay, the detector’s low noise floor clarifies early binding and equilibrium transitions. By generating inherently clean raw signals, this hardware-native approach dramatically enhances sensitivity and long-term stability for label-free biosensing and inline process analytics while rendering AI-based or complex post-processing entirely unnecessary. The concept generalizes across platforms and opens a compact route to robust, high-fidelity SPR in complex environments, with a clear path toward multi-wavelength and arrayed detectors for high-throughput chemical monitoring. KW - Drift-free SPR KW - Hardware-native sensing KW - Noise suppression KW - On-detector amplification KW - Small-signal detection KW - Surface plasmon resonance Y1 - 2025 U6 - https://doi.org/10.2139/ssrn.5971170 ER - TY - CHAP A1 - Bartl, Mathias A1 - Hausladen, Matthias A1 - Asgharzade, Ali A1 - Buchner, Philipp A1 - Krysztof, Michal A1 - Knápek, Alexandr A1 - Bachmann, Michael A1 - Schreiner, Rupert T1 - Experimental method for investigation of the emission pattern characteristics of individual field emission tips using a CMOS image sensor T2 - 38th International Vacuum Nanoelectronics Conference (IVNC) N2 - The emission pattern characteristics of individual silicon field emission tips were investigated using a CMOS image sensor. The quality of the image was improved by spatial and temporal averaging, so that individual emission centers could be identified and their temporal changes investigated. By mapping the emission current onto the image, the distribution of the current density on the image sensor could be calculated. KW - CMOS image sensors KW - Silicon KW - Current density KW - Nanoelectronics Y1 - 2025 U6 - https://doi.org/10.1109/IVNC65669.2025.11121040 PB - IEEE ER - TY - CHAP A1 - Jannsen, Kai A1 - Ehrnsperger, Matthias T1 - Edge-efficient convolutional neural network for real-time doppler radar gesture recognition T2 - 2025 IEEE Radar Conference (RadarConf25), 4.-9. Oktober 2025, Krakow N2 - Embedded gesture recognition using radar sensors enables intuitive and robust human-machine interfaces, which is appealing for automotive applications such as trunk opening via foot gesture. Designing a radar-based classifier that runs ondevice (edge) under strict resource constraints poses several challenges. The system must achieve real-time inference (e.g. under 200 ms) on a microcontroller unit (MCU), while maintaining high accuracy, and minimize false detections. This paper focuses on a binary classification task, while distinguishing a valid trunkopening “kick” gesture from other motions. Firstly, we evaluate classical machine learning (cML) models (Random Forests or support vector machines (SVMs)) for baseline performance, however they face difficulties with higher false positive rates and do not meet real time criteria. We then employ Convolutional Neural Networks (CNNs) and apply neural architecture search (NAS) to discover a compact CNN tailored for a 60 GHz Doppler radar dataset of 50 subjects, each with 10 leg gestures. By constraining network depth, filter sizes, and hyperparameters, NAS yields a small but accurate “edge” CNN that fits within the limited memory of a STM32 Nucleo F446RE microcontroller. The final model achieves 95.1 % accuracy on the binary classification task with 96.6 % precision and 2.17 % false positive rate (FPR), and requires only 167.5 ms to run inference on the MCU. Y1 - 2025 SN - 979-8-3315-4433-1 U6 - https://doi.org/10.1109/RadarConf2559087.2025.11205096 SP - 877 EP - 881 PB - IEEE ER - TY - CHAP A1 - Baranowski, Kamil A1 - Zychla, Michał A1 - Krysztof, Michał A1 - Żółtowski, Michał A1 - Hausladen, Matthias A1 - Schreiner, Rupert A1 - Knápek, Aleksandr T1 - Experimenal method for studying electron beams in gaseous environments using a CMOS image sensor T2 - 38th International Vacuum Nanoelectronics Conference (IVNC) N2 - Detecting and analyzing electron beams in atmospheric conditions remains a significant challenge due to scattering and absorption of electrons by gas molecules. In this work, a novel approach using a CMOS image sensor for real-time electron beam detection after its transmission through air is presented. The setup enables visualization of beam divergence, emission profiles, and dynamic behavior under atmospheric pressure. Presented results demonstrate the potential of CMOS image sensor for electron beam analysis in gaseous environment. Y1 - 2025 SN - 979-8-3315-3705-0 U6 - https://doi.org/10.1109/IVNC65669.2025.11120851 PB - IEEE ER - TY - CHAP A1 - Allaham, Mohammad M. A1 - Burda, Daniel A1 - Knápek, Alexandr A1 - Krysztof, Michał A1 - Baranowski, Kamil A1 - Hausladen, Matthias A1 - Schreiner, Rupert T1 - Testing the performance of tungsten-graphite cathodes as MEMS Electron microscope electron source T2 - 38th International Vacuum Nanoelectronics Conference (IVNC) N2 - This work presents preliminary results of the performance testing of exfoliated graphene layers deposited on the nanotip of a tungsten field emission cathode. The obtained tungsten-graphite cathodes were then operated in a 3D-printed MEMS electron microscope testing model for later applications. The results were promising, where a maximum emission current of 50.2 μA was obtained with an extraction voltage of 1 kV and anode voltage of 3 kV. Y1 - 2025 U6 - https://doi.org/10.1109/IVNC65669.2025.11121041 PB - IEEE ER - TY - JOUR A1 - Wolfgramm, Alex A1 - Abb, Valerius A1 - Samp, Artur A1 - Samp, Rafal A1 - Hoffmann, Jens Christoph A1 - Müller, Rainer A1 - Kammler, Martin T1 - Structural and functional evolution of HKUST-1 nanoparticles induced by ball milling JF - Next Materials N2 - In this study, the effect of post-synthetic ball milling on the structural and functional properties of as-synthesized nanoparticles of the copper-based metal-organic framework (MOF) HKUST-1 was investigated for the first time. Nanoparticles were synthesized using sodium formate as a capping agent. The crystalline particles were subjected to a controlled ball milling process, which induced significant structural changes. Powder X-ray diffraction (PXRD) revealed a reduction in crystallite size from 91 nm to 21 nm and the introduction of microstrain, partially disrupting the MOF's long-range crystalline order, as evidenced by peak broadening and the diminished intensity of high-angle reflections. Particle morphology pre- and post-milling was further studied with scanning electron microscopy (SEM) imaging, verifying a narrow particle size distribution of ± 22 nm after milling. Fourier-transform infrared spectroscopy (FTIR) indicated protonation of carboxylate groups in the larger pores of the framework, likely due to moisture incorporation during milling. Brunauer-Emmett-Teller (BET) surface area analysis showed a substantial decrease in specific surface area from 521 m²/g to 226 m²/g, suggesting a partial collapse of the porous framework. We discuss the applicability of ball milling as a versatile means of post-synthetic approach to reduce MOF particle sizes, a key element in the preparation of MOF-based thin films using inks or polymers. KW - Ball milling KW - Copper-based metal-organic framework KW - HKUST-1 KW - Nitrogen adsorption Y1 - 2026 U6 - https://doi.org/10.1016/j.nxmate.2025.101544 N1 - Corresponding author der OTH Regensburg: Alex Wolfgramm VL - 10 PB - Elsevier ER - TY - CHAP A1 - Asgharzade, Ali A1 - Bartl, Mathias A1 - Hausladen, Matthias A1 - Chen, Yang A1 - Buchner, Philipp A1 - Edler, Simon A1 - Bachmann, Michael A1 - She, Juncong A1 - Schreiner, Rupert T1 - Investigation on the influence of internal voltage drops on the emission behavior of silicon field emission arrays using CMOS image sensor T2 - 38th International Vacuum Nanoelectronics Conference (IVNC) N2 - In this paper we report on an improved measurement and analysis method for determining the emission current distribution of field emitter arrays with CMOS sensors. It can also be used for field emission arrays where not all surfaces of the emitters are at the same electrical potential (e.g. for p-doped Si tips, where a strong current saturation occurs). To demonstrate the functionality of this method, a n-doped field emission array was measured using a variable external series resistance. Brightness variations in emission spots were analyzed to re-calculate the known series resistances for comparison. The re-calculated value is in good agreement with the actual value of the resistance. This method offers a quantitative approach to assess internal voltage drop effects on field emission using optical readout KW - field emission imaging KW - field emission KW - CMOS sensor Y1 - 2025 U6 - https://doi.org/10.1109/IVNC65669.2025.11120937 PB - IEEE 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 - TY - CHAP A1 - Schreiner, Rupert A1 - Mulot, M. A1 - Gauggel, H. P. A1 - Schweizer, H. A1 - Laue, C. K. A1 - Wallenstein, R. T1 - Dynamic and spectral properties of red DFB lasers T2 - Technical Digest. Summaries of papers presented at the Conference on Lasers and Electro-Optics. Postconference Technical Digest (IEEE Cat. No.01CH37170) ; Baltimore, May 6 - 11, 2001 (Trends in optics and photonics series ; 56) N2 - Summary form only given. Narrow linewidth GaInP/AlGaInP DFB lasers are promising light sources for spectroscopy, for optical data storage systems and for plastic optical fiber WDM applications. However, little is known about the dynamic behavior of red DFB lasers. In this paper, we report on the dynamic and spectral properties of those devices. The lasers were first characterized under cw operation at 25/spl deg/C. Threshold currents are /spl sim/14 mA (475 /spl mu/m length) and /spl sim/18 mA (900 /spl mu/m length). The lasers show stable single mode emission at 680 nm with a SMSR better than -25 dB. The spectral linewidth of the 900 /spl mu/m long devices was measured by using a scanning-Fabry-Perot interferometer. Y1 - 2001 UR - http://ieeexplore.ieee.org/document/947498/ SN - 1-55752-662-1 U6 - https://doi.org/10.1109/CLEO.2001.947498 SP - 81 EP - 82 PB - IEEE ER - TY - PAT A1 - Hummel, Helmut A1 - Lechner, Alfred T1 - Miniaturized on-line trace analysis [Patentschrift] N2 - The invention relates to a measuring apparatus comprising an apparatus for forming a liquid optical waveguide having a substrate (1) having an at least partially curved closed microchannel (2) having a low-refractive coating (13), whereby there is formed in the substrate (1) at least one feed line (6) for supplying liquid, and whereby there is provided at least at one end of the closed microchannel (2) an apparatus for coupling light axially into the closed microchannel and/or for coupling light axially out of the closed microchannel (2), further comprising a light source (4), a light detector (5), and a first liquid pump (9) which supplies a sample liquid (7) to the closed microchannel (2) via the at least one feed line (6, 6a). Y1 - 2015 UR - https://depatisnet.dpma.de/DepatisNet/depatisnet?action=bibdat&docid=US000008948563B2&zd=1#zd ER - TY - CHAP A1 - Barik, Ranjan Kumar A1 - Rawat, Vikram Singh A1 - Manna, Subhrajit A1 - Bandyopadhyay, Ayan Kumar A1 - Hausladen, Matthias A1 - Asgharzade, Ali A1 - Schreiner, Rupert T1 - On Chip Electron Gun Design Using Silicon Tip Field Emitter Array T2 - 2025 IEEE Microwaves, Antennas, and Propagation Conference (MAPCON), 14-18. Dezember 2025, Kochi, India N2 - Silicon based silicon tip array emitter has developed at OTH Regensburg, Germany. This array emitter is the basis for development of a novel electron gun. This field emitter electron sources were fabricated using laser-micromachining technique followed by MEMS technology. In this work, the design and development of electron gun using complete silicon structure is reported. The goal of this work is to develop electron gun using less effort, easy and hassle free technique. Y1 - 2025 SN - 979-8-3315-3722-7 U6 - https://doi.org/10.1109/MAPCON65020.2025.11426578 PB - IEEE ER - TY - JOUR A1 - Tan, Jing Jie A1 - Schreiner, Rupert A1 - Hausladen, Matthias A1 - Asgharzade, Ali A1 - Edler, Simon A1 - Bartsch, Julian A1 - Bachmann, Michael A1 - Schels, Andreas A1 - Kwan, Ban-Hoe A1 - Ng, Danny Wee-Kiat A1 - Hum, Yan-Chai T1 - SiMiC: Context-aware silicon microstructure characterization using attention-based convolutional neural networks for field-emission tip analysis JF - Journal of Vacuum Science & Technology B N2 - Accurate characterization of silicon microstructures is essential for advancing microscale fabrication, quality control, and device performance. Traditional analysis using scanning electron microscopy (SEM) often requires labor-intensive, manual evaluation of feature geometry, limiting throughput and reproducibility. In this study, we propose SiMiC: Context-aware Silicon Microstructure Characterization Using Attention-based Convolutional Neural Networks for Field-Emission Tip Analysis. By leveraging deep learning, our approach efficiently extracts morphological features—such as size, shape, and apex curvature—from SEM images, significantly reducing human intervention while improving measurement consistency. A specialized dataset of silicon-based field-emitter tips was developed, and a customized convolutional neural network architecture incorporating attention mechanisms was trained for multiclass microstructure classification and dimensional prediction. Comparative analysis with classical image processing techniques demonstrates that SiMiC achieves high accuracy while maintaining interpretability. The proposed framework establishes a foundation for data-driven microstructure analysis directly linked to field-emission performance, opening avenues for correlating emitter geometry with emission behavior and guiding the design of optimized cold-cathode and SEM electron sources. The related dataset and algorithm repository that could serve as a baseline in this area can be found at https://research.jingjietan.com/?q=SIMIC. KW - Field emitter arrays KW - Quality assurance KW - Convolutional neural network KW - Deep learning KW - Image processing KW - Machine learning KW - Cold cathodes KW - Scanning electron microscopy KW - Electron sources KW - Chemical elements Y1 - 2025 U6 - https://doi.org/10.1116/6.0005068 VL - 43 IS - 6 PB - AVS ER -