Prof. Dr. Anton Grabmaier

Eletronic Devices and Circuits
University of Duisburg-Essen

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  • Adaptation of cluster analysis methods to optimize a biomechanical motion model of humans in a nursing bed
    Demmer, J. and Kitzig, A. and Stockmanns, G. and Naroska, E. and Viga, R. and Grabmaier, A.
    European Signal Processing Conference 2021-January (2021)
    The paper considers the optimization of a Hidden-Markov Model (HMM) based method for the generation of averaged motion sequences. To create averaged motion sequences, motion sequences of different test persons were originally recorded with a motion capture system (MoCap system) and then averaged using an HMM approach. The resulting averaged data sets, however, partly showed serious motion artifacts and uncoordinated intermediate movements, especially in the extremities. The aim of this work was to combine only movements with similar courses in the extremities by a suitable cluster analysis. For each test person, model body descriptions of 21 body elements are available, each of which is represented in three-dimensional time series. For optimization, the MoCap data are first compared using time warp edit distance (TWED) and clustered using an agglomerative hierarchical procedure. Finally, the data of the resulting clusters are used to generate new averaged motion sequences using the HMM approach. The resulting averaged data can be used, for example, in a simulation in a multilevel biomechanical model. © 2021 European Signal Processing Conference, EUSIPCO. All rights reserved.
    view abstract10.23919/Eusipco47968.2020.9287503
  • A hybrid framework for bearing fault diagnosis using physics-guided neural networks
    Krupp, L. and Hennig, A. and Wiede, C. and Grabmaier, A.
    ICECS 2020 - 27th IEEE International Conference on Electronics, Circuits and Systems, Proceedings (2020)
    Emerging smart sensor systems are the main driver of innovation in many fields of application. A prominent example is condition-based monitoring and especially its subdomain fault diagnosis. The integration of advanced machine and deep learning-based signal processing into sensor systems enables new intelligent condition monitoring solutions. However, the data-based nature of machine and deep learning methods still impedes their applicability in many cases, due to a severe lack of data. In this paper, we introduce a new hybrid physics- and data-based framework aiming to solve the issue of small datasets for vibration-based fault diagnosis applied to rolling-element bearings. The framework combines a vibration simulation model and a neural network with embedded physics-based knowledge into a physics-guided neural network. Our approach aims to generate physically consistent data for the training of fault classifiers without extensive data acquisition. © 2020 IEEE.
    view abstract10.1109/ICECS49266.2020.9294902
  • Acquisition of Multiple Events in Direct Time-of-Flight LiDAR using Single-Photon Avalanche Diodes
    Buchner, A. and Hosticka, B. and Schrey, O. and Haase, J.F. and Ruskowski, J. and Grabmaier, A.
    Proceedings of IEEE Sensors 2020-October (2020)
    Single-Photon Avalanche Diode (SPAD)-based 'Light Detection And Ranging' (LiDAR) systems often use the first photon measurement principle to acquire ranging information. While those systems provide accurate distance measurements, they can easily saturate in high background scenarios. Recent improvements in SPAD quenching circuit technology open up the opportunity for SPAD LiDAR systems to detect multiple photons while measuring with a single laser pulse, partially circumventing this challenge. The theoretical framework for the distribution of higher order single photon detections is presented and discussed how the sensor's typical quenching times influence it. Measurements with a SPAD circuitry capable of detecting multiple events in a single measurement are presented. Differences to first-photon and continuous detection implementations are discussed and advantages in high background light scenarios are shown. © 2020 IEEE.
    view abstract10.1109/SENSORS47125.2020.9278854
  • Eye safety considerations and performance comparison of flash- And MEMS-based lidar systems
    Burkard, R. and Viga, R. and Ruskowski, J. and Grabmaier, A.
    Proceedings of SPIE - The International Society for Optical Engineering 11353 (2020)
    Automotive and robotic applications demand three-dimensional (3D) imaging systems, that are reliable, small and low-cost. A promising technology to satisfy these demands are LiDAR-systems based on the direct time-of-flight principle. To greatly reduce the costs and footprint of current LiDAR-systems new compelling concepts are emerging. These concepts mainly differ in the used illumination techniques of the field-of-view (FOV). Micro-electro-mechanical systems (MEMS)scanners are replacing the bulkier and more expensive polygon mirrors, which were earlier used to deflect the laser beam and partially illuminate the FOV. In contrast to this approach the full illumination of the FOV with a single widened laser beam is used by the concept known as flash-illumination. The range performance of the direct time-of-flight principle is directly proportional to the emitted laser pulse power and is either limited by detector noise or background radiation. High-power near-infrared laser diodes are announced, which offer higher pulse peak power and shorter laser pulses. The high energy density of these laser sources can, however, be hazardous to the human eye. Therefore, the energy density of the laser pulse must be limited and classified according to the IEC 60825-1:2014. While this is particularly easy for Flash LiDAR-systems, a two-dimensional consideration is necessary to determine the accessible emission limits (AEL) for MEMS-based LiDAR-systems, which takes the time dependent scanning-motion of the mirror into account. This work presents a framework to describe and calculate the differences between the calculations of the AEL for Flash- and MEMS-based LiDAR-systems. To achieve this the framework incorporates the calculation of the two-dimensional pulse distribution based on the time dependent behaviour of the MEMS-scanner for the most commonly used one- and two-dimensional scanning-patterns. To further estimate and compare the performance of the LiDAR-systems this work describes an automotive and robotic application use case scenario, which are used to compare the performance for various performance metrices. © 2020 SPIE
    view abstract10.1117/12.2554726
  • 2D metamaterial Luneburg lens for enhancing the RCS of chipless dielectric resonator tags
    Zhao, Y. and Weidenmueller, J. and Vom Bögel, G. and Grabmaier, A. and Alhaj Abbas, A. and Solbach, K. and Jiménez-Sáez, A. and Schüßler, M. and Jakoby, R.
    2019 2nd International Workshop on Mobile Terahertz Systems, IWMTS 2019 (2019)
    In this paper, a 2D Luneburg lens is proposed to improve the Radar Cross Section (RCS) of dielectric resonator (DR) tags, which would be used for an indoor localization system at THz frequencies where the low RCS of the tag makes the detection against clutter signals difficult. A Luneburg lens made of PTFE is fabricated using milling technique based on metamaterial concept, and characterized using a Vector Network Analyzer (VNA). Three ceramic resonators with different resonance frequencies are placed at different positions in the lens focal area to test the performance of the lens. To prove the concept, the simulation and measurement have been performed at scaled frequencies in the 4.5-7 GHz range. The RCS improvement is found to depend on the lens dimensions and frequencies of operation. A Luneburg lens with a height of 35 mm and a diameter of 66 mm boosts the RCS by 18 dB at 6.2 GHz. © 2019 IEEE
    view abstract10.1109/IWMTS.2019.8823784
  • Measurement and analysis of local pulse transit time for emotion recognition
    Beckmann, N. and Viga, R. and Dogangun, A. and Grabmaier, A.
    IEEE Sensors Journal 19 (2019)
    Emotion recognition based on physiological parameters is a research field that pushes forward from lab settings to real-life investigations. Wearable devices facilitate this advance. However, these devices are still functionally limited compared to stationary medical devices. Our goal is to extend the capability of wearable devices by developing a method that measures the pulse transit time (PTT) locally. The PTT is an interesting parameter regarding emotion recognition. A method for local PTT measurement can be implemented using two photoplethysmography (PPG) sensors. However, this method is error-prone. In this paper, the physiological background that is presumably responsible for erroneous PPG-based PTT measurements is discussed. We present an algorithm that is capable to handle the derived physiological effects. The algorithm analyzes and compares the two PPG-signals to adapt to time-varying physiological effects. By using this algorithm, calculating and analyzing of the local PTT in the context of emotion recognition become possible. A study ( {n} = {40} ) to test the algorithm and investigate the usefulness of local PTT analysis for emotion recognition in combination with other physiological signals was conducted. PTT-based parameters, which were derived from the frequency domain of the signal, showed a statistically significant ( {p} < {0.05} ) difference between induced emotional states, if calculated by the developed algorithm. Our findings indicate that parameters derived by our method are significantly affected by emotional stimuli. We suggest that this method can be used to advance emotion recognition investigations in real life as it can potentially be integrated into a single wearable device. © 2001-2012 IEEE.
    view abstract10.1109/JSEN.2019.2915529
  • Novel Distance Measurement Method Using Inband-RFID-Technology
    Schmidt, P. and Kuhn, P. and Grenter, T. and Grabmaier, A.
    Progress in Electromagnetics Research Symposium 2019-June (2019)
    For many RFID applications it is desirable to get more information about an item than the unique ID, e.g. the position of a unique item often is of great interest. In this paper we present first simulation results of a novel method for measuring the distance between a reader and commercial off-the-shelf tags. This implies that the communication between a reader and a tag or a bulk of tags is not influenced or interrupted by this novel distance measuring method. It is expected to achieve a distance measuring accuracy of about 1% referred to the maximum communication distance between a reader and a tag. Additionally to the state-of-the-art RFID communication principle, which uses a well-known amplitude modulated (amplitude modulated due to the data transmission from reader to tag) RFID carrier, this novel measuring method uses an overlaid phase modulation. For the measuring principle to work it is important that the wavelength corresponding to the data rate of the phase modulation is not higher than twice the distance between reader and tag. If this condition is truly fulfilled, the phase information of the phase modulated signal will be clearly corresponding to the distance between reader and tag. The reader transmits the phase information to the tag which is returned to the reader due to the backscatter modulation. In a coherent reader structure the phase difference between the transmitted and received baseband signal can be used to calculate the distance from reader to tag. This distance calculation could be realized by correlation. Therefore the cross-correlated of the transmitted and received phase information can be subtracted from the auto correlation of the transmitted phase information. In case of this the distance can be calculated. © 2019 IEEE.
    view abstract10.1109/PIERS-Spring46901.2019.9017553
  • An HMM-based averaging approach for creating mean motion data from a full-body Motion Capture system to support the development of a biomechanical model: Sensor-assisted functionalization of furniture in the hospital and care sector
    Kitzig, A. and Demmer, J. and Bolten, T. and Naroska, E. and Stockmanns, G. and Viga, R. and Grabmaier, A.
    Current Directions in Biomedical Engineering 4 (2018)
    Motion capture systems or MoCap systems are used for game development and in the field of sports for the assessment and digitalization of human movement. Furthermore, MoCap systems are also used in the medical and therapeutic field for the analysis of human movement patterns. As examples gait analysis or examination of the musculoskeletal system and its function should be mentioned. Most application relate to a specific person and their movement or to the comparison of movements of different people. Within the scope of this paper an averaged motion sequence is supposed to be generated from MoCap data in order to be able to use it in the field of biomechanical modeling and simulation. For the averaging of individual movement sequences of different persons a Hidden Markov Model (HMM) based approach is presented. © 2018 author name(s).
    view abstract10.1515/cdbme-2018-XXXX
  • Considering skin inhomogeneity in photoplethysmography-based local pulse transit time measurement
    Beckmann, N. and Viga, R. and Dogangun, A. and Grabmaier, A.
    2018 IEEE Life Sciences Conference, LSC 2018 (2018)
    The local measurement of pulse transit time in blood vessels can be implemented using photoplethysmography-based sensors. Therefore, at least two sensors must be placed such that the measured signals originate from the same artery. However, results from our previous research suggest that this kind of measurement does not always provide reliable results. We assumed that the inhomogeneous structure of the skin causes this behavior. Based on this theoretical background related experiments $(\mathbf{n}=\mathbf{8})$ were executed. The results suggest a signal distortion that strongly depends on the mounting position of the sensors. It can be shown that this distortion is presumably responsible for erroneous calculations of pulse transit time. © 2018 IEEE.
    view abstract10.1109/LSC.2018.8572210
  • Current Controlled CMOS Stimulator with Programmable Pulse Pattern for a Retina Implant
    Raffelberg, P. and Burkard, R. and Viga, R. and Mokwa, W. and Walter, P. and Grabmaier, A. and Kokozinski, R.
    PRIME 2018 - 14th Conference on Ph.D. Research in Microelectronics and Electronics (2018)
    In this work the constant current stimulator of a new epiretinal implant is presented. It consists of a digital waveform generator device, which permits to modify the pulse pattern via a programming interface, a digital-to-current converter, which translates the digital waveform into current pulses with adjustable amplitude, and an output driver, which combines the function of an electrode multiplexer and a high voltage current source for driving large resistive loads. For each of those subcircuits the simulated performance and its designed layout is presented. © 2018 IEEE.
    view abstract10.1109/PRIME.2018.8430332
  • Implantable multi-sensor system for hemodynamic controlling
    Weidenmüller, J. and Dogan, O. and Stanitzki, A. and Baum, M. and Schröder, T. and Wünsch, D. and Görtz, M. and Grabmaier, A.
    Technisches Messen 85 (2018)
    A miniaturized implantable multi-sensor system for cardiovascular monitoring of physiological parameters is presented. High accuracy pressure measurements within the vessel can be performed by a capacitive pressure sensor. Additional information about the patient, e. g., sudden movement, inclination or increased temperature can be obtained by additional sensor components such as an acceleration sensor and a temperature sensor unit. This information facilitates compensation of interferences for more accurate pressure measurements. A multi-functional ASIC enables, amongst others, sensor signal processing, power management and telemetric communication with extracorporeal electronics. Sensor chips, the multi-functional ASIC and passive components are assembled on a LTCC circuit board in which an antenna coil is integrated for telemetric energy and data transmission at a frequency of 13.56 MHz. In order to support further miniaturization, the implant shall be encapsulated with a stack of very thin and hermetic ceramics applied by ALD instead of using bulky metal housings. Further encapsulation with polymers, which can be functionalised with appropriate biomolecules, is necessary for a proper shape, a biocompatible interface to the surrounding tissue and, thereby, reduction of thrombogenicity. © 2018 Walter de Gruyter GmbH, Berlin/Boston.
    view abstract10.1515/teme-2017-0116
  • Use of an automotive seat occupancy sensor for the functionalization of a nursing bed-An overview of the sensor and the possible applications in the clinic and care sector
    Kitzig, A. and Demmer, J. and Naroska, E. and Stockmanns, G. and Viga, R. and Grabmaier, A.
    SII 2017 - 2017 IEEE/SICE International Symposium on System Integration 2018-January (2018)
    A common procedure for the derivation of patient parameters is the use of measuring methods according to the so-called 'gold standard'. This may be e.g.The electrocardiogram (ECG) to derive the cardiac activity of a human. A great advantage of these methods is that they are widely accepted and clinically recognized and that they provide very good measurement-And diagnostic-results. A major disadvantage of these methods is often the complex measurement setup, e.g. by means of special electrodes attached to the skin or the need of a trained specialist. This is, of course, irrelevant in the field of emergency medicine, but if the general state of a person is to be monitored over a longer period of time e.g.To detect possible negative changes in the patient's condition at an early stage, such methods are rather unsuitable. Furthermore, a measurement setup used in clinical settings often puts the patient into a mode of discomfort. To avoid these disadvantages and to be able to perform a long-Term monitoring, the measurement should be preparation free by using e.g. functionalized furniture. Within the scope of the paper, a prototype of a preparation-free measurement setup based on a nursing bed is presented that is functionalized with load cell seat occupancy sensors from the automotive sector. Furthermore, the work carried out so far on the basis of the prototype is presented and discussed as an overview of our research activities in recent years. © 2017 IEEE.
    view abstract10.1109/SII.2017.8279265
  • MoveHN-a database to support the development of motion based biosignal processing systems
    Kitzig, A. and Schröter, S. and Naroska, E. and Stockmanns, G. and Viga, R. and Grabmaier, A.
    25th European Signal Processing Conference, EUSIPCO 2017 2017-January (2017)
    In the field of signal processing, pattern recognition and also modeling and simulation, it is often necessary to use large data sets. These allow reliable, independent and test case spanning development of algorithms or even of complete systems. The data is usually taken from existing data sets such as TIMIT for speech recognition and processing or EPILEPSIAE to develop algorithms for epileptic seizure prediction, to give just two examples. Apart from the fact that some of these databases imply a considerable cost factor and thus are not accessible to all research groups, even greater problems arise if no data is available at all. In the field of speech recognition, this problem was solved more or less by creating databases. In the area of biosignal processing with a focus on the functionalization of furniture for care and clinical facilities, there is still a need for large data sets. This was also the case with biomechanical modeling of functionalized furniture, since up to now none or few data on the human movement sequences were available. In order to overcome this deficiency, the following paper presents a new database of motion patterns, which is intended to support the development of algorithms for motion detection as well as modeling biosignal processing. The database can be used and downloaded by any interested researcher for free. © EURASIP 2017.
    view abstract10.23919/EUSIPCO.2017.8081628
  • Reproducibility of photoplethysmography-based local pulse transit time measurement
    Beckmann, N. and Viga, R. and Dogangun, A. and Grabmaier, A.
    Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS (2017)
    There are several previously published approaches of measuring local pulse transit time (PTT). One of these approaches is to use two optical sensors based on photoplethysmography (PPG). However, little information about reproducibility in PPG based PTT measurement is available. Therefore, we performed a small sample size study (n = 5) to investigate quantitative criteria for reproducible PTT measurement. The inflection point as a characteristic feature of the pulse wave showed the most stabile results under varying conditions. Furthermore, we found that correlation between related pulse waves could be used as a threshold for signal quality. We suggest to implement a real-time operator feedback based on the found criteria to ensure reproducible PTT measurements. © 2017 IEEE.
    view abstract10.1109/EMBC.2017.8036808
  • A novel approach to creating artificial training and test data for an HMM based posture recognition system
    Kitzig, A. and Naroska, E. and Stockmanns, G. and Viga, R. and Grabmaier, A.
    IEEE International Workshop on Machine Learning for Signal Processing, MLSP 2016-November (2016)
    Demographic change in the next few years will lead to a pronounced disparity in generation distribution. Hence there is a need to develop intelligent systems to support and maintain the autonomy of the elderly at home. A high priority in this case assumes the preparation-free acquisition of vital signs and patient parameters in long-term monitoring systems to detect early changes or deterioration in health. It is thus possible to initiate treatment of a disease at an early stage. One way to carry out a long-term monitoring of vital signs at home is based on the functionalization of furniture, for example, through the use of suitable sensors in chairs [1] and beds [2, 3] to derive various patient parameters. In addition to monitoring basic parameters, e.g. the heart rate and respiratory activity, it is also possible to access information regarding motion or sleep patterns by means of pattern recognition systems. In addition to the challenge of building a suitable pattern recognition system there is a need for corresponding training data to create reference patterns. Typically, the necessary sensor data for the reference pattern training is generated in time-consuming sessions with real people. In this paper, a novel approach is presented, which provides a multi-stage model to create artificial training or test data. The model can be used as a supporting tool in the development of posture recognition systems and to create artificial data for training and testing. © 2016 IEEE.
    view abstract10.1109/MLSP.2016.7738879
  • Analysis of time variant reliability information used in a multilevel decoding scheme for RFID and sensor signals
    Jacobi, R.C. and Vom Bögel, G. and Grabmaier, A. and Kolossa, D.
    International Journal of RF Technologies: Research and Applications 7 (2016)
    In medicine and other high-tech sectors, mobile RFID or sensor transponder systems are designed with high-Q antenna coils to increase the energy efficiency. Hence, the range of inductively coupled systems is improved; however, the bandwidth is decreased by 1 over Q. As a result, the reading performance is not limited by the energy supply, but instead by a high bit error rate. In this paper, we describe how the data detection in such narrow-band systems can be improved by a multilevel decoding scheme composed of an advanced maximum-likelihood receiver in the first stage and a soft Viterbi decoding scheme utilizing time variant reliability information in the second stage. An analysis of potential time-variant reliability information is given. The analysis relies on an underlying Bayesian model, which provides an a-posteriori probability indicating the reliability of the received input. As the final building block, a last decoding stage is discussed, which can be composed of a forward error correction that further exploits the reliability information at the second decoder output. Overall, the suggested system architecture results in a notable improvement of both bit and packet error rate, thus allowing the use of high-quality-factor antennas for efficient and reliable mobile RFID systems. © 2015/2016 - IOS Press and the authors. All rights reserved.
    view abstract10.3233/RFT-150077
  • Comparison on Powering Passive Sensor RFID via Variation of Modulation Indexes
    Kuhn, P. and Schmidt, P. and Meyer, F. and Grabmaier, A.
    Procedia Engineering 168 (2016)
    In this paper we present data on how powering passive sensor radio frequency identification (RFID) transponder can be performed more efficiently. We focused on the industrial, scientific and medical (ISM) band around 5.8 GHz. We investigated how different modulation indexes for amplitude shift keying (ASK) affect the rectification process. The rectifier configuration is Greinacher one with two HSMS2862 and the other with two PCC110 diodes from Avago and Powercast, respectively. The highest achieved power gain was 6.4 dB at a modulation index m of 100% compared to a continuous wave signal at an input power of -12.7dBm for the HSMS2862 rectifier. © 2016 The Authors.
    view abstract10.1016/j.proeng.2016.11.476
  • Wireless tear glucose sensor
    Hennig, A. and Lauko, J. and Grabmaier, A. and Wilson, C.
    Procedia Engineering 87 (2014)
    This paper presents a novel wireless tear glucose level sensor for diabetes patients. The miniaturized sensor can be worn noninvasively under the eye lid. It is composed of a chronoamperometric glucose sensor and an ASIC set with integrated potentiostat and transponder circuits. Wireless energy and data transmission according to the passive transponder standard ISO18000-3 is used to power and readout the sensor. A special coil shape enables high comfort for the patient. High integration level is achieved by a combination of antenna and sensor electrode wires. A complete demonstrator system including ASIC and sensor fabrication as well as assembly was manufactured and the function is demonstrated. © 2014 The Authors. Published by Elsevier Ltd.
    view abstract10.1016/j.proeng.2014.11.267
  • An ultra-thin bendable Si-monolithic imaging test sensor
    Dogiamis, G.C. and Hafner, J. and Mokwa, W. and Hosticka, B.J. and Grabmaier, A.
    2013 Transducers and Eurosensors XXVII: The 17th International Conference on Solid-State Sensors, Actuators and Microsystems, TRANSDUCERS and EUROSENSORS 2013 (2013)
    In this work an ultra-thin bendable imaging test structure is presented and experimental results are put forward. The deployed design and layout rules in order to achieve an independent operation on the applied mechanical stress are discussed. Moreover, experimental results of the optical characteristics of standard n+/p photodiodes on ultra-thin silicon chips embedded into a polyimide foil under several bending configurations are discussed and presented. © 2013 IEEE.
    view abstract10.1109/Transducers.2013.6626929
  • Investigations on an ultra-thin bendable monolithic si CMOS image sensor
    Dogiamis, G.C. and Hosticka, B.J. and Grabmaier, A.
    IEEE Sensors Journal 13 (2013)
    In this paper, theoretical as well as experimental results of the investigations on a bendable ultrathin Si monolithic CMOS image sensor are presented. The electro-optical behavior of a thinned flexible CMOS active pixel sensor for the application of uniaxial mechanical stress is theoretically and experimentally analyzed. The necessity of a correlated double sampling readout scheme to achieve a stress-independent operation is underlined. Optical as well as electrical characteristics of standard photodiodes on ultrathin silicon chips embedded into a polyimide foil under several bending configurations are discussed and experimental data are presented. Moreover, design rules for the stress-independent operation of a flexible ultrathin image sensor are given and the thinning and the encapsulation processes are shortly presented. © 2013 IEEE.
    view abstract10.1109/JSEN.2013.2254474
  • A modular and wireless exg signal acquisition system with a dense array of dry electrodes
    Ghoshdastider, U. and Lange, C. and Viga, R. and Grabmaier, A.
    Proceedings of IEEE Sensors (2012)
    A modular, configurable, wearable bio-potential signal measurement diagnostic system is developed. The system is wirelessly configurable for multiple numbers of channels from 1 to 256 channels according to their field of applications. EEG (Electroencephalography), ECG (Electrocardiography), EMG (Electromyography) can be measured with the system by encapsulating in a cap, in a vest and in a hand sleeves respectively. Active dry electrodes with 19 Au-Pins are utilized. It achieves a high signal quality due to high special resolution. An electrode-bus containing eight of such dry electrodes is designed utilizing the modern hard-flex PCB concept so that it can be molded like an S and be placed on the area of measurement. A Meridian-ADC digitalizes the amplified analog signal with a 24-bit Δ∑-ADC. The central component of the system is an Islandcontroller, incorporating an AVR-μC and a Wi-Fi-module with an external patch antenna. © 2012 IEEE.
    view abstract10.1109/ICSENS.2012.6411473
  • Flexible development and testing environment for implementation of new algorithms in RFID systems
    Grey, S. and Vom Bögel, G. and Grabmaier, A.
    Proceedings - 2012 4th International EURASIP Workshop on RFID Technology, RFID 2012 (2012)
    This paper presents a rapid-prototyping platform for test and implementation of new algorithms in RFID Systems. The platform offers the possibility to evaluate and test new approaches, in communications aspects in RFID systems, that can not be tested in state-of-the-art systems, due to hardware or standards limitations. This includes new radio architectures, source-/line-coding schemes, multiple access control algorithms and many other system elements that can not be accessed or changed in a RFID system. Two platforms are presented: one for algorithm development and a second one for product development. © 2012 IEEE.
    view abstract10.1109/RFID.2012.9
  • Flow measurement technique for unknown fluids based on hot wire by self-calibration via thermal time-of-flight (TTof)
    Engelien, E. and Kirchgaesser, H. and Viga, R. and Grabmaier, A.
    Procedia Engineering 47 (2012)
    For measurement problems with unknown fluids a new calibration-free volume flow measurement technique is developed. This measurement technique includes a controlled heat source associated with a minimum of two thermal sensors arranged downstream [5,6]. The heat source is used to generate a rectangular signal code [dT/dt] by injection of regulated thermal pulses into a flow line, the flow velocity being based on two measurands. Rapid changes in flow velocity are determined by the flow dependent variable (inversely proportional to the velocity) which is controlling the temperature of the filament. By analysis of the rising edge of the thermal signal of subsequent sensors the velocity can be measured less frequently but precisely and in unknown fluids (TToF) [6,7]. The combination of these two measurement techniques (hot wire and TToF) can be applied to both, liquids and gasses. © 2012 The Authors. Published by Elsevier Ltd.
    view abstract10.1016/j.proeng.2012.09.281
  • Sensor transponder system for cardiovascular diseases
    Hennig, A. and Vom Bogel, G. and Grabmaier, A.
    2012 IEEE International Conference on RFID-Technologies and Applications, RFID-TA 2012 (2012)
    By the use of sensor transponder technology, the therapy of heart failure can be significantly improved. Through continuous monitoring of the heart an optimal adaption of drug dosage is possible. First, the state of the art and examples of existing solutions are outlined. A novel sensor transponder system is presented that enables high read range and small antenna dimensions and thus allows direct implantation into the heart. © 2012 IEEE.
    view abstract10.1109/RFID-TA.2012.6404567
  • Thermo-fluid dynamic Time-of-Flight flow sensor system
    Ecin, O. and Zhao, R. and Hosticka, B.J. and Grabmaier, A.
    Proceedings of IEEE Sensors (2012)
    The authors report on a novel linear time-invariant (LTI) modeling of a flow sensor system based on thermal Time-of-Flight (TOF) principle by using pulsed hot wire anemometry. Thermal heat pulses are electrically generated at the hot wire centered in a pipe, carried along by the fluid in flow direction, and detected at several positions downstream. The flow sensor consisting of a hot wire and several temperature sensors is entirely regarded as an LTI system which is characterized by the fluid velocity, the fluid media and some heat transfer effects. Hence, a mathematical model with thermodynamic and fluid mechanical parameters is built. The thermo-fluid dynamic step and impulse responses of the hot wire are analyzed with respect to their signal parameters like rise and fall time and referred to the parameters of thermodynamics and fluid mechanics. The flow velocity and flow media are determined by signal analysis of the hot wire and by the thermo-fluid dynamic TOF measurement. © 2012 IEEE.
    view abstract10.1109/ICSENS.2012.6411270
  • Calibration-free volume flow measurement principle based on thermal time-of-flight (TToF)
    Engelien, E. and Ecin, O. and Viga, R. and Hosticka, B.J. and Grabmaier, A.
    Procedia Engineering 25 (2011)
    For measurement problems with unknown fluids a new calibration-free volume flow measurement technique is developed. This measurement technique includes a discontinuous heat source associated with a minimum of two thermal sensors arranged downstream. The heat source is used to generate a signal code [dT/dt] by injection of local thermal pulses into the flow line. The thermal sensors detect the time-dependent thermal gradients in the fluid at different positions. Herewith, the measurement technique aims at the determination of the flow velocity by ToF, with the particular advantage of applying to measurements of any fluids with unknown properties. The volume flow is determined by integrating the flow profile. © 2011 Published by Elsevier Ltd.
    view abstract10.1016/j.proeng.2011.12.188
  • CMOS 3D image sensor based on pulse modulated time-of-flight principle and intrinsic lateral drift-field photodiode pixels
    Spickermann, A. and Durini, D. and Süss, A. and Ulfig, W. and Brockherde, W. and Hosticka, B.J. and Schwope, S. and Grabmaier, A.
    European Solid-State Circuits Conference (2011)
    Design and measurement results of a CMOS 128 x 96 pixel sensor are presented, which can be used for three-dimensional (3D) scene reconstruction applications based on indirect time-of-flight (ToF) principle enabled by pulse modulated active laser illumination. The 40μm pitch pixels are based on the novel intrinsic lateral drift-field photodiode (LDPD) that allows for a 30ns complete charge transfer from the photoactive area into the readout node, and accumulation of signal charge over several readout cycles for extended signal-to-noise ratio (SNR). Distance measurements have been performed using a specially developed camera system. © 2011 IEEE.
    view abstract10.1109/ESSCIRC.2011.6044927
  • Modeling and calibration of 3D-time-of-flight pulse-modulated image sensors
    Matheis, F. and Brockherde, W. and Grabmaier, A. and Hosticka, B.J.
    2011 20th European Conference on Circuit Theory and Design, ECCTD 2011 (2011)
    Scannerless 3D-Time-of-Flight image sensors serve to acquire three-dimensional (3D) information of objects in a scene. This contribution is devoted to modeling and calibration of scannerless 3D-Time-of-Flight image sensors based on pulse modulation. After a short description we introduce a 3D image sensor model that includes system nonlinearities due to nonideal photodetectors and signal processing circuitry. This is followed by the model defined for the nonideal light source waveform. The influence of these nonlinearities on the sensor responsivity and, hence the distance calculation will be shown. Finally, based on our findings we propose an efficient calibration procedure for the proposed distance measurement system. © 2011 IEEE.
    view abstract10.1109/ECCTD.2011.6043375
  • Signal characterization of a pulsed-wire and heat flow system at a flow sensor
    Ecin, O. and Viga, R. and Hosticka, B.J. and Grabmaier, A.
    2011 20th European Conference on Circuit Theory and Design, ECCTD 2011 (2011)
    This article describes a pulsed thermal Time-of-Flight (TTOF) flow sensor system as two subsystems i.e., a pulsed-wire system and a heat flow system. The entire flow sensor is regarded system-theoretically as a linear time-invariant (LTI) system and is described by its transfer function or impulse response. The characterization of the thermo-fluid dynamic signals obtained by a pulsed-wire and by a heat flow is strived. Hence, the impulse response of both pulsed-wire and heat flow is analyzed according to the flow velocity. Experimental and theoretical results are compared in a flow velocity range in air between 0.1 m/s and 1.4 m/s. © 2011 IEEE.
    view abstract10.1109/ECCTD.2011.6043374
  • System-theoretical analysis and modeling of pulsed thermal Time-of-Flight flow sensor
    Ecin, O. and Engelien, E. and Viga, R. and Hosticka, B.J. and Grabmaier, A.
    2011 7th Conference on Ph.D. Research in Microelectronics and Electronics, PRIME 2011 - Conference Proceedings (2011)
    A system-theoretical model of an air flow sensor based on the principle of pulsed thermal Time-of-Flight (TTOF) is described. The region of interest (ROI) in the pipe flow is regarded as a linear time-invariant (LTI) system with an input and output signal. Based on the experimental results the simulation model is created and applied for analysis of different input signals and system's responses with respect to the flow velocity. Experimental and simulated results are compared in an air flow velocity range between 0.1 m/s and 0.7 m/s. © 2011 IEEE.
    view abstract10.1109/PRIME.2011.5966239
  • Investigation of the temperature coefficient of electrical resistance and 1/f noise of laser-annealed amorphous silicon layers
    Foerster, J. and Yogt, H. and Grabmaier, A.
    18th International Conference on Advanced Thermal Processing of Semiconductors, RTP 2010 (2010)
    In order to investigate whether the performance of microbolometer based heat imaging devices can be improved by excimer laser annealing, we performed several experiments on amorphous silicon layers. Samples with unstructured and structured amorphous silicon layers, which are fabricated with different doping concentrations using a plasma enhanced chemical vapor deposition process, are annealed with Krypton Fluoride excimer laser light at various energy densities. The samples are then electrically analyzed to verify laser annealing. They are also characterized in terms of their electrical conductivity, their temperature coefficient of electrical resistance and their 1/f noise as a function of energy density of the laser. The measurements are used to discuss whether excimer laser annealing is of use to improve microbolometer performance. A threshold value for the energy density at which recrystallization caused by laser irradiation occurs is observed to be 100 mJ/cm2 for both structured and unstructured samples. The temperature coefficient of electrical resistance decreases with increasing energy density from a value of 2%K-1 down to a value of approximately 0.9%K-1. © IEEE.
    view abstract10.1109/RTP.2010.5623794
  • Lateral drift-field photodiode for low noise, high-speed, large photoactive-area CMOS imaging applications
    Durini, D. and Spickermann, A. and Mahdi, R. and Brockherde, W. and Vogt, H. and Grabmaier, A. and Hosticka, B.J.
    Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 624 (2010)
    In this work a theoretical concept and simulations are presented for a novel lateral drift-field photodetector pixel to be fabricated in a 0.35 μm CMOS process. The proposed pixel consists of a specially designed n-well with a non-uniform lateral doping profile that follows a square-root spatial dependence. "Buried" MOS capacitor-based collection-gate, a transfer-gate, and an n-type MOSFET source/drain n floating-diffusion serve to realize a non-destructive readout. The pixel readout is performed using an in-pixel source-follower pixel buffer configuration followed by an output amplifier featuring correlated double-sampling. The concentration gradient formed in the n-well employs a single extra implantation step in the 0.35 μm CMOS process mentioned and requires only a single extra mask. It generates an electrostatic potential gradient, i.e. a lateral drift-field, in the photoactive area of the pixel which enables high charge transfer speed and low image-lag. According to the simulation results presented, charge transfer times of less than 3 ns are to be expected. © 2010 Elsevier B.V. All rights reserved.
    view abstract10.1016/j.nima.2010.03.162
  • Thermal signal behaviour for air flow measurements as fundamentals to time-of-flight
    Ecin, O. and Engelien, E. and Strathena, B. and Malek, M. and Gu, D. and Viga, R. and Hosticka, B.J. and Grabmaier, A.
    Electronics System Integration Technology Conference, ESTC 2010 - Proceedings (2010)
    Thermal flow measurement is currently based on the principle of heat energy displacement caused by a flowing fluid (mass flow measurement). The heat is induced by a continuous heating element immersed into the fluid. This kind of sensor is only applicable for fluids with known homogeneity properties [3]. The presented investigation is based on a discontinuous heating element using the pulsed Thermal Time-of-Flight principle (TTOF). The aim is to analyse a measurement technique which determines the flow velocity of any kind of fluid with unknown properties (volume flow measurement). The authors characterise the fundamentals of a measurement principle for determining the air velocity flow in a range from 0.1 m/s to 2 mls. Therefore, analysing the thermal transfer behaviour of a differential volume of flowing air in a pipe is crucial. For this purpose a sensor model consisting of a filament as heating element and a movable thermocouple as detection unit in a pipe construction under flow conditions is employed [6],[7]. The air flow model represents a thermal transmission system. A filament serves as a heating element and describes the input signal into the system. The output signal of the system is obtained by the thermocouple. Considering a linear time-invariant (LTI) system the impulse responses are measured for different flow velocities by applying an approximated Dirac delta function to the filament, and additionally the 3dB cut-off frequencies are obtained.
    view abstract10.1109/ESTC.2010.5642983
  • optoelectronics

  • photodiodes

  • RFID

  • signal processing

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