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Printed electronics (PE) is a fast-growing field with promising applications in wearables, smart sensors, and smart cards, since it provides mechanical flexibility, and low-cost, on-demand, and customizable fabrication. To secure the operation of these applications, true random number generators (TRNGs) are required to generate unpredictable bits for cryptographic functions and padding. However, since the additive fabrication process of the PE circuits results in high intrinsic variations due to the random dispersion of the printed inks on the substrate, constructing a printed TRNG is challenging. In this article, we exploit the additive customizable fabrication feature of inkjet printing to design a TRNG based on electrolyte-gated field-effect transistors (EGFETs). We also propose a printed resistor tuning flow for the TRNG circuit to mitigate the overall process variation of the TRNG so that the generated bits are mostly based on the random noise in the circuit, providing a true random behavior. The simulation results show that the overall process variation of the TRNGs is mitigated by 110 times, and the generated bitstream of the tuned TRNGs passes the National Institute of Standards and Technology - Statistical Test Suite. For the proof of concept, the proposed TRNG circuit was fabricated and tuned. The characterization results of the tuned TRNGs prove that the TRNGs generate random bitstreams at the supply voltage of down to 0.5 V. Hence, the proposed TRNG design is suitable to secure low-power applications in this domain.
A Gamified and Adaptive Learning System for Neurodivergent Workers in Electronic Assembling Tasks
(2020)
Learning and work-oriented assistive systems are often designed to fit the workflow of neurotypical workers. Neurodivergent workers and individuals with learning disabilities often present cognitive and sensorimotor characteristics that are better accommodated with personalized learning and working processes. Therefore, we designed an adaptive learning system that combines an augmented interaction space with user-sensitive virtual assistance to support step-by-step guidance for neurodivergent workers in electronic assembling tasks. Gamified learning elements were also included in the interface to provide self-motivation and praise whenever users progress in their learning and work achievements.
In this work a method for the estimation of current slopes induced by inverters operating interior permanent magnet synchronous machines is presented. After the derivation of the estimation algorithm, the requirements for a suitable sensor setup in terms of accuracy, dynamic and electromagnetic interference are discussed. The boundary conditions for the estimation algorithm are presented with respect to application within high power traction systems. The estimation algorithm is implemented on a field programmable gateway array. This moving least-square algorithm offers the advantage that it is not dependent on vectors and therefore not every measured value has to be stored. The summation of all measured values leads to a significant reduction of the required storage units and thus decreases the hardware requirements. The algorithm is designed to be calculated within the dead time of the inverter. Appropriate countermeasures for disturbances and hardware restrictions are implemented. The results are discussed afterwards.
This paper presents a novel low-jitter interface between a low-cost integrated IEEE802.11 chip and a FPGA. It is designed to be part of system hardware for ultra-precise synchronization between wireless stations. On physical level, it uses Wi-Fi chip coexistence signal lines and UART frame encoding. On its basis, we propose an efficient communication protocol providing precise timestamping of incoming frames and internal diagnostic mechanisms for detecting communication faults. Meanwhile it is simple enough to be implemented both in low-cost FPGA and commodity IEEE802.11 chip firmware. The results of computer simulation shows that developed FPGA implementation of the proposed protocol can precisely timestamp incoming frames as well as detect most of communication errors even in conditions of high interference. The probability of undetected errors was investigated. The results of this analysis are significant for the development of novel wireless synchronization hardware.
Advances in printed electronics (PE) enables new applications, particularly in ultra-low-cost domains. However, achieving high-throughput printing processes and manufacturing yield is one of the major challenges in the large-scale integration of PE technology. In this article, we present a programmable printed circuit based on an efficient printed lookup table (pLUT) to address these challenges by combining the advantages of the high-throughput advanced printing and maskless point-of-use final configuration printing. We propose a novel pLUT design which is more efficient in PE realization compared to existing LUT designs. The proposed pLUT design is simulated, fabricated, and programmed as different logic functions with inkjet printed conductive ink to prove that it can realize digital circuit functionality with the use of programmability features. The measurements show that the fabricated LUT design is operable at 1 V.
Printed electronics (PE) enables disruptive applications in wearables, smart sensors, and healthcare since it provides mechanical flexibility, low cost, and on-demand fabrication. The progress in PE raises trust issues in the supply chain and vulnerability to reverse engineering (RE) attacks. Recently, RE attacks on PE circuits have been successfully performed, pointing out the need for countermeasures against RE, such as camouflaging. In this article, we propose a printed camouflaged logic cell that can be inserted into PE circuits to thwart RE. The proposed cell is based on three components achieved by changing the fabrication process that exploits the additive manufacturing feature of PE. These components are optically look-alike, while their electrical behaviors are different, functioning as a transistor, short, and open. The properties of the proposed cell and standard PE cells are compared in terms of voltage swing, delay, power consumption, and area. Moreover, the proposed camouflaged cell is fabricated and characterized to prove its functionality. Furthermore, numerous camouflaged components are fabricated, and their (in)distinguishability is assessed to validate their optical similarities based on the recent RE attacks on PE. The results show that the proposed cell is a promising candidate to be utilized in camouflaging PE circuits with negligible overhead.
The authentication method of electronic devices, based on individual forms of correlograms of their internal electric noises, is well-known. Specific physical differences in the components – for example, caused by variations in production quality – cause specific electrical signals, i.e. electric noise, in the electronic device. It is possible to obtain this information and to identify the specific differences of the individual devices using an embedded analog-to-digital converter (ADC). These investigations confirm the possibility to identify and authenticate electronic devices using bit templates, calculated from the sequence of values of the normalized autocorrelation function of noise. Experiments have been performed using personal computers. The probability of correct identification and authentication increases with increasing noise recording duration. As a result of these experiments, an accuracy of 98.1% was achieved for a 1 second-long registration of EM for a set of investigated computers.
In this study, a facile method to fabricate a cohesive ion‐gel based gate insulator for electrolyte‐gated transistors is introduced. The adhesive and flexible ion‐gel can be laminated easily on the semiconducting channel and electrode manually by hand. The ion‐gel is synthesized by a straightforward technique without complex procedures and shows a remarkable ionic conductivity of 4.8 mS cm−1 at room temperature. When used as a gate insulator in electrolyte‐gated transistors (EGTs), an on/off current ratio of 2.24×104 and a subthreshold swing of 117 mV dec−1 can be achieved. This performance is roughly equivalent to that of ink drop‐casted ion‐gels in electrolyte‐gated transistors, indicating that the film‐attachment method might represent a valuable alternative to ink drop‐casting for the fabrication of gate insulators.
Wireless communication technologies play a major role to enable megatrends like Internet of Things (IoT) and Industry 4.0. The Narrowband Wireless WAN (NBWWAN) introduced to meet the long range and low power requirements of spatially distributed wireless communication use cases. These networks introduce additional challenges in testing because the network topology and RF characteristics become particularly complex and thus a multitude of different scenarios must be tested. This paper describes the infrastructure for automated testing of radio communication and for systematic measurements of the network performance of NBWWAN.
Financing trade and development sustainably will be crucial for Africa. Enhanced collaboration between multilateral development banks, development finance institutions and ECAs could greatly enhance intra-regional trade. Furthermore, setting up a ‘level playing field’ on the continent will allow governments to make strategic interventions for successful export credits and trade finance solutions, fostering growth through trade. African trade is already showing signs of rebounding from the coronavirus- induced recession. Through concerted, co-operative and continent-wide efforts, drawing on the knowledge and resources of all types of institutions and policy experts, Africa will continue to grow confidently and quickly into its increasingly important role as an engine of economic growth and global trade.
In this report, we have studied field-effect transistors (FETs) using low-density alumina for electrolytic gating. Device layers have been prepared starting from the structured ITO glasses by printing the In 2 O 3 channels, low-temperature atomic layer deposition (ALD) of alumina (Al 2 O 3 ), and printing graphene top gates. The transistor performance could be deliberately changed by alternating the ambient humidity; furthermore, ID,ON/ID,OFF-ratios of up to seven orders of magnitude and threshold voltages between 0.66 and 0.43 V, decreasing with an increasing relative humidity between 40% and 90%, could be achieved. In contrast to the common usage of Al 2 O 3 as the dielectric in the FETs, our devices show electrolyte-typegating behavior. This is a result from the formation of protons on the Al 2 O 3 surfaces at higher humidities. Due to the very high local capacitances of the Helmholtz double layers at the channel surfaces, the operation voltage can be as low as 1 V. At low humidities (≤30%), the solid electrolyte dries out and the performance breaks down; however, it can fully reversibly be regained upon a humidity increase. Using ALD-derived alumina as solid electrolyte gating material, thus, allows low-voltage operation and provides a chemically stable gating material while maintaining low process temperatures. However, it has proven to be highly humidity-dependent in its performance.
Rectifiersare vital electronic circuits for signal and power conversion in various smart sensor applications. The ability to process low input voltage levels, for example, from vibrational energy harvesters is a major challenge with existing passive rectifiers in printed electronics, stemming mainly from the built-in potential of the diode's p-njunction. To address this problem, in this work, we design, fabricate, and characterize an inkjet-printed full-wave rectifier using diode-connected electrolyte-gated thin-film transistors (EGTs). Using both experimental and simulation approaches, we investigate how the rectifier can benefit from the near-zero threshold voltage of transistors, which can be enabled by proper channel geometry setting in EGT technology. The presented circuit can be operated at 1-V input voltage, featuring a remarkably small voltage loss of 140 mV and a cutoff frequency of ~300 Hz. Below the cutoff frequency, more than 2.6-μW dc power is obtained over the load resistances ranging from 5 to 20 kQ. Furthermore, experiments show that the circuit can work with an input amplitude down to 500 mV. This feature makes the presented design highly suitable for a variety of energy-harvesting applications.
Analysis of Amplitude and Phase Errors in Digital-Beamforming Radars for Automotive Applications
(2020)
Fundamentally, automotive radar sensors with Digital-Beamforming (DBF) use several transmitter and receiver antennas to measure the direction of the target. However, hardware imperfections, tolerances in the feeding lines of the antennas, coupling effects as well as temperature changes and ageing will cause amplitude and phase errors. These errors can lead to misinterpretation of the data and result in hazardous actions of the autonomous system. First, the impact of amplitude and phase errors on angular estimation is discussed and analyzed by simulations. The results are compared with the measured errors of a real radar sensor. Further, a calibration method is implemented and evaluated by measurements.
Analysis of Miniaturized Printed Flexible RFID/NFC Antennas Using Different Carrier Substrates
(2020)
Antennas for Radio Frequency Identification (RFID) provide benefits for high frequencies (HF) and wireless data transmission via Near Field Communication (NFC) and many other applications. In this case, various requirements for the design of the reader and transmitter antennas must be met in order to achieve a suitable transmission quality. In this work, a miniaturized cost-effective RFID/NFC antenna for a microelectronic measurement system is designed and printed on different flexible carrier substrates using a new and low-cost Direct Ink Writing (DIW) technology. Various practical aspects such as reflection and impedance magnitude as well as the behavior of the printed RFID/NFC antennas are analyzed and compared to an identical copper-based antenna of the same size. The results are presented in this paper. Furthermore, the problems during the printing process itself on the different substrates are evaluated. The effects of the characteristics on the antenna under kink-free bending tests are examined and subsequently long-term measurements are carried out.
Cooling towers or recoolers are one of the major consumers of electricity in a HVAC plant. The implementation and analysis of advanced control methods in a practical application and its comparison with conventional controllers is necessary to establish a framework for their feasibility especially in the field of decentralised energy systems. A standard industrial controller, a PID and a model based controller were developed and tested in an experimental set-up using market-ready components. The characteristics of these controllers such as settling time, control difference, and frequency of control actions are compared based on the monitoring data. Modern controllers demonstrated clear advantages in terms of energy savings and higher accuracy and a model based controller was easier to set-up than a PID.
While prospect of tracking mobile devices' users is widely discussed all over European countries to counteract COVID-19 propagation, we propose a Bloom filter based construction providing users' location privacy and preventing mass surveillance.
We apply a solution based on Bloom filters data structure that allows a third party, a government agency, to perform some privacy-preserving set relations on a mobile telco's access logfile.
By computing set relations, the government agency, given the knowledge of two identified persons, has an instrument that provides a (possible) infection chain from the initial to the final infected user no matter at which location on a worldwide scale they are.
The benefit of our approach is that intermediate possible infected users can be identified and subsequently contacted by the agency. With such approach, we state that solely identities of possible infected users will be revealed and location privacy of others will be preserved. To this extent, it meets General Data Protection Regulation (GDPR)requirements in this area.
The TriRhenaTech alliance presents a collection of accepted papers of the cancelled tri-national 'Upper-Rhine Artificial Intelligence Symposium' planned for 13th May 2020 in Karlsruhe. The TriRhenaTech alliance is a network of universities in the Upper-Rhine Trinational Metropolitan Region comprising of the German universities of applied sciences in Furtwangen, Kaiserslautern, Karlsruhe, and Offenburg, the Baden-Wuerttemberg Cooperative State University Loerrach, the French university network Alsace Tech (comprised of 14 'grandes écoles' in the fields of engineering, architecture and management) and the University of Applied Sciences and Arts Northwestern Switzerland. The alliance's common goal is to reinforce the transfer of knowledge, research, and technology, as well as the cross-border mobility of students.
Astronomical phenomena fascinate people from the very beginning of mankind up to today. In this paper the authors will present their experience with photography of astronomical events. The main focus will be on aurora borealis, comet Neowise, total lunar eclipses and how mobile devices open up new possibilities to observe the green flash. Our efforts were motivated by the great impact and high number of viewers of these events. Visitors from over a hundred countries watched our live broadcasts.
Furthermore, we report on our experiences with the photography of optical phenomena such as polar lights Fig. 1, comet Neowise with a Delta Aquariids meteor Fig. 11, and lunar eclipses Fig. 12.