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Item type:Publication, Access status: without files , Analog-to-Probability Conversion - Efficient Extraction of Information Based on Stochastic Signal ModelsAnalog-to-probability conversion is introduced as a new concept for efficient parameter extraction from analog signals that can be described by nonlinear models. The current state of information about these parameters is represented by a multivariate probability distribution. Only a digital-to-analog converter and a comparator are required as acquisition hardware. The introduced approach reduces the number of comparisons to be done by the hardware and therefore the total energy consumption. As a proof of concept the algorithm is implemented on a system-on-chip and compared to a nonlinear least squares approach.Publicationtype: Conference Paper178 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Optimisation of inductive telemetry links in an implantable medical device for a wireless range of 25 cm(2018-11-15); ; ; ; The optimisation of inductive telemetry link for increasing wireless range of a medical implant device is studied in detail. An active implant device using separate wireless power and data links at 2 MHz and 420 kHz has been fabricated and tested. A test setup consisting of RF power transmitter and data reader hardware has been implemented. Measurement results show that the fabricated device achieved a wireless range of 25 cm.Publicationtype: Journal Article155 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Bioimpedance analysis of L929 and HaCaT cells in low frequency range(De Gruyter, 2018-09-01); ; ; In this work, Bioimpedance Spectroscopy (BIS) is used to study fuids and cell solutions. A new four-electrode-terminal (4T) chamber using 3D printing and stainless steel corrosion resistant V4A was designed to measure the impedance of live cell solutions at the frequency range 0.1Hz-1MHz. At f < 1kHz the double layer (DL) that builds at electrode's surface raises the impedance substantially preventing the observation of the real impedance of the cells. The new 4T design circumvents the DL, is more robust and cheap, and allows for the repeatability of the results. Experiments were performed in vitro with two cell lines, L929 (mouse fbroblasts) and HaCaT (human keratinocytes). Results show that it is possible to distinguish between the two cell types by means of its BIS measurements in the new setup. Also, a low-frequency dispersion (α-dispersion) was observed in HaCaT cells solution, but not in L929. Furthermore, a potentiostat circuit model was developed in LTSpice to simulate the hardware setup and two different circuit models were used to ft cell's data. © 2018 Viviane S. Teixeira et al.Publicationtype: Journal ArticleScopus© Citations 6 298 434 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Super-capacitors for implantable medical devices with wireless power transmissionPatients using implantable devices with wireless power transmission (such as inductive telemetry) as the energy source are required to carry external hardware and antennas on their body continuously during the monitoring period. This discomfort can be reduced by integrating tiny super-capacitors as an energy source for the device. The external wireless telemetry unit used to activate and interrogate the implantable device charges the super capacitors integrated on it. When the wireless telemetry unit is removed, the super capacitor powers the implantable device. This paper shows the benefits of integrating super capacitors onto an existing pressure sensing medical implant that utilises an inductive telemetry link. Test results show that the implant can be powered for a full day using an 88 mF super capacitor. This super capacitor can be fully charged using the inductive telemetry link at a wireless distance of 20 cm in 81 seconds.Publicationtype: Conference Paper460 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Integration of Double Barrier Memristor Die with Neuron ASIC for Neuromorphic Hardware Learning(IEEE, 2018-04-26); ; ; ; This paper details the design of an integrate fire (I F) neuron ASIC and its integration with a double barrier memristor device. The memristor has a non-volatile analog memory characteristic which changes with time and voltage. The neuron ASIC is designed to interact with the memristor by integrating its current and firing when a certain threshold is reached. The resulting spikes increase the memristor's conductance and consequently the firing rate of neuron increases. Together, the ASIC and the memristor mimics neuromorphic learning on hardware. The ASIC has been fabricated in AMS 350nm process.Publicationtype: Conference Paper186 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , A Stent Graft Occlusion Detection : Pressure Sensing Implant Device with Inductive Power and Data Telemetry(IEEE, 2018-04-26); ; ; ; Transjugular intrahepatic portosystemic shunt (TIPS) procedure has been used for the treatment of portal hypertension induced due to liver cirrhosis. A small metallic tube called stent graft is inserted during TIPS for rerouting blood flow in the liver. Common complications after TIPS is partial or complete blockage inside or at either ends of the stent graft. This paper presents the design and fabrication of a smart stent graft containing two pressure sensors for detecting blockages occuring after TIPS. The active implant device with pressure sensor is powered wirelessly and it transmits measured pressure data wirelessly to the external monitoring station using inductive coupling. Ferrite inductor antennas are used for wireless power reception and PCB trace antenna is used for wireless data transmission in the implant device. A smart stent graft is fabricated by coating PTFE membrane on the bare stent followed by mounting of the implant devices. The in vivo setup is emulated by placing the smart stent graft inside meat and powering the implant device with wireless inductive telemetry link. Test result shows that implant device can be operated for a wireless range of 4.5 cm using 15 W 2.05 MHz RF power sender.Publicationtype: Conference Paper177 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Development of an impedance spectroscopy device for on-line cell growth monitoring(Wiley, 2017-07-20); ; ; The impedance and dielectric properties of biological samples are often used to estimate the number of cells growing in a culture, and monitor the cell growth in real time. For these type of studies, high-cost and complex commercial equipment is often required. The design and implementation of a standalone device for impedance spectroscopy of cell samples is presented, featuring low cost, portability and easy reconfigurability of frequency and voltage. The device can generate sinusoidal, square and triangular signals with frequencies up to 125 kHz, at voltages in the range from 0 V to 100 mV. Cell growth experiments were carried out with yeast cultures, and the results are compared with a commercial Agilent 4284A LCR meter. The error percentages for magnitude and phase measurements are <5%.Publicationtype: Journal Article77 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Integrated circuit with memristor emulator array and neuron circuits for biologically inspired neuromorphic pattern recognition(World Scientific Publishing (WSPC), 2017-04-27); ; ; ; This paper details an application-specific integrated circuit (ASIC) with an array of switched-resistor-based memristors (resistor with memory) and integrate & fire (I & F) neuron circuits for the development of memristor-based pattern recognition. Since real memristors are not commercially available, a compact memristor emulator is needed for device study. The designed ASIC has five memristor emulators with one having a conductance range from 4.88ns to 4.99μs (200kOhm) to 204.8MOhm)) and other four having conductance ranging from 195ns to 190μs (5.2kOhm) to 5.12MOhm)). Signal processing has been planned to be off-chip to get the freedom of programmability of a wide range of memristive behavior. This paper introduces the memristor emulator and the realization of synapse functionalities used in neuromorphic circuits such as long term potentiation (LTP), Long Term depression (LTD) and synaptic plasticity. The ASIC has two I & F neuron circuits which are intended to be used in conjunction with memristors in a multiple chip network for pattern recognition. This paper explains the memristor emulator, I & F neuron circuit and a respective neuromorphic system for pattern recognition simulated in LTspice. The ASIC has been fabricated in AMS 350nm process.Publicationtype: Journal ArticleScopus© Citations 11 372 470 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , An enhanced lumped element electrical model of a double barrier memristive device(IOP Publishing, 2017-04-13); ; ; ; The massive parallel approach of neuromorphic circuits leads to effective methods for solving complex problems. It has turned out that resistive switching devices with a continuous resistance range are potential candidates for such applications. These devices are memristive systems - nonlinear resistors with memory. They are fabricated in nanotechnology and hence parameter spread during fabrication may aggravate reproducible analyses. This issue makes simulation models of memristive devices worthwhile. Kinetic Monte-Carlo simulations based on a distributed model of the device can be used to understand the underlying physical and chemical phenomena. However, such simulations are very time-consuming and neither convenient for investigations of whole circuits nor for real-time applications, e.g. emulation purposes. Instead, a concentrated model of the device can be used for both fast simulations and real-time applications, respectively. We introduce an enhanced electrical model of a valence change mechanism (VCM) based double barrier memristive device (DBMD) with a continuous resistance range. This device consists of an ultra-thin memristive layer sandwiched between a tunnel barrier and a Schottky-contact. The introduced model leads to very fast simulations by using usual circuit simulation tools while maintaining physically meaningful parameters. Kinetic Monte-Carlo simulations based on a distributed model and experimental data have been utilized as references to verify the concentrated model.Publicationtype: Journal ArticleScopus© Citations 17 277 364 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , New data recording plugin for the integration of an integrated circuit for neural recordings into the electrophysiology open source user interface Open EphysThe research of various diseases like epilepsy or schizophrenia requires an accurate study of bioelectrical signals. An Application Specific Integrated Circuit (ASIC) for the recording of neural signals from neonatal mice was developed [1]. To integrate the developed ASIC into Open Ephys, an open source electrophysiology user interface, a specific plugin is presented. It enables simple configuration of the ASIC, recording of biomedical signals and enables the utilization of many of Open Ephys’ functions. The user interface is well known to neuroscientific researchers and the presented plugin simplifies the use of the integrated circuit for the researchers dramatically. It also enables the use of the ASIC to other kind of applications like neural recordings from mammalians or recordings for brain computer interfaces.Publicationtype: Conference Paper402 414