A wireless, low-power, smart sensor of cardiac activity for clinical remote monitoring

International audienceThis paper presents the development of a wireless wearable sensor for the continuous, long-term monitoring of cardiac activity. Heart rate assessment, as well as heart rate variability parameters are computed in real time directly on the sensor, thus only a few parameters are sent via wireless communication for power saving. Hardware and software methods for heart beat detection and variability calculation are described and preliminary tests for the evaluation of the sensor are presented. With an autonomy of 48 hours of active measurement and a Bluetooth Low Energy radio technology, this sensor will form a part of a wireless body network for the remote mobile monitoring of vital signals in clinical applications requiring automated collection of health data from multiple patients

Design and Implementation of Biopotencial Electrodes

Import 03/11/2016Bakalářská práce se zabývá návrhem a realizací alternativních nekovových biopotenciálových elektrod a svodů (vodičů) z vodivých polymerů polyanilinu a polypyrrolu. Tyto alternativní nekovové biopotenciálové elektrody a svody (vodiče) jsou určeny k měření EKG z hrudníku pomocí trička. V teoretické části bakalářské práce jsou popisovány základní bioelektrické signály generované lidským tělem, problematika biopotenciálových elektrod a úvod do vodivých polymerů. V praktické části bakalářské práce jsou navrženy a realizovány alternativní nekovové biopotenciálové elektrody včetně jejich svodů (vodičů) s využitím vodivých polymerů (polyanilinu a polypyrrolu). Tyto elektrody a svody (vodiče) jsou připevněny na tričko pro umožnění kontinuálního snímání EKG. Alternativní elektrody a svody (vodiče) jsou testovány a porovnávány vůči Ag/AgCl elektrodám a klasickým (kovovým) vodičům.The bachelor thesis addresses the design and the implementation of alternative non-metallic biopotential electrodes and leads (conductors) made of conductive polymers polyaniline and polypyrrole. These alternative non-metallic biopotential electrodes and leads (conductors) are intended for ECG measuring from the chest using a T-shirt. In the theoretical section of the bachelor thesis, the basic bioelectric signals generated by human body, the issues of biopotential electrodes and the introduction to conductive polymers are dealt with. In the practical section of the bachelor thesis, alternative non-metallic biopotential electrodes, including their leads (conductors) using the conductive polymers (polyaniline and polypyrrole) are designed and implemented. These electrodes and leads (conductors) are fixed to the T-shirt to allow continuous monitoring of ECG. The alternative electrodes and leads (conductors) are tested and compared to Ag/AgCl electrodes and usual (metal) conductors.450 - Katedra kybernetiky a biomedicínského inženýrstvívýborn

Comb-shaped Polymer-based Dry Electrodes for EEG/ECG Measurements with High User Comfort

Soft, comfortable polymer-based dry electrodes are fabricated. Impedance and biopotential measurements are carried out to compare the performance of conventional gel electrodes with our dry electrodes. The impedance of our dry electrodes is reduced by adding more conductive additives to the polymer material. To further lower the impedance, two skin pretreatment techniques are evaluated regarding their influence on skin impedance. However, these techniques are found to have only temporary beneficial effects. Finally biopotential measurements (both ECG and EEG) are performed using our soft polymer electrodes. The ECG signal acquired with both gel and our polymer electrodes demonstrates high degree of similarity. Therefore, heart beat detection is straightforward. To enable monitoring of EEG signals with smaller amplitudes, our dry electrodes need to be combined with pre-amplifiers. Initial EEG tests show that the alpha waves are clearly identifiable with the dry electrodes when subjects close their eyes. Based on the results, combining with sophisticated signal acquisition electronics, the dry electrodes provide a high user comfort solution for high quality biopotential measurements, even on very hairy skin

Comb-shaped polymer-based Dry electrodes for EEG/ECG measurements with high user comfort

Soft, comfortable polymer-based dry electrodes are fabricated. Impedance and biopotential measurements are carried out to compare the performance of conventional gel electrodes with our dry electrodes. The impedance of our dry electrodes is reduced by adding more conductive additives to the polymer material. To further lower the impedance, two skin pretreatment techniques are evaluated regarding their influence on skin impedance. However, these techniques are found to have only temporary beneficial effects. Finally biopotential measurements (both ECG and EEG) are performed using our soft polymer electrodes. The ECG signal acquired with both gel and our polymer electrodes demonstrates high degree of similarity. Therefore, heart beat detection is straightforward. To enable monitoring of EEG signals with smaller amplitudes, our dry electrodes need to be combined with pre-amplifiers. Initial EEG tests show that the alpha waves are clearly identifiable with the dry electrodes when subjects close their eyes. Based on the results, combining with sophisticated signal acquisition electronics, the dry electrodes provide a high user comfort solution for high quality biopotential measurements, even on very hairy skin.status: publishe

Ultra-thin and flexible CMOS technology: ISFET-based microsystem for biomedical applications

A new paradigm of silicon technology is the ultra-thin chip (UTC) technology and the emerging applications. Very thin integrated circuits (ICs) with through-silicon vias (TSVs) will allow the stacking and interconnection of multiple dies in a compact format allowing a migration towards three-dimensional ICs (3D-ICs). Also, extremely thin and therefore mechanically bendable silicon chips in conjunction with the emerging thin-film and organic semiconductor technologies will enhance the performance and functionality of large-area flexible electronic systems. However, UTC technology requires special attention related to the circuit design, fabrication, dicing and handling of ultra-thin chips as they have different physical properties compared to their bulky counterparts. Also, transistors and other active devices on UTCs experiencing variable bending stresses will suffer from the piezoresistive effect of silicon substrate which results in a shift of their operating point and therefore, an additional aspect should be considered during circuit design. This thesis tries to address some of these challenges related to UTC technology by focusing initially on modelling of transistors on mechanically bendable Si-UTCs. The developed behavioural models are a combination of mathematical equations and extracted parameters from BSIM4 and BSIM6 modified by a set of equations describing the bending-induced stresses on silicon. The transistor models are written in Verilog-A and compiled in Cadence Virtuoso environment where they were simulated at different bending conditions. To complement this, the verification of these models through experimental results is also presented. Two chips were designed using a 180 nm CMOS technology. The first chip includes nMOS and pMOS transistors with fixed channel width and two different channel lengths and two different channel orientations (0° and 90°) with respect to the wafer crystal orientation. The second chip includes inverter logic gates with different transistor sizes and orientations, as in the previous chip. Both chips were thinned down to ∼20m using dicing-before-grinding (DBG) prior to electrical characterisation at different bending conditions. Furthermore, this thesis presents the first reported fully integrated CMOS-based ISFET microsystem on UTC technology. The design of the integrated CMOS-based ISFET chip with 512 integrated on-chip ISFET sensors along with their read-out and digitisation scheme is presented. The integrated circuits (ICs) are thinned down to ∼30m and the bulky, as well as thinned ICs, are electrically and electrochemically characterised. Also, the thesis presents the first reported mechanically bendable CMOS-based ISFET device demonstrating that mechanical deformation of the die can result in drift compensation through the exploitation of the piezoresistive nature of silicon. Finally, this thesis presents the studies towards the development of on-chip reference electrodes and biodegradable and ultra-thin biosensors for the detection of neurotransmitters such as dopamine and serotonin