Bioelectronics for Amperometric Biosensors

The Discrete-to-Integrated Electronics group (D2In), at the University of Barcelona, in partnership with the Bioelectronics and Nanobioengineering Group (SICBIO), is researching Smart Self-Powered Bio-Electronic Systems. Our interest is focused on the development of custom built electronic solutions for bio-electronics applications, from discrete devices to Application-specific integrated circuit (ASIC) solutions. The integration of medical and electronic technologies allows the development of biomedical devices able to diagnose and/or treat pathologies by detecting and/or monitoring pathogens, multiple ions, PH changes, and so on. Currently this integration enables advances in various areas such as microelectronics, microfluidics, microsensors and bio-compatible materials which open the door to developing human body Lab-on-a-Chip implantable devices, Pointof- Care in vitro devices, etc. In this chapter the main attention is focused on the design of instrumentation related to amperometrics biosensor: biopotentiostat amplifiers and lock-in amplifiers. A potentiostat is a useful tool in many fields of investigation and industry performing electrochemical trials [1], so the quantity and variety of them is very extensive. Since they can be used in studies and targets as different as the study of chemical metal conversions [2] or carcinogenic cells detection, neuronal activity detection or Deoxyribonucleic acid (DNA) recognition, their characteristics are very varied..

Design of a fast computer-based partial discharge diagnostic system

Partial discharges cause progressive deterioration of insulating materials working in high voltage conditions and may lead ultimately to insulator failure. Experimental findings indicate that deterioration increases with the number of discharges and is consequently proportional to the magnitude and frequency of the applied voltage. In order to obtain a better understanding of the mechanisms of deterioration produced by partial discharges, instrumentation capable of individual pulse resolution is required. A new computer-based partial discharge detection system was designed and constructed to conduct long duration tests on sample capacitors. This system is capable of recording large number of pulses without dead time and producing valuable information related to amplitude, polarity, and charge content of the discharges. The operation of the system is automatic and no human supervision is required during the testing stage. Ceramic capacitors were tested at high voltage in long duration tests. The obtained results indicated that the charge content of partial discharges shift towards high levels of charge as the level of deterioration in the capacitor increases

Design and Implementation of an Integrated Biosensor Platform for Lab-on-a-Chip Diabetic Care Systems

Recent advances in semiconductor processing and microfabrication techniques allow the implementation of complex microstructures in a single platform or lab on chip. These devices require fewer samples, allow lightweight implementation, and offer high sensitivities. However, the use of these microstructures place stringent performance constraints on sensor readout architecture. In glucose sensing for diabetic patients, portable handheld devices are common, and have demonstrated significant performance improvement over the last decade. Fluctuations in glucose levels with patient physiological conditions are highly unpredictable and glucose monitors often require complex control algorithms along with dynamic physiological data. Recent research has focused on long term implantation of the sensor system. Glucose sensors combined with sensor readout, insulin bolus control algorithm, and insulin infusion devices can function as an artificial pancreas. However, challenges remain in integrated glucose sensing which include degradation of electrode sensitivity at the microscale, integration of the electrodes with low power low noise readout electronics, and correlation of fluctuations in glucose levels with other physiological data. This work develops 1) a low power and compact glucose monitoring system and 2) a low power single chip solution for real time physiological feedback in an artificial pancreas system. First, glucose sensor sensitivity and robustness is improved using robust vertically aligned carbon nanofiber (VACNF) microelectrodes. Electrode architectures have been optimized, modeled and verified with physiologically relevant glucose levels. Second, novel potentiostat topologies based on a difference-differential common gate input pair transimpedance amplifier and low-power voltage controlled oscillators have been proposed, mathematically modeled and implemented in a 0.18μm [micrometer] complementary metal oxide semiconductor (CMOS) process. Potentiostat circuits are widely used as the readout electronics in enzymatic electrochemical sensors. The integrated potentiostat with VACNF microelectrodes achieves competitive performance at low power and requires reduced chip space. Third, a low power instrumentation solution consisting of a programmable charge amplifier, an analog feature extractor and a control algorithm has been proposed and implemented to enable continuous physiological data extraction of bowel sounds using a single chip. Abdominal sounds can aid correlation of meal events to glucose levels. The developed integrated sensing systems represent a significant advancement in artificial pancreas systems

A Bulk Driven Transimpedance CMOS Amplifier for SiPM Based Detection

The contribution of this work lies in the development of a bulk driven operationaltransconducctance amplifier which can be integrated with other analog circuits andphotodetectors in the same chip for compactness, miniaturization and reducing thepower. Silicon photomultipliers, also known as SiPMs, when coupled with scintillator materials are used in many imaging applications including nuclear detection. This thesis discuss the design of a bulk-driven transimpedance amplifier suitable for detectors where the front end is a SiPM. The amplifier was design and fabricated in a standard standard CMOS process and is suitable for integration with CMOS based SiPMs and commercially available SiPMs. Specifically, the amplifier was verified in simulations and experiment using circuit models for the SiPM. The bulk-driven amplifier’s performance, was compared to a commerciallyavailable amplifier with approximately the same open loop gain (70dB). Bothamplifiers were verified with two different light sources, a scintillator and a SiPM.The energy resolution using the bulk driven amplifier was 8.6% and was 14.2% forthe commercial amplifier indicating the suitability of the amplifier design for portable systems

Малошумящий программируемый усилитель постоянного тока с дистанционным управлением

Introduction. The developmental direction of information-measuring systems used to record, pre-process and analyse excess low-frequency noise (flicker noise) in modern experimental technology is well known. Every measuring channel is presented in the form of a multistage circuit with specified parameters at each stage. This creates difficulties in adapting a measuring system to specific experimental conditions. While the solution may be to unify all the components of the channel, the problem lies in estimating the intrinsic noise of the electronic elements which provide a change in amplifier parameters. Objective. To analyse the intrinsic noise of electronic potentiometers. To develop a low-noise unified DC amplifier with the possibility of external digital control parameters. To study the characteristics of a DC amplifier thus developed. Materials and methods. The superposition method was used to perform theoretical calculation of noise gain for each component of a non-inverting amplifier. Experimental studies were based on a system consisting of a low-noise amplifying path and spectroanalyser using the data acquisition module E14-440. Software "Power-Graph" was used. Results. The results of the theoretical analysis of noise amplification for metal-film resistors and experimental studies of the characteristics of electronic potentiometers indicated that their noise voltages specific values are almost identical. The use of a digital potentiometer as a feedback element and a low-noise bipolar-powered bias source (AD8400) permitted the implementation of a unified module with cascading capability. External digital control was based on a single-chip microcontroller PIC18F2550, using the "Master-Slave" channel level protocol and ASCII-command-line interface based on RS-485 network. This control enabled adaptation for measuring electronic component noise, low currents and voltages, flicker noise and the construction of systems for information collecting and processing. Conclusion. The theoretical and practical results achieved herein enable the design of multichannel distributed DC measuring systems. The systems will offer adaptability for measuring channels to the tasks required, and the possibility of correction of real time characteristics.Введение. В современной технике эксперимента известно направление, связанное с разработкой информационно-измерительных систем регистрации и анализа избыточных низкочастотных шумов. Любой измерительный канал представлен в виде многокаскадной схемы с заданными параметрами каждого каскада, что затрудняет адаптацию измерительной системы к конкретным условиям эксперимента. Решением проблемы является унификация всех компонентов канала, однако при этом одной из основных проблем является оценка собственных шумов электронных элементов, обеспечивающих изменение параметров усилителя. Цель работы. Анализ собственных шумов электронных потенциометров, разработка малошумящего унифицированного усилителя постоянного тока с возможностью внешнего цифрового управления параметрами и исследование его характеристик. Материалы и методы. С помощью метода суперпозиции произведен теоретический расчет шумового усиления для каждого компонента неинвертирующего усилителя. Экспериментальные исследования проводились на базе установки, представляющей собой малошумящий усилительный тракт и спектроанализатор на основе модуля сбора данных E14-440 и программного обеспечения «PowerGraph». Результаты. По результатам теоретических расчетов шумового усиления для металлопленочных резисторов и экспериментальных исследований характеристик электронных потенциометров показано, что их удельные значения напряжений шумов практически идентичны. Использование цифрового потенциометра в качестве элемента обратной связи и малошумящего источника смещения с двухполярным питанием (AD8400), позволяют реализовать на их основе унифицированный модуль с возможностью каскадирования. Внешнее цифровое управление на основе однокристального микроконтроллера PIC18F2550, разработанного протокола канального уровня «Master-Slave» и ASCII-интерфейса командной строки на базе сети RS-485 позволяет адаптировать его к задачам измерения шумов электронных компонентов, малых токов и напряжений, фликкер-шумов, построения распределенных систем сбора и обработки информации. Заключение. Полученные теоретические и практические результаты делают возможным проектирование многоканальных распределенных измерительных систем постоянного тока с адаптацией измерительных каналов к поставленным задачам и возможностями программной коррекции характеристик в реальном времени

Low-Power, Event-Driven System on a Chip for Charge Pulse Processing Applications

This dissertation presents an electronic architecture and methodology capable of processing charge pulses generated by a range of sensors, including radiation detectors and tactile synthetic skin. These sensors output a charge signal proportional to the input stimulus, which is processed electronically in both the analog and digital domains. The presented work implements this functionality using an event-driven methodology, which greatly reduces power consumption compared to standard implementations. This enables new application areas that require a long operating time or compact physical dimensions, which would not otherwise be possible. The architecture is designed, fabricated, and tested in the aforementioned applications to demonstrate its highly flexible and low-power operation. Advisors: Sina Balkır and Michael W. Hoffma

Low-Power, Event-Driven System on a Chip for Charge Pulse Processing Applications

This dissertation presents an electronic architecture and methodology capable of processing charge pulses generated by a range of sensors, including radiation detectors and tactile synthetic skin. These sensors output a charge signal proportional to the input stimulus, which is processed electronically in both the analog and digital domains. The presented work implements this functionality using an event-driven methodology, which greatly reduces power consumption compared to standard implementations. This enables new application areas that require a long operating time or compact physical dimensions, which would not otherwise be possible. The architecture is designed, fabricated, and tested in the aforementioned applications to demonstrate its highly flexible and low-power operation

Performance assessment of W-Band radiometers: direct versus heterodyne detections

W-Band radiometers using intermediate frequency down-conversion (super-heterodyne) and direct detection are compared. Both receivers consist of two W-band low noise amplifiers and an 80-to-101 GHz filter, which conforms to the reception frequency band, in the front-end module. The back-end module of the first receiver comprises a subharmonic mixer, intermediate frequency (IF) amplification and a square-law detector. For direct detection, a W-Band detector replaces the mixer and the intermediate frequency detection stages. The performance of the whole receivers has been simulated requiring special techniques, based on data from the experimental characterization of each subsystem. In the super-heterodyne implementation a local oscillator at 27.1 GHz (with 8 dBm) with a x3 frequency multiplier is used, exhibiting an overall conversion gain around 48 dB, a noise figure around 4 dB, and an effective bandwidth over 10 GHz. In the direct detection scheme, slightly better noise performance is obtained, with a wider bandwidth, around 20 GHz, since there is no IF bandwidth limitation (~15 GHz), and even using the same 80-to-101 GHz filter, the detector can operate through the whole W-band. Moreover, W-band detector has higher sensitivity than the IF detector, increasing slightly the gain. In both cases, the receiver performance is characterized when a broadband noise input signal is applied. The radiometer characteristics have been obtained working as a total power radiometer and as a Dicke radiometer when an optical chopper is used to modulate the incoming signal. Combining this particular super-heterodyne or direct detection topologies and total power or Dicke modes of operation, four different cases are compared and discussed, achieving similar sensitivities, but better performances in terms of equivalent bandwidth and noise for the direct detection radiometer. It should be noted that this conclusion comes from a particular set of components, which we could consider as typical, but we cannot exclude other conclusions for different components, particularly for different mixers and detectors.This research was funded by the Spanish Ministry of Science and Innovation through the grant: PID2019-110610RB-C22 and by the Spanish Ministry of Economy and Competitiveness, Program CONSOLIDER-INGENIO reference CSD2010-00064, CONSOLIDER-SPATEK Network of Excellence and University of Cantabria, Industrial Doctorate reference 12.DI05.648