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Title: Study of bioimpedance measurement systems and development of bioimpedance amplifiers
Author: Zhao, Yiqiang
ISNI:       0000 0004 2676 2994
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2008
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This thesis is prepared for the examination of the Master of Philosophy degree from University College London. It provides fundamental knowledge in the field of bio-impedance, including basic concepts, measurement techniques and derived various applications for improving health care options for the wide community of human being. The thesis is organized into six chapters. Chapter One starts the thesis by introducing the concept of bio-impedance. Some representative designs of measurement cells and probes are briefly presented and classified into two categories for in vivo and in vitro application; so as to provide the parameter reference for designing an integrated version of bio-impedance measurement system (BMS). In addition, a brief mathematic foundation is included to explain the signal path of bio-impedance measurement system. A few applications of bio- impedance techniques, including the Electrical Impedance Tomography (EIT) are discussed. This chapter concludes with the limitation of BMS implemented using discrete components and proposes an integrated version of BMS to be applicable for increasingly challenging needs of health care service. This chapter also defines the system specification of BMS, such as operating frequencies, input dynamic range, and safety voltage/current requirement. Chapter Two investigates the origins of bio-impedance by studying the biological structure of a cell and its passive electrical parameter, such as at macro level impedance, and at the micro level, permitivity and conductivity. Chapter Three reviews various macro level electrical models of biological tissue, such as finger, leg, nerve etc, proposed by previous researchers. The disagreement of various electrical modelling presents a big challenge for fair comparison of various BMS performance. Chapter four reviews four categories of fundamental techniques underlying various BMS structures. The current/voltage technique is preferred by most current designs. Chapter five focuses the design of a monolithic instrumentation amplifier (in-amps) for BMS. Formulas of various critical system parameters, such as Gain/Bandwidth, Noise, Input/output impedance are derived. Schematics of amplifier are implemented in Cadence Virtuoso custom design platform with AMS 0.35μm technology. Simulation results, which proves the design meets specification are summarised in the end. Chapter Six ends the entire research thesis by summarising achievements of this work. In addition, some possible future work for the project are suggested and discussed.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available