Modeling the non-stationary behaviour of time-varying bioimpedance

Benjamin Sanchez, Ebrahim Louarroudi, Rik Pintelon, Ramon Bragos

Abstract

The electrical bioimpedance (EBI) measurement of varying biological systems <i>Z</i>(<i>&omega</i>,<i>t</i>) (e.g. the heart, the lungs, …) by means of electrical impedance spectroscopy (EIS) remains an open challenge today. Briefly stated, the bioimpedance is widely assumed to be <i>time-invariant</i> when it is measured with the frequency sweep EIS approach. Hence, time-varying changes are thus ignored or treated as a noise source. In this work, we attempt to model the time-variant effects and obtain a simple (periodically) time-varying [(P)TV)] electrical circuit model with (P)TV parameters from experimental <i>in vivo</i> EBI data using the model proposed by Fricke- Morse. The aim is then to illustrate that a limited number of harmonic components of the electrical circuit parameters, which corresponds to an integer number of the bio-system periodicity, can be used to have a realistic evolution of the bioimpedance over time as well as in frequency.

Keywords

electrical bioimpedance, Electrical Impedance Spectroscopy, Periodically Time-Varying bioimpedance

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IMEKO-TC4-2013-093.pdf

DOI

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IMEKO TC

TC4 - Measurement of Electrical Quantities

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