Phase/Magnitude Retrieval Algorithms in Electrical Bioimpedance Spectroscopy

Abstract

The use of an amplitude/phase retrieval algorithm in electrical impedance spectroscopy(EIS) that allows a new method to calculate the impedance spectrum in EIS systems from partial data information is described. To the authors’ knowledge, this is the first time such an algorithm has been used to calculate the magnitude/phase of an impedance in EIS from one of these two available parameters. The use of magnitude or phase retrieval circuits in EIS systems may become unnecessary with the proposed technique, reducing EIS systems cost and complexity. The algorithm is theoretically validated by using a reference impedance obtained from a simulated 2R1C function that represents a model for biological tissue whose parameters are readily obtainable from literature. Experimental validation is demonstrated by using a complete EIS system to obtain the values of a known impedance across a frequency interval from 100Hz up to 500kHz, where only phase is used as input data for the algorithm to calculate the impedance magnitude. Algorithm performance is studied when noise is added to typical bioimpedance simulated data. The algorithm shows robustness with typical bioimpedance noisy data and experimental results are shown to be consistent with simulation.