Modeling and experimental validation of parasitic capacitance effects on emulated bioimpedance measurements with high‐impedance residuals

Abstract

SummaryParasitic capacitances and high‐residual impedances (typical of electrode/tissue interfaces) have significant effects on estimated electrical impedances of tissues under study. This leads to deviations (especially at high frequency) from the true tissue impedance. This work outlines the circuit theory describing estimation errors occurring when one and two parasitic capacitances are present in tetrapolar electrode configurations typical for bioimpedance measurements. The described circuit theory was validated using both simulations and measurements of a fabricated printed circuit board that implemented the tetra‐polar model. Using the presented model, correction procedures using (a) measurements of the source and sink excitation currents and (b) averaging measurements of forward and reverse electrode configurations have been validated in simulation showing reductions in the estimation errors at frequencies greater than 1 MHz.

Parasitic Effects on Electrical Bioimpedance Systems: Critical Review

“…However, parasitic capacitances introduce errors to experimentally measured variables. Systematic errors caused by leakage currents can be compensated throughout the signal's analog processing stage if the measurement system is properly calibrated and known [41,51]. In addition, one would also observe in some situations at high frequencies, in a range reaching the usable limit of 1 MHz in EIT systems, certain effects that could be interpreted as parasitic effects of an interplay of inductive and capacitive nature [52].…”

Reproducibility analysis of bioimpedance-based self-developed live cell assays

“…To exploit the potential of this nowadays’ new technique, many technological barriers still need to be eliminated 10 – 12 . As far as difficulties emerging with the employment of the technique are concerned, a further, almost impenetrable problem is that the effects of the measurement artifacts also depend on the unknown impedance itself 13 . A thorough review of the international literature revealed, that the measurement methodology and the mathematical methods generally implemented in the data evaluation procedure, as well as other efforts to improve BI-based technologies have not fulfilled the expectations yet 11 , 14 .…”