A 2D electrode-skin model for electrical & contact impedance characterization of Bio Impedance

Bio Impedance Analysis (BIA) is an emerging technology for analysis and detection of abnormalities using physiological signals. An important factor in BIA is electrode-skin contact impedance. This contact impedance could act as a barrier for obtaining accurate bio-physiological signals (such as aortic pulse waveform). Hence in order to design such an instrument for BIA, we need to ideally model the contact impedance around the electrode-skin interface. This paper proposes a generalized 2D electrode-skin impedance model, that could be used to study the current density, electric field pattern, and various other electrical characteristics around the point of contact (electrode-skin). In this work we used a sinusoidal wave for the excitation purpose, but this model, being a generalized model, can be used to simulate different type of excitation pulse, and thereby observe the changes. The proposed model could be used by system designer, to design such instruments wherein human safety with regards to electric current is of paramount importance. The same model could also be used by researchers for carrying out simulations related to electrode-skin interface, and thereby determine electrical characteristics which might be of much importance. The model has been realized and simulated in Finite Element Solver, COMSOL version 4.4.