Harmonic analysis of low-frequency bioelectrode behavior

This paper concerns the modeling and interpretation of harmonics observed as a result of the nonlinear electrical properties of biomedical electrode/electrolyte interfaces. The higher order harmonics have been calculated assuming that the nonlinearity of the interfacial impedance is dominated at low frequencies by the nonlinear faradaic charge transfer resistance. The harmonic distribution in the output signal is compared between 1) the author's theoretical model based on the Butler-Volmer equation and 2) Schwan's empirical model and results. The influence of different parameters such as the number of electrons involved in the faradaic reaction and the transfer coefficient was investigated in order to physically interpret the experimental results. A good agreement was found between the authors' model and some of the experimental data previously reported in the literature. Further, potentially productive areas of research have been identified.