Authors:

Deniz Eksioglu

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About Paper:

Impedance evaluation is a critical tool to obtain detailed information regarding the functionality of neural interfacing electrodes. A key parameter during electrochemical impedance spectroscopy (EIS) is to ensure that the output of the system receiving the EIS stimulus signal is linear. Otherwise, the fundamental assumption of Ohm's Law in EIS is invalidated, leading to misrepresentation of the system, caused by the presence of harmonic responses to the input stimulus. Faradaic processes, such as the reduction and oxidation (redox) of chemical species at the electrode/electrolyte interface, occur at specific applied voltages that cause the system of interest to depict nonlinear behaviors. Moreover, as modern neural interfaces experience high impedance due to their small geometric surface area, it is crucial to deliver large amplitudes of stimulus signal during EIS experiments to drive sufficient measurement current, which can be distinguished from the background noise. Therefore, this project provides a verified systematic experimental plan for the determination of linear operation regions of neural interfaces. This study employs the use of Tafel and Lissajous plots to identify regions where the kinetics of redox reactions do not control the current at the interface. These experiments were conducted in a phosphate buffer saline solution with four different metal electrodes, all with the same surface area: platinum, tungsten, steel, and gold. By integrating Tafel and Lissajous analyses, the approach aims to distinguish regimes where electrode behavior remains governed by linear impedance principles rather than redox kinetics. Keywords: Electrochemical Impedance Spectroscopy; Linearity; Neural Interface; Tafel; Lissajous

Source:

Purdue University / 2025

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No topics listed

Co-authors:

Deniz Eksioglu