A Portable and Low-cost Electrochemical Impedance Spectroscopy Platform for the Characterisation of Implantable Electrodes

Implanted electrodes are exposed to harsh environmental conditions, such as electrode temperature variations and corrosion risk. These conditions, when considered alongside operational requirements, may lead to reduced charge transfer and initiate electrochemical processes that alter the characteristics of the electrodes. The characteristics of neural electrodes can undergo changes post-implantation in various environmental conditions, and their efficiency may degrade over time. Electrochemical impedance spectroscopy (EIS) is an essential tool to observe and understand these changes. It offers insights into the electrode-tissue interface and overall electrode performance. This research aims to create a compact and cost-effective Printed Circuit Board (PCB) -based impedance measurement system for EIS, as compared to traditional bench-top EIS instruments. The custom device was tested using a deep brain stimulation (DBS) electrode in a Phosphate buffered saline (PBS) solution and compared to a bench-top electrochemical workstation. The results from the EIS demonstrate the root mean square (RMS) error of ±3.6528Ω of impedance magnitude across the frequency range. Consequently, The successful implementation of the designed device suggests its potential application in testing other types of neural electrodes in the future. In addition, all source files, including code and PCB design files, are openly accessible to the community for utilization and continued development.