Time-domain finite element models of electrochemistry in intracochlear electrodes

Most neural prostheses feature metallic electrodes to act as an interface between the device and the physiological tissue. When charge is injected through these electrodes, potentially harmful reactions may result. Others have developed finite element models to evaluate the performance of stimulating electrodes in vivo. Few however, model an electrode-electrolyte interface, and many do not address electrode corrosion and safety concerns with respect to irreversible reactions. In this work, we successfully develop a time domain finite element model of cochlear implant electrodes that incorporate oxygen reduction and platinum oxidation reactions. We find that when electrodes are stimulated with current pulses (0.5 mA, 25 μs), faradaic reactions may cause an increase in the peripheral enhancement of the current density.