In Vitro Electrochemical Properties of Titanium Nitride Neural Stimulating and Recording Electrodes as a Function of Film Thickness and Voltage Biasing

Thin film titanium nitride (TiN), with a geometric surface area of 2,000 mu m(2), was deposited on planar test structures with thicknesses of 95, 185, 315, and 645 nm. Electrochemical measurements of electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and voltage transient (VT) were performed. We found that impedance values decreased and charge storage and charge injection capacities increased with increasing film thicknesses. Additionally, applying a anodic bias to TiN can increase the charge injection of the film to nearly double that of a non-biased film.