Iridium oxide/platinum gray composite coatings on microelectrodes for neural stimulation

Abstract

The shrinking size of microelectrodes leads to high electrode/tissue interfacial impedance and low charge injection ability. In order to achieve safe, efficient and durable electrode performances, we proposed a layer-by-layer electrodeposition method to modify the bare platinum microelectrodes with nanostructures. Combining the advantages of platinum gray (Pt gray) with iridium oxide (IrO x ), herein a low impedance, high cathodic charge storage capacity (CSC c ) and high charge injection IrO x /Pt gray microelectrode was fabricated with nanoscale roughness, which was much higher than each simple coating. Furthermore, it demonstrated superior mechanical and electrochemical stability. Morphological tests showed that nanocone-shaped Pt gray provided large area and hence good adhesion for dense IrO x deposition, which was beneficial for long-term mechanical stability of the composite coating.