Surface modification of neural stimulating/recording electrodes with high surface area platinum-iridium alloy coatings

High-surface area platinum-iridium alloys were electrodeposited by on Pt and Au microelectrodes using a potential sweep technique. Detailed investigations of the structure and morphology and the electrochemical properties of the electrodeposited Pt-Ir alloy coatings were performed. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used for the determination of the surface morphology and the chemical composition of the Pt-Ir coatings, respectively. The elemental analysis by EDS showed a nearly 60-40% Pt-Ir composition of the coatings. The electrochemical properties of the Pt-Ir coatings were evaluated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). CV and EIS measurements revealed that the Pt-Ir coated electrodes exhibit significantly increased charge storage capacity and real surface area compared to uncoated Pt electrodes. Charge injection experiments of the Pt-Ir coated microelectrodes revealed low potential excursions, indicating high charge injection capabilities within safe potential limits.