Sputtered platinum-iridium layers as electrode material for functional electrostimulation

In this study co-sputtered layers of platinum-iridium (PtIr) are investigated as stimulation electrode material. The effects of different sputter parameters on the morphology and the electrochemical behavior are examined. It is shown that films sputtered at the lowest incident energy possess the highest charge storage capacity (CSC). At a Pt:Ir atomic-ratio of 55:45 the obtained CSC of 22 mC/cm2 is enhanced compared to the standard stimulation material platinum (16 mC/cm2) but inferior to iridium which has a CSC of 35 mC/cm2. Long term cyclic voltammetry measurements show that PtIr can be activated which increases the CSC to 29 mC/cm2. Also a change in the film morphology is observed. Sputtered platinum-iridium films promise to combine high mechanical strength and increased charge storage capacity.