Batch fabricated thin-film electrodes for stimulation of the central auditory system

Silicon micromachining and thin-film technology were used to fabricate iridium stimulating arrays which can be used to excite discrete volumes of the central nervous system. Silicon multichannel probes with thicknesses ranging from 1 to 40 mu m and arbitrary two-dimensional shape can be fabricated using a high-yield, circuit-compatible process. Iridium stimulating sites are shown to have similar characteristics to iridium wire electrodes. Accelerated pulse testing with over eight million 100 mu A biphasic current pulses on 8000 mu m ² sites demonstrated the long-term stability of iridium and activated iridium sites. In vivo tests were performed in the central auditory pathways to demonstrate neural activation using the devices. These tests show a selective activation both as a function of site separation and site size.