Microelectronic retinal prosthesis: I. A neurostimulator for the concurrent activation of multiple electrodes

An application specific integrated circuit (ASIC) capable of delivering charge to multiple electrodes in unison has been developed. The ASIC is designed to function as part of an epi-retinal prosthesis driving an array of electrodes in a hexagonal mosaic. This unique organization of electrodes and the use of current sources and sinks is implemented to reduce the electrical cross-talk that occurs when many electrodes are activated in unison. Due to the large numbers of electrodes needed to provide useful vision to implantees, the interleaving strategies used in cochlear implants will not suffice for a vision prosthesis, where the "frame rate" is important for acceptable perceptual outcomes. This paper describes the design, and architectural approaches and performance testing of the developed ASIC.