Development of a micromachined epiretinal vision prosthesis

Microsystems engineering offers the tools to develop highly sophisticated miniaturized implants to interface with the nervous system. One challenging application field is the development of neural prostheses to restore vision in persons that have become blind by photoreceptor degeneration due to retinitis pigmentosa. The fundamental work that has been done in one approach is presented here. An epiretinal vision prosthesis has been developed that allows hybrid integration of electronics on one part of a thin and flexible substrate. Polyimide as a substrate material is proven to be non-cytotoxic. Non-hermetic encapsulation with parylene C was stable for at least 3 months in vivo. Chronic animal experiments proved spatially selective cortical activation after epiretinal stimulation with a 25-channel implant. Research results have been transferred successfully to companies that currently work on the medical device approval of these retinal vision prostheses in Europe and in the USA.