Silicon retinal tack for the epiretinal fixation of the polyimide electrode array

Silicon-micromachined retinal tacks were developed for the fixation of the epiretinal-type retina-stimulating microelectrode array. Silicon retinal tacks were fabricated by using the silicon on insulator (SOI) process, a method of releasing silicon structures in a SOI wafer. The dimensions of the retinal tack were substantially smaller than those of the conventional titanium tack, at 1.5 mm long, 150 μm wide, and 150 μm thick. To enhance the durability and biocompatibility of the retinal tack, 3 μm-thick parylene film was uniformly deposited on the entire surfaces. Short-term evaluation of the durability of the silicon retinal tack in vivo showed acceptable biocompatibility and firm fixation of the microelectrode array onto the retina.