Performance improvement and in vivo demonstration of a sophisticated retinal stimulator using smart electrodes with built-in CMOS microchips

A retinal stimulator for next-generation retinal prosthesis was fabricated and demonstrated through in vivo experiments. The most significant element of the stimulator is a smart electrode that has built-in CMOS microchips to achieve high functionality with four bus wirings. The proposed architecture of the smart electrode allows large arrays such as a 1,000-electrode array, which can provide high-resolution restored vision. The design of the CMOS microchip was optimized to achieve a high-yield assembly. Circular fabricated microchips were embedded in the microcavities of stimulus electrodes. The assembly process of smart electrodes with built-in microchips was also optimized. A floating power supply system was proposed. and this system improved the stimulus capability of the smart electrode. To validate the functionality of the fabricated stimulator, an in vivo experiment was performed. Neural responses were successfully observed as potential peaks recorded from the visual cortex of the brain. (C) 2018 The Japan Society of Applied Physics