Flexible and extensible retinal prosthesis based on multi-chip architecture

We present a multi-chip electric stimulator for a retinal prosthesis. The stimulator consists of small silicon devices (unit chips) molded in a thin film. It has an advantage over the conventional devices in physical flexibility and extendibility. The smart unit chip (600 mu m square, in this work) is an integrated circuit (IC) that includes digital serial interface circuits; analog switch circuits and on-chip stimulus electrodes. In contrast to conventional stimulators, the present stimulator can be driven with only four wires. The multi-chip configuration enables to make the stimulator flexible and durable to bending stress. The device can be bended to place the stimulation electrodes in good contact with retinal tissue. In this paper, we present the design of the stimulator device with 0.35-mu m complementary metal-oxide semiconductor (CMOS) technology. We also report a thin, flexible packaging technique for the stimulator and preliminary experimental results of a sputtered iridium oxide (IrOx) film that can be used for chronic stimulation.