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Fabrication and Validation of Multichip Neural Stimulator for In vivo Experiments toward Retinal Prosthesis

A complementary metal oxide semiconductor (CMOS) multichip neural stimulator was fabricated and characterized. The device was designed specifically for retinal prosthesis. In this work, to achieve required performances for in vivo experiments, a new CMOS unit chip was designed with a power-on-reset mechanism and a low series resistance. We have developed a fabrication process for the proposed device focusing on the tight-seal performance of the device against saline solution to achieve a reliable long term operation. The proposed packaging technology is based on a flip-chip technique and has a feature of embedded Pt bulk electrodes. The basic functionality of the fabricated CMOS chip and packaged stimulator was confirmed. The device passed a 10-day endurance test in saline solution.