Integrated Retinal Implants

Author: Li, Wen

Year: 2009

Degree: Dissertation (Ph.D.)

Advisor: Tai, Yu-Chong

Committee Members: Tai, Yu-Chong; Emami, Azita; Yang, Changhuei; Weiland, James D.; Burdick, Joel Wakeman

Option: Electrical Engineering

DOI: 10.7907/AMK6-TA42

Abstract

Integrated wireless implants have always been the ultimate goal for neural prostheses. However, technologies are still in development and few have actually been transferred to clinical practice due to constraints in material biocompatibility, device miniaturization and flexibility. In this dissertation, emphasis is placed on the development of Parylene devices for neural prostheses, and particularly, for retinal prostheses that partially restore lost vision for patients suffering from outer retina degeneration.

A basic Parylene-metal-Parylene skin technology for making planar Parylene micro-electro-mechanical systems (MEMS) devices, such as electrode arrays and radio-frequency (RF) coil, is first discussed, followed by accelerated lifetime soaking tests to investigate the long term stability of such skins in hot saline under both passive and active electrical stressing. Discussion is further expanded on a detailed description of the design, fabrication, and testing procedure of two types of MEMS coils, which serve as receiver coils for wireless power and data transfer in a retinal implant system. After that, an embedded chip integration technology is presented, which allows the integration of complementary metal-oxide-semiconductor (CMOS) integrated circuit (IC) chips with other MEMS devices and discrete components so as to achieve high-level system functionality. Finally, an integrated wireless neural stimulator is designed and successfully fabricated using a test chip.

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