Development of a Wireless High-Frequency Microarray Implant for Retinal Stimulation

Abstract

We have developed an electrical stimulator and diagnostic research microarray with wireless power and communications to facilitate spatial stimulation of retinal tissue. A third generation 32× 32 prototype of this retinal neural implant array has been developed. Integrated into the microarray is a functionally graded Ti/IrO2 microbump electrode system for interface with neural tissue with decreased impedance for stimulation. The microarray is designed for basic research to determine retinal tissue stimulation thresholds and spatial effects. The array is connected to a telemetry chip, which uses magnetic induction for wireless power with a digital overlay for communication. In our design, changes in the induced current in the telemetry coil are used to send information to the reading coil. Since the reading and telemetry coil are magnetically coupled, the current change can be sensed for bidirectional communication. Combined, this chip set provides a 1024 array that can stimulate neural tissue spatially, can sense neural signals spatially, and has wireless power and communication in a package of less than 2 mm size.