Ranjeet Jhutti: Configurable Reverse Telemetry Protocol for Retinal Prosthesis

Ranjeet Jhutti is a 4th year undergraduate student in the Electrical Engineering and Computer Science major at UC Berkeley. As part of the NSF Summer 2004 SURF-IT program he worked with the BMES (Biomemetic Micro Electronic Systems) group on Retinal Prosthesis.

Retinal Prosthesis aims to provide vision for 33 million people suffering from lost vision caused by Age-related Macular Degeneration (AMD) or Retinitis Pigmentosa (RP). The prosthetic device includes the external unit which sends image data to the intraocular unit. The intraocular unit controls the microelectrode array which delivers current pulses for retinal stimulation.

The intraocular unit receives power from the external unit using coils. Changes in coil separation and eye movement can induce a variation in the power being received. To compensate for these instantaneous changes in power, Reverse Telemetry is used as a part of a closed-loop feedback system. It is also used to transmit information such as electrode impedance, temperature, and pH level in the eye.

Ranjeet worked on verilog code for the reverse telemetry system, which involves efficient encoding and decoding of data packets. Since encoding will be done by the chip residing inside the eye, conserving power and area is of prime importance.

The Reverse Telemetry protocol was designed to be adaptable. Hence it uses configurable parameters when encoding and decoding data. This allows for flexibility in design because when an analog component of the reverse telemetry protocol changes, you can simply reconfigure the parameters.