A fully intraocular high-density self-calibrating epiretinal prosthesis.
This paper presents a fully intraocular self-calibrating epiretinal prosthesis with 512 independent channels in 65 nm CMOS. A novel digital calibration technique matches the biphasic currents of each channel independently while the calibration circuitry is shared among every 4 channels. Dual-band telemetry for power and data with on-chip rectifier and clock recovery reduces the number of off-chip components. The rectifier utilizes unidirectional switches to prevent reverse conduction loss in the power transistors and achieves an efficiency > 80%. The data telemetry implements a phase-shift keying (PSK) modulation scheme and supports data rates up to 20 Mb/s. The system occupies an area of 4.5 ×3.1 mm². It features a pixel size of 0.0169 mm² and arbitrary waveform generation per channel. In vitro measurements performed on a Pt/Ir concentric bipolar electrode in phosphate buffered saline (PBS) are presented. A statistical measurement over 40 channels from 5 different chips shows a current mismatch with μ = 1.12 μA and σ = 0.53 μA. The chip is integrated with flexible MEMS origami coils and parylene substrate to provide a fully intraocular implant.
Manuel
M
Monge
Mayank
M
Raj
Meisam Honarvar
MH
Nazari
Han-Chieh
HC
Chang
Yu
Y
Zhao
James D
JD
Weiland
Mark S
MS
Humayun
Yu-Chong
YC
Tai
Azita
A
Emami
D002138:Calibration; D004582:Electronics, Medical / Q000295:instrumentation*; D004867:Equipment Design; D006801:Humans; D008954:Models, Biological; D058117:Neural Prostheses; D013686:Telemetry / Q000295:instrumentation*; D057488:Visual Prosthesis