A fully intraocular high-density self-calibrating epiretinal prosthesis

IEEE Trans Biomed Circuits Syst. 2013 Dec;7(6):747-60. doi: 10.1109/TBCAS.2014.2298334.


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.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Calibration
  • Electronics, Medical / instrumentation*
  • Equipment Design
  • Humans
  • Models, Biological
  • Neural Prostheses*
  • Telemetry / instrumentation*
  • Visual Prosthesis*