A Low-Stimulus-Scattering Pixel-Sharing Sub-Retinal Prosthesis SoC With Time-Based Photodiode Sensing and Per-Pixel Dynamic Voltage Scaling

Kyeongho Eom, Minju Park, Han Sol Lee, Seung Beom Ku, Namju Kim, Seongkwang Cha, Yong Sook Goo, Sohee Kim, Seong Woo Kim, Hyung Min Lee

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

This article proposes a 505-channel pixel-sharing sub-retinal prosthesis (PSRP) system-on-chip (SoC) that aims to effectively restore patients' visual acuity using the modular active/return electrode (Mod-A/R) scheme to mitigate current scattering and time-based photodiode (T-PD) sensing to increase the dynamic range (DR) of light sensing. To improve stimulation efficiency, the PSRP SoC adopts per-pixel dynamic voltage scaling (DVS) that can adaptively select different optimal supply voltages for each pixel. The proposed PSRP SoC has a small area of 0.01 mm2 per pixel, while the Mod-A/R scheme reduces the current scattering by up to 95.4%. By combining five pixels into a single structure, the five-pixel sharing set can accommodate the T-PD sensor and the per-pixel DVS. The proposed T-PD sensor with internal clock modulation can detect the light in the range of 0.13-19 klux with a DR of 35.8 dB, while the per-pixel DVS reduces stimulation energy consumption by up to 64%. The PSRP SoC coated with sputtered iridium oxide film (SIROF) electrode can be applied to clinical trials by adapting the light detection range and stimulus intensity with 44-bit external control. Ex vivo experiments with retinal samples of mice have verified the effectiveness of the PSRP SoC.

Original languageEnglish
Pages (from-to)2976-2989
Number of pages14
JournalIEEE Journal of Solid-State Circuits
Volume58
Issue number11
DOIs
Publication statusPublished - 2023 Nov 1

Bibliographical note

Publisher Copyright:
© 1966-2012 IEEE.

Keywords

  • Dynamic voltage scaling (DVS)
  • electrode array
  • image sensor
  • implantable medical devices (IMDs)
  • photodiode (PD)
  • pixel sharing
  • retinal prosthesis (RP)
  • stimulator
  • stimulus scattering
  • sub-retina
  • time-based

ASJC Scopus subject areas

  • Electrical and Electronic Engineering

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