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

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 inc...

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Bibliographic Details
Published in:IEEE journal of solid-state circuits 2023-11, Vol.58 (11), p.1-14
Main Authors: Eom, Kyeongho, Park, Minju, Lee, Han-Sol, Ku, Seung-Beom, Kim, Namju, Cha, Seongkwang, Goo, Yong Sook, Kim, Sohee, Kim, Seong-Woo, Lee, Hyung-Min
Format: Article
Language:English
Subjects:
Dynamic voltage scaling (DVS)
Electric potential
electrode array
Electrodes
Energy consumption
image sensor
implantable medical devices (IMDs)
Iridium
Luminous intensity
Neural prostheses
Oxide coatings
photodiode (PD)
Photodiodes
pixel sharing
Pixels
Prostheses
Prosthetics
Retina
retinal prosthesis (RP)
Scattering
Sensors
Stimulation
stimulator
stimulus scattering
sub-retina
System on chip
time-based
Visual acuity
Visualization
Voltage
Voltage control
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Description
Summary: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 mm ^{2} 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.
ISSN:0018-9200
1558-173X
DOI:10.1109/JSSC.2023.3305521