Experimental evaluation of stimulus current generator with Laplacian edge-enhancement for 3-D stacked retinal prosthesis chip

Kenji Shimokawa, Zhengyang Qian, Yoshiki Takezawa, Hisashi Kino, Takafumi Fukushima, Koji Kiyoyama, Tetsu Tanaka

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

To restore visual sensation of blind patients suffering from age-related macular degeneration (AMD) and retinitis pigmentosa (RP), we have been developing fully-implantable retinal prosthesis consisting of three dimensional (3-D) stacked retinal prosthesis chip with high density through silicon vias (TSVs), flexible cable, and a stimulus electrode array. Using 3-D integration technology, a photoreceptor chip with more than 1000 pixels can be fabricated in the top layer, and stimulus current generator with various image processing functions can also be fabricated in the bottom layer. In this paper, we presented experimental evaluation results of the stimulus current generator with Laplacian edge-enhancement function. The proposed edge enhancement (EE) function used a four-neighbor Laplacian filter circuit as analog signal processing and was implemented in a 0.18-μm 1P6M CMOS technology. A pixel size including the four-neighbor Laplacian filter circuit was 75 × 75 μm2, and 37 × 37 pixels occupied a very small active circuit area of 3.2 × 3.2 mm2. Experimental results showed the fabricated stimulus current generator completely captured an input image and successfully performed the EE processing for the input image data. Furthermore, total output current from photo-diodes, which became input currents of biphasic pulse generator, was reduced by 87% with the EE circuit. Safer electrical stimulations to the retina cells can be realized with the stimulus current generator with Laplacian EE in the 3-D stacked retinal prosthesis chip.

Original languageEnglish
Title of host publication2017 IEEE Biomedical Circuits and Systems Conference, BioCAS 2017 - Proceedings
PublisherInstitute of Electrical and Electronics Engineers Inc.
Pages1-4
Number of pages4
ISBN (Electronic)9781509058037
DOIs
Publication statusPublished - 2018 Mar 23
Event2017 IEEE Biomedical Circuits and Systems Conference, BioCAS 2017 - Torino, Italy
Duration: 2017 Oct 192017 Oct 21

Publication series

Name2017 IEEE Biomedical Circuits and Systems Conference, BioCAS 2017 - Proceedings
Volume2018-January

Other

Other2017 IEEE Biomedical Circuits and Systems Conference, BioCAS 2017
Country/TerritoryItaly
CityTorino
Period17/10/1917/10/21

Keywords

  • biphasic stimulus current generator
  • edge enhancement
  • four-neighbor Laplacian filter
  • retinal prosthesis

ASJC Scopus subject areas

  • Biomedical Engineering
  • Electrical and Electronic Engineering
  • Instrumentation

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