title: Light-controlled biphasic current stimulator IC using CMOS image sensors for high-resolution retinal prosthesis and in vitro experimental results with rd1 mouse.
abstract: Retinal prosthetic devices stimulate retinal nerve cells with electrical signals proportional to the incident light intensities. For a high-resolution retinal prosthesis, it is necessary to reduce the size of the stimulator pixels as much as possible, because the retinal nerve cells are concentrated in a small area of approximately 5 mm × 5 mm. In this paper, a miniaturized biphasic current stimulator integrated circuit is developed for subretinal stimulation and tested in vitro. The stimulator pixel is miniaturized by using a complementary metal-oxide-semiconductor (CMOS) image sensor composed of three transistors. Compared to a pixel that uses a four-transistor CMOS image sensor, this new design reduces the pixel size by 8.3%. The pixel size is further reduced by simplifying the stimulation-current generating circuit, which provides a 43.9% size reduction when compared to the design reported to be the most advanced version to date for subretinal stimulation. The proposed design is fabricated using a 0.35 μm bipolar-CMOS-DMOS process. Each pixel is designed to fit in a 50 μ m × 55 μm area, which theoretically allows implementing more than 5000 pixels in the 5 mm × 5 mm area. Experimental results show that a biphasic current in the range of 0 to 300 μA at 12 V can be generated as a function of incident light intensities. Results from in vitro experiments with rd1 mice indicate that the proposed method can be effectively used for retinal prosthesis with a high resolution.
authors.forename: Sungjin
authors.initials: S
authors.lastname: Oh
authors.forename: Jae-Hyun
authors.initials: JH
authors.lastname: Ahn
authors.forename: Sangmin
authors.initials: S
authors.lastname: Lee
authors.forename: Hyoungho
authors.initials: H
authors.lastname: Ko
authors.forename: Jong Mo
authors.initials: JM
authors.lastname: Seo
authors.forename: Yong-Sook
authors.initials: YS
authors.lastname: Goo
authors.forename: Dong-il Dan
authors.initials: DI
authors.lastname: Cho
mesh_terms: D000818:Animals; D054707:Cyclic Nucleotide Phosphodiesterases, Type 6 / Q000235:genetics; D004599:Electric Stimulation Therapy / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation*; D051379:Mice; D008822:Mice, Transgenic; D010783:Photometry / Q000295:instrumentation*; D012162:Retinal Degeneration / Q000503:physiopathology* / Q000534:rehabilitation; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D014173:Transistors, Electronic; D057488:Visual Prosthesis
chemical_list: D054707:Cyclic Nucleotide Phosphodiesterases, Type 6; C517438:Pde6b protein, mouse