Light-Controlled Biphasic Current Stimulator IC Using CMOS Image Sensors for High-Resolution Retinal Prosthesis and In Vitro Experimental Results With rd1 Mouse

摘要

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 . In this paper, a miniaturized biphasic current stimulator integrated circuit is developed for subretinal stimulation and tested . 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 area, which theoretically allows implementing more than 5000 pixels in the 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 experiments with rd1 mice indicate that the proposed method can be effectively used for retinal prosthesis with a high resolution.