Implantable CMOS active microphotodiode pixel for subretinal electrical stimulation

This paper presents a new implantable CMOS active microphotodiode pixel for subretinal electrical stimulation, which is an effective solution to recover visual capabilities for patients of outer retinal pathologies. An accurate photodiode circuit macro-model is built for SPICE simulation and used in the design of the microphotodiode pixel circuit. The pixel has several advantages: simple structure, low power consumption and application to natural light illumination. It is suitable for high integration densities of pixels owing to small pixel size, which provides a higher resolution of visual stimulation. The power supply of an artificial retina chip composed of the proposed microphotodiode pixel can be implemented by RF power induction because of low power consumption. SPICE simulation results show the pixel meets the requirements of subretinal electrical stimulation well and possesses good stability.