Design of CMOS chip for retinal prosthesis with power supply voltage monitoring circuit for stabilizing constant-current stimulation

To advance the practical application of retinal prostheses with high spatial resolution through parallel stimulation, we developed a dynamic power supply voltage control system designed to enable stable constant-current stimulation in vivo, regardless of the number of active stimulation points. The proposed retinal prosthesis integrates a CMOS chip, containing current sources and electrode selection circuits, into a stimulation electrode array implanted in the eye. This configuration facilitates individual control of over 1000 electrodes with minimal wiring. In this study, we designed and integrated a power supply voltage monitoring circuit into the chip, allowing for real-time control of an external power generation circuit through feedback from the intraocular monitoring circuit. We demonstrated that the proposed system rapidly restored the power supply voltage when a voltage drop of 1 V occurred in the Pt wiring between the power supply unit and the chip, even while delivering a stimulation current of 1.5 mA in parallel across more than 100 electrodes.