Retinal prosthesis is a promising treatment for vision degeneration. However, clinical experiments show that the patients can only recognize several grayscales at low resolution with electrical stimulation. This paper proposes a retinal prosthesis chip with binarization and edge detection functions to maximize the brightness difference and reduce redundant information. The binarization operation is designed as a column-parallel processing element for saving space. Moreover, the fill factor achieves 50.79% by separating the sensor and stimulator into different chips. Finally, the SPICE simulator verified the effectiveness of the proposed circuit, which achieves an FoM of 110 nW/(frame•pixel).

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This paper presents the first circuit that enables microsaccade function in an artificial eyeball system. Currently, the artificial eyeball is receiving increasing development in vision restoration. The main challenge is that the human eye is born with microsaccade that helps refresh vision, avoiding perception fading while the gaze is fixed for a long period, and without microsaccade, high-quality vision restoration is difficult. The proposed electronic microsaccade (E-μSaccade) circuit addresses the issue, and it is intrinsically safe because only charge-balanced stimulus pulses are allowed for stimulation. The E-μSaccade circuit adopts light-to-frequency modulation; due to the circuit’s leakage and dark current of light-sensitive elements, stimulus pulses of a frequency lower than tens of Hz occur, which is the cause of flickering vision. A flicker vision prevention (FVP) circuit is proposed to mitigate the issue. The proposed circuits are designed in a 0.18 μm standard CMOS process. The simulation and measurement results show that the E-μSaccade circuit helps refresh the stimulation pattern and blocks the low-frequency output.