A new light-activated CMOS retinal-pulse generation circuit without external power supply for artificial retinal prostheses

A new approach to implement the artificial retinal prosthesis using a silicon retina chip is proposed in this paper. In the proposed new approach, a new light-activated CMOS retinal pulse generation circuit is designed by using the gate-controlled lateral npn and pnp bipolar junction transistors (BJTs) to form the new BJT-based silicon retina structure. With the BJT serving as a photovoltaic device, which generates power under incident light, the designed circuit does not require an external power supply. Moreover, the proposed new circuit can function as photoreceptors, horizontal cells, and bipolar cells of the real vertebrate retina to generate retinal pulses under moving object or flash light image. Both static and dynamic functions of the proposed circuit have been verified by using HSPICE simulation. An experimental chip with 32×32 silicon retina cell array is designed by using 0.25 μm one-poly-five-metal CMOS technology with deep n-wells. The chip will be implanted into eyes in animal tests