FPGA design of a pulse encoder for optoelectronic neural stimulation and recording arrays

This paper presents a new control methodology for high throughput optoelectronic/optogenetic prostheses. Optogenetic prostheses use a gene therapy method to photosensitize neurons, for which the most efficient stimulation is short pulses of just enough high intensity light. We have previously demonstrated that stimulation can be achieved with combined CMOS-Nitride micro-photonic systems. We have now explored operating schemes to provide accurate short pulses of high radiance light in an intensity modulation scheme for the purpose of retinal prosthesis. We have shown that by utilizing the sparse nature of retinal code, it is possible to have an adaptive system which minimizes information transfer compared to raster or purely asynchronous bit serial modes. We are thus being able to provide more dynamic and thus intensity accuracy. We have implemented our schemes on an FPGA to measure relative modes.