Despite considerable advances in retinal prostheses over the last two decades, the resolution of restored vision has remained severely limited, well below the 20/200-acuity threshold of blindness. To address this challenge, we have worked on a scalable retinal prosthesis, in which each stimulation electrode based on ultra-high photosensitive silicon nanowires is directly activated by incident light. For ex vivo validation with rat retina tissues, we integrated a complete bench-top system comprising inductive telemetry link, stimulation pulse generator, charge-balancing scheme, and nanowire-based electrode array [Ha et al., JNE, 2016].
We plan to develop an innovative retinal prosthesis design that includes in situ recording of retinal activity in conjunction with high-density stimulation. This work will require thinning of a custom designed silicon-on-insulator (SOI) chip down to 1 μm for flexibility, and encapsulation with a biocompatible substrate such as a liquid crystal polymer. We anticipate this work to lead to the first CMOS-based flexible retinal prosthesis with in situ recording. This retinal prosthesis will not only enhance the resolution by characterizing and resolving different types of retinal ganglion cells, but also provide an unprecedented in vivo tool to revolutionize research on the retina activity mapping and development of retinal prostheses.