Implantable CMOS-based stimulator/reader design for retinal prosthesis

In a retinal prosthesis, digitized pixels of image are multiplexed and transmitted wirelessly, and received pixels are decoded and scanned on the probes array to stimulate the retina to reproduce the image. This paper presents an implantable CMOS-based 5×5 array retinal stimulator (RS), which receives time-multiplexed pixels of an image from a wireless receiver through only six interface wires irrespective of array size and scans them on the probes array to reproduce the image on the retina. RS doesn´t need address to route the pixels. It is fabricated by MOSIS using 0.5μm CMOS technology and is tested for its functionality as a stimulator as well as a reader and found working as expected. This paper also presents the design of serial to parallel converter (SPC), digital to analog current converter (DACC), and programmable biphasic current controller (BCC) necessary to process signal and generate biphasic current waveform for RS.