An implanted retinal prosthesis device using an image sensor based on a pulse frequency modulation

Abstract

We propose an implanted retinal prosthesis device using an image sensor based on pulse frequency modulation. A dynamic range of the device is found to be limited by the balance between the charge current and the photocurrent. For implanting the device in a retina, the characteristic are required to be controlled externally. We have fabricated and demonstrated a simple circuit to control the output pulse frequency. Also programmable waveform generation circuits and biphasic output circuits have been demonstrated.