Photovoltaic Pixels for Neural Stimulation: Circuit Models and Performance

—Photovoltaic conversion of pulsed light into pulsed electric current enables optically-activated neural stimulation with miniature wireless implants. In photovoltaic retinal prostheses, patterns of near-infrared light projected from video goggles onto subretinal arrays of photovoltaic pixels are converted into patterns of current to stimulate the inner retinal neurons. We describe a model of these devices and evaluate the performance of photovoltaic circuits, including the electrode-electrolyte interface. Characteristics of the electrodes measured in saline with various voltages, pulse durations, and polarities were modeled as voltage-dependent capacitances and Faradaic resistances. The resulting mathematical model of the circuit yielded dynamics of the electric current generated by the photovoltaic pixels illuminated by pulsed light. Voltages measured in saline with a pipette electrode above the pixel closely matched results of the model. Using the circuit model, our pixel design w...

• Type: Journal
• Year: 2016
• Where: TBCAS
• Authors: David Boinagrov, Xin Lei, Georges Goetz, Theodore I. Kamins, Keith Mathieson, Ludwig Galambos, James S. Harris, Daniel V. Palanker
• Keywords: TBCAS 2016