Abstract
Purpose: :
To develop and characterize a flexible recording electrode array capable of transmitting a substantial fraction of incident light energy. This array will be used chronically as part of a telemetry system reporting retinal ganglion cell output in an ambulatory animal model.
Methods: :
A polyimide–based microfabrication process was used to create an array matrix within which indium tin oxide (ITO) electrodes were embedded. Patterning was performed by a photolithographic lift–off process for the sputtered ITO material. The recording array was designed with folding umbrella–like sections and gold traces along hinge areas to reduce bending stresses on the ITO after the device is tacked to the epiretinal surface.
Results: :
A set of microlithography, physical vapor deposition, spin coating, and etching processes has been engineered to create substantially transparent ITO conductors at a sufficiently low temperature to avoid significant yellowing of the flexible polyimide membrane in which they are embedded. Subsequently, a 100 electrode, 9 mm diameter flexible prototype recording array was fabricated for future chronic epiretinal placement. The device is intended to be used for recording in awake animals, and in conjunction with a subretinal stimulating electrode array to study the correlation between artificial percepts resulting from coded electrical stimuli, and those arising from naturally occurring visual inputs.
Conclusions: :
A building block for a platform technology to study the neural code for vision has been developed in the form of a flexible, light–transmitting epiretinal recording electrode array that subtends a substantial visual angle and that can be used in ambulatory animal models.
Keywords: age-related macular degeneration • retinal degenerations: hereditary • electrophysiology: non-clinical