A Flexible 202-Channel Epidural ECoG Array With PEDOT: PSS Coated Electrodes for Chronic Recording of the Visual Cortex

Electrocorticography (ECoG) electrode arrays for epidural implantation allow establishing neural interfaces, which promote investigation of complex distributed brain functions and development of neuroprosthetic systems while having reduced invasiveness in comparison to intracortical or subdural electrode placement. In this paper, we present the design, fabrication, and both
in-vitro
and
in-vivo
evaluation of a flexible ECoG array with 202 closely spaced electrodes of 560-
$\mu \text{m}$
diameter, each coated with the polymer poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT: PSS) for chronic recording in two visual cortical areas V1 and V4 of macaque monkeys. The specific layout of the array provides a close fit to the curved surface of the brain. We confirm its chronic recording functionality
in-vivo
by estimating visual receptive fields for the individual electrodes.