Authors: D.C. Rodger, W. Li, A.J. Fong, and Y.C. Tai Company: California Institute of Technology Date Published: 5/3/2007
Medical Electronics Symposium
Abstract: Novel flexible parylene-based high-density electrode arrays and radiofrequency coils have been developed for electrical stimulation systems in retinal and spinal cord applications. The electrode arrays are microfabricated according to single-metal-layer and, most recently, dualmetal-layer processes. A new heat-molding process has been implemented to conform electrode arrays to the approximate curvature of canine retinas, and chronic implantation studies have been undertaken to study the mechanical effects of parylene-based prostheses on the retina, with excellent results to date. Electrode arrays have also been implanted and tested on the spinal cords of murine models, with the ultimate goal of facilitation of locomotion after spinal cord injury; these arrays provide a higher density and better spatial control of stimulation and recording than is typically possible using traditional finewire electrodes. Spinal cord stimulation typically elicited three muscle responses, an early (direct), middle (monosynaptic), and a late (polysynaptic) response, classified based on latency after stimulation. Stimulation at different rostrocaudal levels of the cord yielded markedly different muscle responses, highlighting the need for such high-density arrays. RF coils have shown admirable data transmission and accelerated-lifetime saline soak capability.