THE SUCCESSFUL ARTIFICIAL STIMULATION OF LIVING TISSUE BY ELECTRODE IMPLANTATION HOLDS FORTH THE PROSPECT OF VISUAL PROSTHESIS FOR THE BLIND, COCHLEAR PROSTHESIS FOR THE DEAF, AND THE USE OF HITHERTO PARALYZED LIMBS.

THE SUCCESSFUL ARTIFICIAL STIMULATION OF LIVING TISSUE BY ELECTRODE IMPLANTATION HOLDS FORTH THE PROSPECT OF VISUAL PROSTHESIS FOR THE BLIND, COCHLEAR PROSTHESIS FOR THE DEAF, AND THE USE OF HITHERTO PARALYZED LIMBS. A KEY PROBLEM IN EVOLVING AN ELECTRODE IMPLANT TECHNOLOGY BASE IS THE ABILITY TO MAINTAIN POINT SOURCES OF BARE METAL AT THE TIP OF AN INSULATED WIRE WHICH REPRODUCIBLY DELIVERS KNOWN AMOUNTS OF ELECTRICAL STIMULATION OVER LONG PERIODS OF TIME. THE PERCUTANEOUS SALINE ENVIRONMENT AND FLEXING OF THE IMPLANT SERIOUSLY DEGRADE THE ADHESION OF THE INSULATING COATING TO THE WIRE THEREBY INCREASING ELECTRODE AREA WITH CONCOMITANT FAILURE OF THE DEVICE. DURING PHASE I OF THIS PROGRAM, WE PROPOSE TO ELECTROCHEMICALLY GENERATE THIN, COHERENT POLYPHENYLENE OXIDE COATINGS ONTO PLATINUM WIRE SUBSTRATES FROM PHENOLIC MONOMERS. PREVIOUS WORK HAS SHOWN THESE COATINGS TO MANIFEST EXCELLENT ADHESION TO METALLIC SUBSTRATES DUE TO CHEMICAL BOND FORMATION BETWEEN THE SUBSTRATE AND POLYMER AS IT IS FORMED IN SITU. THE INTEGRITY OF THESE COATINGS WILL BE ASSESSED BY SEM AND ESCA. ELECTROCHEMICAL TECHNIQUES DESIGNED TO ASSESS THE COATINGS' RESISTANCE TO SALINE WILL ALSO BE APPLIED. PHASE II WORK WILL FOCUS ON IN-DEPTH CHEMICAL, ELECTROCHEMICAL, AND MECHANICAL EVALUATION OF THE OPTIMIZED COATINGS. BIOCOMPATIBILITY EXPERIMENTS WILL ALSO BE CARRIED OUT SO THAT BY THE END OF PHASE II HARDWARE MAY BE SUPPLIED TO NINCDS FOR IN VIVO STUDIES.