THIS PHASE I, 6-MONTH FEASIBILITY STUDY IS TO ADDRESS PROBLEMS OUTLINED BY THE FUNDAMENTAL NEUROSCIENCES PROGRAM OF THE NATIONAL INSTITUTE OF NEUROLOGICAL AND COMMUNICATIVE DISORDERS AND STROKE (NINCDS).

THIS PHASE I, 6-MONTH FEASIBILITY STUDY IS TO ADDRESS PROBLEMS OUTLINED BY THE FUNDAMENTAL NEUROSCIENCES PROGRAM OF THE NATIONAL INSTITUTE OF NEUROLOGICAL AND COMMUNICATIVE DISORDERS AND STROKE (NINCDS). ULTIMATE LONG TERM SUCCESS OF AN AUDITORY PROSTHESIS REQUIRES AN ELECTRODE DESIGN WHICHIS FLEXIBLE ENOUGH FOR EASY INSERTION, CAN BOND SUFFICIENTLYWITH METALS TO WITHSTAND BENDING AND ELIMINATE WICKING OF PHYSIOLOGICAL FLUIDS INITIATED AT ELECTRODE CONTACT POINTS. THREE FUNDAMENTAL OBJECTIVES RELATED TO A FLEXIBLE SCALA TYMPANI ELECTRODE WILL BE ADDRESSED: (1) ADHESION OF METALLIC CONDUCTORS TO POLYMER (INSULATOR) SUBSTRATE, (2) ETCHING AND PROCESSING OF METALLIC CONDUCTOR TO OBTAIN OPTIMUM GEOMETRY AND (3) EVALUATE PHYSICAL PROPERTIES OF METAL/POLYMER COMPOSITE. A POROUS POLYSULFONE WILL BE EVALUATED FOR METAL ADHESION UNDER HYDRATED CONDITIONS AND WITH APPROPRIATE CURRENT STIMULATION. DELAMINATION IS A SEVERE PROBLEM WITH PRESENT ELECTRODE CONFIGURATIONS. PRELIMINARY WORK HAS DEMONSTRATED THAT POROUS POLYMER SURFACES ENHANCE METAL ADHESION BY MECHANICAL INTERLOCKING. PRELIMINARY STUDIES WITH METAL COATING ON POROUS POLYSULFONEHAVE DEMONSTRATED EXCELLENT ADHESION EVEN UNDER PROLONGED HYDRATED CONDITIONS. CONTROL OF POLYMER SURFACE ENERGETICS AND SURFACE POROSITY APPEARS TO ENHANCE METALLIC COATING ADHESION SUFFICIENTLY TO WARRANT FURTHER INVESTIGATION. A POROUS POLYSULFONE WILL BE EVALUATED FOR LONG TERM (>2 MONTHS) ADHESION, USING TITANIUM UNDERCOATINGS FOLLOWED WITHPLATINUM AND RHODIUM COATINGS. ADHESION WILL BE EVALUATED UNDER HYDRATED CONDITIONS WITH APPROPRIATE LEVELS OF CURRENTSTIMULATION. FLEXURAL PROPERTIES OF ELECTRODE COMPOSITES WILL BE EVALUATED AND COMPARED TO EXISTING DISCRETE 6-WIRE ELECTRODE SYSTEMS CURRENTLY IN USE FOR COCHLEAR STIMULATION.PHYSICAL PROPERTIES OF THE POLYMER-METAL COMPOSITE WILL BE EVALUATED FOR PROCESSING VIA PHOTOLITHOGRAPHY TECHNIQUES. BOTH CHEMICAL AND REACTIVE ION ETCHING (RIE) PROCESSING WILLBE STUDIED FOR GENERATION OF SUITABLE ELECTRODE GEOMETRIES COMPATIBLE WITH CURRENT MICROCIRCUIT FABRICATION TECHNOLOGY.