THIN-FILM HERMETIC COATINGS

WE WILL DEVELOP THIN-FILM, ELECTRICALLY INSULATING HERMETIC COATINGS CAPABLE OF PROTECTING BIOIMPLANTABLE DEVICES AND ELECTRICAL CABLES FROM DEGRADATION IN THE IN VIVO ENVIRONMENT. THESE COATINGS WILL BE SUBSTANTIALLY IMPERVIOUS TO H2O, O2, AND IONS OVER THE ANTICIPATED LIFETIME OF CHRONICALLY IMPLANTED DEVICES (20 YEARS). THE COATINGS ARE COMPRISED OF DIELECTRIC AND "METALLIC" THIN FILMS. THE DIELECTRIC LAYERS PROVIDE ELECTRONIC ISOLATION AND SOME RESISTANCE TO H2O, AND ION TRANSPORT WHILE THE METAL LAYERS PROVIDE THE PRINCIPAL H2O, OXYGEN AND ION BARRIER. THE METALLIC LAYERS MAY BE ELECTRICALLY BIASED TO ENHANCE THE HERMETICITY OF THE COATING. IN PHASE I, THE VALIDITY OF THE APPROACH WILL BE DEMONSTRATED BY FABRICATINGPROTOTYPE COATINGS ON PLANAR SI SUBSTRATES PATTERNED WITH INTERDIGITATED ELECTRODES. DEPOSITION PARAMETERS FOR MULTI-LAYER HERMETIC COATING WILL BE DEVELOPED AND THEIR MORPHOLOGY, CRYSTALLINITY AND AC IMPEDANCE CHARACTERISTICS DETERMINED. THE HERMETICITY OF THE COATINGS WILL BE EVALUATED BY LEAKAGE CURRENT MEASUREMENTS DURING CHRONIC SOAK TESTS IN SALINE AT 37 DEGREES CENTIGRADE. IN PHASE II,THE COATING TECHNOLOGY WOULD BE EXPANDED TO INCLUDE POLYMER AND METAL SUBSTRATES AND ADDRESS ISSUES OF MATERIALS AND COATING OPTIMIZATION, MECHANICAL TESTING, AND PHOTOLITHOGRAPHIC PATTERNING. WE WILL DEVELOP THIN-FILM, ELECTRICALLY INSULATING HERMETIC COATINGS CAPABLE OF PROTECTING BIOIMPLANTABLE DEVICES AND ELECTRICAL CABLES FROM DEGRADATION IN THE IN VIVO ENVIRONMENT. THESE COATINGS WILL BE SUBSTANTIALLY IMPERVIOUS TO H2O, O2, AND IONS OVER THE ANTICIPATED LIFETIME OF CHRONICALLY IMPLANTED DEVICES (20 YEARS). THE COATINGS ARE COMPRISED OF DIELECTRIC AND "METALLIC" THIN FILMS. THE DIELECTRIC LAYERS PROVIDE ELECTRONIC ISOLATION AND SOME RESISTANCE TO H2O, AND ION TRANSPORT WHILE THE METAL LAYERS PROVIDE THE PRINCIPAL H2O, OXYGEN AND ION BARRIER. THE METALLIC LAYERS MAY BE ELECTRICALLY BIASED TO ENHANCE THE HERMETICITY OF THE COATING. IN PHASE I, THE VALIDITY OF THE APPROACH WILL BE DEMONSTRATED BY FABRICATINGPROTOTYPE COATINGS ON PLANAR SI SUBSTRATES PATTERNED WITH INTERDIGITATED ELECTRODES. DEPOSITION PARAMETERS FOR MULTI-LAYER HERMETIC COATING WILL BE DEVELOPED AND THEIR MORPHOLOGY, CRYSTALLINITY AND AC IMPEDANCE CHARACTERISTICS DETERMINED. THE HERMETICITY OF THE COATINGS WILL BE EVALUATED BY LEAKAGE CURRENT MEASUREMENTS DURING CHRONIC SOAK TESTS IN SALINE AT 37 DEGREES CENTIGRADE. IN PHASE II,THE COATING TECHNOLOGY WOULD BE EXPANDED TO INCLUDE POLYMER AND METAL SUBSTRATES AND ADDRESS ISSUES OF MATERIALS AND COATING OPTIMIZATION, MECHANICAL TESTING, AND PHOTOLITHOGRAPHIC PATTERNING.