Project Grant R01NS136987

SCALABLE FABRICATION OF HIGH-DENSITY AMORPHOUS SILICON CARBIDE MICROELECTRODE ARRAYS FOR CHRONIC NEURAL INTERFACING - PROJECT SUMMARY INTRACORTICAL MICROELECTRODE ARRAYS HAVE LONG BEEN USED TO RECORD NEURAL ACTIVITY IN BASIC SCIENCE AND CLINICAL RESEARCH STUDIES OF THE BRAIN. TO DATE, CARBON FIBER MICROELECTRODES HAVE ACHIEVED THE HIGHEST QUALITY NEURAL RECORDING DATA WITH MINIMAL IMMUNE RESPONSE AFTER IMPLANTATION, BUT THE TECHNIQUES REQUIRED TO FABRICATE CARBON FIBER ARRAYS DO NOT ALLOW FOR THE MANUFACTURING SCALE REQUIRED FOR NEXT-GENERATION DEVICES. RECENT ADVANCES IN THIN-FILM FABRICATION HAVE LED TO A NEW CLASS OF FLEXIBLE MICROELECTRODE ARRAYS BUT THEY REQUIRE AN ECOSYSTEM OF COMPLEX IMPLANTATION FIXTURES, LIMITING THEIR WIDESPREAD ADOPTION. AS A RESULT, THIN-FILM DEVICES WITH NEURAL RECORDING QUALITY EQUIVALENT TO CARBON FIBER ELECTRODES HAVE SO FAR ELUDED THE NEURAL ENGINEERING COMMUNITY. THIS PROJECT AIMS TO USE SCALABLE FABRICATION METHODS TO DEVELOP SELF-INSERTING 128-CHANNEL ULTRA-MICROELECTRODE ARRAYS WITH UNMATCHED RECORDING LONGEVITY. BY PROVIDING HIGH-QUALITY NEURAL SIGNALS OVER LONGER PERIODS, WE AIM TO ADVANCE STUDIES OF LONG-TERM CHANGES IN NEURAL CIRCUITS AND IMPLICATIONS FOR CLINICAL TREATMENTS OF NEUROLOGICAL DISORDERS. TO ACCOMPLISH THIS, THE PROJECT USES AMORPHOUS SILICON CARBIDE IN STANDARD THIN FILM FABRICATION. THE ELECTRODE ARRAYS ARE FABRICATED IN A FORM FACTOR EASILY IMPLANTED IN THE BRAIN WITHOUT ANY COMPLEX IMPLANTATION MECHANISMS. THE HIGH DENSITY OF MICROELECTRODES AND ULTRA-SMALL DIMENSIONS OF EACH INSERTED SHANK ARE DESIGNED TO ELICIT MINIMAL IMMUNE RESPONSE. THE FOCUS OF THIS PROJECT IS A VALIDATION OF THE FABRICATION METHODS AND DEVICE RECORDING CAPABILITIES THROUGH A SERIES OF ENGINEERING STEPS AS WELL AS IN VITRO AND IN VIVO TESTING. SPECIFICALLY, THE PROJECT SEEKS TO REFINE THE FABRICATION PROCESS FOR SCALABLE PRODUCTION OF 128-CHANNEL ULTRA-MICROELECTRODE ARRAYS AND TO ESTABLISH SINGLE UNIT YIELD, STABILITY, AND CHRONIC TISSUE RESPONSE FOR DEVICES IN SMALL ANIMAL MODELS. ENGINEERING STEPS INCLUDE DESIGN VARIATIONS TO ESTABLISH REPEATABLE FABRICATION OF AMORPHOUS SILICON CARBIDE ARRAYS WITH CROSS-SECTION DIMENSIONS BELOW 10 MM THAT INSERT WITHOUT THE NEED FOR ADDITIONAL GUIDES, SHUTTLES, OR OTHER STRUCTURES. FINALLY, THE PROJECT SEEKS TO QUANTIFY THE PERFORMANCE OF THE DEVICES IN MULTI-MONTH IN VIVO STUDIES.