Development and Translation of novel SiC encapsulation thin film for chronic auditory nerve implant electrodes

Abstract A range of neurological diseases are now being researched or treated using fully implantable electronic systems to either record or modulate brain activity in humansThese implants are currently being protected using polymer coatings that envelop the implant and help keep body fluids away from the sensitive electronicsBrain implants with complex three dimensional geometrieslike the Utah Electrode ArrayUEAprovide a challenge for current encapsulation techniquesParylene has been the gold standard for encapsulation of neural and biomedical implants in general due to its well suited combination of biocompatibilityelectrical properties and chemical inertnessHowever recording capabilities of long term neural implantsandgtmonthsencapsulated with Parylene show signs of degradationTo address this problemwe propose to develop and evaluate performance and biocompatibility safety of a new Silicon CarbideSiCbased encapsulation designed to extend the long term stability and implantable lifetime for a high density Utah Slant Electrode ArrayHD USEAin line with lifetime expectations for conventional cochlea implant electrodesThe HD USEA is used as penetrating auditory nerve electrode in a new type of intracranial auditory prosthesis that targets the auditory nerve en route to the brainstem in order to substantially improve hearing performance over the current standard of carethe cochlear implantCINIHUG NSSiC has been studied in the past as encapsulation and electrode material due to its outstanding inherent material propertiesThis encapsulation layernovel to biomedical fieldwill retain all the advantages of Parylene while utilizing vastly superior dielectric properties of silicon carbide layer to create a much longer lasting and more electrically stable biomedical implantsThis layer encapsulation scheme may be seamlessly incorporated into our existing fabrication process flow for our flagship productthe UEAThis encapsulation will work on different surfacesmetalsemiconductorpolymerceramicand on devices with integrated wireless components making it ideal for coating any complex medical device intended for long term implantOur preliminary results with silicon carbide coated UEA are very promising in support of the proposed workWe have shown that silicon carbide yields more stable leakage currentand stable impedancewith andltchangeThis superior performance of suggests its potential usefulness for chronic implants with complex surface geometries Project Narrative Neuroprosthetic systems require chronic implantation of neural interfaces which are able to perform for years or decades to reduce surgical risks from follow up surgeries and generate levels of efficacy that justifies the risks associated with the implantsThe device has to be protected from the harsh body environment to allows it to perform its intended useThereforeencapsulation of implantable device is critical to its functionalitystabilityand longevityThis project addresses one of the key failure modes of current biomedical devicesWe are developing a novel encapsulation scheme specifically for neural interfaces that can be extended to cover other biomedical implantsOur encapsulation scheme will be transformed to manufacturing scale and applied to commercially available neural interfaces from Blackrock MicrosystemsThis technology has great potential to outperform the existing Parylene encapsulation methods