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

摘要 一系列神经系统疾病正在研究或治疗使用完全植入式 电子系统来记录或调节人类的大脑活动。这些植入物 目前使用聚合物涂层保护植入物， 让液体远离敏感的电子设备脑植入物与复杂的三维 像犹他州电极阵列（UEA）这样的几何形状为当前的封装提供了挑战 技术.聚对二甲苯一直是神经和生物医学封装的金标准 由于其良好的生物相容性、电性能和 化学惰性然而，长期神经植入物的记录能力（>6个月） 用聚对二甲苯包封的材料显示出降解迹象。为解决这个问题，我们建议 开发并评价新型碳化硅（SiC）的性能和生物相容性/安全性 基于封装设计，可延长长期稳定性和植入寿命， 犹他州倾斜电极阵列（HD-USEA）的密度符合传统电极的寿命预期 耳蜗植入电极。HD-USEA用作穿透性听神经电极， 一种新型的颅内听觉假体，其目标是通往 脑干为了实质性地改善超过当前护理标准的听力表现， 人工耳蜗（CI）（NIH 1UG 3 NS 107688 -01）。 SiC由于其优异的物理化学性能， 固有的材料特性。该封装层对于生物医学领域来说是新颖的，将保留所有的生物相容性。 Parylene的优点，同时利用碳化硅层的非常优越的上级介电性能 来制造更持久和更电稳定的生物医学植入物。该层 封装方案可以无缝地结合到我们现有的制造工艺流程中 我们的旗舰产品UEA这种封装将在不同的表面（金属， 半导体、聚合物、陶瓷）和具有集成无线组件的设备， 适用于长期植入任何复杂医疗器械的涂层。我们的初步 结果与碳化硅涂层的UEA是非常有前途的支持所提出的工作。我们 已经表明，碳化硅产生更稳定的漏电流和稳定的阻抗（具有 <5%变化）。的这种上级性能表明其对慢性植入物的潜在有用性 具有复杂的表面几何形状。

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 humans. These implants are currently being protected using polymer coatings that envelop the implant and help keep body fluids away from the sensitive electronics. Brain implants with complex three-dimensional geometries, like the Utah Electrode Array (UEA) provide a challenge for current encapsulation techniques. Parylene has been the gold standard for encapsulation of neural and biomedical implants in general due to its well-suited combination of biocompatibility, electrical properties and chemical inertness. However recording capabilities of long-term neural implants (>6 months) encapsulated with Parylene show signs of degradation. To address this problem, we propose to develop and evaluate performance and biocompatibility/safety of a new Silicon Carbide (SiC) based encapsulation designed to extend the long term stability and implantable lifetime for a high density Utah Slant Electrode Array (HD-USEA) in line with lifetime expectations for conventional cochlea implant electrodes. The 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 care, the cochlear implant (CI) (NIH 1UG3NS107688-01). SiC has been studied in the past as encapsulation and electrode material due to its outstanding inherent material properties. This encapsulation layer, novel to biomedical field, will 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 implants. This layer encapsulation scheme may be seamlessly incorporated into our existing fabrication process flow for our flagship product, the UEA. This encapsulation will work on different surfaces (metal, semiconductor, polymer, ceramic) and on devices with integrated wireless components making it ideal for coating any complex medical device intended for long term implant. Our preliminary results with silicon carbide coated UEA are very promising in support of the proposed work. We have shown that silicon carbide yields more stable leakage current, and stable impedance (with <5% change). This superior performance of suggests its potential usefulness for chronic implants with complex surface geometries.