Plasma-assisted atomic layer deposition of alumina and Parylene-C bi-layer encaps

描述(申请人提供)：目前正在研究或治疗一系列神经疾病，使用完全可植入的电子系统来记录或调节人类的大脑活动。这些植入物目前正在使用聚合物涂层进行保护，这种涂层包裹植入物，并帮助使体液远离敏感的电子设备。具有复杂三维几何结构的脑植入物，如图中所示的犹他州电极阵列(UEA)，对当前的封装技术提出了挑战。由于其生物相容性、电学性能和化学惰性的完美结合，对二甲苯已成为神经和生物医学植入物封装的黄金标准。然而，用对二甲苯包裹的长期神经植入物(&gt；6个月)的记录能力显示出退化的迹象。为了解决这一问题，BlackRock MicroSystems提出了一种新颖的双层封装方案，该方案将等离子体辅助原子层沉积(PA-ALD)氧化铝层结合在对二甲苯层下。这种对生物医学领域新颖的封装方案将保留对二甲苯的所有优点，同时利用底层ALD氧化铝层极佳的介电性能来创建更持久、更稳定的生物医学植入物。这种双层封装方案可以无缝地整合到我们的旗舰产品UEA的现有制造流程中。采用集成电子封装方法的双层UEA将适用于不同的表面(金属、半导体、聚合物、陶瓷)和具有集成无线元件的设备，使其成为用于长期植入的任何复杂医疗设备的理想涂层。该项目有4个具体目标：具体目标1：优化ALD氧化铝/对二甲苯双层封装方案，并在测试设备上与仅对二甲苯封装进行性能比较。具体目标2：发展蚀刻方法，选择性地暴露在涂有优化的AlD氧化铝/对二甲苯双层的UEA上的活性电极位置。具体目标3：评估ALD氧化铝/对二甲苯双层涂层UEA的电荷注入/阻抗特性。具体目标4：比较ALD氧化铝/对二甲苯双层包被的尿电阻滞剂和仅对二甲苯的尿电阻滞剂的体内性能。我们对对二甲苯和氧化铝涂覆的平面交指电极(IDE)测试结构的初步结果非常有希望支持所提出的工作。我们已经证明，双层封装产生了更稳定的漏电流和稳定的阻抗(在67�C下变化5%)，持续约5个月(约相当于37�C下的40个月)。这种双层封装的优异性能表明，它在具有复杂表面几何结构的慢性种植体中具有潜在的用途。在第一阶段“实验室到市场”的SBIR项目结束时，BlackRock预计将开发出协议和标准，将这项研究从目前的早期实验室环境转变为商业级的制造过程。

DESCRIPTION (provided by applicant): 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) shown in the figure, 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 combat this problem Blackrock Microsystems proposes a novel bi-layer encapsulation scheme that combines Plasma Assisted Atomic Layer Deposited (PA-ALD) alumina layer underneath the Parylene layer. This encapsulation scheme, novel to biomedical field, will retain all the advantages of Parylene while utilizing vastly superior dielecric properties of underlying ALD alumina layer to create a much longer lasting and more electrically stable biomedical implants. This bi-layer encapsulation scheme may be seamlessly incorporated into our existing fabrication process flow for our flagship product, the UEA. The bi-layer The UEA with integrated electronics encapsulation method 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. The project has 4 specific aims: Specific Aim 1: Optimize an ALD alumina/Parylene bi-layer encapsulation scheme and compare performance with Parylene-only encapsulation on test devices. Specific Aim 2: Develop etch methods to selectively expose active electrode sites on UEAs coated with optimized ALD alumina/Parylene bi-layer. Specific Aim 3: Evaluate charge injection/impedance characteristics of ALD alumina/Parylene bi-layer coated UEAs. Specific Aim 4: Comparison of in vivo performance of ALD alumina/Parylene bi-layer coated UEAs to Parylene-only coated UEAs. Our preliminary results with Parylene and alumina coated planar interdigitated electrode (IDE) test structures are very promising in support of the proposed work. We have shown that the bi-layer encapsulation yields more stable leakage current, and stable impedance (with <5% change) at 67 �C for about 5 months (approximately equivalent to 40 months at 37 �C). This superior performance of bi-layer encapsulation suggests its potential usefulness for chronic implants with complex surface geometries. At the end of the Phase I 'Lab to Marketplace' SBIR project, Blackrock expects to have developed protocols and standards to transform this research from its current early-stage lab setting into a commercial-grade manufacture process.