Hermetically sealed coatings for neural implants

神经植入是一种很有前途的方法，可以持续治疗许多目前无法治愈的严重疾病，如失明、帕金森氏症或闭锁综合征。这些系统由非常薄而灵活的绝缘和导电层箔组成，必须长期植入。他们必须在大脑中工作20年甚至更长时间。这需要密封的稳定性，这是今天的微技术无法提供的。该项目旨在寻找一种薄膜封装和一种技术，可以在大脑液中提供20年的可靠运行。申请人建议研究由聚合物和氧化中间层组成的夹心层。作为聚合物，聚酰亚胺和聚酰亚胺将被研究。中间层将是金属氧化物，由原子层沉积而成。此外，还将分别准备和分析每个电气互连具有全密封的系统。这一创新首先是对一种新概念的发展、分析和改进。其次，创新是一种新的工艺流程，以各向同性和完美的方式在柔性基板上沉积无机-有机屏障。选择的科学方法是首先制定测试程序，然后准备一系列样品并对其进行分析。主要的测试程序将是加速浸泡测试，这意味着将探针浸入热盐水中并通过介电光谱测量它们。制备了不同形貌的样品。它们被涂上不同的屏障层，然后进行分析和评估。对于一种或几种选定的屏障涂层，将组装和测试整个系统。水扩散的理论描述将采用基于活化能的模型。由于如果存在液态水就会发生腐蚀，因此也将模拟扩散的水分子在聚合物和金属氧化物层边界处的冷凝。

Neural implants are a promising approach towards sustainable treatment of a number of severe illnesses which cannot be healed today, such as blindness, Parkinson’s disease or the locked-in syndrome. These systems consist of very thin and flexible foils of insulating and conducting layers, which must be chronically implanted. They have to work 20 years and more in the brain. This needs a stability of hermetic sealing which cannot be provided by today’s micro technology.The project aims at finding a thin film package and a technology which provide reliable operation for 20 years in the brains liquor. The applicants propose to investigate sandwich layers from polymers and oxidic interlayers. As polymers, Parylene and Polyimide will be investigated. The interlayers will be metallic oxides, made by atomic layer deposition. Also systems with full hermetic sealing for each electric interconnect separately will be prepared and analyzed. The innovation is first the development, analysis and the improvement of a new concept for hermetically sealing neural implants. Second, innovation is a new process flow to deposit anorganic-organic barriers on flexible substrates in an isotropic and flawless way. The scientific method chosen is first to develop test procedures, next to prepare a series of samples and to analyze them. The primary test procedure will be the accelerated soak test, which means immersing the probes in hot saline and measuring them by dielectric spectroscopy. Samples with different topographies are prepared. These are coated with different barrier layers, then analyzed and evaluated. For one or several selected barrier coatings a full system will be assembled and tested.Theoretical description of the water diffusion will be made by a model based on activation energies. Since corrosion happens if liquid water is present, the condensation of the diffused water molecules at the boundary of polymer and metal oxide layers at micro cavities will also be modelled.