IEEE Trans Biomed Eng. 2020 May;67(5):1357-1365. doi: 10.1109/TBME.2019.2936577. Epub 2019 Aug 21.
Implanted electronics require protection from the body's fluids to avoid moisture induced failure. This study presents an injection molded liquid crystal polymer (LCP) package to protect active implantable devices for chronic applications, such as in optogenetic research. The technology is applied and assessed through a custom package for a fully implantable optogenetic stimulation system, built on a versatile telemetry system that can incorporate additional stimulating and recording channels. An adapted quasi-steady state model predicts the lifetime of an enclosure, where the definition of the lifetime is the time before the internal relative humidity (RH) reaches a time constant, or 63%RH, a conservative limit to minimize the risk of corrosion. The lifetime of the LCP optogenetic device is 94 days, and can be extended to 326 days with the inclusion of 5% w/v silica gel desiccant. Samples of the LCP optogenetic device containing humidity sensors testing in saline at 38 °C support the RH change predictions. Desiccants inside the implant enclosure can store permeating moisture and prolong the life expectancy of LCP-based implants to years or decades. The results of this study demonstrates the feasibility of providing reliable protection for chronic optogenetic implants, and the technology can be transferred to other applications as an easily-manufactured, cost-effective, radiofrequency compatible alternative to hermetic packaging for chronic studies.
植入式电子设备需要防止体液进入，以避免因潮湿而导致的故障。本研究提出了一种注塑成型的液晶聚合物（LCP）封装，用于保护用于慢性应用的有源植入式设备，例如在光遗传学研究中。该技术通过定制的全植入式光遗传学刺激系统的封装进行应用和评估，该系统建立在一个多功能遥测系统上，可以整合额外的刺激和记录通道。经过适应性准稳态模型预测了外壳的使用寿命，其中使用寿命的定义是内部相对湿度（RH）达到时间常数或 63%RH 之前的时间，这是一个保守的限制，可最大程度降低腐蚀风险。LCP 光遗传学设备的使用寿命为 94 天，如果包含 5%w/v 的硅胶干燥剂，则使用寿命可延长至 326 天。在 38°C 的盐水中进行测试的含有湿度传感器的 LCP 光遗传学设备样本支持 RH 变化预测。植入物外壳内的干燥剂可以储存渗透的水分，并将基于 LCP 的植入物的预期寿命延长至数年或数十年。本研究的结果证明了为慢性光遗传学植入物提供可靠保护的可行性，并且该技术可以作为一种易于制造、具有成本效益且与射频兼容的替代方案，用于慢性研究的密封包装，从而应用于其他领域。
