植入式生醫微系統於神經功能修復的應用，已引起神經介面研究之熱潮。先前本實驗室之研究中，我們在印刷電路板上，使用了表面黏著元件。發展出一套由微處理器控制之電刺激系統，可在動物體作功能性電刺激之研究。本研究最主要之目的為評估植入式微電刺激器封裝設計之可行性。研究中，運用簡單微機電製程技術，將先前本實驗室研究中之微電刺激器電路以及銬型電極製作於聚亞醯胺材質之軟性基板上，組成植入式微電刺激模組，以達到模組化封裝。軟性結構之設計，使之更適合發展於模組化封裝及植入動物體內之應用。整個微電刺激器之封裝方面則是採用雙層封裝方式，內層使用Dam-and-Fill Encapsulation 方式封裝以保護微電刺激器電路，外層則是選用生物相容性的高分子材料-醫療用矽膠，作為植入體內後與生物體內組織間之介面，減低免疫系統之反應。目前整個元件大小約為直徑4 cm及高度8 mm之微電刺激器連結至銬型電極。整個植入式微電刺激器之可靠度及密封度試驗，分別作體外及生物體內之評估方式來進行。體外部分是將微電刺激器放置於生理食鹽水中，定期的測試其功能並作紀錄，目前在生理食鹽水中存活最長的微電刺激器為30天；動物實驗部分，則是將微電刺激器植入在兔子的坐骨神經上，量測電刺激對兔子屈膝所產生之力矩，來評估微電刺激器在植入兔子體內後是否會遭到損壞。

Implantable biomicrosystems for neural function restoration have gained more attention for studying the characteristics of various types of neural interfaces. In our previous study, we have developed a microprocessor-based microstimulation system by using the Surface Mount Devices (SMDs) components on Printed Circuit Board (PCB) and stimulating electrodes, prepared for implantation on animal functional electrical stimulation (FES) studies. The main theme of this study is to investigate the feasibility of packaging design of an implantable microstimulator. In current study, Micro Electro Mechanical System (MEMS) fabrication process for microassembly and interconnection on flexible polyimide substrates was employed to integrate microstimulator circuitry and nerve cuff electrodes as an implantable biomicrosystem for peripheral nerve applications to achieve a module package. The flexible mechanical structure design of microstimulator is more suitable for module design and implantation purposes. Dam-and-fill process was applied to seal the module, which was later encapsulated with medical grade silicone rubber for biocompatible package. The implantable microstimulator measured 4 cm in diameter and 8 mm in height with cuff electrode interconnected to it. Finally, in vitro experiment in the normal saline has confirmed that it is feasible to employ dam-and-fill encapsulation and medical-grade silicone rubber to package the biomicrosystem for a period of 30 days. The microstimulator is undergoing in vivo tests through the implantation to stimulate rabbit’s sciatic nerve.

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