在神經義肢的應用裡，銬型電極已經被提供來作周邊神經的電刺激以及訊號感測的使用。為了有效性的感測和達到刺激目的，對於植入式電極的阻抗量測是相當重要的。研究目標為實現一個藉由磁場耦合進行無線傳輸的可植入式生醫微系統，用以量測植入式銬型電極阻抗。為了要在體內進行長時間的阻抗值的測量，我們採用的是以在皮質上層用磁場耦合的方法來傳送電能與指令進入到內部的模組中，並讓其可回傳出所測得的阻抗值。由於是阻抗的量測，所謂的二極式和四極式的方法被吾人採行，用以在銬型電極和電極與組織間介面的阻抗作測量。而為了避免需要高取樣率，我們利用增益與相位偵測器(a gain-phase detector)可以直接輸出所測量到的阻抗值之大小與相位偏移值。研究中首先進行的有效性測試為將阻抗的量測以模型包括一個電阻並聯一個電容表示，而後再進行將完整的植入式無線生醫微系統與銬型電極一同浸泡在食鹽水溶液中的實驗。測量到的數據與精確LCR量測計比較所得的相對誤差是小於10%。在體外的食鹽水測試後，生醫微系統可以進行急性的植入動物體內的實驗。而整個可植入式的裝置也已經可以在紐西蘭大白兔體內進行長時間的動物實驗監測。

In neural prosthetic applications, cuff electrodes have been utilized for providing peripheral nerve electrical stimulation and signal sensation. It is imperative for monitoring the impedance of implantable cuff electrode for the effective sensing and stimulating schemes. This study aimed to implement an implantable wireless biomicrosystem for measuring the implanted cuff electrode impedance via a magnetic-inductive link. For continuous in vivo impedance monitoring, a transcutaneous magnetic coupling technique was adopted for transmitting power and command into the internal module and transmitting outwards the impedance measurement. For impedance measurement, the two-terminal and four-terminal methods were adopted for impedance measurement of the cuff electrode and electrode-tissue interfacing impedance. To avoid high sampling rate required, a gain-phase detector was utilized for direct output of the magnitude and phase shift of impedance measurement. Validation tests of impedance measurement was first performed in an impedance model of resistor in parallel with capacitor and later by immersing the entire implantable wireless biomicrosystem with cuff electrode in NaCl saline solution. The measured impedance differences were less than 10 % in comparison with those measured by precision LCR meter. After in vitro NaCl saline solution tests, the implantable biomicrosystem was implanted for in vivo acute animal experiments. Now it is ready for the fully implantable device to be time-course study in the white New Zealand rabbit.

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