心電圖、腦電波、肌電波等臨床上重要的診斷儀器，通常使用濕式生理量測電極，而傳統濕式電極必須在量測部位給予導電凝膠，不僅有導電阻抗變化的問題，也會造成受試者的不適。尤其是腦電波的量測，濕式電極會將受試者的頭髮弄髒，導致量測上的不方便與不舒服。因此，本研究致力於設計一套對身體訊號有高敏感度的乾式電極，藉由設計高阻抗的前端電路來提高整體系統的量測電阻係數，利用主動屏蔽(active shield)來隔絕外在雜訊，並提供良好共模抑制比(CMRR)與阻抗匹配，以穩定生理訊號的接收。本論文所設計的乾式電極已經成功在低接觸的情況下量測出心電圖與腦電波訊號。針對乾式電極與貼片電極所接收到的訊號進行比較，兩者的方均根差值(RMSE)為0.28 mV，驗證本論文所開發的乾式電極已經可以對生理訊號進行實測，具有臨床應用的價值。;Electrocardiogram (ECG), electroencephalography (EEG), electromyogram (EMG), and etc. are important diagnosis instruments in clinics. Traditional instruments usually utilize wet type electrode for measuring biomedical signals. However, the use of wet type electrodes has to smear electrolyte gel on the measurement sites. The application of electrolyte gel is neither comfortable nor convenient. Especially, in EEG measurements, the electrolyte gel will inevitably make subject’s hairs dirty. This study aims to develop a high sensitive dry electrode for the measurement of electrophysiological signals. We have designed active electrode to increase the impedance in the frontal-end circuit. By providing active shield, external noise was decreased and common mode reject (CMRR) was increased to provide better impedance matching. The proposed dry electrode has proved its feasibility in the low-contact condition. Comparing the signal quality between our dry electrode and traditional wet-type electrode, the root-mean-square error (RMSE) is 0.28 mV which demonstrates the feasibility of our dry electrode for clinical applications.
