本研究著重於開發一電容式生物感測器應用於人類血清白蛋白(Human Serum Albumin，HSA)偵測。研究初期設計指叉式電極感測元件，藉由印刷電路板技術來製作實現，並透過量測分析感測元件在不同人類血清白蛋白濃度下，觀察電容、電阻、阻抗與相位之變化特性。而從固定頻率為1 kHz來觀察，可發現在人類血清白蛋白濃度為0.01 mg/ml ~ 1 mg/ml之間，四種量測值分別對於人類血清白蛋白呈現半對數變化，其與電容量測值之關係式為y = -0.0344 Ln(x) + 0.5366；電阻量測值之關係式為y =139.11 Ln(x) + 834.8；阻抗量測值之關係式為y = 23.103 Ln(x) + 305.78；相位量測值之關係式為y = -2.7804 Ln(x) - 71.16。 而為將偵測系統整合，因此藉由國家晶片中心(CIC)所提供之台積電(TSMC)晶片下線之技術，設計電容式生物感測振盪器，希望能以積體電路之方式，將感測元件與振盪電路整合在相同晶片上，藉由輸出振盪頻率之差異性，分辨感測溶液之不同。其感測方式，是將生物分子散佈於指叉電極的內部環境中，因指叉電極在不同溶液中所產生不同的電容值，再由振盪器將電容變化量放大並讀出。This research focused on developing a capacitance type biosensor for human serum albumin (HSA) detection. An interdigital electrode was designed in early study, with fabrication on printed circuit board (PCB) technique. The measurement and analysis of interdigital electrodes under different HSA concentrations were to observe the capacitance, resistance, impedance and phase variation. The measurement results showed a semi-log correlation between the measured data and the concentrations of HSA from 0.01 mg/ml to 1 mg/ml. The regression equation was y = -0.0344 Ln(x) + 0.5366 on measured capacitance, y =139.11 Ln(x) + 834.8 on measured resistance, y = 23.103 Ln(x) + 305.78 on measured impedance, y = -2.7804 Ln(x) - 71.16 on measured phase. In order to integrate the interdigital electrode and detection system, the capacitor bio-sensing oscillator circuit was designed by using TSMC CMOS process from CIC. The detection method adopted in this oscillator circuit is variable capacitance sensing, the variable capacitance is related to the dielectric constant in-between the interdigital capacitor which is changed by different liquids, and the oscillator frequency thus changed accordingly by LC tank or ring oscillator.
