表面電漿共振(Surface Plasmon Resonance, SPR)現象，被發現已經有近一百年的歷史，而近幾年來，隨著生物醫學的發展，這項技述更是被廣泛的應用在生物檢測的範圍內，由於它對不同折射率的待測物有高靈敏度的特性，因此，常常被用來作生物醫學檢測。常見的表面電漿共振量測方式有四種，角度調制、波長調制、強度調制以及相位調制，其中以相位靈敏度最高，因最大的相位變化發生在SPR曲線最窄處，也是探測電場向量最大處，所以為了取得反射光相位資訊，本論文使用低同調干涉的表面電漿感測器架構來檢測微小核醣核酸的濃度變化。
在本論文中，通訊波段寬頻譜光源作為我們低同調干涉技術的主要來源，接著利用兩級的Mach–Zehnder干涉儀，作為此實驗架構的主體，並結合表面電漿共振現象，達到生物醫學感測目的，也因為使用兩級Mach–Zehnder干涉儀，成功解決一級Mach–Zehnder干涉儀沒有基準點可以做為濃度變化依據的問題，最後透過電腦分析不同濃度待測物之實驗結果。本實驗生醫量測在無探針(Probe)時，濃度變化的靈敏度為0.0606 (μm/(μg/mL))，而有探針的濃度變化靈敏度為0.088 (μm/(μg/mL))，從此可見靈敏度上升了1.45倍，解析度也相對增加了1.45倍，此說明了固定化探針可有效抓取標的物(miRNA)，也有更好的解析度。

With the biomedical technique development, surface plasmon resonance (SPR), which phenomenon has been found for nearly a hundred years, is widely utilized in biological detection due to its high sensitivity. There are four kinds of SPR characterizations - angle, wavelength, intensity and phase modulation. Among them, the phase modulation demonstrates the highest sensitivity because the maximum phase change occurs in the SPR curve dip where the largest electric field is happening. In order to retrieve the reflected light phase information, the low coherence interferometry based SPR sensor is utilized to detect various concentrations of microRNA in this thesis.
A superluminescent emitting diode with the center wavelength of 1550 nm is utilized as the light source to demonstrate low coherence interferometry in two-stage Mach-Zehnder interferometer where the SPR is built within one of two stages. The advantage for two-stage Mach-Zehnder interferometer is that the bench mark can be taken as a reference point during biosensing. A DNA sequence antisensed from microRNA DNA utilized as the prober and the sensitivity and resolution demonstrate as 0.088 (μm/(μg/mL)) and 4.5399×10^(-7), respectively.

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