糖尿病是人類目前的重大疾病之一，在臺灣地區平均每一個小時就有一個人因糖尿病死亡，血糖感測是掌握糖尿病病情最重要的指標，正常人飯後兩小時的血糖應小於140 mg /dl，若大於200mg /dl則可判定為糖尿病，介於此範圍者則屬於高危險群。
光波導除了應用在光通訊，過二十年多來在生醫感測的領域亦有蓬勃的發展，特點為高敏感度、高穩定性、反應迅速以及易於量產，其應用範圍包括醫藥、環境、食品、國防等。與目前市售血糖偵測器相比，矽線馬克-詹德干涉儀具有成本低廉、體積小、測試範圍大、不需使用試紙等優點，具有商業開發的潛力。
本論文以絕緣層上覆矽(SOI)為基板，使用光學步進機(I-line stepper)作為曝光機台，製作出Mach-Zehnder結構的矽線波導，寬度為0.5μm，蝕刻深度0.26μm。Mach-Zehnder波導其中一路徑覆蓋二氧化矽與外界隔絕作為基準區；另一路徑則開有長1000至8000μm的空間可與糖水溶液接反應，作為感測區。由於糖水折射率與濃度成正相關，利用低同調干涉的原理架構，量測上下兩路徑干涉圖形封包的極值間距，便可推算其濃度變化。
由於光功率對濃度變化的改變量為一餘弦函數，若元件設計不佳將會使得量測結果不為一對一函數，使量測結果失去正確性，使用低同調干涉的量測方法將可避免此情形發生。
本實驗以0%、5%、10%、20%的糖水為樣本，成功量測其相位變化，敏感度為0.002963μm/RIU。感測極限目前為 ，若使用光學尺或光學編碼器，解析度將可達到 ，理想上系統的最低解析度為 ，可以偵測4.55mg/dl的變化量，將可有效應用於糖尿病的診斷。

In Taiwan, one person passed away per hour from diabetes, which is a serious disease for human beings. Blood glucose concentration measuring is the way to tell if one have pre-diabetes or diabetes. A normal glucose level is 110 milligrams per deciliter (mg/dl) or below, a diabetic level is 126 mg/dl or higher, and a pre-diabetes level is between 110 mg/d land 125mg/dl.
Optical waveguide can be used not only in optical communications, but also in biosensing in the healthcare, environmental pollution, food, and military defense for over twenty years due to its characteristics of high sensitivity, stability, quick reaction and mass production. The extension of application includes Compared with current diabetes sensing products, the superior parts of silicon-wire Mach-Zehnder interferometer are low cost, small foot print, wider sensing region, and test paper needless, thus with the potential for commercial product applications.
In this article, we utilized the silicon-on-insulator (SOI) as a substrate, and I-line stepper for lithography, to fabricate silicon wire Mach-Zehnder interferometer with the width of 0.5μm and etching depth of 0.26μm. One arm of the interferometer is cladded with TEOS oxide and is thus isolated from the sugar solution, while the other is exposed to the sugar solution. The sensing length is from1000 to 8000μm. Since the refractive index of sugar solution is proportional to its concentration, we could use the low-coherence interferometer to measure the distance between different interferograms, thus to derive the concentration difference.
We successfully characterized the phase differences between 0%, 5%, 10%, and 20% sugar solutions, the sensitivity is 0.002963μm/RIU, and detection limit is . It can be lowered to if the optical encoder is implemented. Ideally the limit is for the system and is equal to 8.4mg/dl sugar concentration variation. This approach can effectively be utilized in diabetes differentiation.

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