心血管相關疾病長期佔據國人十大死因的第二或第三名。本研究主要目的是建立一個非侵入式多層次紅外光血管容積波形量測系統，可同時針對同一部位進行穿透式與反射式PPG訊號量測，並以時域參數(FDT、FRT、PW)與頻域參數(諧波能量比例、諧波能量變異度)來探討不同層次血管間的差異變化。希望透過本系統的建置與臨床的量測採樣數據後，期望能開發出有用的相關臨床疾病偵測指標。
在臨床量測的實驗中，本研究主要針對正常人運動前後之效應以及新陳代謝症候群患者做量測分析。從前者的實驗結果中，我們發現在時域參數FRT、PW的部分，對於周邊血管變硬的狀態是具有解析能力的，且在頻域的諧波參數中，也發現對應手部與腳部的諧波是具有相關變化的；而在後者的實驗中，本研究觀察到時域參數FDT對於動脈硬化，是具有一定的解析能力的，並且在諧波的參數中，觀察到能反應出高血壓等心血管疾病的諧波指標，也具有一些趨勢及顯著性差異。
本系統之建置對於使用者的量測穩定性、便利性、擷取速率已有良好的提升，在未來希望能對PPG系統持續改良，並針對系統的微小化進行改良。最終希望透過更多的臨床實驗量測，開發出更多疾病偵測指標，增進遠距醫療的實現可能，為人體微循環檢測提供更方便且快速的量測方式。

Cardiovascular diseases occupied top factors of main death cause. Compare to cancer, cardiovascular diseases have no obvious symptoms. The aim of our research in to build a non-invasive PPG measurement system, which can detect the transmiting and reflective PPG signal simultaneously. Time(FDT, FRT, PW) and frequency-domain(amplitude ratio, harmonic variability) analysis were performed on the acquired signals.
In clinical experiment, we focused on the difference between before and after exercising in healthy subjects and also subjects with metabolic syndrome. Difference in FRT, PW and harmonic index can be used to monitor the changes in the arterial elastic and blood-flow following exercise. Moreover, FDT and harmonic index can be used to discriminate subjects at different stages of metabolic syndrome. The present finding may have meanings in diagnosis of important cardiovascular diseases.

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