光學脈搏血氧計是一種無創、可連續量測脈搏血氧濃度的裝置，而在目前的非侵入血氧計的應用上，因技術的限制導致目前市售血氧計多為侷限於身體末梢使用的穿透式血氧探頭，對日常生活有頗多的不便。本論文的目的在於開發反射式的光學脈搏血氧計以提升使用者舒適度，我們藉由自行設計的血氧量測硬體電路，同步量測指尖的穿透式血氧與手臂的反射式血氧訊號以進行比較，以校正出反射式光學脈搏血氧計的血氧校正曲線，開發能夠配戴於手臂上的血氧量測手錶。在本研究中我們量測八位年齡介於20~30歲之間，血氧濃度介於94~100之間的受測者，在一個月期間內各量測八到十筆數據，以觀察系統之穩定性與再現性。在204筆數據中，指尖穿透式量測結果與市售血氧計相較誤差小於2%，而穿透式與反射式光學脈搏血氧計，血氧量測誤差小於6%。在我們的研究中，我們發現反射式光學脈搏血氧計會受到不同的量測位置、光源亮度的影響，使得血氧量測會有精準度上的差異，因此本論文將先針對上述兩變數固定情況下，校正出一條反射式血氧曲線，未來會嘗試加入自動調光程式量測在不同位置下的訊號，提高使用的便利性。;Optical pulse oximetry is a non-invasive device for continuously monitoring of atrial oxygen saturation (SpO2). Most of current non-invasive oximeters use a pair of red- and infrared- light transceiver module to measure SpO2 from tip of fingers or toes which usually cause inconvenience in daily life or disturbance to users. The purpose of this study was to develop reflectance-based pulse oximetry to improve the usability. We use hardware designed by ourselves to measure the light transmittance from users’ fingertip and light reflectance from users’ wrist simultaneously. Therefore, the measurements of reflectance-based SpO2 can be calibrated from transmission-based SpO2. In this study, we measured eight healthy subjects, all were healthy nonsmokers with ages ranged from 20 to 30 years old, whose SpO2 values were between 94 to 100. Each subject participated in the SpO2 measurements for 8~10 times within one month in order to analyze the stability and repeatability of the proposed system. Our results showed the reflectance-based SpO2 device was able to accurately measure with error percentages lower than ± 2% for transmission-based SpO2 and lower than ±6% for reflectance-based SpO2. Our study also found that different measurement positions and the changes of illumination of emitters were also factors to affect the accuracy of the pulse oximetry. Therefore, we fixed these two factors and has calibrated a curve for our reflectance-based SpO2 oximetry.
