用單手指的方式來探取血液複雜的成分，長久以來一直是光學體積描計器值得研究的課題。生理檢測的發展方向朝向可攜式、穿戴式、及簡易化，此時功率的消耗就更凸顯其重要性。本論文先從探討脈衝式血氧計的功耗開始，因為脈衝式血氧計可更深入探取食指末梢血液的狀態，然而週期式脈衝的工作週期(Duty cycle)對於量測值的準確度影響程度還是不夠清楚的。在此論文中，我們使用每秒512次交替發射於雙波長夾指式探頭內之可見紅光（VS）及紅外線（IR）發光二極體(LED)，並經光接收器取樣，數位濾波後計算VS與IR之對數比值相對於脈波光發射時間長短（tpw）之關係。實驗顯示當tpw從約1000 μs縮短至70 μs後，比值仍未有明顯變化。此結果顯示光元件可以減少點亮時間而延長其使用壽命，更可以改善整體設備之電源功率消耗。
由於血液的成分複雜，人體可能因吸入異常的空氣，尤其是有害的氣體分子會干擾血液中的氧與血紅蛋白的結合，此時人體動脈中血液成份不能單純使用去氧血紅蛋白及氧合血紅蛋白兩條吸收率不同來解釋，多波長的可攜式指夾探頭可更精確地量取人體動脈血液之狀態。本論文以人體吸入高濃度的二氧化碳為例，使用脈波寬度約300 μs之脈衝式光學體積描計圖來分析動脈中血液對於各波長之吸收量變化，結果顯示在620 nm或640 nm波長附近的光吸收量變化最大。實用上可藉由檢測此比值，若低於設定值則發送警示信號，告知體內已累積過多的二氧化碳，達到健康照護的目地。

Providing an easiest way to gather the information on the complex blood components conveniently from a single finger in a short time, plethysmographs have always been a topic worthy of studies. For a long time, it has been hoped that physiological data collection could be so developed as to be conducted in a portable, wearable and simple manner. For these purposes, power consumption is a significantly important matter. This study began with a pulse oximeter, as it was possible to acquire the information on the peripheral blood (index finger) using this oximeter; however, it remains unclear how the pulse width of light emission affects human tissue. In this thesis, alternating red and infrared light emitting diodes from a finger clip probe were set at 512 Hz. After conducting optical receiver sampling and digital filtering, the log ratio of the red and infrared light was used to examine their relationship to the pulse width. The pulse width varied from 70–1000 μs, yielding no observable effects on the ratios. These findings suggest that reducing the illumination time of optical components may reduce the amount of power consumed by the equipment and extend the lifetime of the power supply.
Because the blood components were far more complex than we thought, the use of dual-wavelength SpO2 sensors was not enough to meet the demands of our times. Thus, we use a portable multiwavelength probe for application of optical plethysmography when inhaling abnormal air, especially certain harmful gas molecules, can disturb the bonding of oxygen and hemoglobin in the blood. As a result, the arterial blood composition in the human body cannot be explained by the different absorbabilities of the two wavelengths for oxyhemoglobin and deoxyhemoglobin. Therefore, the traditional dual wavelength oximeter has become outdated. People often stay in confined spaces and are unaware of the high concentration of CO2. Therefore, we take inhaling high concentration CO2 as its example; the portable non-invasive multi-wavelength optical finger probe is used, with the paired light emitting diodes (LEDs) in the probe lit up alternately by the most energy-saving impulse. The analysis results show that as the CO2 concentration increases, the rate of visible light absorption decrement of blood for small wavelength (about 620 nm or 640 nm) close to deoxyhemoglobin absorptivity increases gradually. The ratio is checked in practice; if it is lower than the set value, a caution signal is sent, informing the occurrence of excessive accumulation of CO2 in vivo for health care.

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