葡萄糖溶液濃度之光聲量測

Abstract

糖尿病是一種常見的內分泌系統失調的慢性病，為了有效控制糖尿病，持續監測血糖濃度十分重要，目前的血糖量測技術通常採侵入式採集指尖血液檢測。非侵入式血糖檢測不僅避免疼痛，還可以改善病患的生活品質。本文以光聲效應評估葡萄糖溶液的濃度，葡萄糖溶液受到Nd:YAG脈衝雷射照射會產生光聲訊號，以超音波換能器感測，建立光聲訊號振幅與相位特徵對於葡萄糖溶液濃度的關係曲線。本研究採用兩種實驗架構，第一種架構中，脈衝雷射照射葡萄糖溶液與樣本容器的固液耦合界面，在固體中傳遞之光聲訊號穩定。以超音波探頭的中心頻率相位為基準，建立光聲訊號特徵頻率的相位差與低濃度樣本之關係，經統計迴歸驗證具高度相關性。採用不同超音波探頭、不同光源波長，並以脂肪乳劑模擬人體組織散射特性，皆有良好的量測結果。第二種架構將雷射聚焦於水溶液中產生光聲效應，以沒水式超音波換能器接收，光聲訊號不僅受到葡萄糖濃度的影響，對於溶液的其他條件也敏感，較難達成穩定的相關性。

Diabetes mellitus is a common endocrine disorder. Continuous monitoring blood sugar is of importance to keep diabetes under control, although currently piercing finger invasively is the most usual method of blood-glucose testing. Noninvasive glucose monitoring will not only avoid physical pain during glucose testing, but also improve life quality of a diabetic. This thesis characterizes glucose concentration in solutions using photoacoustic effect. In experiment, a photoacoustic signal is induced and detected by an ultrasonic transducer when the glucose solution is irradiated by a pulsed Nd:YAG laser. Two experimental setups have been carried out to establish the correlations between amplitude and phase of photoacoustic signals and glucose concentration in solutions. In the first one, photoacoustic signals are induced near the solid-liquid interface between glucose solution and the container. Photoacoustic signal induced in solid media is stable. The difference between the phase at the central frequency of ultrasonic transducers and that at the characteristic frequency of photoacoustic signal has a high correlation, which has been verified by regression and statistical analysis. In the second experiment, the photoacoustic effect is induced in solution by a point-focusing pulsed laser and captured by an immersion ultrasonic transducer. The photoacoustic signal was sensitive to other influences besides glucose concentration. The last experiment results in a difficulty to establish a reliable correlation. Various experimental conditions and their influences have been also studied, such as ultrasonic transducers of different central frequencies, light with distinct wavelengths, and solutions filled with intralipid to emulate scattering properties in human bodies.