螢光量子點應用於氣體感測器之研製

Abstract

本研究使用 CdSe/ZnS 量子點作為材料，結合自製微型光學感測器的紙張型感測器，以材料光致發光的特性檢測揮發性有機化合物 (Volatility Organic Compound，VOC) 的紙片型感測器。微型光學感測器使用市售之綠光感測器結合雙低通濾波放大電路，與光譜儀相比，大幅降低了成本。本研究做幾項影響因素的探討，包含光源的選擇、感測器的比較及其數據計算方式，成功的測量七種有機氣體於爆炸下限 1/10 的濃度，其結果具有良好的再現性及穩定性，線性迴歸係數大多大於 0.99。奈米銀具有奈米金屬增強螢光之特性，因此在本研究中還觀察 CdSe/ZnS 量子點混合奈米銀 Ag@C16 之螢光強度變化，結果為混合 Ag@C16 的量子點對有機氣體的選擇性及螢光強度的增強無太大的幫助，其可能原因為量子點溶液被稀釋或量子點與奈米銀的距離不適當所導致的。而此感測器對於水也有良好的反應及再現性，使其亦有潛力成為濕度感測器。最後，在本研究中，通過氣體吸附與表面反應、電荷轉移機制等方式，去探討量子點接觸氣體後螢光上升的可能機制。

In this study, a paper-type sensor using CdSe/ZnS quantum dots in combination with a micro-optical sensor was used to detect volatile organic compounds (VOCs) using the photoluminescent property of the material. The miniature optical sensor uses a commercially available green light sensor combined with a dual low-pass filter amplifier circuit, which significantly reduces the cost compared to a spectrometer. In this study, several influencing factors were investigated, including the choice of light source, the comparison of sensors, and the calculation of data, and seven organic gases were successfully measured at a concentration of 1/10 of the lower explosive limit, with good reproducibility and stability, and most of the linear regression coefficients were greater than 0.99.Nano-silver has the property of nano-metal to enhance the fluorescence, so in this study, we also observed the fluorescence intensity change of CdSe/ZnS quantum dots mixed with nano-silver Ag@C16, and the result was that the quantum dots mixed with Ag@C16 did not help much in the selectivity of the organic gases and the enhancement of the fluorescence intensity, and the probable reason was that the quantum dots were diluted in the solution or the distance between the dots and the nano- III silver was not appropriate. This sensor also has good response and reproducibility to water, which makes it a potential humidity sensor. Finally, in this study, the possible mechanisms of the fluorescence rise of the quantum dots after contacting with gas are investigated through gas adsorption and surface reaction and the charge transfer mechanism.