開發用於檢測空氣中揮發性有機物的直流驅動針板式微電漿

Abstract

電漿是物質的第四態，將電漿的尺度控制在微米等級的微電漿會有體積小、功耗低等優勢，電漿光譜在分析化學上擁有高靈敏度與可用於檢測的潛力，然而若是要將電漿光譜的分析方式，實地運用於空氣環境下的檢測仍有一定的困難度，因此本研究希望設計出一套氣體檢測平台用於偵測揮發性有機氣體，為了測試其偵測表現，本研究將使用乙醇蒸氣作為待測氣體，並研究和調控實驗參數，期望可用於分析與定量。 本研究所使用的氣體檢測平台，為自激振盪的升壓模組產生高壓直流電，以驅動微電漿。實驗中，以檢測平台的性能測試與穩定性和再現性作為研究的基礎，進而將實驗參數納入檢測平台最適化的考量，以期望可以找出在空氣環境中有利於有機氣體檢測的條件。影響程度最大的是迴路中串聯鎮流電阻值的改變，在間距400 μm的選擇下，測試0.5到400 kΩ等不同阻值，發現電阻會影響系統的操作線，使其有不同的放電模式與不同的電漿光譜，在調控為自脈衝的模式下，當鎮流電阻值越小，峰值功率越大，電漿光譜上，乙醇造成的CN特徵峰也會越明顯，將有利於此平台的檢測能力。其他參數，如電極間距、氣體流速、環境濕度，亦會有不同程度的影響。 本研究將電性特徵，光譜表現，與特徵峰的穩定度等實驗結果進行評估。最終將電極間距控制在400 μm，氣體流速為1.84 slm，並在常溫常壓下將相對濕度調控在50-55%左右以模擬在含有水氣的真實空氣環境下，進行檢測三種揮發性有機氣體，結果顯示直流微電漿系統具有良好的線性響應，R2皆大於0.97，甲醇、乙醇、異丙醇的偵測極限可達81.8、26.0、13.9 ppm。

Plasma is the fourth state of matter. Microplasma, which controls plasma on a micron scale, has the advantages of small size and low power consumption. Plasma spectroscopy is highly sensitive and holds significant potential for analytical chemistry. However, applying plasma spectroscopy for detection in an air environment remains challenging. Therefore, this study aims to design a gas detection platform for volatile organic gases. To test this detection platform, ethanol vapor will be used as the target gas. Experimental parameters will be studied and regulated, with the goal of achieving effective analysis and quantification. The gas detection platform used in this study generates high-voltage direct current for the self-oscillating boost module to drive microplasma. In the experiment, the performance, stability, and reproducibility of the detection platform were evaluated, and experimental parameters were optimized to improve the detection of organic gases in the air. The value of the series ballast resistor in the circuit has the greatest impact. With an electrode gap of 400 μm, different resistance values ranging from 0.5 to 400 kΩ were tested. It was found that the resistance affects the system's operating line, resulting in different discharge modes. In self-pulse mode, a smaller ballast resistance value and higher peak power enhance the CN characteristic peak caused by ethanol in the plasma spectrum, improving the platform's detection capabilities. Other parameters, such as electrode gap, gas flow rate, and environmental humidity, also influence the results. This study evaluates experimental results, including electrical characteristics, spectral performance, and the stability of characteristic peaks. Ultimately, the optimal conditions were identified: an electrode gap of 400 μm, a gas flow rate of 1.84 slm, and a relative humidity of 50-55% under room temperature and atmospheric pressure. These conditions were used to simulate the detection of three volatile organic compounds in a real air environment containing water vapor. The results demonstrate that the DC microplasma system has a good linear response, with R² values greater than 0.97, and detection limits for methanol, ethanol, and isopropyl alcohol reaching 81.8, 26.0, and 13.9 ppm, respectively.