結合可攜式微電漿產生器與藍芽遙控高壓模組應用於偵測揮發性有機物

Abstract

電漿被視為物質的第四態，當對氣體分子施加高能量使其電子發生躍遷後，電子由高能階返回低能階的過程中常伴隨光子的釋放。由於不同氣體分子具備不同的化學結構與鍵結特性，其所釋放之光譜亦呈現特定差異，因此電漿發射光譜可作為辨識與分析有機物的重要工具。微電漿（microplasma）係指放電區尺度小於數毫米的電漿形式，具有低成本、低功耗、高反應性及易於攜帶等優點，本研究旨在建立一套可攜式之常壓微電漿系統，應用於揮發性有機化合物（Volatile Organic Compounds, VOCs）之偵測。為達此目的，本研究設計並開發一組具備藍芽遠端控制功能與可調整操作頻率之高壓電源模組。 本研究所設計之藍芽遙控高壓模組以智慧型手機作為訊號產生端，透過應用程式設定輸出訊號之正弦波頻率與振幅，並以藍芽傳輸至高壓模組內之藍芽接收晶片。接收訊號經由 LM386 功率放大器進行波形修飾與放大後，作為控制BJT開關之驅動訊號。系統以行動電源提供直流電源，藉由BJT開關製造電流變化，透過變壓器將電壓升至數千伏用於點起電漿。 本研究結合介電阻擋放電（Dielectric Barrier Discharge, DBD）與藍芽遙控高壓模組，在氬氣環境中產生電漿以進行有機物偵測。所採用之 DBD 結構為銅電極–介電層–銅電極，介電層材質為玻璃纖維（Glass Fiber），其基材為含碳之環氧樹脂（Epoxy Resin）。透過碳粉熱轉印之濕式蝕刻法於銅電極表面進行電極設計。 實驗中發現，在純氬氣環境下放電時，介電層會產生CH與C₂等特徵有機發射峰，顯示介電層存在燒蝕現象，且其強度隨放電時間增加而增強。為降低燒蝕程度，本研究透過調整電極幾何形狀進行優化，並以電性參數與光譜特徵作為評估依據。最終確認當高壓電極為三角形（0.3 × 0.2 cm，74⁰）、浮動電極為正三角形（0.26 × 0.23 cm，59⁰）、背電極寬度為 0.5 cm 時，燒蝕現象最為輕微。此外，此電極設計在固定乙醇濃度下進行多次重複放電時，不僅同一片 DBD間放電強度離散度最低，不同批次間之重複性亦表現最佳。

Plasma is regarded as the fourth state of matter. When high energy is applied to gas molecules, causing electronic excitation, the transition of electrons from higher to lower energy levels is often accompanied by the emission of photons. Due to the distinct chemical structures and bonding characteristics of different gas molecules, the resulting emission spectra exhibit unique features. As such, plasma emission spectroscopy serves as a powerful tool for the identification and analysis of organic compounds. Microplasma refers to a form of plasma with a discharge region on the sub-millimeter to millimeter scale. It offers advantages such as low cost, low power consumption, high reactivity, and portability. The objective of this study is to develop a portable atmospheric-pressure microplasma system for the detection of volatile organic compounds (VOCs). To achieve this goal, a high-voltage power module featuring Bluetooth-based remote control and adjustable operating frequency was designed and implemented. The Bluetooth-Modulated Power Source (BMPS) developed in this study utilizes a smartphone as the signal source. Through a dedicated mobile application, the user can configure the frequency and amplitude of the output sine wave, which is then transmitted via Bluetooth to a receiver chip embedded within the BMPS. The received signal is processed and amplified using an LM386 power amplifier, serving as the driving signal for the BJT switch. The system is powered by a portable power bank supplying direct current. By modulating the current through the BJT switch, the system generates a voltage fluctuation, which is subsequently stepped up to several kilovolts via a transformer to initiate plasma discharge. In this study, a dielectric barrier discharge (DBD) system was integrated with the BMPS to generate plasma in an argon environment for the detection of organic compounds. The DBD configuration employed consisted of a copper electrode–dielectric layer–copper electrode structure, with the dielectric material composed of glass fiber reinforced with a carbon-containing epoxy resin. Electrode patterns were fabricated on the copper surface using a wet etching process based on the heat toner transfer method. Experimental results revealed that during discharge in pure argon, characteristic organic emission peaks such as CH and C₂ appeared, indicating ablation of the dielectric layer. The intensity of these peaks increased with prolonged discharge time. To mitigate the ablation effect, electrode geometry was optimized based on electrical characteristics and spectral signatures. It was ultimately determined that when the high-voltage electrode was triangular (0.3 × 0.2 cm), the floating electrode was an equilateral triangle (0.26 × 0.23 cm), and the width of the backing electrode was 0.5 cm, the extent of ablation was minimized. Moreover, this electrode configuration demonstrated superior stability: during repeated discharges at a fixed ethanol concentration, it exhibited the lowest intensity variation among discharges on the same DBD unit, as well as the highest reproducibility across different batches.