| Summary: | 碩士 === 國立臺灣大學 === 化學工程學研究所 === 105 === Many researches of atmospheric-pressure microplasma system has been reported in the recent year, because it can be operated without vacuum system, and it has a lot of advantages, such as high electronic density, high energy density and high reactive in the local area and so on. Atmosphere microplasma system has been also paid attention by the researchers of biomedical engineering, because using the system to treat sample in air can be sterilized by compounds which is produced from reaction of plasma and air.
The research used a low-cost and atmospheric-pressure microplasma generation system (MGD) which was driven by AC as an experimental device, and the device can produce microdischarges below 1 mm at any dimension. The device was a dielectric-type MGD which was composed by two electrodes and dielectric, and it had a sandwich structure of “electrode-dielectric-electrode”. The electrode pattern of device was fabricated by Toner Transfer Method, and the device had many advantages, such as customized, short fabricated time and easy operation, so it was suitable for research of laboratory investigation.
The investigation used above device to conduct experiment of water acidification. By applying a high voltage to MGD to generate plasma, and the system formed key products which was reacted by plasma and air, such as NO2. The products was transported to 10 μL of DI water droplet which was sit adjacent to the plasma generation electrode of the MGD with a distance of 3-5 mm by a stream formed by MGD, and the pH value decreased from 5.5 to 3 in 60 seconds by the dissolving of NO2. The forming mechanism of the stream was that ions which was generated by MGD collided with molecular in air by affect of electronic field, then the collision caused the gas stream flew to direction of electronic field. In the research, flow velocity and flow pattern measured by a Particle Image Velocimetry (PIV) system which is made by our team. Experimental factors were including power-applied frequency, power-applied voltage and geometric parameters of electrodes. Results showed that higher flow velocity could be obtained under circumstances of higher frequency or higher voltage, and higher flow velocity caused higher acidification rate. Also, changing geometric parameters of electrodes could change flow pattern, and it effected acidification rate.
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