Application of Micro Discharge for Air Purification

Shimizu, Kazuo; Sugiyama, T.; Nishamani, L S Manisha; Kanamori, Masaki

doi:10.1541/ieejpes.127.1269

Cited by 6 publications

(4 citation statements)

References 18 publications

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“…Microplasma is a small but useful plasma. [11][12][13][14][15][16][17][18][19] The name originates from the size of the space where plasma is generated. Only a very simple equipment is necessary to produce microplasma.…”

Section: Introductionmentioning

confidence: 99%

Low-pressure N₂ microplasma treatment for substrate surface cleaning prior to GaN selective growth

Kusakabe

Sugiyama

Takenaka

et al. 2018

Jpn. J. Appl. Phys.

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Low-pressure microplasma treatment was performed to clean a substrate surface prior to the selective growth of GaN by chemical beam epitaxy. To investigate the cleaning mechanism, the process pressure and process time were systematically varied. The plasma distribution was also studied using a special sheet, whose color changes following the irradiation of plasma species. Consequently, it was found that the range of microplasma irradiation increased with decreasing process pressure, and simultaneously, the morphology of selective growth was improved. Secondary ion mass spectrometry measurements show that the oxygen concentration at the growth interface was reduced from 9.7 × 1014 to 2.6 × 1013 atoms/cm2 by the microplasma treatment. Otherwise, the surface oxides resulted in the growth of a rough surface with the suppression of the layer-by-layer growth.

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Section: Introductionmentioning

confidence: 99%

Low-pressure N₂ microplasma treatment for substrate surface cleaning prior to GaN selective growth

Kusakabe

Sugiyama

Takenaka

et al. 2018

Jpn. J. Appl. Phys.

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“…In order to investigate the impact of different radical species formed in the microplasmas, the experiments were performed using two different carrier gases: air and nitrogen. of the stainless-steel electrodes [17], [18]. The diameters of the electrodes are ∅58 mm, and the thickness of each electrode is 0.6 mm.…”

Section: Introductionmentioning

confidence: 99%

Basic Study of Bacteria Inactivation at Low Discharge Voltage by Using Microplasmas

Shimizu

Yamada

Kanamori

et al. 2010

IEEE Trans. on Ind. Applicat.

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Inactivation of microorganisms, such as Escherichia coli, by exposure to a microplasma is experimentally investigated. A microplasma is an atmospheric-pressure nonthermal plasma. Microplasmas, which generate high-intensity electric fields, can be formed using relatively low discharge voltages (0.7-1.1 kV) across small discharge gaps (0-100 μm). The key benefits of the practical application of exposure to a microplasma are as follows: 1) the low discharge voltage and 2) the simple apparatus because a vacuum enclosure is not required. Hence, the apparatus for generating a microplasma could be relatively small and inexpensive and could be integrated into a portable device. The ozone generated by a microplasma at a low power level was measured, although the specific power density of the microplasma was larger than that of large-scale conventional plasmas. The emission spectra of the microplasma discharge in N 2 was measured: 1) to confirm the UV light emission and 2) to identify the active chemical species generated by the microplasma discharge. The emission spectra was also measured with the presence of water droplets. The UV light from the microplasma discharge showed excited nitrogen molecules and OH radicals. In this paper, two cultures of bacteria, i.e., gram-negative Escherichia coli HB101 and gram-positive Bacillus subtilis JCB 20036 were the target microorganisms to be inactivated. In the experiments reported here, the number of bacteria decreased after microplasma treatment. The inactivation rate increases as the discharge voltage increases. Escherichia coli is completely inactivated when air is used as carrier gas at a plasma discharge voltage of 1.05 kV. Using nitrogen as carrier gas, the highest inactivation rate is 77% at a discharge voltage of 1.15 kV. In addition, Bacillus subtilis is inactivated with a rate of 97% at 1.07 kV with air as carrier gas. Using nitrogen as carrier gas and a discharge voltage of 1 kV results in an inactivation rate of 70% of bacteria. The inactivation of microorganisms by microplasma may be due to several factors either individually or in combination of the following: 1) the excited molecules and ions; 2) ozone; 3) high electrical fields; and 4) UV light. The effect of active species such as OH radicals may also be important since all the bacteria were carried within a small water droplet in between the electrodes.

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“…1 shows a schematic image of the electrodes used in the experiments. It is a stainless steel covered with dielectric barrier materials both faces [12], [13]. The suspension of bacteria in gas is flowed through the holes and could be attacked with active species between the electrodes, which are supplied with an alternating voltage.…”

Section: Introductionmentioning

confidence: 99%

Basic Study of Sterilization at Low Discharge Voltage by Using Microplasma

Shimizu

Yamada

Kanamori

et al. 2008

2008 IEEE Industry Applications Society Annual Meeting

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Sterilization of micro-organism, such as Escherichia coli, is experimentally investigated by using microplasma. Microplasma is suitable for practical application of sterilization, since its discharge voltage is low and its apparatus could be small and inexpensive.In this study, Gram-negative Escherichia coli HB101 and Gram-positive Bacillus subtilis JCB 20036 are used as the target to be sterilized. From the series of experiments, decrease in the amount of germs is effectively obtained after microplasma treatment. The effect of sterilization increases as the discharge voltage increases. When air is used as carrier gas, sterilization rate is 100% at the discharge voltage of 1.05 kV and when nitrogen is the carrier gas, sterilization rate is 77% at the maximum discharge voltage of 1.15 kV for the Escherichia coli. These results could be the combined actions of active radical species such as ozone, UV radiation and, high electrical fields of microplasma.Bacillus subtilis was sterilized with a rate of 97% at a discharge voltage of 1.07 kV in the case of air carrier gas and in the case of gas carrier nitrogen with a rate of 70% at a discharge voltage of 1 kV.

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Application of Micro Discharge for Air Purification

Cited by 6 publications

References 18 publications

Low-pressure N₂ microplasma treatment for substrate surface cleaning prior to GaN selective growth

Low-pressure N₂ microplasma treatment for substrate surface cleaning prior to GaN selective growth

Basic Study of Bacteria Inactivation at Low Discharge Voltage by Using Microplasmas

Basic Study of Sterilization at Low Discharge Voltage by Using Microplasma

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Application of Micro Discharge for Air Purification

Cited by 6 publications

References 18 publications

Low-pressure N2 microplasma treatment for substrate surface cleaning prior to GaN selective growth

Low-pressure N2 microplasma treatment for substrate surface cleaning prior to GaN selective growth

Basic Study of Bacteria Inactivation at Low Discharge Voltage by Using Microplasmas

Basic Study of Sterilization at Low Discharge Voltage by Using Microplasma

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Low-pressure N₂ microplasma treatment for substrate surface cleaning prior to GaN selective growth

Low-pressure N₂ microplasma treatment for substrate surface cleaning prior to GaN selective growth