Browsing by Author "Wu, Ching-Jung"

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Atomic Oxygen and Hydroxyl Radical Generation in Round Helium-Based Atmospheric-Pressure Plasma Jets by Various Electrode Arrangements and Its Application in Sterilizing Streptococcus mutans
(2014-12-01)
Liu, Chih-Tung
;
Wu, Ching-Jung
;
Yang, Yi-Wei
;
Lin, Zhi-Hua
;
Wu, Jong-Shinn
The reactive chemical species generated in an atmospheric-pressure plasma jet (APPJ), such as hydroxyl radical and atomic oxygen, are generally regarded as the major sources for several biomedical applications. In this paper, we propose an APPJ with a 25-kHz high-voltage powered stainless steel tube fixed inside a quartz tube and an aluminum grounded electrode that is wrapped around the quartz tube. The results show that the radical intensities of atomic oxygen and hydroxyl radical, gas temperature, and power absorption increase with increasing distance of discharge gap distance under the same applied voltage. Increasing the width of grounded electrode increases gas temperature and causes higher power absorption but only slight change of radical generation. We have applied the APPJ with the conditions of highest radical generation (grounded electrode width = discharge gap distance = 15 mm) for effectively sterilizing Streptococcus mutans within 15 s, which shows a highly potential application for root canal disinfection.
Effect of Ground and Floating Electrode on a Helium-Based Plasma Jet and Its Applications in Sterilization and Ceramic Surface Treatment
(2016-12)
Liu, Chih-Tung
;
Cheng, Kuang-Yao
;
Lin, Zhi-Hua
;
Wu, Ching-Jung
;
Wu, Jane-Yii
In this paper, we compare the helium-based atmospheric pressure plasma jets (APPJs) with power-ground (PG) and power-floating (PF) configurations by using optical analysis. We find that the PG jet traps plasma between two electrodes (discharge region); thus, the hydroxyl radical intensity is significantly strong in discharge region; however, the plasma intensity in downstream region is relatively weak as compared with that of PF configuration. In contrast, using the APPJ with PF configuration, the hydroxyl radical and nitric oxide are approximately two and three times stronger, respectively, in the downstream region, even though the gas temperature and power consumption are lower. The PF jet successfully eradicates S. mutans and decreases water contact angle by similar to 40 within 15-s treatment, which demonstrates higher efficient than that of PG jet, and shows highly potential for dental filling demand.
Effect of Ground and Floating Electrode on a Helium-Based Plasma Jet and Its Applications in Sterilization and Ceramic Surface Treatment
(2016-12-01)
Liu, Chih-Tung
;
Cheng, Kuang-Yao
;
Lin, Zhi-Hua
;
Wu, Ching-Jung
;
Wu, Jane-Yii
In this paper, we compare the helium-based atmospheric pressure plasma jets (APPJs) with power-ground (PG) and power-floating (PF) configurations by using optical analysis. We find that the PG jet traps plasma between two electrodes (discharge region); thus, the hydroxyl radical intensity is significantly strong in discharge region; however, the plasma intensity in downstream region is relatively weak as compared with that of PF configuration. In contrast, using the APPJ with PF configuration, the hydroxyl radical and nitric oxide are approximately two and three times stronger, respectively, in the downstream region, even though the gas temperature and power consumption are lower. The PF jet successfully eradicates S. mutans and decreases water contact angle by similar to 40 within 15-s treatment, which demonstrates higher efficient than that of PG jet, and shows highly potential for dental filling demand.
Production Enhancement of Reactive Oxygen and Nitrogen Species at Interface of Helium Plasma Jet and Agar
(2016-12)
Liu, Chih-Tung
;
Wu, Ching-Jung
;
Lin, Zhi-Hua
;
Wu, Jane-Yii
;
Wu, Jong-Shinn
Even though atmospheric-pressure plasma jet (APPJ) has been shown highly effective in many biomedical applications because of reactive oxygen/nitrogen species (RONS) generated in the discharge, free jet region, and at the interfacial region with the treated surface. However, most of the studies characterized APPJ only in either discharge or free jet region. In this paper, we measured optical emissions of RONS in free jet and plasma/surface interfacial regions of a helium-based dielectric barrier discharge APPJ. The results show that the emissions caused by RONS (nitric oxide, hydroxyl radical, and atomic oxygen) are enhanced 3-5 times at plasma/surface interfacial region as compared with those of free jet region. Some typical sterilization experiments using the current helium-based APPJ show that this helium-based APPJ effectively kills the oral bacteria (S. mutans) in 15 s, which was caused by the cell wall disruption. We believe that measuring the properties at plasma/surface interfacial region is more important than in the free jet region in characterizing APPJ for most realistic applications.
Production Enhancement of Reactive Oxygen and Nitrogen Species at Interface of Helium Plasma Jet and Agar
(2016-12-01)
Liu, Chih-Tung
;
Wu, Ching-Jung
;
Lin, Zhi-Hua
;
Wu, Jane-Yii
;
Wu, Jong-Shinn
Even though atmospheric-pressure plasma jet (APPJ) has been shown highly effective in many biomedical applications because of reactive oxygen/nitrogen species (RONS) generated in the discharge, free jet region, and at the interfacial region with the treated surface. However, most of the studies characterized APPJ only in either discharge or free jet region. In this paper, we measured optical emissions of RONS in free jet and plasma/surface interfacial regions of a helium-based dielectric barrier discharge APPJ. The results show that the emissions caused by RONS (nitric oxide, hydroxyl radical, and atomic oxygen) are enhanced 3-5 times at plasma/surface interfacial region as compared with those of free jet region. Some typical sterilization experiments using the current helium-based APPJ show that this helium-based APPJ effectively kills the oral bacteria (S. mutans) in 15 s, which was caused by the cell wall disruption. We believe that measuring the properties at plasma/surface interfacial region is more important than in the free jet region in characterizing APPJ for most realistic applications.