To determine an efficient sterilization mechanism, Bacillus subtilis spore samples were exposed to an atmospheric plasma jet. By using argon/ oxygen mixture gas, the decimal reduction value was reduced from 60 s (using argon gas) to 10 s. More dramatically, after 5 min treatment, the colony-forming unit (CFU) was reduced by six orders. To understand the underlying mechanism of the efficient sterilization by plasma, the contributions from heat, UV radiation, charged particles, ozone, and reactive oxygen radicals were distinguished in this work, showing that charged particles and ozone were the main killing factors. The shape changes of the spores were also discussed.

Atmospheric pressure plasma jet utilizing Ar and Ar/H 2 O mixtures and its applications to bacteria inactivation * Cheng Cheng(程 诚) a)b) † , Shen Jie(沈 洁) a) , Xiao De-Zhi(肖德志) a) , Xie Hong-Bing(谢洪兵) a) , Lan Yan(兰 彦) a) , Fang Shi-Dong(方世东) a) , Meng Yue-Dong(孟月东) a) , and Chu Paul K(朱剑豪) b) ‡

No abstract