Local disinfection of microorganism through torch‐type atmospheric pressure plasma

Abstract

Torch-type atmospheric pressure plasma with two ring-type copper electrodes has been analyzed to investigate the characteristics of plasma plume and local sterilizing effect on microorganisms. The concentration of ozone as an active oxygen species in plasma plume was varied with the level of applied voltage and the proportion of gasses in a mixture composed of helium and oxygen. The temperature of the plasma flume could be increased to 38 C as a maximum temperature under an exposure time of 10 min, which suggests that the plasma plume can be directed manually by a user to come in contact with delicate objects and materials without causing any heating or painful feeling. An advantage of the plasma is that it is controllable at low temperatures with high stability. Sterilization for E. coli was strongly affected by the applied voltage, the oxygen ratio in the gas mixture of He/O 2 , and the treatment time. Reactive oxygen species, including atomic oxygen and ozone, which are generated by the plasma plume, play an important role in the bacteria inactivation processes. Our plasma can be used successfully to sterilize E. coli for biomedical applications.