Sterilization of contaminated matter with an atmospheric pressure plasma

The primary methods now used to sterilize contaminated media (infectious waste, tools, liquids, ...) are exposure to UV radiation, incineration, or autoclaving. These methods have recently raised public controversies concerning their environmental effects and other health issues. In an attempt to eliminate these drawbacks, new approaches based on different technologies are being investigated. Irradiation by electron beam is an example of such new sterilization means. This paper describes a new sterilization technique which has recently been developed at the Plasma Science Laboratory of the University of Tennessee. This technique involves the generation and use of a glow discharge plasma at atmospheric pressure. The fact that no pressurized or vacuum system is needed in this apparatus makes this sterilization method practical, economical, and technically very attractive. The plasma, in which the medium to be sterilized is immersed, is generated between two insulated metal plate electrodes powered by a low-frequency RF supply. Inside the plasma, the medium is constantly bombarded by charged particles, active free radicals, and radiation (including UV radiation). It is found that an exposure of a few minutes is sufficient to destroy the microorganisms living in the exposed medium, without damaging the medium itself.