Ph.D. Research Proposal - Analysis of the Degree and the Mechanism of Airborne Bacterial Inactivation using Dielectric Barrier Discharge
Date: August 20, 2010
Time: 3:00 PM
Location: Bossone Research Enterprise Center, Room: 709
Advisors: Alexander Fridman, Ph.D. and Kambiz Pourrezaei, Ph.D.
Non-thermal Plasma technology has emerged as a very attractive technology for sterilization treatment. Plasma is the fourth state of matter. It is defined as ionized gas produced by electrical discharge. There are various configurations of producing plasma. These different types of plasmas have a variety of applications. Non-thermal plasma is the type of plasma where the ionized gas is at room temperature, while the high energy electrons produced by the discharge produce reactive species from impact of the high energy electrons with neutral gas molecules.
This study investigates the effectiveness and mechanisms of sterilization using the Dielectric Barrier Discharge (DBD) plasma. An experimental setup was constructed for studying the effect of DBD on a bacterial aerosol (bioaerosol). The bacterium used in these experiments was the Escherichia coli bacterium. The effectiveness of the DBD setup was demonstrated by batch treatment of the bioaerosol. After a single exposure to DBD discharge, ~5log reduction was observed in the concentration of viable airborne bacteria. The different DBD treatment systems have been developed for inactivation studies. These results have led to the investigation into the mechanism of inactivation of airborne bacteria by DBD with application to bioaerosol decontamination.
DBD produces Ultraviolet Radiation, Ozone and other Reactive Oxygen Species (ROS) such O2-, OH-, O2(1Δg) etc. The experiments with pure Ozone have demonstrated that it Ozone produced by the plasma alone cannot be the cause of inactivation. The UV measurement also indicates that UV produced by plasma has too low intensity to produce such rapid inactivation. The focus has then shifted to ROS. Experimental evidence suggests a working hypothesis that bacteria are inactivated through the action of ROS, with charges produced by DBD playing a role. The study employs methods such as survival of gene suppression mutants, flow cytometry, and fluorescence studies to determine the effect of DBD plasma on the bacteria.
The Bossone Research Enterprise Center is located at the corner of 32nd and Market Streets.