Enhanced efficacy of a novel atmospheric non-thermal microplasma brush for surface sterilization

摘要

Summary form only given. The application of non-thermal plasmas for surface sterilization is of particular interest due to the increase of secondary infections in hospitals by drug resistant strains of bacteria. Traditional sterilization methods are often too harsh for sensitive equipment and surfaces, and non-equilibrium plasma has been investigated as an alternative. This work details the development and improved efficacy of an atmospheric non-thermal plasma brush for the surface inactivation of bacteria. The plasma brush, driven by 145 ns 9.5 kV pulses at a repetition rate of 2 kHz, consists of 11 microplasma plumes that are 12 mm long, 1.5 mm wide and 0.11 mm thick each. Bacterial inactivation studies were performed on two common nosocomial pathogens, Acinetobacter baumannii and Staphylococcus aureus, inoculated to laminate plates. At a flow rate of 1 slpm of helium and a 5 mm nozzle to surface distance, only 0.2 log (37%) reduction was achieved on a dry laminate surface for a treatment time of 5 minutes. Application of a thin layer of water to the treatment surface increased the reduction by 100-fold (2.2 log reduction, 99.4%) compared to the treatment for a dry surface. Addition of water vapor to the helium flow was also able to improve the inactivation efficacy. Bacterial inactivation was maximized at 1.1 log (92%) for He/(1.4%)H2O with the plasma jet applied to dry laminate surfaces. Optical emission spectroscopy was performed for the plasma brush at various conditions to determine the changes in the production of electronically excited species in the presence of water at the treatment surface and in the feed gas.