Atmospheric pressure microwave microplasma microorganism deactivation

This paper is focused on the experimental investigations of microorganism decontamination by using low temperature Ar and Ar/O2 microwave microplasma. Microplasma in the form of a microflame was generated using a simple coaxial microwave microplasma source (MmPS). The MmPS was operated at standard microwave frequency of 2.45 GHz. The electron density, microplasma temperatures and active species identification were determined on the way of Optical Emission Spectroscopy. The results of the spectroscopic measurements confirmed the MmPS usefulness in biomedical applications. The microplasma deactivation concerned two types of bacteria (Escherichia coli, Bacillus subtilis) and one fungus (Aspergillus niger). The investigations involved influence of the O2 concentration, absorbed microwave power, microplasma treatment time and microplasma distance from the treated sample on the microorganism deactivation efficiency. All reported results were obtained for Ar and Ar/O2 microplasma with gas flow rates of single l/min and O2 admixture not exceeding 2%. The absorbed microwave power was up to 50 W. The sample treatment time was up to 10 s.