Effect of Water Vapor on the Virucidal Behavior of RF-Hollow Cathode Cold Plasma: A Study by Optical Emission Spectroscopy

Atmospheric pressure cold plasma generated using a radio frequency hollow cathode (RFHC) device recently showed its potent virucidal characteristics. For this purpose, the atmospheric pressure cold plasma of Ar was generated with a specially designed electrode using RF (13.56 MHz) power. In order to establish a correlation between the generated plasma species and its virucidal activity, systematic optical emission spectroscopy (OES) investigations were conducted on the plasma. OES studies revealed that the generated plasma using this device shows the emission of important species in the ultraviolet (UV) region and reactive oxygen species (ROS) in the optimized operation condition, required for virucidal action. Furthermore, investigations revealed that similar active species can be generated by placing a commercial nebulizer in front of plasma. Investigations conducted on the aerosol capturing efficiency of N-95 mask revealed that cold plasma treatment leaves functional aspects of this medical personal protection equipment (PPE) unchanged. The results indicate that such an RF-HC device in combination with a nebulizer for introducing water mist in plasma can effectively destroy bacteriophage of Aeromonas bacteria at low operating power (70–90 W).