Assessing effectivity and toxicity of misty plasma systems for disinfecting personal protective equipment*

Approximately 1.7 million health care associated infections occur each year in the U.S., killing 98,000 patients. COVID-19 has revealed further weaknesses in the preparedness of health care facilities, which lacked the ability to adequately disinfect existing personal protective equipment (PPE), exacerbating an already precarious situation. Chemical germicides, UV light etc. approaches have proven insufficient. Recently, application of dielectric barrier discharge (DBD) on biological substrates has been a topic of intense research.

We present a novel, portable, planar DBD device with an electrically insulated annular flow channel built through the planar powered electrode. The discharge medium is air saturated with water vapor that flows through the annulus and forms a stagnation discharge plane between the powered dielectric and the substrate. Application on E. coli and Bacillus atrophaeus spores on agar and filter papers showed that usage of a flowing humid discharge medium has a ~40% higher efficacy than either a static or a dry flowing medium. Preliminary analyses indicated that the substrate turned acidic potentially due to the formation and dissociation of hydrogen peroxide. Future studies will include spectroscopic measurements and tests on bacteriophages. This approach promises to be efficient at disinfecting PPEs, which include soft surfaces, against SARS-CoV-2 or other coronaviruses which are not as resilient as the spores against which current tests are being performed.