Division of Environmental Physics -
Students Faculty of Mathematics, Physics and Informatics, Comenius University Bratislava
Martin SELVEK alumni student
MSc. study 2018 - 2020
Supervisor: Karol Hensel Consultant: Katarína Kučerová Title: The effect of barrier discharge on surface sterilization of materials Abstract: New and innovative plasma reactor utilizing surface dielectric barrier discharge (SDBD) was constructed and tested in this study. Its design was based on reactors used in our laboratory in the past, considering their various advantages and disadvantages. The advantages include its ability to move plasma panel in controlled manner and given distance under treated sample in air-tight design. As a way of testing, the effect of different gases (laboratory air, oxygen, nitrogen) and different distances (0.6 and 1.2 mm) between plasma panel and a sample teflon plate with dried Escherichia coli on the disinfection efficiency was studied. Starting at approximately 109 CFU/ml, log reduction of 1.85 was observed probably caused by drying the sample, and further log reduction of 3.14 was observed after 300 s treatment in air and at a distance of 0.6 mm. Significant difference between air and oxygen generated plasma was observed after 60 s, showing oxygen as the more efficient medium for dry plasma disinfection. Plasma generated in nitrogen did not seem to be effective even after 120 s. No significant difference in log reduction was observed when distance between the plasma element and the sample was changed from 0.6 mm to 1.2 mm. It could indicate that beside direct treatment of bacteria with the plasma, reactive species generated by the plasma may be responsible for disinfection as being able to diffuse toward the sample without significant decay. Constructed reactor appears suitable for and will be used in future experiments.