Surface micro-discharge (SMD)
b'There is an urgent need for an efficient technology of disinfection and sterilization\\nin view of the alarming dimensions health care-associated infections (HAIs) have\\nreached. Cold atmospheric pressure plasma (CAP) can be utilized for hygienic and\\nmedical purposes, in particular in surface decontamination applications, and provides\\na promising alternative to the conventionally used sterilization techniques. Surface\\nMicro-Discharge (SMD) offers a technology for generating CAP that can be applied to\\nwide areas.\\nIn the present work, I investigate the plasma chemistry involved in the inactivation\\nof microorganisms by application of the SMD in order to optimize the antimicrobial\\neffect. For this purpose, different strains of vegetative bacteria and bacterial\\nendospores are exposed to the SMD with experimental parameters such as the gas\\ncomposition, power input, treatment duration and humidity varied. At the same time,\\nthe concentration of ozone produced by the SMD is monitored, and its correlation with\\nthe antimicrobial efficacy is investigated.\\nI demonstrate that the bactericidal effect of the SMD on both the Gram-negative\\nEscherichia coli and Gram-positive Enterococcus mundtii is similar and strongly correlates\\nwith the ozone concentration. The sporicidal effect on Geobacillus stearothermophilus\\nis crucially affected by the humidity, whereas the ozone concentration appears to have\\nno influence. In addition, I investigate the dynamic behavior of ozone produced by\\nthe SMD by varying the geometry and the time interval for the plasma generation and\\nby igniting the plasma in two subsequent phases with different frequencies. Possible\\nexplanations for the obtained results are provided.\\nThis work fortifies the role of SMD as an efficient sterilization method and discloses\\ndiverse possibilities for optimizing the antimicrobial effect.'