Biocidal Eﬀects of Non-thermal Atmospheric Pressure Plasma
Ph.D. Programme: Electrical Engineering and Information Technology
Branch of study: Plasma Physics,
Faculty of Electrical Engineering Department of Physics
Czech Technical University in Prague
The subject of this PhD thesis covers bio-chemical pathways in plasma activated liquids (PAW), that are under intensive investigation during last decades. Three possible ways of bacteria inactivation with PAW were studied.
The DC plasma jet generated plasma in gas phase (N2 / O2 ) during under-water operation was used to provide post-discharge bacteria treatment. The synergistic eﬀect of transition metal ions and reactive oxygen and reactive nitrogen species was considered to play the dominant role in bacteria inactivation. Moreover, toxicity of the copper ions even in sublethal doses should be taken into account, due to possible DNA damages induced in the cell.
Electro-spraying of natural de-contaminant (essential oil) through the transient spark discharge was used to examine bactericidal properties of essential oils activated with plasma. Essential oils in general as well as oregano essential oil in particular are known for their antiseptic properties, i.e. bactericidal, fungicidal, analgetic, sedative, etc., and are usually used in vaporized phase. However, vaporization is highly time consuming process and takes up to 72 hours, depending on experimental conditions.
The transient spark discharge was used to decrease the time needed to provide bacteria and fungi inactivation (in this experiment from 12 hours to 4 minutes) and at the same time to induce processes, which can lead to gain more eﬃcient bactericidal eﬀect of OEO.