Enhancement of microwave plasma characteristics for biomedical applications using pulse modulation method

Pulse modulation technique was applied for microwave excited atmospheric pressure air and Ar plasmas with fixed average power. Breakdown and sustain powers were measured and UV-Vis emission spectra were observed. As the duty ratio decreased, pulse modulated plasmas showed enhanced results as compared to continuous signal excited plasmas. Breakdown powers of both of air and Ar plasmas were reduced as duty ratio decreased. Reactive species including hydroxyl radicals, atomic oxygen and nitric oxide were increased with the decrease of duty ratio. The change of breakdown power and increase of reactive species give advantages for biomedical applications. Gas temperature was reduced also in both of air and Ar plasmas with the decrease of duty ratio. The results related to the high energy electrons which were generated during on-time of the microwave signal. Blood coagulation experiment of the air plasma was conducted and it showed ~7 times faster coagulation than natural coagulation.