Influence of Pressure Wave Generated During Plasma Formation on the Reactive Species Distribution

Atmospheric pressure low-temperature plasmas have been studied for recent years in different applied fields. Plasma–liquid interaction is one of the important considerations that has been actively studied in industrial, agricultural, and medical applications. The pressure wave launches into the open atmosphere with the aid of helium gas flow in an atmospheric pressure plasma jet (APPJ) and the influences of the irradiation distances and, electrode geometry that cause the compressibility of the helium/air mixture, to the intensity of the pressure wave to the target medium was studied. These were experimentally investigated by the optical-wave microphone using the helium plasma jet with sinusoidal pulsed voltage. The gel reagent with iodine–starch reactions was used as the target to visualize and investigate the reactive oxygen species (ROS) distribution with the influences of pressure waves. Moreover, altering the burst cycles of the applied voltage can influence the generation of pressure waves during plasma formation, thereby impacting plasma-induced liquid flow. The amplitude of the pressure wave signal propagated from the plasma jet affects the ROS distribution patterns. Controlling and changing the burst interval periods helps in understanding the relationship between pressure wave and ROS species distribution and provides useful information for the biological application of plasma technology in medical applications.