Development and characterization of touchable air plasma jet device for inactivation of oral bacteria

A compact low-temperature and atmospheric-pressure air plasma jet source is developed for the inactivation of oral bacteria. Electrical and optical measurements are carried out to understand the fundamental characteristics of the custom-built system. The adjustable operating parameters are optimized to regulate the length of the plasma plume and control the generation of the reactive species. Results show that the temperature of the plasma jet is around 40–45 °C during 5 min plasma-on, without inducing any thermal effects on bacterial cells. Importantly, the safety of the device is estimated by evaluating the current through the human body via an equivalent electrical circuit. Antibacterial studies indicate that the plasma jet can effectively inactivate E. coli, P. aeruginosa and S. aureus within 20 s. Further analysis on the morphology of bacterial cells and the intracellular DNA leakage is performed to evaluate the integrity of the cell. This study suggests that the developed portable air plasma jet can effectively deactivate oral bacteria and has great potential in future dental or clinical medical applications.