A miniaturized and low-cost atmospheric pressure helium plasma jet device with high antimicrobial efficiency

This paper reports an atmospheric pressure non-thermal plasma jet device (mini plasma jet) for antibacterial application. The device includes a glass tube, two copper ring electrodes, a custom-made power supply, a helium supply source, and flow control system. The power supply in our device is smaller and lighter compared to other commercially available power supplies. The plasma jet tube is made using a standard glass tube with a narrow outlet. We also simulated the electric field distribution inside and outside the glass tube using COMSOL Multiphysics and optimized the ring electrode distance based on the simulation results. The final system including the power supply and glass tube costs less than U.S. $45. Additionally, our mini plasma jet demonstrates excellent antibacterial performance and outperforms two commercial portable plasma jet devices (kINPen^® MED Plasma Jet and J-Plasma^®) and a lab-based plasma jet system with respect to in vitro antimicrobial efficacy. Our mini plasma jet eradicated five different strains of bacteria in planktonic culture (Staphylococcus aureus ATCC 25923, ATCC 33592, ATCC BAA-1717, and EMRSA-16, as well as Pseudomonas aeruginosa PAO1) within 40 s, which is significantly shorter than the eradication times required by commercial and the lab-based plasma jets under the same conditions. In contrast, two commercial plasma jets could not disinfect effectively within 300 s and the lab-based system within 180 s. The test results show that our mini plasma jet can generate more reactive oxygen species (ROS, specifically H₂O₂) and reactive nitrogen species (RNS, specifically NO₃ ^-) than the other three systems.