A compact pulse-modulation cold air plasma jet for the inactivation of chronic wound bacteria: development and characterization

A compact low-temperature plasma jet device was developed to use ambient air as plasma gas. The device was driven by a 2.52-kV high-voltage direct-current pulse in a burst mode, with a repetition rate of 2 kHz. The maximum plasma discharge current was 3.5 A, with an approximately 10 ns full-width half-maximum. Nitric oxide, hydroxyl radical, atomic oxygen, ozone, and hydrogen peroxide—important reactive oxygen and nitrogen species (RONS)—were mainly produced. The amount of plasma-generated RONS can be controlled by varying the pulse-modulation factors. After optimization, the plasma plume length was approximately 5 mm and the treatment temperature was less than 40 °C. The preliminary bactericidal effects were tested on Staphylococcus aureus, Pseudomonas aeruginosa, and methicillin-resistant S. aureus (MRSA), and their biofilms. The results showed that the plasma can effectively inactivate S. aureus, P. aeruginosa, and MRSA in both time- and pulse-dependent manner. Thus, this produced plasma device proved to be an efficient tool for inactivating deteriorating bacteria. Further versatile utilization of this portable plasma generator is also promising.