Study of plasma parameters of non-thermal plasma jet for antimicrobial treatment

This study examined the effectiveness of inhibiting bacteria that cause skin diseases using a homemade plasma system known as a microwave-induced plasma jet (MIPJ) operating under atmospheric pressure (APPJ). The system utilized argon gas and a voltage source of up to 2.4 GHz to generate a non-thermal plasma. The inhibition efficiency of thermal plasma was tested against gram-positive (Staphylococcus aureus) and gram-negative (Pseudomonas aeruginosa) bacteria. These bacteria were exposed to the plasma column at various voltages (175-200 V), with a gas flow rate of 5 L/min, a 60-second exposure time, and a 5 cm distance between the plasma and the bacteria samples. The plasma system inhibited Gram-negative bacteria (Pseudomonas) by changing voltages during exposure. At 175 volts, the rate of bacterial inhibition was measured (100%), at 180 volts, the rate was (85%), at 185 volts, the rate was (75%), at 190 volts, the rate was (80%), at 195 volts, the rate was (99%), at 200 volts, the rate was (60%), when exposed to the plasma system, gram-positive bacteria (Staphylococcus aureus) were completely inhibited at all voltage levels. The MIPJ system proved to be an effective tool for treating different types of bacteria. The study also highlighted the impact of argon gas flow rate on bacteria inactivation, emphasizing that the increased gas flow rate and high-speed particle discharge could penetrate the external structure of bacteria, playing a crucial role in bacteria inactivation by the plasma jet.