Flexible Low-Temperature RF Plasma Source for Biomedical Applications

A flexible low-temperature plasma (LTP) source device was developed utilizing a radiofrequency (RF) generator coupled to a coaxial cable through a homemade L-shape matching network and a supple plastic hose that conveys a gas flow and shields the coaxial cable up to the reactors nozzle. The impedance matching network provides an electric power transfer of minimum of 94.11% operating under normal conditions. The LTP device arrangement is described, and later characterized via optical emission spectroscopy and electric power consumption. This procedure is essential to determine the adequate application of the generated plasma over heat-sensitive materials, primarily organic matter, to provide adequate information about its physicochemical activity. The produced LTP interacts with surrounding air particles, generating reactive oxygen and nitrogen species (RONS) that exhibit bactericidal and antiseptic properties due to their strong biochemical reactivity. The electromagnetic irradiation, ultraviolet (UV) emission, and thermal surface effect produced under normal working conditions of the LTP source device are safe to apply to heat-sensitive matter. The devices inactivation property was validated through qualitative deactivation trials of Escherichia coli and Enterococcus faecalis and quantitative deactivation trials of Escherichia coli. The device inactivated 99.996% of E. coli at a concentration of 3.6106 colony forming units per mL (CFU/mL) in 180 s at 16 W, this result corresponds to a 4.43-log10 reduction in E. coli viability.