Inactivation of a 25.5 μm Enterococcus faecalis biofilm by a room-temperature, battery-operated, handheld air plasma jet

Effective biofilm inactivation using a handheld, mobile plasma jet powered by a 12V dc battery and operated in open air without any external gas supply is reported. This cold, room-temperature plasma is produced in self-repetitive nanosecond discharges with current pulses of similar to 100 ns duration, current peak amplitude of similar to 6mA and repetition rate of similar to 20 kHz. It is shown that the reactive plasma species penetrate to the bottom layer of a 25.5 mu m-thick Enterococcus faecalis biofilm and produce a strong bactericidal effect. This is the thickest reported biofilm inactivated using room-temperature air plasmas.