Plasma Scouring Device Quickly Disinfects Surfaces

A prototype plasma-based disinfectant and sanitizer pad can eliminate 99.99% of the bacteria on surfaces, including textiles and metals, in just 90 seconds.

Developed at Princeton Plasma Physics Laboratory (PPPL; NJ, USA) and the New Jersey Institute of Technology (NJIT; Newark, USA), the device is based on a dielectric barrier discharge (DBD) flexible printed circuit that operates in ambient air, atmospheric pressure, and room temperature, without additional gas flow. The DBD activates a 3% hydrogen peroxide (H₂O₂) solution that reduces the bacterial load of surface contaminant by more than 6log10 in 90s, about 3log10 and 2log10 better than H₂O₂ alone or the flex-DBD alone (respectively), for the same treatment time.

According to an experimental study, the synergy between plasma and H₂O₂ is based on the combined action of plasma-generated reactive oxygen species (ROS) in the solution, reactive nitrogen species (RNS) supplied by the plasma effluent, and electron swirls, electrical currents, electromagnetic fields, and ultraviolet (UV) rays. The synergistic addition of the RNS increases the disinfection efficiency of the ROS and other reactive oxygen species (ROS). The study was published on February 25, 2021, in Nature Scientific Reports.

“The flexible hand-held DBD is built like a sandwich. It's a high-voltage slice of ‘bread’ on cheese that is an insulator and a grounded piece of bread with holes in it,” said lead author Sophia Gershman, PhD, of PPPL. “The high-voltage slice of bread is an electrode made of copper tape; the other slice is a grounded electrode patterned with holes to let the plasma flow through. Between these slices lies the ‘cheese’ of insulating tape. The ground electrode faces the users and makes the device safe to use.”

The mechanisms of bacterial inactivation of plasma remain unclear, but it is thought its chemical and electrical properties may affect a bacterial cell in stages. The electrons and the electric field affect the cell membrane and aid in penetration of the RNS and some long-lived ROS. ROS are also involved in lipid peroxidation and other oxidative reactions damaging the cell membrane and aid transport of RNS/ROS into the cell. Inside the cell, the ROS/RNS damage proteins, lipids, and the DNA. The combined effect of these processes is bacterial cell inactivation.

Related Links:
Princeton Plasma Physics Laboratory
New Jersey Institute of Technology