One of the many problems we have with the spread of COVID-19 is the ability of the coronavirus to survive on the surface for hours at a time. When we can effectively clean hard materials or sterilize them with alcohol, what about more delicate surfaces like cardboard?
Even in the atmosphere, SARS-Cavi-2 can last for a few hours; On cardboard it can last up to 24 hours, and soluble particles have been found on plastic for up to three days after contamination.
Scientists in many disciplines are throwing their vast skills to fight the epidemic. Now, a team led by Zeitong Chen, an engineer at the University of California, Los Angeles, may have found a solution. He just demonstrated that cold plasma has the ability to destroy viruses on a wide surface without damaging the material.
“Everything we use comes from the air,” explains aerospace engineer Richard Weirz. “Air and electricity: This is a very healthy treatment with no side effects.”
Plasma, the least known of the four major states of matter (the other three solids, liquids and gases) comes naturally into our upper atmosphere. It forms when electrons separate from their atoms (charge the atoms positively), and together form a soup of charged particles that are unstable and therefore more reactive than their similar gas state.
Cold plasma has been shown to work against drug resistant bacteria. It interferes with their surface texture and DNA without damaging human surfaces. It also works against cancer cells.
Chen, Virz, and colleagues designed and printed 3D an atmospheric plasma jet device powered by argon gas – one of the most abundant gases in our air. The device sends fast electrons through the gas, stripping the outer electrons of the gas atoms that collide with them; It only needs 12 W constant power to work.
The team directed the flow at room temperature near the reactive particles on the contaminated surfaces, exposing them to electric current, charged atoms and molecules (ions) and UV radiation.
They tested the effect of plasma on six surfaces, including cardboard, football effect leather, plastic and metal, and found that on each of these, most of the virus particles became inactive after only 30 seconds. Three minutes of contact with the plasma destroyed all the viruses.
The team believes it is a reactive oxygen and nitrogen ion, in contact with plasma air, which is destroying viral particles; When they tested helium-derived plasma, which produces less of the molecule of this species, it was not effective even after five minutes of application.
They explain that charged particles accumulate on the surface of virion, damaging its envelope by electrostatic forces leading to its differentiation. Ions can also break structurally important bonds, such as between two carbon atoms, carbon and oxygen, and between carbon and nitrogen atoms.
Experiments on the effects of plasma on bacteria and viruses may contain important proteins to bind the host cells to damage in the outer envelope of the virus.
“These results also suggest that cold plasma should be examined for inactivation of SARS-Co-2 born of cold rosol.” Virz and colleagues wrote in their paper.
Last year another team created a plasma filter that can sterilize air with 99 percent of viruses. In their device, as the borosilicate glass structure passes through air barriers in the bed, it oxidizes the volatile molecules forming plasma. This damages the viral particles, reducing our ability to infect.
Of course, there is still another way to go from concept proof to device that we can all use but Virz and team are now working to create such a device.
Virze said, ‘This is just the beginning. “We are very confident and have high expectations for Plasma in future work.”
This research was published The physics of fluids.