Posted on 11/11/2020 6:04:31 AM PST by Red Badger
(Chen et al, Physics of Fluids, 2020)
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Amongst the many problems we've had with the spread of COVID-19 is the coronavirus's ability to survive on surfaces for hours on end. While we can effectively wipe down hard materials or sterilize them with alcohol, what about more delicate surfaces like cardboard?
Even in the atmosphere, SARS-CoV-2 can survive up to a few hours; on cardboard it can last for up to 24 hours, and viable particles have been detected on plastic up to three days after it was contaminated.
Scientists across many disciplines are throwing their vast talents into tackling the pandemic. Now, a team led by engineer Zhitong Chen from the University of California in Los Angeles may have found a solution. They just demonstrated cold plasma has the ability to destroy the virus on a wide range of surfaces without damaging the material.
"Everything we use comes from the air," explains aerospace engineer Richard Wirz. "Air and electricity: It's a very healthy treatment with no side effects."
Plasma, the least well known of the four main states of matter (the other three being solid, liquid and gas), occurs naturally in our upper atmosphere. It forms when electrons become separated from their atoms (making the atoms positively charged), and together create a soup of charged particles that are unstable and so more reactive than in their equivalent gas state.
Cold plasma has already been shown to work against drug resistant bacteria. It interferes with their surface structure and DNA without harming human tissue. It even works against cancer cells.
Chen, Wirz and colleagues designed and 3D-printed an atmospheric plasma jet device fuelled by argon gas - an inert and stable element that's one of the most abundant gases in our air. The device sends speeding electrons through the gas, stripping the gas atoms of outer electrons as they collide; it requires just 12 W of continuous power to work.
The team directed a near-room-temperature stream of reactive particles onto contaminated surfaces, exposing them to an electric current, charged atoms and molecules (ions), and UV radiation.
They tested the plasma's effect on six surfaces, including cardboard, football leather, plastic and metal and found that on each of these, most of the virus particles were inactivated after only 30 seconds. Three minutes of contact with the plasma destroyed all of the virus.
The team believes it's the reactive oxygen and nitrogen ions, formed as the plasma interacts with air, that are destroying the viral particles; when they tested a helium-fed plasma, which produces less of these species of atoms, it was not effective even after five minutes of application.
They explain that as charged particles gather on the virion's surface, they can damage its envelope through electrostatic forces leading to its rupture. The ions can also break structurally important bonds such as those between two carbon atoms, carbon and oxygen, and carbon and nitrogen atoms.
Experiments on the effects of plasma on bacteria and viruses have revealed the damage to the virus's outer envelope can include proteins important for binding to host cells.
"These results also suggest that cold plasma should be investigated for the inactivation of aerosol-borne SARS-CoV-2," the Wirz and colleagues wrote in their paper.
Last year another team created a plasma filter that could sterilise the air from 99 percent of viruses. In their device, as air moves through gaps in a bed of borosilicate glass beads, it's oxidised the unstable atoms that form the plasma. This damages viral particles, leaving them with a greatly diminished ability to infect us.
Of course, there is still a way to go from proof of concept to a device we can all use. But Wirz and team are now working on building such a device.
"This is only the beginning," Wirz said. "We are very confident and have very high expectations for plasma in future work."
This research was published in Physics of Fluids:
https://aip.scitation.org/doi/10.1063/5.0031332
Cold Plasma Ping.
Cold Plasma Fusion is only 25 years away.
Plain old UV radiation will do, much more cheaply and requiring no further tech.
And sunlight is even better probably, with heat+UV.
The usual way of disinfecting masks here is to place them in the sun.
Granted you need sunlight in the first place.
* Most of the virus particles were inactivated after only 30 seconds.
* Three minutes of contact with the plasma destroyed all of the virus.
Those contact times suggest very slow air velocities in a plasma filter which in turn suggest a huge filter.
Is a plasma generator just another term for ozone generator?
I just purchased one and reading the description in the article describes it.
It’s a good way of getting rid of germs with the high oxidation of O3.
I’m still learning why they say they are dangerous.
You need UV-C, but it is easy to make and there are already lots of disinfecting boxes on the market with UV-C diodes.
What still isn’t clear is how much spread is due to surface contact.
The team believes it’s the reactive oxygen and nitrogen ions, formed as the plasma interacts with air, that are destroying the viral particle.
Is this much different than using an ozone generator. Ozone generators are inexpensive and readily available.
I’m not impressed with any solution until it’s available and affordable for everyone.
One gizmo in one secure lab does nothing for the masses.
You joke, but plasma is actually key to one of the more promising “hot fusion” methods.
It might be about the same process, but it seems like you could use this to “target” those ions at a particular area to disinfect it, while an ozone generator is just spewing them on random trajectories into the room.
Good grief.... let’s just keep it simple... air purifiers (ozone generators) will destroy them little buggers as well as other pathogens floating around.
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