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How to generate far uvc light?

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Answer # 1 #

A new generation of compact chips could safely neutralise airborne coronavirus in buildings, vehicles and even outdoor spaces using far-UVC radiation, according to Seth Coe-Sullivan of technology company NS Nanotech.

The semiconductors, which will cost less than $200 each and can run on battery power, could play "a significant role in fighting the pandemic," said Coe-Sullivan, who is CEO and co-founder of the US nanotech company.

The potential for the technology to disinfect public and private spaces without harming people is "nearly limitless," Coe-Sullivan told Dezeen in an email interview.

The chips could also help deactivate influenza and other pathogens, potentially protecting people against future pandemics.

Called ShortWaveLight Emitter, the chips are expected to be commercially available in the second half of this year, assuming they gain regulatory approval, at a price "much less" than $200.

Designers will be then able to use the chips, which measure 40 millimetres by 40 millimetres, in lighting products and sanitising devices.

The tile-like components emit visible blue light as well as the invisible far-UVC ultraviolet light so people know when they are turned on.

To showcase the technology, the company is set to launch a desktop device called the ShortWaveLight Purifier, which contains a far-UVC chip.

This could "purify the entire personal airspace around a single user in a matter of minutes," according to Coe-Sullivan.

The technology is also "ideal for use in an automobile," he added. "One or more units can be used to help provide constant sanitization of the airspace of the driver and/or passengers."

NS Nanotech, which is based in Ann Arbor, Michigan, developed the chips last year after it read a groundbreaking research paper by professor David Brenner of Columbia University.

Published in Nature last June the paper found that, unlike regular "germicidal" UVC radiation, far-UVC "efficiently kills pathogens potentially without harm to exposed human tissues".

Far-UVC has a wavelength of 222 nanometres, which is too short to penetrate human skin or eyes, unlike regular UVC, which has a wavelength of 254 nanometres.

"In conclusion, we have shown that very low doses of far-UVC light efficiently kill airborne human coronaviruses carried by aerosols," concludes the paper, which is titled Far-UVC light (222 nm) efficiently and safely inactivates airborne human coronaviruses.

Technologists at NS Nanotech, which builds nitride semiconductors for LED displays, read the paper and realised its nanotechnology could also make chips that emit far-UVC.

"We realized we could quickly develop and deliver the world's first and only semiconductor that emits far-UVC light," Coe-Sullivan said.

"We got to work virtually during the shutdown developing a product that we believed could play a significant role fighting the pandemic."

Related story "Urban Sun is not intended to create a guaranteed safe space" says Studio Roosegaarde

Coe-Sullivan is an entrepreneur who has a PhD from MIT and whose previous business, QD Vision, developed quantum-dot display technology.

QD Vision was sold to Samsung in 2016, with the electronics giant integrating the technology into its QLED (Quantum-dot Light-Emitting Diode) televisions.

Coe-Sullivan claims that NS Nanotech's far-UVC chips are cheaper, smaller and more robust than the excimer lamps that are currently the only commercially viable source of far-UVC.

The solid-state emitters are best suited to smaller spaces as they are most effective at short distances while more powerful excimer lamps are more suitable for larger areas, although NS Nanotech expects to develop more powerful chips in future.

Earlier this month, Dutch designer Studio Roosegaarde unveiled Urban Sun, a concept for outdoor lighting that uses gas-filled excimer lamps to produce far-UVC.

However, Coe-Sullivan said his new chip "runs cool, doesn't use any dangerous materials, can run on DC battery power, is very small, will be less expensive, and can be tuned to deliver a narrow band of far-UVC light."

"We are marketing it on a business-to-business basis to manufacturers who will design it into end products for lighting and disinfection applications," he added.

"The potential applications for human-safe far-UVC disinfection, in public and private spaces worldwide, would be nearly limitless."

Related story "Urban Sun is not intended to create a guaranteed safe space" says Studio Roosegaarde

Far-UVC is not a panacea, Coe-Sullivan cautioned. People should still wear masks, observe social distancing and get vaccinated. Far-UVC is most effective at close range and becomes less effective the further away the source is.

"The degree of protection it offers depends on your environment," said Coe-Sullivan. "If you are sitting next to an infected person in the middle seat of an airplane who is coughing and talking without a mask on, the viral load will be heavy, and the coronavirus germs may not all be eliminated.

"But if you are sitting at your desk at work and colleagues are several feet away, it should offer a much higher degree of protection."

Coe-Sullivan said NS Nanotech has been inundated with enquiries since it first announced its far-UVC technology in December last year.

"Far-UVC disinfection should work equally well inside or outside," he said. "Our initial products are designed for personal use, but we are already talking to customers considering development of arrays of our lights to create room-wide disinfection and protection for open outdoor spaces."

He added that getting regulatory approval "can be a maddeningly slow process".

"While regulators are not in opposition to the technology, they are going through a deliberate process to gather more research data before certifying its use in many public settings," he said, adding that new rules allowing greater use of far-UVC in public places are expected this year.

What is far-UVC and how does it help prevent Covid-19?

Carolle Jentsch
Answer # 2 #

Now researchers show that a type of shorter-wavelength UVC light, in the far-UV region, that is safe for people can kill 98 percent of microbes floating around in a room. As long as the lights were on, microbe levels remained low even as more were continually sprayed into the room. The study, published in Scientific Reports, suggest that far-UVC lamps could be an effective way to fight the spread of viral diseases like COVID and influenza. Getting there, though, will require new light sources, regulations, and increasing public awareness that far-UV light is safe.

“Widely installed far-UVC could maybe prevent the next pandemic or the next yearly influenza epidemic.”—David Brenner, Columbia University

“If the technology had been well developed five years earlier and far-UVC lights had been widely installed, potentially the COVID crisis could’ve been unlike what it has turned out to be,” says David Brenner, director of Columbia University’s Center for Radiological Research, and an author of the paper. “We’ve really lacked the tools to fight COVID. Masks, vaccination, and social distancing all involve people having to make decisions. Far-UVC is a passive device, it’s just up there in the ceiling.”

Humans have known for over a hundred years that UV radiation can kill deadly germs, and hospitals have used germicidal 254-nm UVC to sterilize objects for decades. But its harmful side effects on people mean the lamps can be turned on only when a room is empty, limiting effectiveness, Brenner says. “It’s not much use cleaning a room in the middle of the night, and then people walk in in the morning and start exhaling viruses in the air. You really need a way to clean the air in a room continually when people are around.”

This is where UV light with a shorter wavelength of 222 nm comes in. Its higher-energy light is strongly absorbed in the outer layers of human tissue. It does not get past the dead cells on the outer layer of skin or the tears that coat the eyes.

In 2020, Brenner and his team demonstrated that far-UVC light kills airborne coronaviruses. The study was done in a small chamber in the laboratory. For the new large-scale study, the researchers installed five commercial krypton chloride excimer far-UVC lamps in the ceiling of a ventilated room-sized enclosure. A mist of Staphylococcus aureus bacteria—which is slightly less sensitive to far-UVC than the coronavirus—was sprayed in on one side, while sensors measured their numbers at an air outlet on the other side.

Commercial far-UVC products came on the market right at the beginning of the pandemic, but “the availability of commercial products has outpaced the research,” says Ewan Eadie, a photobiologist at the University of Dundee school of medicine, in Scotland,” who led the latest research with Brenner. “Research needs to prove in what situation it works and how best to deploy it.”

What’s also needed are better sources for far-UVC light, says David Copithorne, vice president of marketing at startup NS Nanotech in Los Angeles, which is developing the world’s first solid-state source of far-UVC wavelengths. Krypton chloride excimer lamps, the only available source, “cost in the thousands of dollars, their lifetimes still are only several thousand hours, they run hot, they use caustic gases, and they are somewhat bulky.”

NS Nanotech’s far-UVC emitter based on a nitride semiconductor overcomes those issues, he says. The company is ramping up production and plans to ship its first product this year, intended for customers who want to purify their personal airspace in vehicles, offices, and airplanes.

Brenner and his colleagues’ groundbreaking work has put far-UVC in the spotlight, Copithorne adds. Regulatory bodies are now setting standards for its use in public spaces, and industry players are working hard to come up with appropriate ways to deploy far-UVC disinfection.

Jeni Manikandan
Physical Science