Coronaviruses inhabit bats, camels, pangolins, and humans alike, and are hard-to-eradicate spiky varmints. At least four hang around every year, making people sick — 229E, NL63, OC43, and HKU1 — in addition to the virus SARS-CoV-2 responsible for COVID-19. Ultraviolet light is one of the antagonists that works against them outside the body — in fact, Cottage Health produced a video in 2015 called “Germ Wars” to introduce “Zac,” the Xenex ultraviolet machine. At UC Santa Barbara, Christian Zollner has found a more efficient way to make a deep-ultraviolet LED that can disinfect coronaviruses.
The UV light Zollner is working on is not the one found hanging above a blacklight poster aglow with fluorescent paint. It’s in the 260-285 nanometer range, which can actually damage humans — skin burns and eye damage result from even brief exposure. (The visible range of light is 400-700 nanometers, and the jury is out on whether sunlight deactivates coronavirus.)
A researcher at UCSB’s Solid State Lighting & Energy Electronics Center, Zollner sees that a product using this light could be deployed when no one is around: “One major application is in medical situations,” he said, “the disinfection of personal protective equipment, surfaces, floors, within the HVAC systems, et cetera.” Center member Seoul Semiconductor has found 99.9 percent efficacy against SARS-CoV-2 with UV LED disinfection of car interiors.
Zollner is pairing silicon carbide and aluminum gallium nitride because their atomic structures match up more closely than the other semiconductor material commonly used: sapphire. His work, described in ACS Photonics, on this promising technology, however, is delayed by the pandemic itself: UCSB’s labs are practicing social distancing and spacing out researchers’ access.