Could ultraviolet LEDs help fight COVID-19?

Ultraviolet LEDs that can decontaminate surfaces from COVID-19 infection are currently being developed by researchers.

According to researchers at UC Santa Barbara's Solid State Lighting & Energy Electronics Center (SSLEEC), these LEDs could also potentially decontaminate air and water that have come into contact with the SARS-CoV-2 virus.

"One major application is in medical situations — the disinfection of personal protective equipment, surfaces, floors, within the HVAC systems, etc," said materials doctoral researcher Christian Zollner, whose work centres on advancing deep ultraviolet light LED technology for sanitation and purification purposes.

Indeed, much attention of late has turned to the power of ultraviolet light to inactivate the novel coronavirus. As a technology, ultraviolet light disinfection has been around for some time. While practical, large-scale efficacy against the spread of SARS-CoV-2 has yet to be shown, UV light shows a lot of promise. SSLEEC member company Seoul Semiconductor in early April reported a "99.9% sterilisation of coronavirus (COVID-19) in 30 seconds" with its UV LED products. Its technology currently is being adopted for automotive use, in UV LED lamps that sterilise the interior of unoccupied vehicles.

Not all UV wavelengths are alike — UV-A and UV-B have important uses, but the rare UV-C is the ultraviolet light of choice for purifying air and water and for inactivating microbes. These can be generated only via human-made processes.

"UV-C light in the 260–285 nm range most relevant for current disinfection technologies is also harmful to human skin, so for now it is mostly used in applications where no-one is present at the time of disinfection," Zollner said.

In fact, the World Health Organization warns against using ultraviolet disinfection lamps to sanitise hands or other areas of the skin — even brief exposure to UV-C light can cause burns and eye damage.

Portable, fast-acting water disinfection was among the primary applications the researchers had in mind as they were developing their UV-C LED technology; the diodes' durability, reliability and small form factor would be a game changer in less developed areas of the world where clean water is not available.

The emergence of the COVID-19 pandemic has added another dimension. As the world races to find vaccines, therapies and cures for the disease, disinfection, decontamination and isolation are the few weapons we have to defend ourselves, and the solutions will need to be deployed worldwide. In addition to UV-C for water sanitation purposes, UV-C light could be integrated into systems that turn on when no-one is present, Zollner said.

"This would provide a low-cost, chemical-free and convenient way to sanitise public, retail, personal and medical spaces," he said.

For the moment, however, Zollner and colleagues are waiting out the pandemic, as research at UC Santa Barbara has slowed to minimise person-to-person contact.

"Our next steps, once research activities resume at UCSB, is to continue our work on improving our AlGaN/SiC platform to hopefully produce the world's most efficient UV-C light emitters," he said.

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