A team led by physicist Chris Barty of the University of California, Irvine is researching the use of diodes from Blu-ray digital videodisc devices as deep-ultraviolet laser photon sources to rapidly disinfect surfaces and indoor air. Barty, UCI Distinguished Professor of Physics and Astronomy, said that such UV-light sterilizers would be cheap compared to current medical- and scientific-grade systems and that it would be possible to deploy them almost anywhere. “If these sources are successful, I think you could build them into a mask and clean the air that’s coming in and out of you,” he said. “Or you could set these things up in the air circulation ducts of major buildings, and the airflow that goes through could be sterilized.” Barty believes the sterilizers could also function in hand-held wand devices, or as a “light curtain” through which people walk as they enter a room, exposing them to UV-C radiation between 200 and 260 nm. He noted that at this wavelength the radiation would destroy viruses and other pathogens, but pose minimal risk to humans. “There is evidence to suggest that the UV-C band is actually not an issue for us, especially at the shorter wavelengths, because it gets absorbed by dead skin cells or by a teardrop on your eye,” Barty said. “Hospitals use UV-emitting robots that are about the size of a dorm room refrigerator. They just wheel them in and plug them into the wall to sterilize the place, but everybody has to leave because in addition to UV-C, they make a lot of UV-A and UV-B, which can cause harm to humans.” The cost of these roaming hospital sterilizers, based on high-current mercury discharge lamps, is too high for deployment at the scale that may be needed to combat the novel coronavirus in places from cruise ships to meatpacking plants. Barty said that Blu-ray diode lasers offer a potential path to a compact, economical solution, since the technology is ubiquitous and priced in the range of tens of dollars per unit. Barty’s team is developing a way to halve the 405-nm wavelength of photons emitted by Blu-ray diodes to the germicidal UV-C band. “This is really more of an applied physics versus a pure physics view of the world,” he said. “The issue is not whether you can make UV-C light. It’s whether you can fundamentally reduce the dollar-per-watt output of a device to a place that it becomes compelling to use UV-C light.” According to Barty, Blu-ray sterilizers could be made in the “same kind of quantities as you can make other telecommunications components, so you could really change the game.” This project and other currently active UCI-based initiatives to confront the virus are being tracked at www.oc-covid19.org.