TOKUSHIMA -- A deep ultraviolet (UV) LED with the ability to inactivate 99.99% of coronavirus particles when shined on surfaces for 30 seconds under certain conditions has been developed by a Japanese firm.
Nichia Corp., based in the city of Anan, Tokushima Prefecture, is ready to mass-produce the LED, and apparently hopes to use it in air purifiers, air conditioning systems and other equipment.
According to the company, the LED emits deep UV light with a wavelength of 280 nanometers, and has an optical output of 70 milliwatts. The inactivation of virus particles is said to be most effective at a wavelength of 260 nm, but the optical output drops at shorter wavelengths, which would reduce the deep UV LED's lifespan. The company says that at 265 nm, the LED has an estimated lifespan of about 2,000 hours. At 280 nm, that can be expanded by about 10 times, to some 20,000 hours.
The company's "Handy UV emitter" trial product uses 12 deep UV LEDs whose optical outputs were raised to 70 mW after adjusting the wavelength to 280 nm. A test by Tokushima University found that 99.99% of virus particles on surfaces were inactivated when hit with the deep UV waves for 30 seconds at a distance of 5 centimeters. It was also confirmed that the UV light with a wavelength of 280 nm had the same effectiveness as that with a wavelength of 260 nm, due to the higher optical output. The firm said that the extended LED lifespan resulting from the adjustments made the product ready for practical application.
Nichia has donated 20 of the LED trial products to the Tokushima Prefectural Government, as well as 30 to Tokushima University, and has been discussing plans to develop and sell products using the deep UV LED with Japanese manufacturers.
(Japanese original by Sakura Iwamoto, Tokushima Bureau)