Citizen Electronics Co., Ltd., located in Fujiyoshida City, Yamanashi Prefecture, has developed a disinfection device called the UV-C LED Assembly Product. The product uses a high-power deep ultraviolet that has 265 nm emission wavelength, which is assumed to have a high germicidal effect. Mass production was scheduled to begin mid-April 2022.
Characteristics of the product include a high-reflection reflector, dustproof and waterproof capabilities and a high-power assembly product enabling replacement with germicidal lamps. Citizen Electronics collaborated with Fujita Health University to verify an inactivation effect on SARS-CoV-2 using the product.
Summary of the test on the inactivation effect on SARS-CoV-2
Test 1: Test on the inactivation effect on SARS-CoV-2
Summary and results of the test
Method: UVC light is lit from the height of 5 cm/15 cm and the time required for inactivation is measured by TCID50 measuring method. UVC illuminance for 5 cm/15 cm was 0.4730mw/cm2 and 0.0518 mw/cm2 each.
Results: From the height of 5 cm, inactivation of 99.9% after 10 seconds, and inactivation of 99.99% after 20 seconds was confirmed.
From the height of 15 cm, inactivation of 99.9% after 100 seconds, and inactivation of 99.99% after 200 seconds was confirmed. The irradiation dose required for inactivation of 99.9% was 4.73mJ/cm2. The irradiation dose required for 99.99% was 9.46mJ/cm2.
Test 2: Inactivation test against SARS-COV-2 by using two LEDs with different peak wavelengths
Summary and results of the test
Method: UVC light of 265 nm and 275 nm each is lit from the height of 20 cm and the time required for inactivation is measured by TCID50 measuring method. Drive conditions were adjusted in order to achieve UVC illuminance of 0.025mw/cm2 for both LEDs.
Results: As for 265 nm, from the height of 20 cm, inactivation of 99.9% after 300 seconds was confirmed. The irradiation dose required was 7.5mJ/cm2.
As for 275 nm, from the height of 20 cm, inactivation of 99.99% after 600 seconds was confirmed. The irradiation dose required was 15.0mJ/cm2.
From the above results, it was confirmed that LED with 265 nm peak wavelength, which is used for the device, is able to achieve an inactivation effect in a shorter time (about half).
For more information, visit ce.citizen.co.jp.
