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奥野　敦史

okuno atsushi

(Former) Advisor, Specified Nonprofit Corporation Japan LED Association
Advisor, General Corporation LED Lighting Association Japan
IEEE Senior Member in USA
Director, Research Center for Microsystem Research and Development, Fudan University
Director, Research Center for Functional Materials, Tongji University

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Regarding the effect of 405nm near-ultraviolet LED on sterilizing the novel coronavirus and its mutants

Difference between 265~280nm deep-ultraviolet LED and 405nm near-ultraviolet LED

Disadvantages of 265~280nm deep-ultraviolet LED

The wavelength of 265~280nm deep-ultraviolet LED has a strong sterilizing effect, but it also has a bad effect on the human body.

Illustration of ultraviolet rays entering through the eyes

For example, blue light has the following effects:

Damage to the retina
Eye strain
Eye pain

Sleep disorder
Obesity
Cancer
Mental state

265~280nm deep UV LED is the light with a wavelength that is blocked by the ozone layer and does not reach the ground under natural conditions. It is strong compared to blue light of which the wavelength is 380 to 500 nm. Exposure to deep-ultraviolet light can cause severe eye damage and skin damage. Therefore, deep-ultraviolet LEDs can be used only for limited purposes such as sterilization of places where there are no people like hospital operating rooms or water purification.

Advantages of 405nm near-ultraviolet LED

On the other hand, 405nm near-ultraviolet LEDs resemble the sunlight and have no effect on the human body, and their sterilizing effects have already been proven.

Light wavelength and positioning of 405 nm

(Table) Inactivation of COVID-19 by using 405nm near-ultraviolet LED

Irradiation time (min)	Virus inactivation rate (%)
0.5	0.5
1.0	90.0
5.0	99.74

(Irradiation distance 20mm)

Since it has little effect on the human body, it can be used for indoor and outdoor lighting in the same way as general lighting, and it can also be used for medical applications such as endoscopic cameras and catheters. Furthermore, as the table shows, 99.74% of coronavirus inactivation has been demonstrated by irradiation for 5 minutes at an irradiation distance of 20 mm. Therefore, it can be used to remove viruses both inside and outside the body. The 405nm near-ultraviolet LED is LED that can be used in a wide range of applications.

Examples of locations where 405nm near-ultraviolet LEDs are used:

Hospital

Department store

Public facility

Gym

Airport

School

Office

Restaurant

Others

Medical application of 405nm near-ultraviolet LED (patent pending):

We came to think of installing 405nm near-ultraviolet LEDs in endoscopes and catheters. LEDs have already been used for lighting endoscopes for more than 10 years. 405nm near-ultraviolet LEDs can be applied to gastroscope cameras and catheters to improve blood flow by inserting and inflating a balloon catheter when blood vessels are narrowed. By applying these, we believe that 405nm near-ultraviolet LEDs can be installed in endoscopic cameras and catheters to remove viruses from the body.

Recently, technological progress has led to the miniaturization of LED chips, and the development of mini LEDs and micro LEDs has made it possible to install them in endoscopic cameras and catheters.

Since this novel coronavirus mutates, there is a limit in dealing with the same vaccine to combat it, and it is always necessary to develop new vaccines. In addition, each vaccine has its expiration date. Irradiation of 405 nm near-ultraviolet LEDs has demonstrated 99.74% inactivation against this virus, and thus, it is considered to be a very effective tool.

Examples of effective use of LEDs:

Do you know that LEDs are full of possibilities?

Power consumption can be reduced by approximately 80% compared to conventional light bulbs and fluorescent lamps.
LEDs have a relatively high conversion rate of electrical energy to light and have a long life.
Therefore, they can make a big contribution to carbon neutrality.
Furthermore, as technology advances, miniaturization is progressing.
They can also reproduce various lights such as "colors", "UV LED" and "infrared LED," etc., depending on wavelengths.
This means that LEDs can be used in a wide variety of situations.

In various places

As I said at the beginning, LEDs can reduce power consumption by about 80% compared to conventional light bulbs and fluorescent lights, and they have a long lifespan.
Therefore, it is easy to use them for indoor lighting at homes and companies and we can also contribute to decarbonization and energy saving by using them for transportation and public facilities.

In addition, since LED lights are less likely to attract insects, they are effective in places where hygiene is a concern, such as restaurants and hospitals.

Furthermore, in museums and other places where historical materials are exhibited, it is necessary to pay close attention to the fact that light causes discoloration and embrittlement.
However, by using white LEDs for cultural property exhibitions, damage can be suppressed.

For various purposes

LEDs are also excellent for exterior lighting, and they brighten people's hearts with artistic characteristics of lighting such as illumination.

LEDs are perfect for situations where a certain amount of miniaturization or brightness is required, and they are also used as backlights for LCDs, lighting for endoscope cameras, and on-vehicle lighting.

LEDs are also used in plant cultivation and fish farming, and by changing the color scheme and intensity of the LEDs, it is becoming possible to promote the growth of leafy vegetables, increase vitamin C, and speed up the growth of fish.

Among UV LEDs, UVA is used for curing nail art and UV resin. Conventionally, large UV lamps were used, but there were problems in that it takes a long time for curing and the equipment is large. However, by using UVA, we succeeded in shortening the curing time by more than half and downsizing the equipment. Nowadays it is UVA that is mostly used.