1. What is the UV?
First, let's review the concept of UV. UV, Ultraviolet, or Ultraviolet, is an electromagnetic wave that ranges from 10nm to 400nm. UV of different bands can be divided into UVA, UVB and UVC.
UVA: With a long wavelength between 320-400nm, it can penetrate clouds and glass into rooms and cars, and penetrate to the dermis of the skin, causing sunburn. UVA can be subdivided into UVA-2 (320-340nm) and UVA-1 (340-400nm).
UVB: the wavelength is in the middle, between 280 and 320nm. It is absorbed by the ozone layer and can cause sunburn and skin redness, swelling, heat and pain, and even blisters or peeling in severe cases.
UVC: The wavelength is between 100-280nm, but the wavelength below 200 nm is vacuum ultraviolet, so it can be absorbed by the air. Therefore, the wavelength of UVC that can pass through the atmosphere is between 200-280nm. The shorter the wavelength is, the more dangerous it is.
2. The principle of UV sterilization?
UV can destroy the DNA (DEoxyribonucleic acid) or RNA(RIbonucleic acid) molecular structure of microorganisms, so that the bacteria die or cannot reproduce, so as to achieve the purpose of sterilization.
3. UV sterilization wavelengths?
According to the International Ultraviolet Society, "the ultraviolet spectrum (' sterilizing 'regions) important for water and air disinfection is the range of absorption by DNA (RNA in some viruses). The germicidal band is about 200-300nm ".
Bactericidal wavelengths have been known to extend above 280nm and are now generally thought to extend to 300nm, although this may change with more research. Scientists have shown that ultraviolet light at wavelengths between 280 and 300nm can also be used to kill bacteria.
4. The best wavelength for sterilization?
One misconception is that 254nm is the best wavelength for sterilization because the peak wavelength of the low-pressure mercury lamp (determined solely by the physics of the lamp) is 253.7nm. In essence, as mentioned above, a certain range of wavelengths are bactericidal. However, the wavelength of 265nm UVC LEDis generally considered to be the best, because this wavelength is the peak of the DNA absorption curve. Therefore, UVC is the most suitable band for sterilization.
6. UVC LED application scenario?
According to LEDinside's "2018 UV LED Application Market Report - Curing, Medical treatment, Sterilization", surface sterilization, still water sterilization and flowing water sterilization will become the main growth drivers outside the curing market in the next five years (2018-2022). According to different application scenarios, we may see UVC LED in these applications in the future:
Surface sterilization: high-frequency public contact surfaces such as medical appliances, maternal and child supplies, smart toilets, refrigerators, cubbyboxes, smart garbage cans, thermos cups, escalator handrails, ticket machine buttons, etc.;
Still water sterilization: drinking water tank, humidifier, ice machine;
Flow water sterilization: flow water sterilization module, straight water dispenser;
Air sterilization: air purifier, air conditioner.
7. How to select UVC LED?
Light power, peak wavelength, lifetime, light Angle and other parameters can be selected.
Optical power: Available UVC LED optical power ranges on the current market range from 2mW, 10MW to 100MW. Different applications have different power requirements. In general, the optical power can be matched in combination with the exposure distance, dynamic or static requirements. The greater the irradiation distance, the more dynamic the demand and the greater the optical power required.
Peak wavelength: as mentioned above, 265nm UVC is the best wavelength for sterilization. However, considering that there is little difference in the mean value of peak wavelength among manufacturers, optical power is actually the most important index to measure the sterilization efficiency.
Life: The demand for life is considered according to the service time of the specific application, and the most suitable UVC LED is the best one.
Light Beam Angle: The light emitting Angle of the lamp enclosed by the plane lens is usually between 120-140°, and the light emitting Angle of the lamp enclosed by the ball lens is adjustable between 60-140°. In fact, no matter how large the UVC LED with light Angle is selected, enough leds can be designed to completely cover the required sterilization space. In scenes that are not sensitive to the sterilization scope, a small light Angle can make the light more concentrated, thus reducing the sterilization time.