Just as white-light application manufacturers choose light efficiency, wavelength and color, the selection of deep UVC-LED also depends on the application scenario. When designing the plan, it is the key to identify the most concerned parameters of the application scenario. Similarly, packaging factories should take these into account when selecting chip parameters.
2.1 optical power
According to the current market situation, the available deep ultraviolet UVC-LED optical power ranges from 2 mW, 10 mW to 100 mW. When selecting the light power to be used, the germicidal efficacy and germicidal time should be given priority. It is known that a 3 mW UVC-LED with an angle of 60 degrees can kill 99.99% of E. coli on its surface in 10 seconds at a distance of 2 cm.
Therefore, similar static sterilization scenarios, such as humidifier, ice maker, drinking water tank, intelligent toilet, etc., are mainly used with a 2-4 mW light power UVC-LED; air purifier, air conditioner and other mobile air sterilization scenarios usually use 10 mW UVC-LED 2-3; direct drinking water machine and other dynamic water sterilization scenarios total light power at least. It should reach 50~100 mW. The cost of the plan can be roughly converted according to the total mW number.
2.2 peak wavelength
When choosing the peak wavelength of UVC-LED, we need to understand the following technical points:
1. The most suitable wavelength for sterilization is 265 nm, not the characteristic wavelength of 254 UV nm mercury lamp. As shown in Fig. 1 (right), UVC ultraviolet rays with wavelengths between 240 and 290 nm have good germicidal efficacy.
2. For UVC-LED, the bactericidal effect also depends on the peak wavelength and the optical power. For example, 270 nm has a good bactericidal effect of 280 nm, 30% light power and 30% of the same bactericidal effect 30%. (Therefore, the sterilization effect of 2.6 mW 280 nm UVC-LED is the same as that of 2 mW 270 nm UVC-LED.) But considering that the average peak wavelength of each manufacturer is not very different, in fact, the light power is the most important index to measure the sterilization efficiency.
2.3 life span
Just like the arms race of the major manufacturers in the early days of the white LED market, the lifetime of the deep ultraviolet LED beads is also regarded as an important standard of product quality. With the experience of white LED, I would like to tell readers that the right ones are the best. Screening the actual life requirements of application scenarios is conducive to reducing project costs and bringing more market opportunities. Or take the mainstream UVC-LED products on the market as an example, declaring a maximum life of 15,000 hours, a minimum of 2,000 hours, but how long does the application need? If we analyze the product demand carefully, we will find that:
Humidifier: 0.8 hours / day *30 days / month *8 months / year *3 =576 hours;
Straight water dispenser: 20 minutes / day *30 days / month *12 months / year *5 =600 hours;
Drinking water tank: 1 hours / day *30 days / month *12 months / year *3 =1080 hours;
Air conditioning: 2 hours / day *30 days / month *6 months / year *5 =1800 hours (evaporator and filter sterilization scheme);
Air purifier: 5 hours / day *30 days / month *12 months / year *3 =5400 hours.
Do you still think that 10000 hours of UVC-LED is better than 5000 hours?
Carefully calculate the application scenarios for the lamp life requirements, find the most matching lamp and price, believe that both from the perspective of suppliers and customers can maximize the value of UVC-LED.
2.4 light angle
The material characteristics of deep ultraviolet LED lead to a higher transverse emission ratio of the chip than that of vertical light. Therefore, the light output angle of the lamp bead encapsulated by a plane lens is usually between 120 and 140 degrees (most manufacturers are at this angle). If encapsulated in a spherical lens, the output angle can be adjusted between 60 and 140 degrees (currently only Deep Purple offers multi-angle beads).
In fact, no matter how large the angle of illumination you choose, you can design enough beads to completely cover the sterilization space you need. In particular, in scenarios that are insensitive to the sterilization range, a small angle of light can make the light more concentrated, thus shortening the sterilization time.
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