1. The principle of ultraviolet sterilization
There have been many articles on UV sterilization that have been popularized recently. Here are three points to reiterate:
First, ultraviolet rays are divided according to wavelength, which can be divided into UVA long-wave ultraviolet (wavelength range 315-400 nm), UVB medium-wave ultraviolet (wavelength range 280-315 nm), UVC short-wave ultraviolet (wavelength range 200-280 nm) and VUV vacuum Ultraviolet (wavelength range 10-200 nm). Among them, UVA long-wave ultraviolet is often referred to as near ultraviolet, and UVC short-wave ultraviolet is often referred to as deep ultraviolet.
Second, ultraviolet light is a mutagen. In a specific wavelength range (mainly UVC) and a sufficiently high dose, ultraviolet light can cause abnormal formation between adjacent pyrimidine molecules in DNA or RNA in microbial cells such as bacteria and viruses. Chemical bonds hinder the replication of DNA or RNA, causing microbial cell death. Deep-ultraviolet LEDs achieve the effect of sterilization and disinfection by emitting deep ultraviolet light with UVC wavelength.
Third, during the SARS period, researchers from the Chinese Center for Disease Control and Prevention found that using deep ultraviolet light with an intensity greater than 90uW/cm2 to irradiate the coronavirus for 60 minutes can kill the SARS virus. The new type of coronavirus is similar to the SARS virus and both belong to single-stranded positive-stranded RNA viruses. Therefore, theoretically, scientifically and rationally using ultraviolet rays can effectively kill the new type of coronavirus.
2. The characteristics of UV sterilization
UV disinfection mainly has the following characteristics:
(1) High efficiency of sterilization and disinfection: The US Food and Drug Administration's Hygiene Evaluation and Research Center has shown that under the irradiation of a UV light source with a characteristic wavelength of 254nm and a radiation intensity of 4016uW/cm2, the killing rate of SARS virus can reach 99.99 after 6 minutes. %. Compared with heat disinfection at 75 degrees Celsius which takes 45 minutes to kill the SARS virus, the efficiency of UV disinfection is much higher.
(2) Broad-spectrum sterilization: Since ultraviolet rays directly affect the DNA and RNA of bacteria and viruses, among all the current sterilization and disinfection methods, ultraviolet sterilization has the highest broad-spectrum sterilization and can be effective against almost all bacteria and viruses. Highly efficient killing.
(3) No secondary pollution: The commonly used sodium hypochlorite disinfectant is harmful to the environment and will cause water pollution, and the free chlorine released by it may cause poisoning. In contrast, ultraviolet light can cause the direct death of bacteria and viruses without other chemical pollutants. But pay attention to avoid using ultraviolet rays with a wavelength less than 243nm to produce ozone.
3. Advantages of UV LED
Currently, there are two main types of ultraviolet light sources used for sterilization: traditional mercury lamps and deep ultraviolet LEDs. Compared with the many shortcomings of traditional mercury lamps, deep ultraviolet LED has obvious policy advantages and technical advantages.
Disadvantages of traditional mercury lamps:
(1) The appearance is cumbersome, the size is large, and it is equipped with high-voltage electricity.
(2) It takes a long time to start up and cannot be used immediately.
(3) Fragile, short service life, up to 90% of the service life is consumed in the frequent switching stage.
(4) It is highly toxic, causing mercury leakage after rupture, polluting the environment, and seriously endangering human health.
Policy advantages of deep ultraviolet LEDs: The "United Nations Minamata Convention" signed by 128 countries in the world has officially entered into force in China in August 2017. The treaty explicitly bans the production and import and export of various mercury-containing products and traditional mercury from 2020. The production and sale of lights will be prohibited. The Chinese government has successively promulgated a series of policy documents such as the "List of Strictly Restricted Toxic Chemicals in China" and the "List of Priority Controlled Chemicals (First Batch)", which put forward clear requirements for the management and control of mercury. As a major country of traditional mercury processing and manufacturing and mercury pollution, the Chinese government actively implements the requirements of the Minamata Convention. Although the UV mercury lamp used for curing and sterilization is not among the main controls this year, in the long run, as the replacement of traditional light sources in the general lighting field is an inevitable trend, deep UV LEDs are a new type of green and environmentally friendly UV solid-state light source. , Will be the only alternative to the traditional ultraviolet light source-mercury lamp. With the entry into force of the "Minamata Convention" and the continuous advancement of deep ultraviolet LED technology, deep ultraviolet LED will usher in the rapid growth of its industrial scale.
Technical advantages of deep-ultraviolet LEDs: Among the various methods of sterilization and disinfection, only deep-ultraviolet LEDs have the advantages of energy-saving, ready-to-use, space-saving, maintenance-free, non-toxic and harmless, long life, no irritating smell, etc. Excellent characteristics. Compared with other sterilization methods, deep ultraviolet LED has obvious technical advantages.
Fourth, the impact of the new crown pneumonia epidemic on the UV LED industry
Bacteria and viruses exist in every corner of human life, but as long as they don’t cause serious health problems, people don’t pay much attention to sterilization, and there are even people who hold the unhealthy attitude of "not clean and sick if you eat." Life concept. In addition, ultraviolet rays and bacteria are invisible and intangible, and it is difficult for consumers to intuitively feel the effect of ultraviolet rays. Therefore, before the outbreak of the epidemic, the market promotion of deep-ultraviolet LEDs has been facing relatively great difficulties.
The epidemic has greatly improved people's awareness of ultraviolet sterilization and has played a role in promoting the cultivation of deep ultraviolet LEDs in the market. Once the terminal consumer market is opened, it will surely drive the development of the entire deep ultraviolet LED industry chain from bottom to top. With the common progress of the industry chain, the price-performance ratio of deep ultraviolet LEDs will continue to be improved, which will further promote the penetration of the terminal application market and form a virtuous circle.
At present, since the price/performance ratio of deep-ultraviolet LEDs does not have significant advantages compared with traditional mercury lamps, most deep-ultraviolet LEDs with low and medium power are mainly used in surface sterilization and other scenarios in the general consumer market. In the industrial application field that requires high optical power, it is still the world of mercury lamps for the time being. Deep ultraviolet LEDs and mercury lamps will co-exist in a complementary form for some time to come. However, as the price-performance ratio of deep ultraviolet LEDs continues to improve, it is believed that in the near future, deep ultraviolet LEDs will complete the transformation of mercury lamps from complement to replacement, from replacement to transcendence, and even to create their own new application areas.
Of course, any powerful new technology has its pros and cons, and proper use will benefit mankind. When we encounter problems, we must not overcorrect, let alone give up food due to choking. What we can do is to maximize the positive effects as much as possible, so that good technology can better serve all mankind.
