At present, the global New Coronavirus pneumonia epidemic is still very tense, and all parties are trying to find ways to fight the virus. Since this year, there have been a dizzying number of related products in the field of ultraviolet sterilization and disinfection. In addition to the common ultraviolet disinfection lamps, innovative products such as automatic disinfection robots and ultraviolet "microwave ovens" have also come out one after another.
At the same time, the study on the bactericidal effect of ultraviolet LED on COVID-19 has been carried out. For example, Nagoya University and Asahi Kasei have developed a laser diode based on AIN (nitrogen aluminide) substrate, which emits the ultraviolet light with the shortest wavelength of 271.8nm under room temperature pulse current injection. Its potential applications include sterilization, dermatology and DNA analysis.
Recently, according to foreign media reports, the solid state lighting and energy Electronics Center (ssleec) of the University of California, Santa Barbara (UCSB) and its member companies are also developing ultraviolet LEDs and studying the sterilization effect of ultraviolet light.
Seoul semiconductor is one of the SSLEEC member companies. Its subsidiary has recently proved that UV LED technology can kill 99.9% of New Coronavirus within 30 seconds. This technology has been used in different environments such as environmental purification and internal sterilization of astronauts at the NASA space station.
It is reported that at present, researchers are developing an ultraviolet LED, which can purify the surface exposed to sars-cov-2 virus, possibly including air and water.
Among them, researchers focusing on deep ultraviolet LED technology for sterilization and purification said that one of the main applications of ultraviolet LED under development is medical places, which can be used for disinfection and sterilization of personal protective equipment, surfaces, floors and air conditioning systems.
Researchers point out that rare deep ultraviolet light can only be produced by artificial processes. Moreover, 260-285nm deep ultraviolet light, which is most related to the current disinfection technology, is harmful to human skin. Therefore, at present, deep ultraviolet disinfection is almost carried out under unmanned conditions.
Before the outbreak of this epidemic, ssleec's material scientists had been studying and promoting UVC LED technology. This field of electromagnetic spectroscopy is relatively advanced for solid-state lighting. Deep ultraviolet light is usually produced by mercury vapor lamp. In order to give full play to the potential of ultraviolet LED in efficiency, cost, reliability and service life, many related technologies need to be improved.
The researcher mentioned that a research report published in the journal ACS photonics showed the method of manufacturing high-quality UVC LEDs, that is, depositing a layer of AlGaN film on silicon carbide (SIC) substrate, which is different from the more widely used sapphire substrate.
Due to the close atomic structure matching of materials, silicon carbide substrate can grow high-quality deep ultraviolet semiconductor materials more efficiently and economically than sapphire substrate.
Generally, the more similar the structure (atomic crystal structure) of substrate and film, the easier it is to produce high-quality materials. The better the quality, the higher the efficiency and performance of the LED. However, sapphire is different in structure, and the production of defect free and deviation free materials usually requires complex additional steps. Although silicon carbide is not a perfect choice, it can achieve high quality without additional high-cost methods. Moreover, the price of silicon carbide is far lower than that of ideal aluminum nitride substrate, which makes it easier to realize mass production.
When developing UVC LED technology, portable and rapid water disinfection is one of the main applications considered by researchers. They said that in addition to being used for water disinfection, deep ultraviolet rays can also be integrated into systems opened under unmanned conditions. This is a low-cost, chemical free and convenient cleaning method for public areas, retail stores, individuals and medical places.
But for now, the UCSB research team has slowed down the research speed in order to reduce the contact between people. After the resumption of research work, they will continue to improve their AlGaN / SiC technology, hoping to produce the world's most efficient deep UV emitter.
According to ledinside, at present, the ultraviolet light source used for medical sterilization mainly comes from ultraviolet mercury lamp. Mercury (mercury) is added into the vacuum quartz lamp tube of mercury lamp, and the discharge is carried out through the voltage difference of electric shock at both ends to excite the ultraviolet radiation wave, and then the wavelength is changed through the fluorescent coating inside the lamp tube.
The germicidal efficacy of ultraviolet light depends on the dose, including radiation intensity (illumination) and time. At present, the main reason why UVC LED can not completely replace medical sterilization UV mercury lamp is that the illumination of LED is still not strong enough. Compared with UV mercury lamp, it is necessary to increase the dosage of UVC LED or prolong the irradiation time to achieve the same sterilization effect. Therefore, for professional medical units with high use frequency and large sterilization space, the cost-effectiveness of UV LED disinfection is not high at this stage.
However, ledinside believes that with more R & D efforts invested in the field of ultraviolet sterilization and disinfection, relevant technologies and products will be commercialized on a large scale faster. From the current market application, UVC LED has begun to play a role in some places, including surface sterilization (portable sterilization products, sterilization lamps, mother and baby products), water sterilization and air purification.
（from： https://www.ledinside.cn/）