UVC semiconductor: a new generation of sterilization technology with broad prospects

 Date:2020-09-11 15:49:39

1. UVC: the first choice for healthy light sources

UV (Ultraviolet) refers to electromagnetic waves with a wavelength between 10nm and 400nm, namely ultraviolet rays. According to the wavelength, ultraviolet rays can be divided into long-wave ultraviolet (UVA), medium-wave ultraviolet (UVB) and short-wave ultraviolet (UVC). The wavelengths are 320~400nm, 280~320nm, and 100~280nm respectively.

Compared with UVA and UVB, UVC has little impact on human body. UVA has strong penetrating ability and can reach the dermis of the skin. On the one hand, UVA directly converts the melanin precursors in the skin into melanin, which makes the skin darken quickly; on the other hand, UVA can produce active oxygen free radicals in the skin. The effect will bring greater oxidative pressure to the skin, and cause damage to collagen, elastin and DNA in the skin, which will cause skin aging, loss of elasticity, and wrinkles. UVB mainly acts on the surface of the skin. UVB activates the tyrosinase in the melanocytes of the basal layer of the epidermis to synthesize melanin. After the melanin is formed, it gradually migrates to the outermost layer, causing the skin to darken, appear erythema, or get sunburned. In short, UVA and UVB are harmful to human skin, while UVC is very low in harm to human body compared with UVA and UVB. This is because UVC has a short wavelength and low penetration power, and cannot penetrate into the skin epidermis.

2. UVC has strong sterilization and disinfection effect, and inactivates viruses more thoroughly.

People often use the sun to eliminate germs on food, achieve the effect of disinfection and quality preservation, and according to the principle of sun disinfection, artificial ultraviolet technology has been gradually developed. Ultraviolet rays are a mutagen, which kills microorganisms by damaging microorganisms and damaging nucleic acids, thereby achieving the purpose of disinfection. In a specific wavelength range (mainly UVC) and a high enough dose, ultraviolet rays can cause abnormal chemical bonds between DNA or RNA adjacent pyrimidine molecules in bacteria and viruses and other microbial cells to form abnormal chemical bonds, hindering the replication of DNA or RNA, thereby causing Microbial cell death. The deep ultraviolet semiconductor achieves the effect of sterilization and disinfection by emitting deep ultraviolet rays of UVC wavelength.

Compared with chemical disinfection, ultraviolet light has the advantage of high disinfection efficiency, inactivation is generally completed within a few seconds, and it does not produce other chemical pollutants. It is also an important sterilization equipment in front-line medical and health institutions. Since the shorter the wavelength of the ultraviolet rays, the higher the frequency, and the higher the energy contained, compared to UVA and UVB, UVC has stronger sterilization ability and faster effect.

UVC is the ultraviolet light with the best sterilization effect in nature, but it is very difficult for people to directly use the UVC in sunlight. This is because UVC has been absorbed and scattered by the ozone layer in the atmosphere and cannot reach the ground because of its short wavelength. Therefore, artificial UVC becomes particularly important.

3. UVC semiconductors have obvious advantages: miniaturization, non-toxic, easy to use

Currently, there are two main types of ultraviolet light sources used for sterilization: traditional mercury lamps and ultraviolet LEDs. The mercury lamp is currently the most mainstream product for ultraviolet disinfection, curing and exposure. The principle of this lamp is very simple. The high-energy electrons emitted by the cathode ray tube excite the atoms of the mercury vapor to be excited, and the excited electrons return to the ground state to emit ultraviolet light. The outside is coated with red, green and blue RGB phosphors, which are fluorescent lamps or energy-saving lamps. Ultraviolet LEDs use the principle of semiconductor luminescence to produce light sources in the UV band. By using the change in the ratio of aluminum indium gallium nitrogen materials, various wavelengths of ultraviolet and visible light can be produced.