Ultraviolet disinfection belongs to the physical disinfection method, ultraviolet light does not directly kill microorganisms, but by destroying the ability of microorganisms to reproduce inactivation. When microorganisms are irradiated by ultraviolet light, their genetic material DNA and RNA absorb a lot of energy from ultraviolet light and are destroyed, losing the ability to divide and replicate, and finally dying naturally or being eliminated by the immune system, and losing the ability to cause disease in the human body.
The visible spectrum of the human eye is generally 400-700nm, wavelengths greater than 100nm, less than 400nm of electromagnetic waves called ultraviolet. Atoms or molecules in the outer layer of the electron to obtain energy by the excitation to the excited state, the electron in the excited state can not be stabilized to stay in the base state jump, in the process of photons in the form of energy radiated, that is, ultraviolet radiation.
According to the biological effects of ultraviolet light can be divided into the following four wavelength bands:
UV-A (400-315nm): also known as black light, the longest wavelength, the lowest energy, the largest share of the natural world's ultraviolet light. Can cause pigmentation of the skin to produce black spots, it is also known as black spot ultraviolet;
UV-B (315-280nm): is the most destructive part of nature's ultraviolet light, can lead to sunburn, erythema, part of which can be absorbed by the atmospheric ozone layer, also known as erythema-causing ultraviolet;
UV-C (280-200nm): all the atmosphere is absorbed! UV-C (280-200nm): all absorbed by the atmosphere, usually can only be generated by artificial light sources. Used for sterilization is the wavelength of the band for the ultraviolet.
Vacuum UV (200-100nm): cannot enter the atmosphere, exists in space.
According to the study of the genetic material nucleic acids DNA and RNA on the ultraviolet absorption spectrum of the range of 250-280nm, the traditional low-pressure mercury lamp hair spectral line mainly 254nm and 185nm two, so when the ultraviolet lamp wavelength of 254nm, the nucleic acids on the ultraviolet ray has the maximum absorption, that is, the best bactericidal effect.
With the white LED solid state lighting triggered by the third lighting revolution of the hot, people will gradually shift the focus of research to high Al component Ⅲ family nitride as the structure of the material of the UV LED. UV LED in the medical treatment, sterilization, printing, lighting, data storage, as well as confidential communications and other aspects of the significant value of the application. And compared with traditional gas UV light sources such as mercury lamps and hernia lamps, UV LEDs have strong advantages.
The birth of the UV light source makes the UV began to get real applications. Gas discharge light sources were the main form of traditional UV light sources before the birth of deep UV LEDs. The spectral radiation of the gas discharge light source covers the ultraviolet region, with an efficiency of up to 60% and a lifetime of 100-1000 hours.
The gas discharge light source is mainly filled with argon and mercury vapor. According to the mercury vapor pressure in the lamp will be divided into low-pressure, high-pressure and ultra-high-pressure mercury lamps. According to the use of different electrodes low-pressure mercury lamps can be divided into hot cathode low-pressure mercury lamps and cold cathode low-pressure mercury lamps. Hot cathode mercury lamps are arc discharge lamps that use a ternary salt oxide as the cathode. Hot and cold cathode mercury lamps are glow discharge lamps, using pure metal as the cathode.
UVLED (ultraviolet LED) composition: sandwiched in a thin GaN sandwich structure to one or more InGaN quantum wells, the formation of the active region for the cladding. By changing the relative proportion of InGaN-GaN in the InGaN quantum wells, the emission wavelength can be changed from violet to other light.AlGaN can be used to make the cladding layer and quantum well layer in the UVLED by changing the proportion of AlN, but the efficiency and maturity of these devices are poor. If the active quantum well layer is GaN, as opposed to InGaN or AlGaN alloys, the device emits in the spectral range of 350 to 370 nm.
Ultraviolet radiation is produced when a blue InGaN light-emitting diode pumps short pulses of electrons. Aluminum-containing nitrides, especially AlGaN and AlGaInN can make shorter wavelength devices to obtain a series of wavelengths of UVLEDs. diodes with wavelengths of up to 247nm have been commercialized, based on aluminum nitride, which can emit 210nm ultraviolet radiation LEDs have been developed successfully, and UVLEDs with a wavelength range of 250~270nm are also under vigorous development.
The new ultraviolet output light source UV LED, with mercury lamps and hernia lamps and other traditional gas ultraviolet light source has a strong advantage over its main features are as follows:
(1) the number of times the opening and closing does not affect the service life; and the traditional ultraviolet source of mercury lamps, UV Fukushima intensity with the cumulative number of times the opening and the ignition time increases and decreases;
(2) long service life. More than 20,000 hours, the traditional ultraviolet light source life of 100-1000 hours;
(3) energy efficient, traditional ultraviolet light source photoelectric conversion efficiency of up to 60%;
(4) spectral concentration, ultraviolet light accounts for more than 98% of the output of all the light, there is no infrared radiation incidental to the traditional light source;
(5) small size, the volume is only 0.1cm3, can be arbitrarily assembled into a variety of forms of lamp array, applied to different needs;
(6) main wave peak narrow single: more than 90% of the light output is concentrated in the main wave peak near the range of ± 10nm;
(7) DC low-voltage drive: suitable for portable UV equipment;
(8) stable and continuously adjustable output power;
(9) Instantaneous light: no warm-up time, response time of microseconds;
(10) Environmental protection: no mercury, no heavy metal pollution.
Ultraviolet sterilization UV lamps can be issued at a wavelength of 253.7nm of ultraviolet light, the most easily absorbed by the bacteria and viruses of proteins, nucleic acids, can make proteins undergo denaturation and dissociation, nucleic acids in the formation of thymine dimer, destruction of a variety of viruses and bacteria in the structure of the DNA and RNA, which in a matter of seconds lead to the death of bacteria and viruses, bactericidal efficiency of up to 99%, can kill Other disinfection methods can not sterilize the bacteria.
(1) Bacteria (more than 18 kinds), such as: hepatobacteria coli, bacillus, Escherichiaceae, Clostridium perfringens, tuberculosis bacteria, Neisseria, Salmonella, etc.;
(2) Molds (more than 8 kinds), such as: Penicillium, black mold, Trichoderma, fecal fungi, etc.;
(3) Filtered pathogens (more than 10 kinds), such as: hepatitis virus, influenza virus, poliovirus and so on.
Since then for uvled can kill poison has a clear answer: uvled can kill poison. The UV LEDs have other uses, too.