The UVC sterilizer is a widely used physical disinfection tool. The basic principles of germicidal UVC and germicidal methods, major product categories, and precautions for use are described; the current market situation of UVC germicidal lamps is analyzed, with attention to technical regulations and market supervision; the development trends of new technologies and new light sources for UVC in the near future are also described, with emphasis on the progress of UVC LEDs and UVC excimer lamps, and hopes for 222 nm excimer UVC lamps. The progress of UV LEDs and UV excimer lamps is highlighted.
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UVC germicidal disinfection technology has many advantages such as broad-spectrum efficiency, no secondary pollution, no resistance, easy management and automation, etc. It has been widely used for many years in the disinfection of surfaces, air, drinking water and wastewater treatment. Low-pressure mercury discharge lamps have been the main light source for UVC sterilization equipment. Low-pressure mercury UVC disinfection apparatus after a long period of development, the process is mature, stable supply chain, the product has the advantages of high UV output efficiency, cost-effective, and ozone-based optional, relatively cheap, good sterilization effect. With the introduction of a variety of new designs of UVC lamps, the application of germicidal UVCis constantly expanding. This article introduces the main categories of UVC germicidal disinfection products, application status and development trends.
1 The main features and considerations of germicidal UVC
The irradiation dose is determined by the sensitivity of different types of microorganisms to UV light. Different types of microorganisms are sensitive to UV light, so when using UV disinfection, it is necessary to determine the appropriate irradiation dose to kill the target microorganism. Less kill efficiency rate is low and high causes undue redundancy of the lamp. In the design of the UVC germicidal disinfection apparatus, the required dose should be determined according to the object of disinfection and the use of scenarios. Dose, thus determining the appropriate UVC lamppower, and according to the test out of the irradiation intensity, calculate the need to irradiate the working time. According to the relevant specifications, the product manual should clearly describe the use of methods and irradiation time. The radiation time. National standards forUVC germicidal lampsradiation irradiance, maintenance There are also corresponding requirements.
Germicidal UVC is achieved by irradiating microorganisms that destroy deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), and the human body may also be harmed by UVC in a C-band ultraviolet (UV-C) light environment. In addition to people to avoid, paintings and other objects should also pay attention to good protection. Therefore, the national health management department issued the “disinfection product labeling instructions management norms” clearly stipulates that product instructions, labels must be listed in the use of precautions and warning signs. Most of the current use of UV germicidal disinfectors, in addition to indirect irradiation, mainly management methods to circumvent UV damage to people, partly through the timer, shaking the controller, but there is still the inconvenience of using and incomplete. Further, there has been the use of intelligent technology to achieve automatic protection of people in the work of the UV germicidal disinfector, such as now has begun to popular intelligent UV disinfection table lamp using induction technology, in the human and animal close to the lamp automatically extinguished; through the cell phone app control, can be operated in the personnel away from the germicidal environment germicidal disinfector work. The irradiation dose is determined by the different types of microorganisms that have different sensitivity to UV light, so when using UV disinfection, the appropriate irradiation dose must be determined to achieve the effect of killing the target microorganisms. Less kill efficiency is low, high caused by the lamp should not be redundant. The design of UV germicidal disinfection apparatus, should be based on the object of disinfection and the use of scenarios, to determine the required dose, which determines the appropriate UVC lamp power, and according to the tested irradiation intensity, calculate the need to irradiate the working time. According to the relevant specifications, in the product manual should describe clearly the use of methods and irradiation time. National standards for UV germicidal lamps radiation irradiance, maintenance rate also have corresponding requirements.
2 UVC sterilizer applications
1) Integrated bracket sterilization lamp
The integrated stand germicidal lamp, as shown in Figure 1, consists of a combination of UVC germicidal lamp and UV-resistant (UV) stand with built-in electronic ballast. The standard T5/T8fluorescent lamp holder size, T5 lamps generally use quartz lamps, through the purple glass lamp T5 ( 15 mm), T6 ( 19 mm), T8 ( 25 mm). T8 lamps use high boron glass, through the purple quartz glass. The lamp can be replaced; wide voltage design: 110 ~ 240 V 50 Hz/60 Hz; ozone and non-ozone two kinds of lamps are available. Luminous direction has directional, not bare light 360 °; power selection is mostly 30W and 40 W ( output efficiency is relatively high); lamp body mechanical properties, not easy to deformation; surface by spraying anti-UV process, anti-rust, anti-corrosion, anti-discoloration, not easy to wear. Plastic parts for flame retardant materials, pressure, high-temperature resistance, UV resistance.
Integrated bracket sterilization lamp is widely used in indoor air and object surface sterilization, the use of direct irradiation, in the case of indoor unoccupied can take the UV lamp hanging sterilization ( Figure 2). The requirements are: indoor installation of UVC sterilization lamps (30 W UVC lamp, the intensity at 1.0 m > 90 μW/cm2) for an average of not less than 1.5 W per cubic meter, irradiation time of not less than 30 min. are mostly used in the following places: hospitals, kindergartens, schools, food factories, cosmetics factories, shoes, assembly lines, kitchens, bathrooms, disinfection cabinets, air purifiers, clean plants, etc.
All-in-one germicidal light high efficiency, light output efficiency of about 90%, reasonable structure design, is the preferred germicidal product for large spaces, lamp size can be selected according to the design. In comparison with other UVC products, bracket lights are used in addition to hospitals with bare UVC lamps, germicidal effect and the highest cost performance of the lamp type.
Fig.1 Integrated bracket sterilization lamp
Fig. 2 Scene of integrated bracket sterilization lamp
Smart germicidal panel light can be shared with the existing home panel light installation, does not take up additional space, lighting and germicidal shared ( Figure 3). Lighting + germicidal; lighting + germicidal + air purification multifunctional options; ozone and ozone-free options according to demand; can be set according to different scenarios of intelligent functions: timing, Bluetooth, remote control, infrared sensor, warning modules to meet the germicidal disinfection at the same time, to prevent UV damage to humans in the process of entry.
Panel lights can also be combined with nano-sterilization technology, that is, attached to the effective medium of nano-particles through the irradiation of a specific light source, and the surrounding water, oxygen in the air to produce a strong oxidation, reduction capacity of the “electron – hole” pair of a technology. This “electron-hole” pair can decompose organic and some inorganic pollutants in air or water into harmless and odorless substances at room temperature, and can destroy the cell wall of bacteria and kill them. Lighting and sterilization at the same time, a wide range of applications, occupied / unoccupied state can provide 24-hour protection.
Because panel lights are generally used for home and indoor lighting, intelligent germicidal panel lights are less applicable scenarios relative to integrated germicidal lights, in the place where panel lights have been used for functional replacement is a good choice, lighting and germicidal together, you can also add air purification. For the office, the humid environment ( bathroom, kitchen) to say it is better germicidal products, there is ozone function germicidal can disinfect the sheltered space.
Smart garden germicidal lamp can be integrated with existing garden lights, one lamp for two purposes, night lighting and germicidal ( Figure 4). Ozone and ozone-free options are available according to demand; Smart functions can be set according to different scenarios: Timer, Bluetooth, remote control, infrared sensor and other intelligent modules to reduce UV damage to humans during work; Smart warning light to remind the germicidal lamp is working; Waterproof, moisture-proof; Human safety voltage design, rechargeable. Generally used in the courtyard or park disinfection
Fig. 4 Intelligent germicidal park lamp
4) Intelligent mobile portable germicidal lamp
Portable germicidal lamp products in a variety of forms ( Figure 5 ~ Figure 7), lightweight and compact ( bowling ball, aliens, germicidal stick, lamp, microphone and so on shape); creative shape in line with public aesthetics, according to the demand for personalized appearance design; easy to carry, for travel consumers is a good choice; with timing, remote control, infrared sensor, app and other intelligent modules. Used in small space or object surface sterilization, such as luggage, hotel bed sheets, toothbrushes, tea cups and other objects disinfection, small area closet, cell phones, refrigerators, cars, washing machines, cabinets, drinking water disinfection, pet houses, fish tanks, baby products disinfection. General to rechargeable battery models; no dead-end sterilization. The germicidal lamp used is generally low-power-based, so the use of the process is relatively longer to achieve better sterilization effect. If applied in the unoccupied can be closed small space, you can add ozone function according to d
Wall-mounted UVC germicidal lamps are generally composed of UVC germicidal lamps and light boxes ( Figure 8), using two or more lamp combinations; input using the national standard three plug power cord, can be grounded, with leakage protection, safe and reliable; shell using aluminum alloy, lightweight, durable, rust-free features; installation using stainless steel chain suspension, convenient and fast; ozone and non-ozone optional; built-in electronic ballast, fast start, no strobe; product can be built-in timer, remote control or infrared sensor, to enrich product performance and increase user experience. Start fast, no strobe; products can be built-in timer, remote control or infrared sensor, to enrich product performance and increase the user experience.
Wall-mounted germicidal lamps compared to integrated germicidal lamps, the advantage is that they can be used directly in places where there are sockets, without the need to install additional wiring. Mainly used in health care, pharmaceutical industry, schools, factories, kitchens, farms, in addition to formaldehyde, basement in addition to odor and other places sterilization.
Wall-mounted germicidal lamps due to the shielding factor of the lamps, and because wall-mounted germicidal lamps are usually single-sided use, plus reflectors, its light efficiency is only 50% more. Therefore, the general sterilization effect is better in relatively small spaces.
Germicidal UVC products with built-in UV-LEDs (Figure 9) are safe to use, low voltage, compact, easy to use and portable. safe to use, low voltage, compact, easy to use and portable. Its irradiation The radiation efficiency is low and is suitable for point, line, or small area germicidal applications; the cost is higher. Compared with traditional mercury germicidal lamps, UVC LEDs are mercury-free, environmentally friendly, low power consumption, spectrum can be customized, radiation intensity can be controlled, fast opening speed, can pulse work, light source shape can be customized, the light output angle is small, etc., for portable germicidal products is a good choice.
Fig. 9 UV － LED sterilizer
3 The development of germicidal UVC outlook
At present, low-mercury UVC lampsalmost occupy the market of UVC sterilization apparatus, but there are two main problems with low-mercury UVC lamps: one is that they contain mercury, which is harmful to the environment; the second is that UVC wavelengths can cause harm to the human body and cannot achieve friendly coexistence between humans and machines. For this reason, the research and development of some new technology applications have been widely carried out and concerned, and new technologies and products in the field of germicidal UVC disinfection have emerged new trends.
1) Ultraviolet LED (UV-LED) Research Continues to Move Forward
The application of LEDs in general lighting has been fully developed in the last decade or so, and has become the leading light source for general lighting. Based on semiconductor technology, UV-LEDcan solve the problem of traditional UV light source containing mercury on the environment, and presents many advantages: single wavelength, high luminous efficiency, low energy consumption; does not produce infrared and ozone; easy to achieve electronic control; long life; small size, flexible and convenient. Therefore, is the development direction of a new generation of UV germicidal systems. So far, UV-LED research can be described as colorful, but to replace the traditional mercury UV lamps to implement industrialization still need time. In contrast, the A-band ultraviolet LED (UVA – LED) technology is more mature, the development of high-power products, but due to the relatively small UVA photon energy, germicidal efficiency is poor, germicidal time is very long, currently used for small area point application of water sterilization. Deep ultraviolet LED ( DUV – LED) especially UVC – LEDwavelength range for sterilization efficiency is higher, but due to the current technical process limitations, UVC – LED chip single power, radiation efficiency is non-low, and expensive, is now only applicable to tiny size point Application sterilization, such as a variety of personal products sterilization, drinking fountain purification, micro small sterilization experimental devices. Overall, UV – LED is currently because of the cost and intensity factors, so that it is widely used will take some time, but UVC – LED as an emerging technology, its development is an unstoppable trend. With the depth of research, breakthroughs in key technologies, UV-LED in the field of germicidal technology will continue to show the potential for application, with broad prospects.
UV excimer lamps, which use high pressure and high frequency outside the UV lamp to bombard the rare gas inside the lamp and use the medium to block it, emit a single spectrum of high intensity excimer UV light with different monochromatic wavelengths (22 types such as 126 nm, 172 nm, 222 nm or 308 nm) obtained by using different excimer gas ratios (Figure 10, Figure 11). The narrow spectral lines and monochromatic UV radiation spectrum of the excimer lamp with monospectral characteristics allow it to perform photoprocessing with more concentrated power, triggering photochemical reactions that are difficult or impossible to achieve with conventional light sources, and broadening the applications of UV radiation. The development of excited excimer lamps is a relatively recent development and was only reported in the 21st century. Currently, excimer vacuum UV light at a wavelength of 172 nm is being used for surface etching in wafer cleaning and flat panel display manufacturing. The wavelength of 222 nm can be used for human-machine coexistence in sterilization.
Recently, a joint study by KobeUniversity and Ushio University in Japan showed that rats exposed to 222 nm germicidal light did not develop skin cancer; the effect on the eyes of rats was also observed, and no abnormalities were found even under a microscope. This indicates that 222 nm with bactericidal effect is safe for eyes and skin. The study was also conducted on humans. Studies have also been conducted on humans, using 222 nm UV-C devices to irradiate the backs of 20 healthy volunteers ranging in age from 20 to 80 years, effectively reducing bacteria on the skin of the volunteers without any signs of erythema or adverse effects. These studies show that deep UV irradiation at 222 nm is highly disinfecting and harmless to human skin, so this technology can be widely used for disinfection.
Fig.10 Spectrum comparison between ultraviolet excimer lamp and mercury ultraviolet lam
Fig. 11 Appearance of 222 nm UV excimer lamp
Currently, domestic attention has been focused on 222 nm excimer lamps. This new human-friendly UVC germicidal disinfection product is yet to be some research institutes with profound technology and rich manufacturing experience The joint efforts of industry, academia and research are needed to make a breakthrough in the application of UVC for public disinfection. The breakthrough in public disinfection by UVC is needed.
The spread of the COVID-19 epidemic pushed the development and use of germicidal UVC productsto a climax, and germicidal UVC disinfection received unprecedented attention. Even after the epidemic returned to normal, but after the baptism of the epidemic, people will pay more attention to germicidal UVC disinfection than before the epidemic, therefore, germicidal UVC disinfection products have good application prospects.
On the one hand, the traditional low-pressure mercury germicidal disinfection apparatus still occupies the main market, on the other hand, new UV light source products are emerging, UV-LED has clearly shown the direction of leading the mainstream, in addition to the new crown pneumonia epidemic, the 222 nm excimer lamp can achieve public disinfection has been cast to the possibility of the market. Traditional products should work on improving the manufacturing process, ensuring product quality, and strictly following the regulations for disinfection products; new products need to be fully validated under the premise of ensuring safety before being introduced to the market.