The epidemic caused by the "new coronavirus" continues to spread around the world. People's needs for anti-virus materials have changed from the initial masks to disinfecting alcohol. Now many people focus on lamps such as LED disinfection lamps. The ultraviolet dose is in the sterilization process. Under the condition of sufficient UV dose, the inactivated virus and bacteria will not be revived, but when the dose is insufficient, many viruses and bacteria inactivated by UV radiation can repair themselves through the assistance of light. Structure.

Ultraviolet light application and sterilization principle

According to the wavelength, ultraviolet (Ultra Violet, UV) light is usually divided into UVA (315nm-400nm), UVB (280nm-315nm), UVC (200nm-280nm). Among them, the wavelength UVC band is also known as the "solar blind" band. Due to the strong absorption of ozone in the atmosphere, the near-Earth solar spectrum contains almost no ultraviolet light in this band. The main applications of UVC mainly include disinfection/purification of water/air/surface, analytical instruments (spectrophotometry, liquid chromatography, gas chromatography, etc.), mineral analysis. The UVC band has a short wavelength and high energy, which can destroy the molecular structure in the cells of microorganisms (bacteria, viruses and other pathogens) in a short time. , air and surface sterilization and disinfection, so that cells can not be regenerated, so it is widely used in sterilization and disinfection such as water and air. The data shows that with only 30mW/cm2 of UVC ultraviolet radiation intensity, almost 100% of the bacteria can be killed in one second, the effect is very significant, and it can be widely used in the medical and health field. In the field of personal health and family hygiene, ultraviolet light can be used for disinfection of cups and tableware, air purification and sterilization, killing worms, sterilizing and deodorizing shoes and socks, and sterilizing baby bottles.

UV sterilization effect

Depending on the type of microorganism, the time and dosage of UV sterilization are also different. Different bacterial species have different absorption peaks for UV light. For example, the maximum absorption wavelengths of DNA and Escherichia coli are both 265nm, while the maximum absorption wavelengths of Cryptosporidium and bacteriophage are 261nm and 271nm, respectively. Therefore, the required sterilization time should also vary. When the ultraviolet radiation intensity is 3×104μW/cm2, the time required to kill viruses, bacteria, mold spores, and algae bacteria is 0.1-1.0s, 1.0-8.0s, and 5.0-40.0s, respectively. According to the research team of Dong Xiaoping, an expert from the Institute for Viral Disease Prevention and Control of the Chinese Center for Disease Control and Prevention, UVC irradiation with an intensity greater than 90 μW/cm2 can kill the SARS virus in 30 minutes. UV dose plays a crucial role in the sterilization process. UV dose can be expressed as the product of UV intensity and irradiation time. Under the condition of sufficient UV dose, the inactivated virus and bacteria will not be revived, but when the dose is insufficient, many virus and bacteria inactivated by UV irradiation can repair their damaged structures through the assistance of light. When the UV dose is the same, high-intensity, short-time or low-intensity, long-time irradiation can be used to achieve the purpose of sterilization. To kill 1×104/mL of Helicobacter, the required UV dose is about 30 mJ/cm2, and to kill the same number of spores, about 70 mJ/cm2 is required.

Brief Analysis of UVC LED Application

With its advantages of safety, environmental protection, compact size, high efficiency and low consumption, deep ultraviolet LEDs are gradually recognized by the market and have been initially used in water treatment, air sterilization, food preservation and other fields.

1. Deep UV LED Market

Deep UV LED has been recognized by the market for its performance advantages such as safety, environmental protection, compactness, high efficiency and low consumption, and has been seen in the fields of water purifiers, maternal and child products, air conditioners, refrigerators and other high-end consumer goods. The principle of deep ultraviolet sterilization and disinfection is that deep ultraviolet rays can destroy the DNA or RNA molecular structure of genetic material in microorganisms, resulting in the inability of bacteria to reproduce or even inactivation, so as to achieve the purpose of sterilization and disinfection. According to BIS Research Analysis data, by 2023, the market size of UVC will be It will be close to US$500 million in 2023, with an average annual growth rate of 41.9%. The main parameter to measure the sterilization efficiency is the irradiation dose received by the bacteria (irradiation dose (mJ/cm2) = irradiation time (s) * deep ultraviolet irradiation intensity (mW/cm2)), the greater the irradiation dose, the higher the disinfection efficiency. .

Second, the advantages of deep ultraviolet LED sterilization

Compared with other sterilization methods such as chlorination, ozone and UV mercury lamp sterilization, deep ultraviolet LED sterilization has many advantages:

Efficient sterilization. The UVC segment ultraviolet light emitted by deep ultraviolet LEDs generally kills bacteria and viruses within a few seconds. Traditional water sterilization methods such as chloride and ozone generally take 20 minutes to 1 to achieve deep ultraviolet sterilization efficiency. Hour;

Extensive sterilization. Since microorganisms such as bacteria and virus antigens are not resistant to ultraviolet light, deep ultraviolet light can efficiently kill almost all bacteria and viruses, and deep ultraviolet LED sterilization technology can also be used to a certain extent. Inhibit the growth of some higher aquatic organisms, such as algae, red worms, paramecia, etc.;

Safe and environmentally friendly (without mercury), the most obvious advantage of deep UV LED devices compared to mercury-excited UV lamps on the market is that their sterilization light source does not contain mercury, and mercury is a heavy metal substance, commonly known as mercury, and mercury can be used at room temperature. Evaporation, mercury vapor and mercury compounds are highly toxic (chronic). In the sterilization process of traditional ultraviolet mercury lamps, once the lamp tube is broken, it will cause serious water pollution, and deep ultraviolet LED devices are a safe and reliable device. No heavy metals, simple operation, safe and reliable operation;

Energy saving, long life and low maintenance cost, deep ultraviolet LED sterilizer is gradually replacing the mercury lamp ultraviolet sterilizer commonly used in the market. One of the important reasons is that the power consumption of ultraviolet LED is low, which is very energy-saving. The power of deep ultraviolet LED is about the same as that of mercury lamp. 1 in 10, which is a significant cost savings;

Small size, flexible design, easy installation, deep ultraviolet LED devices, small size, flexible design of the sterilization device, can be used in small spaces where traditional mercury mercury lamps cannot be used.

3. Application of deep ultraviolet LED

Deep UV LED products are gradually recognized in the market due to their many advantages, and have been initially used in water treatment, air sterilization, food preservation and other fields

Typical UV dosage requirements for UVC disinfection/decontamination applications:

1) Disinfection and purification of water treatment

1. Static water irradiation

According to the formula: irradiation dose (mJ/cm2) = irradiation time (s) * deep ultraviolet radiation intensity (mW/cm2), it can be known that the ultraviolet sterilization efficiency is related to the ultraviolet irradiation dose received by bacteria. In static water irradiation, there are two ways to improve the sterilization efficiency of deep ultraviolet LEDs: 1) increase the irradiation time; 2) increase the intensity of deep ultraviolet LED irradiation. Under the condition that the light power of deep ultraviolet LED remains unchanged, prolonging the irradiation time can improve its sterilization rate. When the sterilization time is certain, when the input current of the deep ultraviolet LED is larger, the optical power is larger, the radiation energy is larger, and the amount of ultraviolet radiation received by the bacteria is also larger, so the sterilization rate is higher. At the same time, for a deep ultraviolet LED with a certain input current, extending the irradiation time can also increase its total radiation energy. The greater the total radiation received by bacteria, the higher the sterilization rate.

2. Dynamic water irradiation

For dynamic water sterilization, in the process of irradiating dynamic water with deep ultraviolet LEDs, the irradiation time is determined by the water flow. In the case of a certain deep ultraviolet intensity, the greater the water flow, the shorter the irradiation time, the lower the irradiation dose received by the bacteria, and the worse the sterilization effect. The reason is that the faster the water flow rate, the less time the bacteria receive deep ultraviolet irradiation, resulting in a lower dose of deep ultraviolet rays received by the bacteria, so the sterilization efficiency is reduced.

(2) Air purification

As a new generation of green light source, deep ultraviolet LED provides an effective solution for air purification with its unique safety and economic advantages. The deep ultraviolet LED air sterilization and disinfection treatment system can also be used in any equipment that needs fresh and fresh air, such as air purifiers, refrigerators, etc. The refrigerator without the deep ultraviolet LED sterilization module has a natural bacterial attenuation rate of 30%, while the refrigerator with the deep ultraviolet LED sterilization module has a bacterial attenuation rate of 85%, which is also a good proof of the deep ultraviolet LED sterilization effect. The bacterial content of the air in the refrigerator compartment is maintained at a low level, which greatly improves the preservation ability of the refrigerator.

(3) Food preservation

In terms of food preservation, deep ultraviolet LEDs have demonstrated their excellent characteristics. Without other chemical reagents, only one deep ultraviolet LED can improve the preservation ability of fresh vegetables and fruits by 10-20 times at room temperature, and reduce the consumption to a greater extent. Losses due to decay.