Imagine how excited you can be if you find a way to create colorful light in an era when people only know about white LEDs. That is what the scientists in the 1960s experienced as they invented the first red LED light. And then LED lights of other visible colors emerged. What’s more, inventors also made progress in another mysterious field: UV LED. With the advent of UV LED lights, it made Ultraviolet Germicidal Irradiation (UVGI) possible with a LED light. Now, the UVC LED has been widely used for disinfection in different areas. Do you want to know the secret of the UVC LED? Read on!
A brief introduction to UVC light
People first found that short-wavelength light could kill bacteria in 1878. And then, in 1903, scientists tried to use UV lights to fight against diseases like tuberculosis. This UV light indicates UVC light, whose wavelength is between 200 and 280nm. The “C” in its name doesn’t have any special meaning. It is just called that because there are two other types of UV light: UVA and UVB. To learn more about UVA and UVB, you can refer to the previous blog post, What Is A UV LED. UVC is mainly used for disinfection, and UVC products include the uv flashlight, the uv led strip, the uvc light bulb, etc.
How does UVC LED work for disinfection?
The principle of disinfection
UVC light is effective for disinfection because of its short wavelength. Under the influence of this wavelength, the DNA or RNA structure of the microbe will be destroyed. Microbes mainly rely on duplication to reproduce. Once its structure is incomplete, it is hard to duplicate. The data shows that using a 30 mW/cm2 UVC light, almost 99.99% of the bacteria can be killed in one second, let alone increasing the intensity.
Use UVC LED for different microbes
According to the different types of microorganisms, the time and intensity of ultraviolet light needed are also different. Different bacterial species have different absorption peaks for UV rays. For example, the maximum absorption wavelength of Escherichia coli is 265nm, while that of Cryptosporidium and bacteriophage is 261nm and 271nm, respectively. Besides, the required sterilization time is also different. When the ultraviolet radiation intensity is 3×104μW/cm2, the time required to kill viruses and bacteria, mold spores, and algae bacteria is respectively 0.1-1s, 1-8s, and 5-40s.
1. Water disinfection
Scientists have tested its effect on killing the microbe in different types of water, for example, drinking water, rainwater, wastewater for reusing, etc. These kinds of water have their own standards for purification. For drinking water, it requires a reduction of 99.99% of microorganisms.
Factors influencing the effect of disinfection
- Dose of the UVC light:
Like what we mentioned above, the required dose of UVC light varies according to the type of microbe. UV dose = UV intensity (mW/cm2) *exposure time (seconds). To improve the effect of UVC light, you can simply extend its duration when using the UVC LED. Or you can increase the input current to achieve a greater intensity.
- Amount of Water:
For dynamic water sterilization, the radiation time is affected by the amount of water. For a certain UV intensity, the faster the water flow, the shorter the irradiation time. As a result, the bacteria receive a lower irradiation dose, and the effect will not be ideal.
- the UVC irradiation types
Whether the UVC LED light is continuous or pulsed also affects the outcome to some extent.
Comparison with traditional methods
Traditionally, people used mercury lamps or chemical methods like chlorination and ozonation for water disinfection. But the UVC LED outperforms these two and has a large market share.
Compared with the mercury uv light lamp, UVC LED defeats it because it is environmentally friendly and has a higher quality. Mercury is harmful to our health, and once the lamp breaks down, there are few ways to handle the remaining mercury. Besides, a mercury lamp is usually big in size, while the UVC LED is super compact. It is important for water disinfection since the size of mercury lamps may be too large to install in the system. Mercury lamps need to be heated up, which is a step skipped by UVC LED users since they can start working at once. As for the lifespan, UVC LEDs can last much longer than mercury lamps. The service life of mercury lamps is about 1000-2000 hours, while that of a UVC LED can go beyond 10000 hours. These many reasons all show that a UVC LED is more worthy of purchase.
One fatal weakness of chemical methods is their safety. While these chemicals are effective in killing the microbe, they may also linger in the water we are drinking and cause side effects. Moreover, microbes can gradually become resistant to these chemicals, making it more difficult to eliminate them. Nowadays, experts are considering combining UVC disinfection with the chemical method. And the chemical disinfection methods generally take 20 minutes to an hour to achieve the bactericidal effect. UVC LED is more efficient than that.
2. Air disinfection
HVAC is a popular concept in interior design. It stands for heating, ventilation, and air conditioning. By adding a UVC LED to this system, the purpose of killing bacteria and viruses can be achieved. In addition, UVC has a unique photolysis effect. It can decompose the odor molecules and turn them into ordinary water molecules and carbon dioxide, thereby freshening the air.
UVC air sterilization and disinfection can also be used on any equipment that needs fresh air. Refrigerators without UVC LED sterilization modules have a natural bacterial attenuation rate of 30%, and after using UVC LED, it increases to 85%. This improves the preservation ability of the refrigerator to a great extent.
3. Surface disinfection
For now, UVC LED has been put in use in some public vehicles to kill the microbe, like planes and subways. It is quite troublesome to use traditional methods, which require the staff to wipe the seats with a sanitizer. With UVC LED, disinfection can be more convenient and efficient.
Another common use of UVC LED is in the food processing industry. Before, people used pasteurization to kill the microbe. But as it is a thermal method, it is not suitable for all kinds of food. The UVC LED is a cold light source and emits little heat. It is suitable for sterilizing those fresh foods and won’t destroy their nutrition or change their flavor.
Places to use UVC LED
Because of this unique function of UVC light, people manage to use it either in their daily life or other technical fields. Places where you may find the UVC LED include:
It can be used to sterilize wards, such as pediatric wards and infectious disease wards, to reduce cross-infection. Since there will be many pathogens floating in the air, UVC lights keep the wards sterile and help the patients recover. When installed at the door, it prevents the bacteria from spreading to other areas.
Some places, like aseptic workshops, food processing workshops, and storage rooms, require a sterile environment. Therefore, people use UVC LEDs that have obtained certifications to eliminate the hidden bacteria.
Schools are crowded with students. During the seasons when diseases like influenza happen frequently, it is necessary to implement an overall disinfection program in the school. It is convenient to use UVC LED in separate classrooms, thus reducing the morbidity of the students.
4. Public buildings:
It is common for many companies to rent offices in one public building. In order to make the public workplace a finer place, people install the UVC LED in the ducts to send sterile air into the room. This is one of the uses of UVC LEDs in the HVAC system.
Books are valuable but also vulnerable. So the UVC LED works to sterilize the libraries and protect books from mildew and insects.
The UVC LED is used to keep furniture, floors, and the air in your house safe and clean. It is easy to use because of its compact size.
People also use the UVC LED in other places like subway stations, carriages, and underground passages. As long as there is a place that has requirements for sterilization, UVC LED can be a considerable choice.
How do I choose a UVC LED?
People have managed to produce UVC light in LEDs using sapphire substrates and aluminum nitride. Besides the change in semiconductors and substrates, other parts of an LED light are also designed for a stronger UVC light. The following content can help you understand several structures of a UVC LED before purchasing it and perhaps identify fake ones.
1. Chips structure
Nowadays, most LED lights on the market use flip chips, but it is not necessarily the best structure for UVC LED. Chips with a vertical structure can expand the current better, absorb less light, and dissipate less heat, making them a better choice. Yet the technique to produce vertical chips is not so mature; now it is a bit hard to produce them on a large scale.
For packaging, the UVC LED is very different from a common LED. There are two reasons. First, most of the traditional packaging materials absorb UVC light, which greatly reduces its intensity. Thus, only high purity silica glass and sapphire are practical as packaging materials. Second, we also need to consider whether the die bonding method is helpful for heat dissipation. The methods include silver paste, solder paste, and gold-tin eutectic soldering. Among them, the eutectic method is mainly soldered by flux, which can relatively improve the bonding strength between the chip and the substrate. The thermal conductivity is more reliable and is conducive to the development of UVC LEDs.
3. Light efficiency
Because of the limitations of semiconductors that produce UVC light, UVC LED has not yet achieved the best light efficiency. To find a UVC LED with a higher efficiency, try to choose a UVC LED with more LED beads.
Always remember, there isn’t any UVC device that is 100% safe. UVC light is the most powerful of the three types of UV light. It can do damage to our eyes and skin, and even our DNA, under certain circumstances. You need to know the precautions and protect yourself while using it. Therefore, once you find some UVC producers who claim that their UVC products are totally safe, you can be sure their products are fake.
Mokolight is a professional LED manufacturer with a robust team of engineers, sales staff, and purchasers. We also have our own factories to produce and package our LED products. We have worked for more than 16 years in the LED industry and are confident that you can rely on us to find the best product you want. Don’t wait anymore and Contact Us today!