Ultraviolet (UV) radiation has been used for many years in the industrial and health field. Nowadays, the new generation of LED appears to be challenging traditional sources of UV fluorescent lamps.

1.What is the wavelength range of UVC LED?

The UVC LED wavelength is usually defined as 200nm to 280nm.

2.What is the “sterilization range” of ultraviolet light?

According to the International UV Association, “The ultraviolet spectrum (‘sterilization’ area), that is very important for the disinfection of water and air, and is a range that is absorbed by DNA (RNA in some viruses). The sterilization range is about 200-300nm”.

It is known that the bactericidal range extends over 280nm. And now, it is generally considered to extend to 300nm. However, this may also will be changed with more research. Scientists have demonstrated that UV light with wavelength between 280nm and 300nm can be used foe disinfection and sterilization.

3.What is the best wavelength for disinfection?

There is a misreading that 254nm is the best wavelength for disinfection. Because the peak wavelength of the low pressure mercury lamp (only determined by the physics of the lamp) is 253.7nm. It is generally recognized that the wavelength of 265nm is to be optimal. Because this wavelength is the peak of the DNA absorption curve. However, a range of wavelength has a disinfecting and sterilizing effect.

4.Why do the ultraviolet mercury lamps have been considered the best choice for disinfection and sterilization?

Historically, mercury lamps have been the only one choice for disinfection and sterilization. With the advancement of UV LED technology, we have new options. Because LED is small, more powerful, non-toxic, long life, more energy efficient, and allows more switching times. That makes the solution simply, battery powered, more portable, and capable of instant full light output.

5.What are the different wavelength characteristics of UVC LED and mercury lamp?

The low pressure mercury lamp emits almost monochromatic light with a wavelength of 253.7nm. The low pressure mercury lamp and the high power mercury lamp are both used for disinfection and sterilization. These lamps have a broader spectral distribution, including wavelength of sterilization. UVC LED can be focus on a narrow, specific wavelength, which allows the solution to be tailored to the specific application needs.

6.Does the peak absorption wavelength of DNA vary with bacteria?

Yes. Different types of peak absorption wavelength are indeed different, but most of them are around 265nm.

7.Can a single wavelength destroy all bacteria?

Yea, a single wavelength can be used. However, bacteria has different optimal absorption wavelength.

8.How to ensure the sterilization effect?

Generally speaking, the bacteria effect is determined using power intensity, wavelength, duration of exposure. For example, in water, there may be many bacteria with different optimal absorption wavelength. For bactericidal ultraviolet light of any settled wavelength, the power and time of irradiation need to be calculated to achieve the desired level of disinfection.