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UV LEDs for disinfection and sterilization from ILS

With the ongoing COVID-19 pandemic, the awareness around ultraviolet (UV) technology for disinfection and sterilisation has increased dramatically. Although the germicide effects of UV light have been recognized for over 100 years, it appears that now more than ever we need to utilize this technology to help to stop the spread of the infection.

When it comes to selecting the appropriate UV light technology for disinfection and sterilization, the customers have two options: LEDs and lamps. Historically, mercury lamps have been the only available technology. However, the field of UV LEDs has been evolving in recent years allowing the implementation of compact, battery-operated disinfection systems.

Unfortunately, the germicidal effectiveness of UV light is limited to a certain wavelength range. According to the International Ultraviolet Association (IUVA), the portion of the UV spectrum that is most effective against germs in water and air is the range between 200nm and 300nm. This corresponds to the UV-C as well as some of the UV-B range, which is often referred to as “germicidal UV” light. Within this range, the UV light can penetrate the cells of microorganisms and disrupt their DNA and, thus eliminating their ability to multiply and cause disease.

Electromagnetic spectrum

Here, we also need to define the difference between disinfection and sterilization processes. Disinfection involves decreasing the number of pathogens as opposed to killing all the microorganisms during the sterilization. UV system designers usually tend to have a certain target for the germicidal effectiveness, which is measured as a logarithmic reduction of germs, i.e. 1-log = 90 %, 2-log = 99 %, 3-log = 99.9 %., etc.

But what is the optimal wavelength for disinfection and sterilization?

Well, there is no simple answer, since it depends on what type of bacteria, virus, or other pathogens that are being targeted. Each microorganism has a related action spectrum that demonstrates how much UV light they absorb at different wavelengths in a graphical form. In most literature, the action spectrum is referred to as the “germicidal effectiveness curve”. The peak of that curve corresponds to complete inactivation and tends to be unique for each pathogen. The peak wavelength for inactivating E. coli [1], for example, is proven to be around 265nm, whereas Bacillus subtilis [2] and Cryptosporidium parvum oocysts [3] require 270nm and 271nm, respectively. Moreover, the medium (water, air, or surface) might have multiple types of pathogens present.

Germicidal effectiveness curve for E.coli compared to UV-C LED emitting at 265nm (From Ultraviolet Germicidal Irradiation Handbook, Fig. 5.5)

What does affect the effectiveness of UV disinfection?

Short answer: wavelength and UV dose. Let me explain why.

The amount of UV light applied over a certain period to disinfect a specific area is called a UV dose. The UV dose is a function of UV light intensity and exposure time. The parameter is commonly measured in mJ/cm2 and varies significantly between different germs. The full list of dosage requirements for 4-log inactivation of various bacteria, protozoa, viruses, and algae is published in this review by IUVA.

UV dose required for 4-log inactivation by various germs

The intensity of UV light is dictated by the power output of the light source. The germicidal power of the light source, however, might be lower than the power generated by the LEDs. To estimate the value of germicidal power most accurately, it is recommended to compare the output light spectrum of the device to the germicidal effectiveness curve of an individual germ.

Exposure times tend to vary greatly depending on the application. For example, static systems (surface or accumulated water sterilization) will have longer exposure times than dynamic systems (circulating air or flowing water sterilization). The same dosage can be achieved by increasing exposure time and decreasing the light intensity.

If it all sounds confusing at this point, let’s consider some practical examples of UV LEDs from Intelligent LED Solutions (ILS).

ILS offers a wide selection of UVB & UVC LED solutions based on N3535 and N5050 series of UV LEDs from TSLC. To start with, they have been categorized according to the three different wavelength ranges: 260–270nm, 270-290nm, and 300-320nm. As has been discussed previously, the germicidal effectiveness of UV disinfection is sensitive to the wavelength and output power of the light source. By having the option of selecting the most optimal wavelength range, the designers have more flexibility around satisfying the power requirements for obtaining the desired level of disinfection. Furthermore, there are three different primary lens options (60°, 90° or 130°) providing control over the light distribution over the target area. And lastly, most models (except for PowerStar) have an equivalent low power alternative for applications where exposure time can be extended.

A compact UV LEDiL Selector offers 25-60mW of radiometric power at 350mA for three wavelength ranges and beam angles. This light source can be used in conjunction with LEDiL lenses to focus the light from greater distance into the area of interest. The UV LEDiL Selector is compatible with the ROSE (201-7701) lens. These lenses are made of optical grade silicone that can withstand UV light in the UV-B and UV-A wavelength ranges.  

UVB & UVC N3535 UV LEDiL Selector

UV LEDiL Selectors

λ (nm)

Lens

MPN

RS Stock number

Minimum Radiometric Power (mW) @350mA

260nm

±60° lens

ILR-XN01-S260-LEDIL-SC201

(201-7457)

25mW

270nm

±60° lens

ILR-XN01-S270-LEDIL-SC201.

(201-7458)

40mW

300nm

±60° lens

ILR-XN01-S300-LEDIL-SC201.

(201-7459)

60mW

260nm

±90° lens

ILR-XO01-S260-LEDIL-SC201.

(201-7461)

25mW

270nm

±90° lens

ILR-XO01-S270-LEDIL-SC201.

(201-7473)

40mW

300nm

±90° lens

ILR-XO01-S300-LEDIL-SC201.

(201-7474)

60mW

260nm

±130° lens

ILR-XP01-S260-LEDIL-SC201.

(201-7475)

25mW

270nm

±130° lens

ILR-XP01-S270-LEDIL-SC201.

(201-7477)

40mW

300nm

±130° lens

ILR-XP01-S300-LEDIL-SC201.

(201-7478)

60mW

 

Similarly, N5050U 1-chip UV LED-based light source solution in PowerStar configuration (201-7445) is available for a wavelength range from 270 to 290nm. The unique PCB shape is designed to match industry-standard Zhaga footprint making this light source compatible with a large array of heat sinks and holders.

N5050 Power Star

Single packaged LEDs such as UV LEDiL Selector might not produce enough optical power required for the disinfection of larger areas. A cluster of four and more LEDs are more suitable for that purpose. 4 UV SCOBs support 100-240mW of radiometric power and compatible with ALISE (201-7691) reflectors and ZORYA (201-7703) lenses from LEDiL. The PCB is made of highly reflective, yet cost-effective material (aluminium), whereas the lenses allow the implementation of uniform distribution of the light in confined spaces.

N3535 UV 4 SCOB

4 UV SCOBs

λ (nm)

Lens

MPN

RS Stock number

Minimum Radiometric Power (mW) @350mA

260nm

±60° lens

ILO-XN04-S260-SC201

(201-7462)

100mW

270nm

±60° lens

ILO-XN04-S270-SC201

(201-7463)

160mW

300nm

±60° lens

ILO-XN04-S300-SC201

(201-7464)

240mW

260nm

±90° lens

ILO-XO04-S260-SC201

(201-7468)

100mW

270nm

±90° lens

ILO-XO04-S270-SC201

(201-7469)

160mW

300nm

±90° lens

ILO-XO04-S300-SC201

(201-7470)

240mW

260nm

±130° lens

ILO-XP04-S260-SC201

(201-7439)

100mW

270nm

±130° lens

ILO-XP04-S270-SC201

(201-7440)

160mW

300nm

±130° lens

ILO-XP04-S300-SC201

(201-7441)

240mW

 

The largest cluster of UV SCOBs contains 9 LEDs and provides 225-540mW of power at 1050mA. ALISE and ZORYA are also the perfect fit for this light source, except for larger diameter versions where ALISE (201-7676) (201-7680) reflectors will be required.

N3535 UV 9 SCOB

9 UV SCOBs

λ (nm)

Lens

MPN

RS Stock number

Minimum Radiometric Power (mW) @1050mA

260nm

±60° lens

ILO-XN09-S260-SC201

(201-7465)

225mW

270nm

±60° lens

ILO-XN09-S270-SC201

(201-7466)

360mW

300nm

±60° lens

ILO-XN09-S300-SC201

(201-7467)

540mW

260nm

±90° lens

ILO-XO09-S260-SC201

(201-7471)

225mW

270nm

±90° lens

ILO-XO09-S270-SC201

(201-7472)

360mW

300nm

±90° lens

ILO-XO09-S300-SC201

(201-7438)

540mW

260nm

±130° lens

ILO-XP09-S260-SC201

(201-7442)

225mW

270nm

±130° lens

ILO-XN09-S260-SC201

(201-7443)

360mW

300nm

±130° lens

ILO-XN09-S270-SC201

(201-7444)

540mW

 

Last but not the least, UV VIOLET strip with 12 LEDs provides up to 720mW of radiometric power and has been designed to fit LEDiL’s VIOLET (201-7709) lens array. Lens and metal frame of VIOLET lens array is made from highly resistant UV materials.

UV VIOLET strip

VIOLET lens array from LEDiL

UV VIOLET strip

λ (nm)

Lens

MPN

RS Stock number

Minimum Radiometric Power (mW) @350mA

260nm

±60° lens

ILS-XN12-S260-0280-SC201-W2

(201-7483)

300mW

270nm

±60° lens

ILS-XN12-S270-0280-SC201-W2

(201-7484)

480mW

300nm

±60° lens

ILS-XN12-S300-0280-SC201-W2

(201-7485)

720mW

260nm

±90° lens

ILS-XO12-S260-0280-SC201-W2

(201-7486)

300mW

270nm

±90° lens

ILS-XO12-S270-0280-SC201-W2

(201-7487)

480mW

300nm

±90° lens

ILS-XO12-S300-0280-SC201-W2

(201-7488)

720mW

260nm

±130° lens

ILS-XP12-S260-0280-SC201-W2

(201-7489)

300mW

270nm

±130° lens

ILS-XP12-S270-0280-SC201-W2

(201-7490)

480mW

300nm

±130° lens

ILS-XP12-S300-0280-SC201-W2

(201-7491)

720mW

 

To complete your UV-C disinfection solution, consider the vast selection of LED Drivers from OSRAM and ILS.

The design of a UV light system for disinfection is a complex process with numerous variables. For specific design-related questions, we would like to ask you to directly contact our partner, Intelligent LED Solutions (ILS).

Disclaimer: DesignSpark/RS Components/ILS did not find scientific evidence to prove the efficacy of UVC LEDs against COVID-19. Please follow this facts sheet from IUVA for their expert opinion.

[1] IESNA. 2000. Lighting Handbook: Reference & Application IESNA HB-9-2000. New York: Illumination Engineering Society of North America.

[2] Waites WM, Harding SE, Fowler DR, Jones SH, Shaw D, Martin M. 1988. The destruction of spores of Bacillus subtilis by the combined effects of hydrogen peroxide and ultraviolet light. Lett Appl Microbiol 7:139–140

[3] Linden KG. 2001. Comparative effects of UV wavelengths for the inactivation of Cryptosporidium parvum oocysts in water. Wat Sci Technol 34(12):171–174.

Hi there! I am an Applications Engineer with the Technical Marketing team at RS Components. I am originally from Kazakhstan and graduated from Nazarbayev University with BEng and MSc degrees in 2017 and 2019, respectively. I create electronics projects, technical articles and videos on DesignSpark. In my spare time, I love learning new languages, travelling and blogging.

11 Jun 2020, 9:07

Comments

June 29, 2020 14:39

This recent paper in Nature Scientific Reports may be relevant to your projects:

Far-UVC light (222nm) efficiently and safely inactivates airborne human coronaviruses. Buonanno, M., Welch, D., Shuryak, I. et al. Sci Rep 10, 10285 (2020). https://doi.org/10.1038/s41598-020-67211-2
https://www.nature.com/articles/s41598-020-67211-2

0 Votes

June 15, 2020 07:27

Are these available for sale to the US?

June 23, 2020 15:32

@XiaoyuZou yes, these products are available in the US. Stock numbers will be different for every region, but you will find the exact products if you search by the manufacturer (Intelligent LED Solutions).