A New Tool for Sterilisation of Surfaces & Materials

It has been known since the mid-20th century that UVC light can be used effectively for sterilisation purposes in many varied sectors such as healthcare, food production and wastewater treatment, and has been trialled for treating medical equipment (1). The technique of disinfecting areas using UVC light is called Ultraviolet Germicidal Irradiation (UVGI).

At the peak of the Covid-19 pandemic Personal Protective Equipment (PPE) became seriously in short supply worldwide. Recycling used PPE using sterilisation became a real option making it safe to reuse (2).

Traditionally mercury low vapour pressure discharge lamps have been used for UVGI procedures. However, these lamps suffer from significant disadvantages, one of which is particularly important at this juncture. 

Namely, that mercury is a toxic substance with considerable negative influence on human and environmental health and is a substance banned by the United Nations since 2013 for use in any equipment. Very significantly, this ban is due to come into effect as of 2020 (3) (4). For this reason, mercury containing products have long been difficult and costly to dispose of. Other disadvantages of mercury lamps for UVGI include:

  • a fixed wavelength of 254nm, whereas scientific evidence indicates that 260-280nm is the optimum UV wavelength for sterilisation of viruses (5)
  • mercury lamps are tubular and radiate in all directions, reducing irradiation of planar targets
  • available only in tubular form with standard fixed lengths; the tubes are fragile
  • long warm-up time and reduced efficiency at low temperatures
  • high energy consumption, short in-service life further reduced by high number of on/off cycles

UVC-LED Solution

For the reasons outlined above alternative UVC-emitting sources for powering new lamp designs are needed to replace the now out-dated and unfavoured mercury lamps. The only other viable and available source of UVC light with the appropriate wavelength for UVGI is the newly developed short wavelength LED lighting (UVC-LED). UVC-LED light covers the UVC wavelength of 200-280nm and is totally dissimilar to the LED lighting used for visible wavelength ranges. Note: UV wavelengths extend from 100–400 nm and the visible spectrum from 400–700 nm. Ever improving UVC-LED technology has enabled the development of LED diodes that emit UVC light at a wavelength best suited for disinfection and, specifically the 260-280nm range, the most effective germicidal wavelength range.

Prolux UVC-LED Strips and Assemblies

Addlux supplies Prolux LED strip lighting in kit form to the market for use in many varied standard lighting applications. Addlux reacted to the outbreak of COVID-19 and commenced developing a new version of Prolux UVC-LED strip adjusted to the appropriate wavelength for sterilisation purposes.

This version is now available for use and research to understand:

  • the duration of UVC dosage needed for sterilisation of various materials and surfaces
  • shadowing effects where multiple layers of material are involved
  • degradation of materials occurring with high UVGI doses

Addlux can also assist in the design and manufacture of unique lamp configurations for sterilising more complex shaped equipment. 

If you are interested in more information about Prolux UVC-LED or require design assistance please contact us on 0333 800 1828.

References

(1) Reed, N. G. The History of Ultraviolet Germicidal Irradiation for Air Disinfection. Public Health Rep. 125, 15–27 (2010).

(2) Lindsley, W. G. et al. Effects of Ultraviolet Germicidal Irradiation (UVGI) on N95 Respirator Filtration Performance and Structural Integrity. J. Occup. Environ. Hyg. 12, 509–517 (2015).

(3) Cheng, Y. et al. Inactivation of Listeria and E. coli by Deep-UV LED: effect of substrate conditions on inactivation kinetics. Sci. Rep. 10, 3411 (2020).

(4) Kim, D.-K. & Kang, D.-H. UVC LED Irradiation Effectively Inactivates Aerosolized Viruses, Bacteria, and Fungi in a Chamber-Type Air Disinfection System. Appl. Environ. Microbiol. 84, (2018).

(5) Umar, M., Roddick, F. & Fan, L. Moving from the traditional paradigm of pathogen inactivation to controlling antibiotic resistance in water - Role of ultraviolet irradiation. Sci. Total Environ. 662, 923–939 (2019).