UV-C LEDs: an effective solution to fight against COVID-19? – An interview with Piséo

UV light sterilization

The current health crisis is causing extremely high demand for disinfection solutions. Among these, devices using UV-C radiation are experiencing renewed interest. There is a lot of communication on this subject from involved industry actors. New LED sources of UV-C radiation have been put forward for the treatment of Covid-19.

According to Yole Développement, in 2019, the UV-C LED market was rather small, reaching $108M. However, in an attempt to respond to growing concerns about the spread of the virus several companies have started to use UV light to eradicate any possible germs and deal with the pandemic. This will have a positive impact on the market in 2020. Piséo is a company that is expert in optical radiation and the implementation of LEDs and applicable regulations. Piséo is very much in demand to bring its expertise to bear on the use of UV-C LED for the treatment of Covid-19.

Pierrick Boulay, Market and Technology Analyst in the fields of Solid State Lighting and Lighting Systems at Yole Développement, asked Joël Thomé General Manager & Innovation Consultant at Piséo the relevance of using UV-C LEDs for the disinfection of places contaminated with Covid-19. Discover the details of their exchange below.

Pierrick Boulay: Could you introduce yourself and your company?

Joël Thomé: I’m Joël Thomé, director of Piséo. Piséo is a France-based innovation center specializing in the design and characterization of illumination, detection and imaging systems.

PB: Could you explain the core activities of Piséo, its business model and position in the supply chain?

JT: Created eight years ago, Piséo is an independent organization that supports companies’ innovation processes by offering analysis, design, simulation and prototyping services, as well as optical metrology tests. We also work on existing systems to optimize them. Our experts come from the industry and have skills in physics, optics, electronics and mechatronics. They work on all types of applications including healthcare, automotive, surveillance and lighting. Piséo also owns an accredited laboratory for photometry tests and photobiological risk assessment of light sources.

PB: Piséo has strong skills in understanding optical radiation. Can you explain how UV-C can be used for disinfection and its interest for the treatment of Covid-19?

UV radiation over electromagnetic spectrum (Courtesy of Piséo)

JT: UV refers to ultra-violet electromagnetic radiation close to the visible light radiation. It is characterized by wavelengths expressed in nanometers, nm, which range from 100 to 400nm. UV-C has wavelengths between 200 and 280nm. It is among the most energetic and can be absorbed by organic materials. Depending on the dose, this radiation causes chemical breakdown within the material as can be seen, for example, in automotive headlight plastics, which become opaque over time. In humans UV-C can damage skin, potentially causing serious lesions or even long-term cancer. According to scientists, UV rays that are most harmful to humans are between 270 and 280 nm. However, it is this phenomenon which is interesting for disinfection because, like all living organisms, bacteria and viruses are sensitive to UV-C. Studies showed more than 40 years ago that by applying an appropriate dose of UV-C radiation the population of these microorganisms can be considerably reduced. We speak of the germicidal effect of UV radiation which, when the amount of energy supplied is sufficient, breaks the chemical bonds inside organic molecules of DNA or RNA, thus neutralizing the reproduction of microorganisms. Covid-19, like all viruses, can therefore be neutralized under suitable UV-C radiation.

PB: So what are the energy doses, the UV spectrum and the time required to destroy the Covid-19 virus?

JT: To our knowledge, there is not yet any precise data as to the effects of UV rays on the Covid-19 virus in particular. On the other hand, a study carried out in the United States and published in 2018 shows that a dose of 1J/cm2 would be sufficient to reduce a population of H1N1 type coronavirus on contaminated masks by 99.9%. This study was carried out under UV-C radiation at 254nm typical of a low pressure mercury vapor discharge lamp type source. In addition, Seoul Viosys and SETi’s Violeds, two Korean industrialists, have succeeded with UV-C LEDs in reducing 99.9% of a population of Covid-19 virus on a surface in 30 seconds with a dose of 1J/cm2. Although LED radiation’s wavelength is 275nm and the test conditions are not specified, these results corroborate those of other studies carried out on coronaviruses and are encouraging for the use of UV-C LEDs in the fight against Covid 19.

PB: So UV-C LEDs could be a solution for Covid-19?

JT: Yes, provided that these components are used correctly to provide the required dose because UV-C LEDs are recent components whose performance is still quite low. The best UV-C LEDs on the market today are approximately 10% efficient. This means that only 10% of the electrical power used is converted into UV-C radiation. This value should be compared with the 40% to 50% efficiency currently observed for UV lamps. The 90% of the electrical power which is not used to produce radiation is transformed into heat, which must be evacuated. When designing the complete system, engineers must also take into account the way in which the radiation is emitted by the LED component. The current performance of UV-C LEDs and their optical characteristics therefore make it necessary to use a large number of components, to distribute them fairly densely on an electronic circuit, as well as to bring them sufficiently close to the surface to be treated to obtain the germicidal effect sought within an acceptable time. This is what the experts at Piséo were able to conclude further to the analyses and design work they carried out recently on disinfection systems linked to Covid-19. In addition, the prospects for efficiency are rather promising because an American laboratory showed recently that it was possible to reach around 40% by using a silicon carbide substrate.

PB: We know that UV-C radiation is dangerous and that the use of LEDs requires processing precautions. Are there regulatory provisions that apply to ensure user protection and tests to verify the safety of products incorporating UV-C LEDs for disinfection?

Photobiological risk assessment of a light source at Piséo

JT: Yes, but we must distinguish uses for domestic use from those for professional use for the disinfection of hospital premises, for example. In this case, it is a question of protecting the workers using disinfection machines. In Europe the provisions of Directive 2006/25/EC supplemented possibly by local laws apply. Domestic use falls under Directive 2001/95/EC on general product safety. For the application of these two directives, the reference standard for measurement and exposure limit levels is EN 62471, the European equivalent of IEC 62471, which takes UV-C radiation into account. There is currently a proliferation of announcements of new products using UV-C. It is important to remember here that marketers have a legal obligation to assess the level of risk of the products they market. They must comply with the legislation on authorized risk levels and user information. Piséo’s laboratory being accredited for carrying out these tests, we can advise manufacturers on these regulatory aspects.


Joel Thomé is General Manager & Innovation Consultant at PISEO. In collaboration with Yole Développement’s team, Joel Thome performs numerous technical and market analyses focusing on Photonics based solutions, in addition to developing innovative optical solutions with PISEO’s R&D team. With a Master’s Degree in mechanical engineering, Joel has been working in the lighting industry for more than 25 years. After beginning his career at Philips Lighting, he has recently held various global business, marketing and R&D senior management positions. During this period he developed strong expertise in lighting controls, LED technology and innovation processes including general management, strategic roadmapping and product portfolio management.


As part of the Photonics, Sensing & Display division at Yole Développement (Yole), Pierrick Boulay works as Market and Technology Analyst in the fields of Solid State Lighting and Lighting Systems to carry out technical, economic and marketing analysis. Pierrick has authored several reports and custom analysis dedicated to topics such as general lighting, automotive lighting, LiDAR, IR LEDs, UV LEDs and VCSELs.
Prior to Yole, Pierrick has worked in several companies where he developed his knowledge on general lighting and on automotive lighting. In the past, he has mostly worked in R&D department for LED lighting applications. Pierrick holds a master degree in Electronics (ESEO – Angers, France).


UV LEDs – Technology, Manufacturing and Application Trends 2018
Within three to four years, disinfection applications will reinvigorate the UV LED market

Source: http://www.yole.fr, http://www.piseo.fr

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