Objective of the report 7

Summary 13

Introduction 14

UV radiation 15

• UV spectrum
• Propagation and biological effects of UV radiation
• Main applications and niche markets

Main applications of UV-C radiation 19

• Disinfection / purification of water
• Disinfection / purification of air
• Disinfection of surfaces and objects
• Analytical instruments
• Other application of UV-C radiation

Disinfection by UV-C radiation                    39

• UV-C radiation disinfection mechanism
• Fundamental quantities
• Benefits of disinfection by UV-C radiation
• Risks of disinfection by UV-C radiation

UV-C light sources                                 69

LED UV-C v. mercury vapor lamp                83

• Benefits of LED UV-C v. mercury vapor lamp
• Weaknesses of LED UV-C v. mercury vapor lamp
• LED UV-C : perspectives

LED UV-C technology           96

DISINFECTION BY UV-C RADIATION

The disinfection ability of UV-C radiation, known for several decades, is no longer to be proven and its germicidal effect is thus used for applications of disinfection and purification of water, air and surfaces.

However, the use of UV-C radiation for disinfection requires knowledge, in particular to determine the necessary dose for the inactivation of a microorganism (the dose depending on a certain number of parameters related to the application, to the environment, etc.), but also in order to take into account the risks associated with the use of this technology.

Indeed, the use of UV-C radiation for disinfection presents two major risks: a photo-biological risk (UV-C radiation is dangerous for humans) and a risk of ineffective disinfection (in the case of a disinfection system which has not been designed correctly in relation to its application).

UV-C LED TECHNOLOGY AND MARKET

The technology traditionally used as a source of UV-C radiation is the mercury lamp. In recent years, manufacturers have put UV-C LEDs on the market, this fairly recent technology offers unique advantages (robustness to on/off cycles, does not contain mercury, compactness, etc.) allowing improvements compared to existing systems, but also opportunities for new applications.

The current low performance and high price are the main brake to wider adoption of UV-C LEDs by the UV-C disinfection market today

However, the analysis of the portfolio and roadmaps of UV-C LED manufacturers confirms the trends observed for several years: a rapid and regular drop in prices and a significant increase in performance (power and efficiency), which should allow UV-C LED to establish itself in the field of disinfection by UV-C radiation, at mid or long term depending on the applications.

UV-C LED technology is more complex than visible LED technology and the market is currently quite small, so there are not so many UV-C LED manufacturers. Late 2019 / early 2020 some major manufacturers have even left the UV-C LED market.

DESIGN AND IMPLEMENTATION OF UV-C LED SYSTEMS FOR DISINFECTION

The design phase of a disinfection system is key to ensure that the microorganism receives the required dose to render it inactive. Concretely, the aim of the design phase is to define the parameters of the UV-C source from the required dose, application parameters (exposure time, size of the target to be treated, etc.) and optical parameters (uniformity, attenuation due to the distance between the source and the target…).

The integration of UV-C LEDs has more constraints than for LEDs in the visible range: UV-C radiation degrades materials usually used for optical systems in the visible, the low efficiency of UV-C LEDs has an impact on its thermal integration …

The replacement of the mercury lamp by the UV-C LED in existing systems is not trivial, for instance the design of a reactor used for disinfection / purification of water must be reworked to be adapted to the properties of LED (optical emission, thermal management, etc.).

REGULATIONS AND STANDARDIZATION

With the Covid-19 epidemic, many UV-C products, mainly for surface disinfection, are appearing on the market. The current regulations and standards cover the safety aspects related to the use of these devices, but do not cover the disinfection aspect (no defined test process that would allow the performance of products to be compared in terms of disinfection, etc.).

For now, manufacturers of disinfection systems generally rely on scientific publications and have their products tested by microbiology laboratories as a guarantee of the quality of their product in terms of disinfection. However, even a laboratory test is not a guarantee for the user, as the test conditions may be different from the conditions of use (type of surface, etc.).

Eventually, faced with the photo-biological risk, countries have decided to ban the sale and use of UV-C disinfection products outside the medical environment.

Acuva, AquiSense Technologies, Bolb, Corning, Cree, Crystal IS, Dietal, Dowa, Everlight, GoodFellow, HCEN, Hexatech, Hönle, Hytecon, Hyundai, KnightOptical, KoppGlass, Ledil, LG-Innotek, Lite-On, Lumileds, Luminus, MetaWater, Nichia, Nikkiso, Osram, Phoseon Technology, Purion, QD Jason, RayVio, Samsung, San’an Optoelectronics, SeoulViosys, Seti, Signify-Philips, Stanley, Sterilway, Typhon Treatment System, Ushio, UV Photonics, UVRER, Violumas, Watersprint, Yole Développement