By Rich Simons, Ph.D.; Oliver Lawal; and Jennifer Pagán, Ph.D., AquiSense Technologies
This article presents a view of the UV-C LED device and systems market from a system manufacturer perspective and includes current deployment of the technology that may not be presently in the public sphere. The intent is to state plainly, and without hyperbole, what is visible to an active player in UV-C LED technology and to provide a point of reference for wider industry professionals and policy makers.
Deployment of UV-C LEDs, and products containing them, continues to follow an exponential growth curve. Overall, the authors calculate a 39% CAGR in commercial single-chip LED output power from 2005 to 2022; exceeding Haitz’s Law over this period. As such, published data rapidly falls out of date as the state-of-the-art advances at a rapid pace.
Though references are not provided for all claims due to their commercially sensitive nature, the authors endorse the validity of the claims made within this document based on the authors’ expert knowledge, internal and third-party data, together with knowledge of an active customer base.
Standalone UV-C LED device overview
UV-C LEDs generate UV photons via the electroluminescence of a semiconductor crystal; these semiconductors crystals most commonly are formed of AlGaN compounds, grown on sapphire or AlN substrates. These solid-state devices have no mercury content and do not depend on other substances subject to environmental restrictions; as such, they may offer a regulation-proof alternative to conventional mercury-containing UV lamps.
Early devices only were available in “TO-can” format, comprising a metal case and integrated window. Over the last decade, a number of advancements have allowed the transition to more efficient and cheaper surface mount device (SMD), chip-on-submount (CoS) and chip-on-board (CoB) packages for single- and multi-chip emitters. Requiring low voltages typically in the 5 to 30 VDC range, having package sizes in the range 1 to 15 mm and emission powers of 10 to 200 mW (ref: Nichia, 2021 also; Bolb, 2018, Violumas, 2020, and Crystal-IS, 2021), modern UV-C LEDs offer a high-power density light-source option. Many technologies exhibit sequential evolutionary curves, with newer designs showing a slow development rate in their early phases followed by rapid advancement and a plateau in maturity. This can be seen with UV-C LED technology in Figure 1 with the largely redundant TO-can format; the present-day intersection between SMD and CoS also can be seen developing since 2016.
The combination of better manufacturing processes, higher production volumes of both the LED chips (dice) and improved device packaging has resulted in rapid and sustained cost reductions; modern UV-C LEDs are available at volume pricing on the order of 0.1 USD/mW (ref: LEDs magazine, 2020), a marked improvement on early devices (~1000 USD/mW). As with most components, it should be noted that UV-C LED unit prices from electronic components resellers are obtainable more easily by authors of industry reports, but rarely are representative of true pricing provided to original equipment manufacturers (OEMs) for mass production.
Thermal management is a key consideration when using UV-C LEDs in real-world applications. Most importantly, devices installed with inadequate thermal control can experience rapid degradation in output power during operation. The real-world operational lifetime of UV-C LEDs varies widely between manufacturers, models, thermal environments and operational drive currents. Though some devices on the market still experience rapid degradation over the course of hundreds of hours, several devices have been demonstrated to achieve L80 performance in the 10,000+ hr range whilst operating in real-world conditions (e.g. commercial lamp platforms, high drive currents, non-climate controlled environment).
Whereas laboratory devices have demonstrated efficiencies (electrical power in vs. UV power out) in excess of 10% (ref: Amano et al., 2020), the efficiency of mass production devices remains relatively low (3.5% to 6%) and is not yet directly competitive with conventional UV lamp technology in this way. However, a key benefit of semiconductor technology is the ability for near instantaneous power cycling (0 to 100% output) without loss of lifetime or efficiency. In certain applications, UV-C LED systems may offer higher operational efficiency by using control systems that ensure no power consumption during latency periods; an obvious example of this would be in a water cooler/dispenser product. Direct comparison of the electrical efficiencies of LED and Hg technologies also disregards the fate of photons emitted by the UV source, since the efficiency with which the UV power is used (reactor efficiency) plays into overall cost competitiveness of such systems. Whereas conventional UV lamps are restricted to conventional form factors, the small size of UV-C LED emitters and their low-voltage DC power requirements mean that they can be arrayed and positioned in novel reactor designs. Maximizing device efficiency and use of considered operational cycles in LED systems therefore can counteract their relatively lower electrical efficiency.
A lot has been said on the importance of UV-C wavelength and the benefits and drawbacks of UV-C LEDs in comparison to monochromatic low-pressure mercury vapor lamps. However, what commonly is missed from the discussion is the long history of accounting for polychromatic UV sources that routinely is applied to medium-pressure mercury vapor lamps. Decades of research provide a deep literature on the action spectra of various microbial pathogens and surrogates (ref: UV Solutions, 2019a). Further, many regulatory bodies, such as US EPA, ÖNORM and DVGW, provide guidance for medium-pressure lamps in disinfection applications. Focus on the source technology has drawn attention away from the most important issue: proper demonstration of system efficacy. For disinfection applications, that’s often framed as “bugs in vs. bugs out,” using proven effective methods to ensure the necessary measurement details.
Systems: Surface disinfection
Consumer goods featuring UV-C LEDs for surface and object disinfection have been on the market for several years. Common formats target toothbrush heads, smartphones, keys, etc. Further interest in UV-C LEDs for surface disinfection applications was bolstered during the first two years of the COVID-19 pandemic, following clear demonstration of the efficacy of conventional UV (254 nm) and UV-C LED radiation against the virus; this prompted the development of several “UV-C LED wands” intended for general surface irradiation. The scalability of consumer product markets means that this continues to be a growth area for UV-C LED applications; however, concerns over efficacy and safety in the use of unshielded UV sources by untrained individuals remain.
Beyond consumer products, interest in fixed installations such as escalator handrails (ref: WAA, 2020) and other “repeat contact” objects in public spaces continues to grow. These installations differ in their application and control of UV radiation within an enclosed system, containing the UV exposure hazard and ensuring exposure levels meet the necessary targets. The use of LED sources within wide area “UV robot” applications is limited at present due to battery life constraints.
Systems: Air disinfection
Another area which has seen growth during the current pandemic is air disinfection, where a long history of use of UV in the limitation of disease transmission and contemporary efficacy data vs. the SARS-CoV-2 virus caused a surge in interest. The directivity of UV-C LEDs makes them particularly suited to upper-air disinfection applications and the potential of this technology has been widely discussed. Despite broad application potential in air treatment – including upper-room, flow-through and disinfection of condensing and filtering elements – widespread uptake of the technology has not materialized. A possible cause is the juxtaposition of low single-device output power and high flow velocities through compact in-duct solutions (a modest conference room application could see flow rates on the order of 4000 lpm). Though commercial product platforms are not currently available in this space, the rapid advancement of LED powers and continued reduction in power cost ($/W) mean that this could change in the near future.
Systems: Premise potable water supply
The application of UV-C LEDs within low-flow (<8 lpm) or point-of-use (POU) drinking water applications now is well established, with numerous system manufacturers on their second/third/fourth generation of such products. This market continues to experience rapid growth that is expected to continue as it benefits from the economies of scale and the advancement of LED performance. More challenging applications such as greywater treatment also are gaining traction. The collaboration between AquiSense Technologies and several Japanese manufacturers such as Mitsubishi and Hitachi is an illustration of deployment within this application (ref: AquiSense, 2020). At the time of writing, there are approaching 200,000 such greywater UV-C LED systems installed in the field.
With the increases in UV-C LED performance, systems capable of operating in the point-of-entry (POE) regime now are available. These systems, operating in the 20 to 50 lpm range, are a clear example of where the differences between conventional and UV-C LEDs systems matter: With domestic plumbing drawing water for just a few hours per day, a UV-C LED system may spend most of its time in low-power standby mode and rapidly engaging on-demand. By comparison, the warm-up time required by a conventional Hg lamp means that it must be in continual operation, drawing maximum power 24 hours a day. The necessary LED power to achieve these higher flow rates means that POE volumes are a few years behind POU-type applications.
Systems: Industrial and municipal water treatment
Long-heralded but often dismissed, the suitability of UV-C LEDs to industrial and municipal drinking water treatment is becoming apparent. As of Q1 2022, three manufacturers have demonstrated MGD-scale (m3/min) drinking water disinfection systems employing UV-C LED sources, with active-service installation of such systems at several sites in Europe and North America. All three systems use contrasting approaches, illustrating the broad design space offered by this technology. In 2018, Typhon Treatment Systems demonstrated the first validation of an MGD-scale drinking water disinfection system according to the USEPA UVDGM protocol (ref: UV Solutions, 2019b), with six units installed to operational service in 2021. Employing thousands of best-in-class LEDs, these systems do not yet represent capital expenditure parity with conventional systems, though their uptake by early adopters is driven by operational benefits over conventional Hg technology.
Alongside drinking water systems, a number of stakeholders are investigating more challenging operational environments, such as water reuse, wastewater treatment and UV-AOP.
Regulations, standards and market acceptance
A long-standing challenge for the application of UV-C LED disinfection systems was the lack of suitable certifications and test standards for many applications. The 2019 revision of NSF/ANSI 55 for POU and POE applications allowed for the certification of UV systems employing UV-C LED sources, where they have previously been excluded. Further revised in 2020, NSF/ANSI 55 now provides a valuable route to market assurance of the quality of POU/POE system construction and performance, albeit with more conservative safety factors than their equivalent Hg lamp systems.
In the case of municipal-scale system validation, the USEPA UVDGM provides a route for third-party validation of UV-C LED systems as has been demonstrated. However, other regions have been slower to adapt to the surge in UV-C LED commercialization, with a recent adaptation of the DVGW W 294 technical rule into DIN 19294 maintaining its restriction to low-pressure mercury lamp sources. Efforts are ongoing within stakeholder groups, though it is likely that the rate of technology maturity will outpace that of the revision of regulations.
Conclusions
The performance of UV-C LED sources and their potential has been openly discussed for over 15 years, leading to a large catalog of information. However, due to the rate of advancement of the technology, information becomes rapidly outdated as investments into improving LED devices, the systems incorporating them and their fields of application expand.
- Estimating global production at the UV-C LED level is complex with production numbers not published.
- Based on known market sectors and products, a reasonable estimate is on the order of 10 million devices per year; this includes high-performance devices as well as ultra-low-cost devices.
- Surface treatment with UV-C LEDs was bolstered by the needs of the COVID-19 pandemic and remains a growth industry, though presently is commercialized more in consumer markets.
- Substantial potential exists within the air treatment market, though conversion of this potential into large-scale application has not yet been demonstrated on a wide scale.
- Small-scale water treatment systems (e.g. <8 lpm) are readily available and in mass-production, with total installations in all applications estimated to be already over 200,000 globally.
- Point-of-entry drinking water treatment applications are expected to grow substantially in the short term, benefiting from experience in proven low-flow applications and growing with ongoing UV-C LEDs development.
- Recent installations of municipal-scale drinking water treatment systems give a strong indication that a tipping point for the widespread application of UV-C LEDs into this area may be closer than many within the water treatment industry had expected.
Rich Simons, Ph.D., is the head of Application Science for AquiSense technologies and offers expertise on evaluation and simulations for UV-C LEDs. Jennifer Pagán, Ph.D., is the CTO, where she brings 20 years of technology experience to the AquiSense team. She’s a well-known force in the world of UV LED product development. Oliver Lawal is the president/CEO and has been involved in the UV market since the 1990s. He has served several positions with the IUVA, including IUVA president. AquiSense Technologies is focused on UV-C LED disinfection innovation. AquiSense works with leading manufacturers to evaluate, then integrate, the best available UV-C LED sources into products that solve real world problems in water, air and surface applications. For more information, visit www.aquisense.com.
References
Nichia, 2021: https://www.nichia.co.jp/en/newsroom/2021/2021_100601.html
Crystal IS, 2021: https://www.einnews.com/pr_news/555345487/crystal-is-launches-klaran-la-the-world-s-first-and-only-100mw-10-000-hour-265nm-germicidal-uvc-led
LEDs Magazine, 2020: https://www.ledsmagazine.com/company-newsfeed/article/14174528/luminus-breaks-the-010-per-mw-barrier-for-uvc-leds
Amano et al., 2020, DOI: 10.1088/1361-6463/aba64c
WAA, 2020: https://www.waa.ca/en/newsroom/view/39/new-technology-helps-further-support-a-safe-and-clean-ywg/
AquiSense, 2020: https://aquisense.com/case-studies/mitsubishi/
UV Solutions, 2019a: https://p6b82f.p3cdn1.secureserver.net/stories/pdf/archives/190201-IUVA_News_Summer2017_final_ActionSpectra_combo.pdf
UV Solutions, 2019b: https://uvsolutionsmag.com/articles/2019/validation-of-a-reactor-containing-uv-leds-for-the-disinfection-of-municipal-drinking-water/
