The need for efficient and long-term sanitation using ultraviolet (UV) light is increasing worldwide, due to the ongoing pandemic and concerns of future outbreaks. Artificial lamps are the primary tool for implementing no-contact, UV-C disinfection. When it comes to lighting technologies, some UV lamps are more efficient and offer better performance than others.
Surprisingly, UV-C LEDs are not leading this trend, as the technology is still under heavy development. Below takes a closer look at the challenges of developing UV-C LEDs and current solutions for effective disinfection.
One of the main issues with UV-C LEDs is thermal efficiency. According to Dr. Giles Humpston, Applications Manager at Cambridge Nanotherm, reducing the UV wavelength output of a UV LED causes efficiency rates to decrease. This is a concern for disinfection-related applications, as the UV-C germicidal range of 200 nm to 280 nm is on the low end of the general UV spectrum (consisting of UV-A, UV-B and UV-C). Notably, UV LEDs that generate 315 nm to 400 nm UV-A bands are approximately 15-40 percent efficient. While UV LEDs that provide UV-C output are roughly 5-8 percent efficient, with 92-95 percent of energy wasted as heat. Effective mechanisms for moving heat away from the UV-C LEDs are required to prevent overheating and rapid degradation of the unit.
Materials and Lifespan
UV rays have degrading effects on certain types of materials used in LED packages, such as epoxy and organic substances (for shorter UV bands, including UV-C). Therefore, using materials found in standard, non-UV LEDs is not recommended as degradation will limit the lamp’s expected lifespan. Selecting durable materials is an important aspect to developing efficient and long-lasting UV LEDs. For UV-C LEDs, inorganic materials for PCB components may help reduce degradation. Ceramics (aluminum oxide or aluminum nitride) would be ideal, however the material is known to be brittle and prone to cracking. This could potentially cause problems in rugged environments for the module PCB. Additionally, high-grade ceramics tend to be costly. Low-cost ceramics, although cheaper, suffer from low performance. To address these challenges, UV-resistant nano-ceramics are being developed to enhance the performance of standard ceramics, such as aluminum nitride.
UV-C Fluorescent and Far-UV Excimer Sanitation Lamps
At this time, UV-C LEDs are simply not viable for mainstream and reliable sanitation. Businesses requiring immediate disinfection solutions to boost health and safety practices during the pandemic may utilize UV-C fluorescent lights or far-UV excimer lamps. Both types of germicidal lamps are capable of inactivating up to 99.9% of viruses, bacteria, mold and spores. UV-C fluorescent units generate powerful UV 254 nm bands, which requires rooms to be empty and operators to be in full protective gear during sanitation.
On the other hand, far-UV excimer lamps provide far-UV 222 nm bands that are eye and skin safe for humans (protective gear is not required during operation). Excimer lamps are also mercury free and ozone free, making the units environmentally friendly. The instant-on lights offer low heat output and can be used in occupied areas or busy locations.
Larson Electronics offers a wide selection of UV-C fluorescent and far-UV excimer sanitation equipment for businesses. Our disinfection units range from UV sanitation carts for large rooms and HVAC disinfection lights, to handheld UV sanitizers and portable eye and skin safe far-UV wearables.