STERILIZATION AND DISINFECTION : THE TRUE POWER OF UV LED
UV stands for ultraviolet rays and it represents only a small part of the electromagnetic spectrum, the arc going from 100nm to 400 nm. Sunlight is composed of 50% visible light, 40% infrared, and 10% ultraviolet. However, at ground level sunlight is 44% visible light, 3% ultraviolet and the remainder infrared.
UV light can be divided into three sub-categories depending on
● UV-A: 315nm to 400nm
● UV-B: 280nm to 315nm
● UV-C: 200nm to 280 nm
UV-A finds the application in curing and in the printing field. UV-B is used for phototherapy and horticulture. As for UV-C its applications are many, starting from water and air purification to surface sterilization, where bacteria are erased through short exposure.
Of the ultraviolet radiation that reaches the Earth's surface, more than 95% is the longer wavelengths of UV-A, with a small remainder of UV-B and essentially no UV-C. Therefore, UV light is generated with artificial help using UV lamps or, a better solution, UV LEDs.
UV LED: POWERFUL DISINFECTION AND STERILIZATION
UV LEDs are the most effective way to utilize the full potential of UV light, incorporating sterilization properties in small and robust technology. The most efficient wavelengths for sterilization were discovered to be in the ranges of UV-A and UV-C.
At wavelengths of 400-405nm (UV-A) a prolonged exposure of hours is able to sterilize surfaces by making bacteria cells inactive through “Visible Light Disinfection.” This technology has no harmful effects and can be safely used to sterilize heavy frequented places.
It was discovered that a wavelength of 265 nm (UV-C) is the most effective bactericide. A short exposure of seconds is able to destroy bacteria and viruses in seconds. This technology may be harmful, but the effects are powerful and allow for extremely short exposure, making it perfect for application where quick sterilization is needed.
Research will allow for more efficient UV LED, which will decrease even further exposure time while drastically decreasing the cost.
UV-C DISINFECTION – THE STERILIZATION OF THE FUTURE
UV radiations, especially the higher energy UV-C radiations, have enough energy to break chemical bonds. Due to their higher energies, UV photons can cause ionization, a process in which electrons break away from atoms. The resulting vacancy affects the chemical properties of the atoms and forces them to form or break chemical bonds. This can be damaging to materials and living tissues, but this damage can be beneficial. For instance, by breaking bond in bacteria and viruses’ DNAs UV-C light is deactivating them, disinfecting and sterilizing surfaces and purifying liquids.
In the past years, the belief was that 254 nm was the bactericidal wavelength, mainly because of the dominance of UV mercury lamps. With the development of better LEDs, able to use a wider variety of wavelengths, it was possible to observe that the perfect wavelength for disinfection was actually 265 nm.
Although there exist UV LEDs that radiate light at a wavelength of 265nm, their power is still on the low side. LG Innotek was able to produce the world most powerful UV-C LED (100mW) that radiates light at 275nm. While the wavelength is not optimal, the tradeoff for more power resulted highly advantageous, showing great results for disinfection and sterilization, allowing for higher percentage of germ killing at a higher speed.Multiple tests have been performed, and they all proved the absolute dominance of UV LEDs over UV lamps. Whether disinfection, sterilization, purification, or mold prevention, UV-C LEDs have proved to be far superior to any other UV source. For instance, an exposure of mere seconds, 3.4 seconds to be precise, to a 100 mW UV-C LED was able to reduce the surface population of harmful bacteria, such as Salmonella and E. coli, by 99.9%. On the other side, even with multiple minutes of exposure UV lamps failed to reach comparable results. Other victories of UVC LEDs were mold prevention for up to two weeks and water purification (99.8% sterilized) in minutes. The main strength of UV-C light, and in particular 265nm light, is extremely quick and powerful sterilization which provides immediate disinfecting solutions. OEMs were able to create practical solutions and designs for applications in medical, residential, and even beauty.