A powerful LED can efficiently disinfect surfaces while remaining safe for people.
RIKEN physicists have engineered a highly efficient LED that is deadly to microbes and viruses but safe for humans. One day it could help countries emerge from the shadows of pandemics by killing pathogens in rooms full of people.
Ultraviolet germicidal lamps are extremely effective at exterminating bacteria and viruses. In fact, they are routinely used in hospitals to sterilize surfaces and medical instruments.Lamps of this type can be constructed with LEDs, making them energy efficient. However, these LEDs produce ultraviolet light in a range that damages DNA and therefore cannot be used around people. The search is on to develop efficient LEDs that shine light within a narrow band of far-ultraviolet light that appears to be both good at disinfecting while remaining safe for people.
Germicidal LED lamps that operate in the absence of humans are often made from aluminum, gallium, and nitrogen. By increasing the amount of aluminum they contain, these LEDs can be modified to work in a wavelength region that is safe for humans. This approach has been used before but has resulted in dramatically reduced power.
To work through this issue, three physicists at RIKEN Quantum Optodevice Laboratory, Masafumi Jo, Yuri Itokazu, and Hideki Hirayama, created an LED with a more complex design. They sandwiched together multiple layers, each containing slightly different proportions of aluminum. In addition, in some layers they also added tiny amounts of silicon or magnesium.