Ultraviolet germicidal lamps are extremely effective in eliminating viruses and bacteria: this is why far-UVC light is routinely used in more and more hospitals to sterilize surfaces and medical instruments.
The core of these lamps is the LED light, which makes them excellent also from the point of view of energy saving. There is only one "very small" problem: these LEDs use ultraviolet light in a range that damages human DNA. In summary: they cannot be used in the presence of people.
This circumstance has sparked a mad rush around the world in search of LEDs that emit good light for both disinfection and humans. With mixed fortunes.
A matter of substance
Current far-UVC LED lamps are often made with aluminum, gallium and nitrogen. The first attempts to improve them have gone through increasing the amount of aluminum. With disappointing results: safer lights, but also (much) less effective.
To get around this, Masafumi Jo, Yuri Itokazu e Hideki Hirayama, all from the RIKEN Quantum Optodevice Laboratory in Japan, have created a more intricately designed LED.
How germicidal but safe LED far-UVC is made
Researchers at the RIKEN Laboratory joined together several layers of varying proportions of aluminum: in some of these layers they also added small amounts of silicon or magnesium.
In short words: they created a real maze for electrons, hindering their movement and trapping them longer in certain areas.
The result? Greater amount of light emitted by the device, and less amount absorbed by people.
An infinitely accurate job
To fine-tune the best design for this lamp, the team used computer simulations with prediction models for all sorts of effects.
The number of simulations was huge. "The biggest challenge," says Masafumi Jo, "was to control the thickness of each layer with extreme precision." A challenge that seems to have been won: they have created a far-LED with an output power almost ten times higher than its predecessor (of which we talked here).
A light (LED) on the future
"We are confident that our results and technologies will be very useful in safeguarding society from this and future pandemics," says Jo. I hope so: Covid has brought unprecedented awareness of how important it is to destroy viruses and microbes on surfaces.
But the researchers don't stop. In their study published in Applied Physics Letters (I link it here) note that there is still enormous room for improvement.
Apparently the light at the end of the tunnel is there, and it sanitizes.
