LED-urile ultraviolete îndepărtate ucid bacteriile și virușii fără a dăuna oamenilor
Figura 1: Majoritatea LED-urilor emit lumină vizibilă, dar fizicienii RIKEN au creat un LED care emite într-o regiune îngustă în ultravioletul îndepărtat, care este inofensiv pentru oameni, dar mortal pentru viruși și bacterii. 1 credit
Un LED puternic face posibilă dezinfectarea eficientă a suprafețelor, rămânând în siguranță pentru oameni.
Fizicienii RIKEN au proiectat un LED extrem de eficient, care este mortal pentru germeni și viruși, dar inofensiv pentru oameni. Într-o zi, ar putea ajuta țările să iasă din umbra pandemiilor, ucigând agenții patogeni în camere pline de oameni.
Lămpile germicide cu ultraviolete sunt extrem de eficiente în uciderea bacteriilor și virușilor. De fapt, ele sunt utilizate în mod obișnuit în spitale pentru a steriliza suprafețele și instrumentele medicale.
Masafumi Jo și doi colegi au proiectat un LED care va ajuta la protejarea societății împotriva pandemiilor. 1 credit
Lămpile de acest tip pot fi construite cu LED-uri, ceea ce le face eficiente din punct de vedere energetic. Cu toate acestea, aceste LED-uri produc lumină ultravioletă într-o gamă care dăunează[{” attribute=””>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.
This effectively created an obstacle course for electrons, hindering their movement across the material and trapping them for longer in certain areas. This resulted in an increased amount of light emitted by the device and a reduced amount absorbed by it.
The team used computer simulations to model all possible effects to help pin down the ideal design. “We then grew samples to see if it was effective or not,” Jo says. Precisely controlling the thickness of each layer was the biggest experimental challenge. They ended up with an LED operating in the far ultraviolet, with an output power almost ten times higher than their previous best.
The COVID-19 pandemic brought a new consciousness of the importance of being able to eradicate viruses and microbes on surfaces. “We trust that our findings and technologies will be very useful for safeguarding society against this and future pandemics,” says Jo.
Jo adds that the trio will strive to improve their LED’s performance even further. “There’s still much room for improvement in the output power and the power efficiency,” he notes.
Reference: “Milliwatt-power far-UVC AlGaN LEDs on sapphire substrates” by Masafumi Jo, Yuri Itokazu and Hideki Hirayama, 25 May 2022, Applied Physics Letters.
DOI: 10.1063/5.0088454