Researchers have developed a prototype infrared contact lens that could allow people to see in the dark – or with their eyelids closed.
The cutting-edge prototype, developed by the University of Science and Technology of China uses nanoparticles that convert infrared to visible light.
Contact lenses imbued with the nanoparticles were given to volunteers to wear during the study, which was recently published in journal Cell. The participants were then able to see flashing signals from an infrared light, which is invisible to the human eye.
As the lenses were transparent, participants were able to see both visible and infrared light at the same time.
“We also found that when the subject closes their eyes, they’re even better able to receive this flickering information, because near-infrared light penetrates the eyelid more effectively than visible light, so there is less interference,” said Professor Tian Xue from the University of Science and Technology in China, who led the study.
The nanoparticles take in near-infrared (NIR) light, with wavelengths between 800 and 1600 nanometres, just beyond what humans can see. The light is then re-emitted in the visible range, from 400 to 700 nanometres.
Near infrared is currently used in active night vision goggles. These work by illuminating the surrounding landscape with an infrared light, then converting that light to something humans can see.
Unfortunately, if you were hoping to see the world in ‘heat-vision’, like the aliens in the Predator movies, you’ll be disappointed – that requires longer wavelengths.
Currently, the contacts are only sensitive enough to detect light from an infrared LED.
The contacts also struggled to capture fine detail, though the team were able to improve this with the use of an additional set of eyeglasses.
It could be possible to adapt the nanoparticles to emit light in many different colours, which would help to make the infrared images clearer and easier to understand. It might even be possible to alter visible light as well, aiding colourblind people.
“By converting red visible light into something like green visible light, this technology could make the invisible visible for colour blind people,” said Xue.
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