Scientists have created contact lenses that enable wearers to see in the dark using infrared vision, an invention that could lead to advances in emergency and rescue operations.
Unlike traditional night vision goggles, these lenses don’t require a power source and enable wearers to see infrared and visible light simultaneously, according to a new study published in the journal Cell.
“Our research opens up the potential for non-invasive wearable devices to give people super-vision,” study senior author Tian Xue from the University of Science and Technology of China, said.
The lens uses tiny nanoparticles that absorb infrared light and convert it into wavelengths that are visible to mammalian eyes.
These particles specifically enable detection of “near-infrared light”, which has a wavelength range of 800-1600 nanometres.
This is just beyond what mammals perceive, which is a fraction of the wavelengths corresponding to visible light, typically in the 400-700 nm range.
Previous research in mice showed that these particles enabled infrared vision when injected into the retina but the Chinese scientists set out to design a less invasive option.
To develop the new lenses, they combined the nanoparticles with flexible, non-toxic polymers used in standard soft contact lenses.
Researchers then tested the lenses in both humans and mice.
They found that when given a choice of a dark box and an infrared-illuminated box, contact lens-wearing mice chose the dark box, whereas those without the eye gear showed no preference.
The pupils of contact-wearing mice also constricted in the presence of infrared light and scans of their brains showed infrared light causing their visual processing centres to light up.
In humans, participants wearing the lens could accurately detect flashing Morse code-like infrared signals.
“It’s totally clear cut: without the contact lenses, the subject cannot see anything, but when they put them on, they can clearly see the flickering of the infrared light,” Dr Xue said.
“We also found that when the subject closes their eyes, they are even better able to receive this flickering information, because near-infrared light penetrates the eyelid more effectively than visible light.”
Currently, the lenses are only able to detect infrared radiation from an LED light source.
The researchers are working to increase the particles’ sensitivity so they can detect lower levels of infrared light.
“In the future, by working together with materials scientists and optical experts, we hope to make a contact lens with more precise spatial resolution and higher sensitivity,” Dr Xue said.
“This technology has a wide range of practical applications, including infrared information encoding and transmission, enhanced vision in poor visibility conditions like foggy or dusty conditions, and integration into smart devices for rescue and emergencies.”