Contact lenses that let you 'see in the dark' in step towards 'super-vision'
by Alice Padgett · LBCBy Alice Padgett
Chinese scientists have developed night vision contact lenses - that even work with closed eyes.
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The lenses detect infrared light, which is normally invisible to the human eye.
Microscopic nanoparticles were embedded into a soft, transparent polymer commonly used in standard contact lenses.
By absorbing infrared light, the particles convert it into visible red, green, and blue wavelengths visible to the human eye.
Unlike traditional night-vision goggles, the design eliminates the need for batteries or an external power source.
“Our research opens up the potential for non-invasive wearable devices to give people super-vision,” Professor Tian Xue of the University of Science and Technology of China told The Times.
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In a paper published in the journal Cell, the research team suggested that with further refinement, the contact lenses could prove useful not only for night vision but also in foggy or dusty environments, where infrared light penetrates more effectively than visible light.
During trials, the lenses showed sensitivity to low-intensity infrared emitted by LEDs.
The detected light falls just beyond the visible spectrum, in the near-infrared range, allowing reflective surfaces like people or landscapes to become visible.
Currently, the clarity of the images remains a barrier for night vision use, as the proximity of the lenses to the retina causes fine details to blur.
To improve image sharpness, the team developed a pair of glasses using the same technology, for a clearer view.
Another challenge lies in detecting low levels of natural infrared present at night, though this might be addressed by illuminating areas with an infrared lamp.
“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,” Xue said.
The technology was initially tested on mice, which were fitted with the lenses before being offered a choice between a dark box and one lit with infrared light invisible to the naked eye.
Rodents consistently chose the darker space, indicating an ability to perceive the infrared illumination.
Pupil contraction and brain scans further confirmed visual processing activity in response to the infrared light.
In human trials, the lenses allowed wearers to detect flashing infrared signals and determine the direction from which the light originated.
“It’s totally clear cut: without the contact lenses, the subject cannot see anything,” said Xue.
“When they put them on, they can clearly see the flickering of the infrared light.”
The lenses can be worn in daylight, where the infrared signal enhances the natural colors visible to the human eye.
A stronger effect was observed when users closed their eyes, suggesting heightened sensitivity to infrared under those conditions.
“Near-infrared light penetrates the eyelid more effectively than visible light,” Xue said.
With less “visual noise” users could detect the flickering signals more clearly.
By modifying the nanoparticles, the researchers made it possible for different types of infrared light to appear as distinct colors—assigning one wavelength to blue, another to green, and another to red.
The same technology could be adapted to assist color-blind individuals by converting hard-to-distinguish hues within the visible spectrum into shades that are easier to perceive.
“By converting red visible light into something like green visible light, this technology could make the invisible visible for colour-blind people,” concluded Xue.