Scientists have developed contact lenses that give humans the ability to see infrared light—allowing people to see in the dark, even with their eyes shut.
The breakthrough, published in the journal Cell, combines neuroscience and materials science to create wearable lenses that convert invisible infrared light into light our eyes can see, all without needing a battery or power source.
Unlike traditional night vision goggles, these new contact lenses are lightweight, transparent, and don’t block natural vision.
They allow wearers to see both regular visible light and infrared light at the same time.
In fact, the lenses work even better when the user’s eyes are closed, because near-infrared light can pass through the eyelid more effectively than visible light, reducing distractions from ambient light.
The key to this technology lies in specially designed nanoparticles.
These tiny particles absorb near-infrared light—wavelengths between 800 and 1600 nanometers—and convert them into visible light in the range that our eyes can detect.
The researchers, led by neuroscientist Tian Xue from the University of Science and Technology of China, previously injected these particles directly into the eyes of mice to test their function.
However, they wanted to create a noninvasive method suitable for humans, which led to the development of infrared-sensitive contact lenses.
To make the lenses, the team embedded the nanoparticles into flexible, safe materials commonly used in commercial contact lenses.
They then tested the lenses on both mice and people. In mice, the lenses clearly allowed the animals to see infrared light.
When given a choice between a dark space and one lit with infrared light, the mice wearing the lenses preferred the dark—indicating they could see the infrared illumination.
Their pupils also shrank in response to the infrared light, and brain scans confirmed activity in the visual centers.
In human trials, participants could detect infrared light flashes and even read coded messages sent through blinking infrared beams.
The researchers also found that users could more easily detect these signals when their eyes were closed, thanks to the way infrared light passes through skin and eyelids.
To enhance the technology further, the scientists engineered the nanoparticles to convert different infrared wavelengths into different visible colors—blue, green, or red—giving users the ability to distinguish between different types of infrared light.
This could have applications in security, rescue operations, and even tools for people who are color-blind.
While the current version of the lenses only detects infrared light from LED sources, the team is working on increasing their sensitivity and resolution.
The goal is to eventually produce wearable, high-resolution infrared contact lenses for both everyday and specialized uses.
Source: Cell Press.
