Being able to detect what our eyes do not naturally see would upset many daily uses, from safety to health through the perception of our environment. The human eye only captures a tiny portion of the light spectrum, limited to the so -called “visible” wavelengths. However, a large part of light information, especially in the infrared, escapes us. Researchers from the University of Science and Technology in China, in collaboration with the University of Massachusetts, have developed unprecedented technology to remedy it: flexible and transparent contact lenses, capable of making the infrared visible.
A discreet, but powerful innovation
The novelty is not only in the ability to see the infrared, but in the radically different way in which this vision is made possible. The lenses developed by the Tian Xue team exploit a precise optical principle: the Upconversion. This process allows certain nanoparticles to capture photons in the nearby infrared – between 800 and 1,600 nanometers. Then they re -move them in the form of visible light. This mechanism works without external energy intake, unlike conventional night vision glasses. The latter amplify light using electronic circuits.
The researchers inserted these particles into a polymer matrix compatible with the human eye. The challenge was the transparency of the material. It was necessary to avoid any opacity due to the dispersion or absorption of light by nanoparticles. To achieve this, the team has carefully adapted the polymer refraction index in order to harmonize it with that of particles, ensuring optimal light transmission.
Manufacturing is based on polymers already used in standard flexible lenses, guaranteeing flexibility, hydrophilia and comfort at the port. The biocompatibility tests carried out on the animal, then on the human, confirmed the absence of toxicity and ocular inflammation. This mastery of optical, mechanical and biological conception today makes it possible to offer a device that naturally integrates into the human eye while giving it an unprecedented sensory capacity.
See in the invisible … eyes closed
What might seem to be science fiction is based here on a well-known physical characteristic: infrared light penetrates biological tissues more easily than visible light. Concretely, this means that a wavelength of 980 nanometers – typical of the nearby infrared – crosses the human or animal eyelid with a much lower attenuation than that of a light visible to 535 nanometers. It is precisely this principle that researchers used to test their technology in extreme conditions.
In real situations, lenses carriers could detect flashing infrared signals even with closed eyes. A first functional demonstration of “transpalpebral” perception. This capacity considerably reduces visual interference from ambient light, which only crosses the eyelids weakly. Thus, paradoxically, infrared acuity increases when the eye is closed.
The experiments were first conducted on mice. In the presence of infrared light, the mice equipped with lenses systematically showed a pupillary reflex. Proof that the signal was well perceived by the visual system, confirmed by brain imaging. The researchers observed the activation of the visual zones of the cortex. In humans, the results are similar: immediate perception of coded flashes and recognition of their orientation.
Three colors for infrared
To transform infrared light into a real interpretable visual language, it is not enough to make the invisible perceptible. It is still necessary that the eye can distinguish from the differences between the wavelengths. This is where the principle of trichromatic vision comes in, on which the perception of human colors is based. The eye detects light thanks to three types of photoreceptors – the cones – sensitively sensitive to red, green and blue. By combining these three signals, our brain reconstructs a full range of colors.
Lentils say tucls (Trichromatic Upconversion Contact Lenses) take up this natural model by transposing it into the infrared. The researchers have designed so -called “orthogonal” nanoparticles capable of absorbing three distinct infrared wavelengths (808 Nm, 980 Nm, 1,532 nm) and converting them into three visible colors – green, blue and red. Each type of particle acts as a selective converter, avoiding interference between signals.
© © Sheng Wang
Procedures for preparing infrared lenses. © Sheng Wang
This spectral coding makes it possible to reconstruct a “palette” of the infrared in visible colors, a bit like an RGB sensor (red, green, blue) in digital photography. By adjusting the relative intensities of the three infrared bands, users could perceive different colors corresponding to specific combinations.
This system therefore authorizes the direct visualization of infrared shades, hitherto processed by software or ignored. It becomes possible to differentiate from materials or objects according to their infrared signature, for example.
From proof of concept to concrete uses
Beyond the technological feat, these lenses open up various and targeted perspectives of use. One of the major advantages of this technology lies in its ability to operate without an external energy source. This makes it adapted to light, discreet and portable devices. In low visibility contexts – smoke, fog, darkness – infrared signals can be detected without interference, making the vision functional even where the human eye is normally blind.
The team explicitly cites safety, rescue, recognition of patterns, or even transmission of visual information coded via indicating infrared signals. In an environment where confidentiality is crucial, only lens carriers could read a hidden light message. Tian Xue underlines: ” The infrared flash could be used to transmit secure information, access control or anti-contais ».
Spatial resolution remains limited by the diffusion of light converted into the eye. To remedy this, the researchers have designed an additional optical system. They created a pair of glasses incorporating nanoparticles into a convex lentil structure. It improves clarity up to 65 cycles per degree, a level comparable to natural human vision. This means to distinguish 65 black and white lines very fine on an angle of a degree.
Finally, lenses could also benefit people with daltonism. By modifying the conversion of invisible wavelengths for these individuals, technology offers a non -invasive solution to widen their perception spectrum.
This advance shows that an extensive and personalized vision, formerly reserved for machines, today becomes a potential capacity of the human eye itself.
Source: Yuqian Ma et al., “Near-Infrared Spatiotemporal Color Vision in Humans Enabled by Upconversion Contact Lenses”. Cell (2025).
With an unwavering passion for local news, Christopher leads our editorial team with integrity and dedication. With over 20 years’ experience, he is the backbone of Wouldsayso, ensuring that we stay true to our mission to inform.
