USTC infrared contact lenses deliver signals through closed eyes

Closing their eyes made an unusual laboratory task easier: volunteers wearing experimental contact lenses could pick out flashes of near-infrared light. The work, published on May 22, 2025, involved the University of Science and Technology of China, Fudan University and collaborators. Cell Press explained that eyelids screened out more of the interfering visible light than the near-infrared signal.

The striking idea is to change the light reaching the eye rather than put a camera's video feed on a miniature display. Nanoparticles perform an optical translation, absorbing near-infrared light and emitting light the visual system can register. Picture a transparent interpreter sitting in front of an otherwise unchanged reader. The reader gains access to another language because the incoming message has been converted.

There is important history behind that translation. A February 2019 study described by the Chinese Academy of Sciences had already given mice near-infrared image perception by introducing upconversion material into the retina. The wearable experiment changes the interface: human participants could try the optical conversion in contact lenses, without an injection into their eyes. The underlying concept of converting infrared photons was not invented with these lenses.

The Cell paper also describes a three-color version. Separate near-infrared spectral inputs became distinguishable visible colors, giving volunteers more information than a simple light-on/light-off cue. In practical terms, color provides labels for otherwise invisible channels. A message could potentially carry distinctions in its timing and spectral composition, rather than relying on brightness alone.

Making the material wearable introduces an optical balancing act. USTC's account describes improving nanoparticle dispersion and matching refractive indices to keep the composite transparent despite a substantial particle loading. Yet converted light spreads out: the contacts alone provided coarse spatial information. An additional eyeglass optical system improved the ability to recognize detailed patterns.

The experiment remains relevant because it shows a route to extending perception with a material layer, alongside the more familiar camera-and-screen approach. It also illustrates why detecting a signal and seeing a useful scene are different engineering goals. According to Cell Press, the demonstrated contacts required infrared light projected by an LED; greater sensitivity remained a development objective.

A flashing beacon can be useful even when it does not produce a sharp picture. Navigating a dark landscape asks much more of brightness, detail and reliable performance together. These were human research demonstrations, not consumer lenses established as a replacement for night-vision equipment. The next meaningful step would bring the signal-detection trick closer to usable everyday vision, without losing the transparency that makes a contact lens wearable.

Original paper published online: May 22, 2025.