Finding a better solution for visual disorders such as color blindness, a team of scientists from home and abroad have jointly devised a unique contact lens that surpasses current human visual capabilities. These contact lenses capture things even naked eyes cannot see, according to the researchers.

In their research, the scientists, including those from the University of Science and Technology of China in Hefei, Anhui province, and Fudan University in Shanghai, ingeniously combined rare earth particles emitting multiple fluorescent signals with contact lenses.

By wearing such special lenses, human eyes can perceive light beyond the visible spectrum into the near-infrared range, allowing individuals to access multi-dimensional information in terms of time, space, and color from near-infrared light.

"With the aid of such invisible glasses, people can see things that were previously invisible to them," said Zhang Fan, one of the lead researchers on the team and a professor of chemistry from Fudan University.

"And for individuals suffering from color blindness, by supplementing visible light information with near-infrared wavelengths, wearers can enhance their ability to differentiate between colors like red and green," he said.

The research results also hold vast application potentials in fields, such as information processing and visual assistance technologies, said the researchers.

"For example, information encoding, transmission and decryption can all be carried out in the near-infrared band. If using near-infrared light to light up particular information such as patterns, only those who wear the special contact lenses can see the patterns, while those who don't will never see them as the near-infrared bands are outside the range of their visual perception," said Zhang.

Scientists explained that there are cone cells on human's retina that respond specifically to the primary colors of red, green and blue. The proportion of activation in these cells responding to the three colors determines the colors that people see.

However, compared to the broad optical spectrum in nature, the human eye can only perceive wavelengths ranging from 400 to 700 nanometers, leading to the neglect of a significant amount of potential information. By extending perception to the near-infrared range, 700 to 2,500 nanometers, the technology may open new possibilities for pushing boundaries for human vision.

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"Rare earth elements possess unique optical properties, allowing the conversion of different colors of light through near-infrared excitation. By discerning the fluorescence colors of nano-particles, individuals can identify near-infrared wavelengths invisible to the naked eye, realizing the recognition of near-infrared 'colors'," said Chen Zihan, a researcher on the team from Fudan University.

The team further modified the surface of the nano-particles and dispersed them in polymer solutions, ultimately creating highly transparent contact lenses.

In their research, volunteers who wore the contact lenses were able to perceive near-infrared light through the fluorescence of red, green and blue visible wavelength bands, and distinguish various compositions of near-infrared light wavelengths and patterns. This demonstrated the effective visualization of near-infrared images using multi-color rare earth luminescent materials, said the scientists.

A paper about the research, a collaborative effort between domestic and international research institutions, was published in the journal Cell on Thursday.

Contact the writer at zhouwenting@chinadaily.com.cn