People could one day see in the DARK! ‘Night-vision’ injections let mice see infra-red light given off by heat sources – and experts say it could also work for humans
- An injection given to mice allowed them to see infrared radiation
- Infrared radiation has a longer wavelength than the light that our eyes detect
- It is the type of light detected by heat-seeking cameras from people’s heat
- It could be developed for humans and allow for soldiers with better eyesight
Humans could soon be able to see in the dark after scientists developed injections that allow animals to detect infra-red light.
The injections – which the scientists said had minimal side effects – allowed mice to see infrared light both night and day and could be developed to work on humans.
All sources of heat – such as any living creature – gives off heat which creates infra-red radiation.
Humans could soon be able to see in the dark after scientists developed injections that allow animals to detect infra-red light
While normally invisible, the infra-red would be detectable a green glow by someone who had received the injections, the scientists said.
The research team from the University of Science and Technology claim the new technique has military and security applications particularly for personnel working in dark environments.
Professor Tian Xue of USTC said: ‘In our study, we have shown that both rods and cones bind these nanoparticles and were activated by the near infrared light.’
‘So we believe this technology will also work in human eyes, not only for generating super vision but also for therapeutic solutions in human red colour vision deficits.’
He added: ‘The visible light that can be perceived by human’s natural vision occupies just a very small fraction of the electromagnetic spectrum.
‘Electromagnetic waves longer or shorter than visible light carry lots of information.’
The team, who worked with the University of Massachusetts Medical School inject nanoparticles into the eyes of the mice.
These particles convert the light-detecting cells in the eye called cones, allowing them to detect infra-red light, which are normally have wavelengths too long to be detected.
But the particles absorb infra-red light, and produce shorter wavelengths which the cones can detect.
Jin Bao, a co-author at USTC said: ‘In our experiment, nanoparticles absorbed infrared light around 980 nanometres in wavelength and converted it into light peaked at 535 nm, which made the infrared light appear as the colour green.’ The researchers tested the nanoparticles in mice, which, like humans, cannot see infrared naturally.
All sources of heat – such as any living creature – gives off heat which creates infra-red radiation
Mice that received the injections showed unconscious physical signs that they were detecting infrared light, such as their pupils constricting, while mice injected with only the buffer solution didn’t respond to infrared light.
To test whether the mice could make sense of the infrared light, the researchers set up a series of maze tasks to show the mice could see infrared in daylight conditions, simultaneously with visible light.
In rare cases, side effects from the injections such as cloudy corneas occurred but disappeared within less than a week.
This may have been caused by the injection process.
Mice that only received injections of the buffer solution had a similar rate of these side effects.
Other tests found no damage to the retina’s structure following the sub-retinal injections.
Current infrared technology relies on detectors and cameras that are often limited by ambient daylight and need outside power sources.
The researchers believe the bio-integrated nanoparticles are more desirable for potential infrared applications in civilian encryption, security, and military operations.
The researchers also think more work can be done to fine tune the emission spectrum of the nanoparticles to suit human eyes, which utilise more cones than rods for their central vision compared to mouse eyes.
‘This is an exciting subject because the technology we made possible here could eventually enable human beings to see beyond our natural capabilities,’ Professor Xue said.
The research is published in the journal Cell.
WHAT IS INFRARED RADIATION?
Infrared radiation is a band of light with a wavelength longer than that of visible light.
It is invisible to the human eye but can be detected with a variety of tools.
Infrared is the energy created by heat and is detected by thermal imaging cameras.
The light has a wavelength of between 800 nm to 1 mm and anything longer than this becomes a microwave.
British astronomer William Herschel discovered infrared light in 1800.
The sun gives off half of its total energy as infrared.