Camouflaged clothing that mimics squid skin is being developed to hide soldiers from night vision equipment.
Most camouflage materials used to disguise soldiers and vehicles during the day show up easily when viewed through night vision goggles and infrared cameras.
This is because leaves and other foliage reflect infrared light in a different way to other fabrics and materials.
However, scientists at the University of California Irvine have created a new “stealth” coating that can change the way it reflects infrared light on command.
The films, which are around 100,000 times thinner than a human hair, can be switched on and off using a chemical signal.
Tests conducted by the researchers have shown that they can make an orange surface blend into green foliage when the coating is activated.
The technology mimics the active camouflage used by squid, where they change the colour and even the texture of their skin to blend into the background.
The researchers claim their new coating can be attached to a wide range of surfaces and is a first step towards developing “shape shifting clothing” capable of adapting to the environment around it.
Dr Alon Gorodestsky, an assistant professor of chemical engineering and material science at University of California Irvine, said: “Our approach is simple and compatible with a wide array of surfaces, potentially allowing many simple objects to acquire camouflage capabilities.
“Our long-term goal is to create fabrics that can dynamically alter their texture and colour to adapt to their environments.
“Basically, we’re seeking to make shape-shifting clothing – the stuff of science fiction – a reality.”
Dr Gorodestsky and his colleagues used a protein called reflectin, which is found in the skin of the long fin squid Doryteuthis pealeii to create the new coating.
These squid can change their colour from a deep red to a soft pink and are known to change their visibility under infrared light.
The scientists, whose work is published in the journal Advanced Materials, created a film by combining reflectin with graphene, the Nobel Prize winning ultra-thin form of transparent carbon that was first isolated in 2003.
The researchers found they could tune the wavelength of light that was reflected by the film so that when it was activated it would reflect infrared light in different ways.
The coating can be switched on either by a change in humidity or by the presence of acetic acid vapour, or vinegar, which cause the reflectin to swell like a gel, changing the way it reflects light.
This would mean that such coatings could be made to turn on at night when humidity typically rises, or by releasing a chemical signal into the clothing itself.
The scientists say a similar method could also be used to change the texture of a surface and they hope to develop new “stealth materials”.
Dr Gorodestsky said: “Given these advantages, our dynamically tunable, infrared-reﬂective films represent a crucial first step towards the development of reconﬁgurable and disposable biomimetic camouﬂage technologies for military stealth applications.”