Last updated October 25, 2018 at 1:18 pm
Flexible infrared cloaking layer to disappear from view.
A new type of camouflage makes a human hand invisible to a thermal camera. Credit: American Chemical Society
A brand new cloaking device, revealed by scientists this week, takes a new approach to previous attempts at disappearing from view. Instead of trying to hide objects from normal vision, this one provides thermal camouflage – making an object appear the same temperature as the surrounding environment.
And while that has been tried before, thanks to a slow response speed, not being able to adjust to different temperatures, or being rigid and unwieldy, they haven’t exactly been a success.
However, the new cloaking device can reconfigure itself to blend in in a matter of seconds thanks to the use of graphene.
The graphene-gold sandwich
The new system, developed by researchers at the University of Manchester, contains a top electrode with layers of graphene and a bottom electrode made of heat-resistant nylon with a gold coating.
Sandwiched between the electrodes is a membrane soaked with a liquid containing both positively and negatively charged ions.
When a small voltage is applied to the material, the ions travel into and intersperse between, the graphene layers, reducing the emission of infrared radiation (IR) from the camo’s surface.
Most night-vision equipment today is based on thermal imaging that detects the IR emitted by an object, which increases with the object’s temperature. When viewed through a night-vision device, warm objects, such as humans or other warm-blooded animals, stand out against a cooler background.
Reduce the IR emission and boom – instantly invisible.
Not only does it effectively block the IR emissions, it is less than 50 micrometres thick – or thinner than a piece of paper. Combined with a low weight and high flexibility, it can easily be bent and moulded to everyday objects.
So far the researchers have demonstrated their device by thermally camouflaging a person’s hand, and camouflaging hot objects as cold, and cold as hot. It matched the temperature of its surroundings within seconds.
The researchers also created a cloak made up of separately controlled sections of electrodes, allowing them to individually “switch on” or change the settings of the different sections, or pixels. From one pixel to the next can be up to a 10 °C difference in apparent temperature, and can be changed in a tenth of a second.
If you had this ability, what would you do? Write words, obviously.
Individually controlled “pixels” of the device allowed the researchers to write words in the cloak. Credit: Salihoglu et al, Nano Letters 2018
This system, the first which has really successfully cracked IR invisibility could lead to new technologies for thermal camouflage, say the researchers.
However the researchers also think it could be useful in space as an adaptive heat shield for satellites.
The research has been published in Nano Letters.
