While we've already seen materials that allow people or objects to hide from heat-detecting cameras, they're typically only effective at one ambient temperature. An experimental new material, however, can be user-adjusted to work over a wide range.
Heat-detecting sensors, such as those found in night-vision goggles, actually work by noting the temperature difference between the surface of an object and its surroundings. Therefore, if the two temperatures are the same, then the object remains undetected.
And although previously-developed camouflage materials have succeeded at maintaining a predetermined temperature, they haven't been very adaptable. That's where the new technology comes in.
Developed by scientists at the University of California San Diego, it's a flexible material consisting of a wax-like phase-change substance, along with a thermoelectric alloy sandwiched between elastomer sheets. It's powered by an integrated battery, and is controlled by its wearer via a wireless circuit board.
In response to an applied electrical current, the alloy is able to change its temperature over a range from 10 ºC to 38 ºC (50 ºF to 100.5 ºF) – it does so in less than a minute. For the time being at least, that temperature-change has to be manually initiated by the user, based on the currently-observed ambient temperature.
The phase-change substance is included to keep the wearer from heating up along with the camouflage material. It does so by melting and absorbing heat at temperatures at and above 30 ºC (86 ºF), which is the surface temperature of human skin. At temperatures below 30 it solidifies, acting as insulation.
The material has already been incorporated into an armband. Ultimately the researchers hope to create an entire jacket, although the technology will have to be refined before that can happen – currently, such as jacket would weigh about 2 kg (4.5 lb), be around 5 mm thick, and only work for an hour.
A paper on the research, which is being led by Prof. Renkun Chen, was recently published in the journal Advanced Functional Materials.
Source: UC San Diego
