Researchers developed a wearable technology that can hide its wearer from heat-detecting sensors such as night vision goggles, even when the ambient temperature changes. The technology can adapt to temperature changes in just a few minutes, while keeping the wearer comfortable.
The device has a surface that quickly cools down or heats up to match ambient temperatures, camouflaging the wearer’s body heat. The surface can go from 10 to 38 °C (50 to 100.5 °F) in less than a minute. Meanwhile, the inside remains at the same temperature as human skin, making it comfortable for the wearer. The wireless device can be embedded into fabric such as an armband; a more advanced version could be worn as a jacket.
To build the device, the team used a phase-changing material that’s similar to wax but with more complex properties. The melting point of the material is 30 °C (roughly 86 °F), the same temperature as the surface temperature of human skin. If the temperature on the outside of the device is higher than that, the material will melt and stabilize, insulating the wearer; if colder, it will slowly solidify, still acting as an insulating layer.
At the technology’s core are materials that can create heating or cooling effects when the ambient temperature changes and flexible electronics that can be embedded into clothing. The outside layer of the device is made of thermoelectric alloys — materials that use electricity to create a temperature difference — sandwiched between stretchy elastomer sheets. It is powered by a battery and controlled by a wireless circuit board. The device physically cools or heats to a temperature that the wearer chooses.
Current state-of-the-art heat camouflage technology consists of a surface coating that changes how much heat clothing emits at the surface. The coating absorbs the heat from the wearer’s body and reflects only enough energy to match the ambient temperature; however, the coating only works at a predetermined temperature. If the ambient temperature rises or falls, it no longer works.
The goal is to create a jacket with the technology built in but under current conditions, the garment would weigh 2 kilograms (about 4.5 lbs.), be about 5 millimeters thick, and only function for one hour. The team is looking to find lighter, thinner materials so the garment could weigh two or three times less.