According to Wired magazine, the Army is in the market for fabric that can change with temperature. "This 'environmentally responsive' material would keep a soldier not too hot and not too cold, constantly adjusting to outside conditions as well as body heat." Pretty neat, right?
Apparently, one way to make this possible, is by creating a fabric made by weaving fibers that contain "two metals bonded together in a tiny spring. As the temperature drops, one metal changes its length more than the other one - resulting in a 'curl' in the fiber. If you have a whole shirt made of this stuff, it would actually change thickness as it got colder, providing more insulation and warmth." For the paper that inspired the Army, check out this PDF.
There's another requirement for this fabric of the future, a tricky one. It's got to be able to hold up to army-laundry, at least 20 washes worth.
Photo credit/ www.army.mil