Nanowire gloves could stop soldiers’ hands from freezing
“Don’t try to invade Russia in the winter,” the old military saying goes. Putting aside the sheer size of the country, Russia’s icy conditions are often held up as an example of what can go wrong in winter warfare. Bitter weather, and what it can do to soldiers’ hands and feet, can make or break a battle.
Researchers at the US Army Natick Soldier Research, Development and Engineering Centre are developing a new material that could soon make arctic soldiering a more comfortable affair. Using a network of thin nanowires, the scientists are developing a set of gloves that can be heated up to 37˚C, using only the power output equivalent of a typical watch battery.
The research, presented at a meeting of the American Chemical Society, is intended to help troops that are dropped into arctic conditions and find themselves losing sensation in their hands and feet. “That’s problematic if soldiers have to operate weapons as soon as they land,” said Dr Paola D’Angelo, one of the leads on the project. “So we want to pursue this fundamental research to see if we can modify hand wear for that extreme cold weather.”
D’Angelo noted that much of the US Army’s cold-weather hand gear has been designed more than 30 years ago, and that soldiers often opt to buy their own gloves from shops. This kit can be heavy and unwieldy, which the researchers want to put right with thinner, lighter, self-heating material.
The scientists’ gloves are inspired by research led by Dr Yi Cui at Stanford University, which synthesised fine silver nanowires and wove them into cotton. Cui found that applying power to the wires causes them to generate heat, which can be used to warm the fabric. Taking that technique, the team at the US Army centre pushed it forward to work with materials better suited for military uniforms, such as polyester and cotton-nylon blends.
A prototype for the material was able to increase temperature to 100˚F (around 37˚C) within one minute, by applying only three volts to 1 x 1in swatches of the fabric. The idea is that if the system were to be integrated into uniforms, soldiers could raise or lower the temperature of the material on the fly. With less need for thick insulation, gear can be lighter and easier to carry.
D’Angelo and her team have also incorporated a layer of sweat-absorbing hydrogel particles to the fabric, designed to stop the gloves from becoming wet and difficult to handle. One issue facing the researchers at the moment is that, while the nanowires can cope with repeated washing and drying, the hydrogel fades after laundering. There’s also the fact that batteries for powering the gloves over prolonged periods of time could add too much weight to uniforms – effectively undermining one of the main advantages of the system.
The scientists plan to extend the fabric to clothing for chest and legs, and could even look into developing similar systems for consumer products. The relationship between army barracks and the high street is indeed a common one, with advances in military textiles frequently finding themselves on shelves sooner or later. The opposite relationship is indeed less common, although the development of lithium-ion battery fabric – allowing textiles to store data – has involved a number of cross-discipline collaborations between fashion designers and NASA engineers.