Battling against the bitter conditions of the Arctic can be a challenge no matter what activity you are partaking in, particularly so if the elements are not the only battle you’re fighting. For soldiers dispatched to or stationed in these testing environments, maintaining body heat and maneuverability could be the difference between life and death, yet the US military’s cold-weather hand gear has seen little improvement from the designs first implemented more than 30 years ago. The problem has become so prevalent that many US military personnel opt to purchase their own winter gloves from conventional retailers as they actually tend to perform better than their government-issued gear.
Thankfully this may be due to change, as researchers at the US Army Natick Soldier Research, Development & Engineering Center have taken inspiration from research conducted by Yi Cui, PhD at Stanford University and are now exploring the potential of silver nanowires as a way to create high-tech, self-heating clothing for use in cold environments.
The work conducted by Cui’s team began with the synthesis of incredibly fine silver nanowires, which were then placed into cotton to create a network of connections throughout the material. By applying a relatively small current to these nanowires, the fabric can be heated in response to dropping temperatures.
|Img: Us Army Natick Solider Research Development & Engineering Centre|
Paola D’Angelo and Elizabeth Hirst, PhD, along with their colleagues at the aforementioned research center, are now looking into how to extend this underlying principle to other fabrics more suitable for use in military uniforms, such as polyester or cotton/nylon blends. In this regard they have already achieved some success, finding that by delivering just 3 volts to an area of 1 square-inch they could raise the temperature of the fabric by 100°F (37°C) in approximately one minute; that roughly equates to the output of a typical watch battery.
It is hoped that if these fabrics do become suitable for use in military uniforms, they could allow soldiers to turn the heat up or down in response to changing conditions, substantially reducing the weight and bulk of cold-weather garments in the process as the added heating functionality would reduce the needs for extra insulation. For soldiers travelling long distances while carrying heavy loads, this would be a substantial help.
The silver nanowires are not the only feature being added to these experimental fabrics however, as the team are also incorporating a hydrogel layer designed to absorb sweat, preventing any moisture from reaching the inner layers of the garments and thereby improving upon both the heat-retention of the clothing and the comfort of the wearer. The hydrogel layers are comprised of polyethylene glycol or poly(N-isopropylacrylamide), and can be easily aired out in warmer indoor conditions to remove any moisture after each outdoor excursion.
The team have already managed to make the silver nanowires robust enough to withstand repeated laundering, and now the hope is to achieve the same in regards to the hydrogel layer. The researchers will also delve into the interactions between the nanowires and the hydrogel to better understand how they will perform when used in conjunction with each other, as well as looking for alternative power sources as they fear that batteries may result in too much excess weight.
D’Angelo and her team are first focusing on implementing these features into military gloves, but hope to extend the principle to other garments should the initial venture prove to be a success. If that too goes well, we may even see these fabrics entering the commercial market in the relatively near future.
The researchers presented their results on August 20th at the 254th National Meeting & Exposition of the American Chemical Society (ACS).
Sam is an aspiring novelist with a passion for the written word. Currently working as a content writer, journalist & editor, his time at many UK festivals has taught him the importance of keeping warm.