Scientists at Stanford University have unveiled a new clothing material made of cotton coated in silver nanowire. According to their research published in Nano Letters, this fabric is more lightweight and breathable than heavy winter clothing, but keeps the wearer just as warm.
The original goal of the researchers was to create a “system of personal thermal management” that could keep someone warm, while being much more energy efficient than the indoor heating systems we use every winter. Metal is an excellent material for reflecting the body’s thermal energy, but it doesn’t work as clothing. Instead, the researchers developed a textile that is coated with nanowires of silver.
The silver coating in the fabric works two ways to heat up the body. First, it traps and reflects 80% of body heat. Secondly, it can use Joule heating to also function like an electric blanket. Joule heating is the process that causes a conductor to release heat when an electric current passes through it. Because silver is such an excellent conductor of electricity, the entire cloth can use small amounts of ambient electricity to warm the wearer via Joule heating.
Although silver-coated clothing sounds expensive, the use of nanowires means that only a small amount of silver is needed – about $1 worth for a shirt and pants. Unfortunately, the fabric is not yet commercially available, and probably won’t be for a few years.
Personal Thermal Management by Metallic Nanowire-Coated Textile
Po-Chun Hsu, Xiaoge Liu, et. al.
Nano Letters 2015 15 (1), 365-371