In 2015 we reported forecasts that smart clothing applications would rise rapidly by 2020 but the bulk of the applications would be fitness-oriented, not associated with healthcare. In 2018 Juniper Research predicted connected clothing would top 7 million units in 2020 and continue to elevate its hockey-stick growth curve. Engineers at the National University of Singapore (NUS) recently published a study in Nature Electronics that explains their work using metamaterial textiles to create wireless body sensor networks.
A metamaterial is an engineered composite material with properties not found in natural materials. So, for example, if someone created a textile that kept you warm and dry, it wouldn’t be a metamaterial because naturally-sourced textiles can do that. If you put on a shirt that deflected radar pulses, that garment would qualify. The NUS textiles won’t render you invisible to radar, but they can enhance wireless signals between wearable electronic devices by up to 1,000 times.
The team of ten students, faculty, and researchers spent a year testing conductive textiles to develop a novel method for devices to connect. Called a “wireless body sensor network.” the design connects multiple sensors. According to the team, the thrust of the work was figuring out how to improve efficiency and minimize or eliminate wasted Bluetooth and Wi-Fi radiations that would normally spread in all directions with no result other than adding to frequency noise.
The key to the innovation was in using conductive metamaterial to channel wireless signals in “surface waves” that move around the body. By holding the signals close, and controlling the direction of their movement from one device to the next, the wearable network would use much less power and sensors could detect weaker signals.
There are two ways to consider this development. One goal could be to conserve battery power. The flip side, with the battery power constant, is boosting signal strength to provide much higher than usual data rates with no power increase.
Physically, as shown in the video and image with this post, the team arranges the conductive route the wireless signal will follow. They accomplish the routing by placing comb-shaped strips of metamaterial on top of the garment with an underlayer of unpatterned conductive material. The result is the ability to arrange direct wireless “paths” between sensors and transmitters. It also eliminates complex wiring normally used to connect sensors and other components.
In tests so far, according to the NUS scientists, the smart garments prove they can be bent and folded, cut and torn, washed, dried, and ironed, all with no significant signal loss. The next steps for the team include finding commercial partners to develop the material technology further for initial applications including specialized athletic clothing and hospital garments that can aid performance and health monitoring.
