Transmission lines replace sensors in new smart fabric
There are now several experimental "smart fabrics," capable of detecting the wearer's respiration or heartbeat via deformations in the material. A new one, however, is claimed to work better by utilizing transmission lines instead of individual sensors.
Most existing vital signs-monitoring smart fabrics utilize multiple linked sensors, incorporated into the material at various locations. Those sensors are typically quite fragile, however, plus many of them are needed in order to cover a large area of the body. Additionally, each sensor can only detect one type of deformation, such as stretching or pressure.
Prof. Fabien Sorin and doctoral assistant Andreas Leber, from Switzerland's EPFL research institute, have developed an alternative that reportedly has none of those drawbacks.
As opposed to many rigid sensors, their fabric has rows of soft, thin transmission lines running through it. Each line is made of a flexible, stretchable elastomer, with multiple liquid metal "sub-lines" running along its length, inside of it.
Electrical pulses are fed into one end of each line, conducted through it via the liquid metal, and then detected at the other end. Based on how long it takes each pulse to travel the length of the line, it's possible to determine – simultaneously – if that line is being stretched, compressed or twisted. What's more, the intensity and location of the deformation can also be ascertained.
Plans now call for the electronic components to be miniaturized, thus making the entire system more compact and thus truly wearable.
"Imagine clothing or hospital bed sheets capable of monitoring your breathing and other vital movements, or AI-powered textiles that allow robots to interact more safely and intuitively with humans" says Leber. "The soft transmission lines that we’ve developed open the door to all of this."
A paper on the research was recently published in the journal Nature Electronics.