Silk could improve wearable body sensors

Chinese researchers are investigating the use of silk in wearable body sensors, with the aim of developing a more sensitive and flexible generation of these devices that can monitor a slew of body functions in real time.

Body sensors, which are usually made with semiconductors, have shown great potential for monitoring human health; however, they do have limitations. For instance, strain sensors, which measure changes in force, cannot be highly sensitive and highly stretchable at the same time.

Silk, a natural material that is stronger than steel and more flexible than nylon, could overcome these problems. In addition, the fibre is lightweight and biocompatible. Unfortunately, silk doesn’t conduct electricity very well.

To address this challenge, researchers at Tsinghua University sought a way to boost the conductivity of silk so it could be successfully used in body-sensing devices. They presented their work last week at the 254th National Meeting & Exposition of the American Chemical Society (ACS), held in Washington, DC.

The researchers decided to try two different strategies. In one approach, they treated the silk in an inert gas environment with temperatures ranging from 600–3000°C. As a result, the silk became infused with N-doped carbon with some graphitised particles, which is electrically conductive. Using this technique, the scientists developed strain sensors, pressure sensors and a dual-mode sensor capable of measuring temperature and pressure simultaneously.

In the other approach, the team fed either graphene or carbon nanotubes to silkworms. Some of these nanoparticles were naturally incorporated into the silk produced by the worms. So far, this method hasn’t produced electrically conductive fibres, but the researchers are still experimenting with this technique and are hopeful they can make it work.

“Silk is the ideal material for fabricating sensors that are worn on the body,” said lead researcher Yingying Zhang, who now wants to explore ways to create an integrated set of silk-based, self-sustaining sensors that would be powered by nano-generators.

“One possibility we foresee is for them to be used as an integrated wireless system that would allow doctors to more easily monitor patients remotely so that they can respond to their medical needs more rapidly than ever before.”

Zhang went on to suggest that her team’s silk sensors might be used to build realistic robots that can sense touch, temperature or humidity and can even distinguish between different people’s voices.

“There is a whole world of possibilities for silk sensors at the moment,” she said.

Image caption: Silk could soon be used to produce more sensitive and flexible body sensors, like this one. Image credit: Yingying Zhang.