A new electronic yarn can measure a wearer’s exhaustion levels during exercise, and warn users when to take a break.

The yarn was developed by researchers at ETH Zurich and consists of two fibers, one made of a conductive, elastic rubber and one made of rigid, thin plastic. 

“These two fibers act as electrodes and create an electric field,” said researcher Tyler Cuthbert. “Together, they form a capacitor that can hold an electric charge.”

Credit: Tyler Cuthbert / ETH Zurich

The electric charge changes depending on a wearer’s movement and is used to identify when a user’s pace changes in response to fatigue – typically by strides shortening or becoming irregular. 

“Since the sensor is located so close to the body, we can capture body movements very precisely without the wearer even noticing,” said study lead Carlo Menon.

This yarn can be sewn directly into workout clothes, making it easier and cheaper to manufacture than other products on the market with electronic components retrofitted in.

In trials, the textile sensor was integrated into a pair of sports leggings, stretching and relaxing at different rhythms as a wearer runs and analyzing subtle changes in running form.

Credit: Photograph: Valeria Galli / ETH Zurich

ETH Zurich has filed a patent for the design, and the team is working to get the prototype ready for commercialization. Potential applications include sports and in the workplace – to prevent exhaustion-​related injuries – as well as to rehabilitation medicine.

“Our goal is to make the manufacture of smart clothing cost-​effective and thus make it available to a broader public,” Menon said.