Researchers at the King Abdullah University of Science and Technology (KAUST) have unveiled a prototype sensor designed to alert athletes when they're nearing their limits — by monitoring muscle fatigue via sweat.
"As we exercise and our muscles get tired, the sensor sees the new chemical environment and produces different electrical resistance versus stress curves," explains Kang Lee, former KAUST postdoc and lead author of the study unveiling the prototype sweat sensor. "By comparing these curves to reference curves for a given sensor, we can determine the pH of the sweat and how fatigued the muscle is."
The trick relies upon a correlation between the acidity or alkalinity of a person's sweat and the build up of acid in their muscle cells — the cause of muscle fatigue during exertion.
The sensor itself is based on an ultra-thin nanomaterial known as an MXene, previously built into a sweat sensor but now combined with a hydrogel which gives the new sensor additional ability to detect mechanical strain. As the sensor tracks muscle movement, it is also able to detect the pH level of the wearer's sweat.
The prototype sensor connects to a smartphone or smartwatch via Bluetooth to transfer its data, though the team warns of work still be to done before the technology could be commercialized. "The most serious challenge is the long-term stability of the sensor," says co-author Husam Alshareef, who led the group responsible for developing the original MXene sensor, "so we're looking at altering compositions and designs in future experiments."
The team's work has been published in the journal Small Methods under open-access terms.