EPFL engineers create a chip that detects stress levels via sweat

It could lead to stress-monitoring wearables.


Engineers from the Swiss Federal Institute of Technology Lausanne (EPFL) have developed a wearable sensing chip that can measure the concentration of cortisol in sweat. Since cortisol is the body's hormone released in response to stress, the chip could lead to wearables like smartwatches that can monitor its user's stress levels throughout the day. "[U]ntil now there has been no way to quantify stress levels in an objective manner," EPFL wrote in its announcement. " This creation has the potential to change that.

Cortisol helps regulate our metabolism, blood sugar levels and blood pressure. It also helps our body respond to stressful situations by redirecting energy to the brain, muscles and heart to prepare them for a fight-or-flight response. The hormone is secreted throughout the day based on a circadian rhythm and not just during especially stressful situations, though. For people who suffer from stress-related issues and diseases, that rhythm is off or the body produces too little or too much of the hormone. Those situations could lead to weight gain and obesity due to stress-related eating, cardiovascular diseases, depression and burnout.

The patch developed by the EPFL’s Nanoelectronic Devices Laboratory (Nanolab) and Xsensio has a transistor and an electrode made from graphene. It has short fragments of single-stranded DNA or RNA that can bind to cortisol in order for a device to measure its concentration in sweat. "That’s the key advantage and innovative feature of our device. Because it can be worn, scientists can collect quantitative, objective data on certain stress-related diseases. And they can do so in a non-invasive, precise and instantaneous manner over the full range of cortisol concentrations in human sweat," Nanolab head Adrian Ionescu said.

The engineers have already tested their creation in the lab, and their next step is testing it in a hospital setting. They're now working with the Lausanne University Hospital to trial the system on human patients, some of whom have Cushing’s syndrome (wherein the body produces too much cortisol), Addison’s disease (wherein the body doesn’t produce enough) and stress-related obesity. Patients with psychological diseases aren't included in those trials, but the team believes the patch could help doctors better understand them.