What Could Sweat-Sensing Devices Tell You about Your Health?

Written by: Denise John, PhD


Published on: June 27, 2024

Photo courtesy of Sarah McColgan/Stills.com

We all sweat. It can be inconvenient (and annoying), but it has a purpose: to help us maintain a steady body temperature so we don’t overheat.

Sweat is mostly water. But it also contains electrolytes (e.g., sodium, potassium, chloride), metabolites (e.g., glucose, lactate), proteins (e.g., cytokines, interleukins), vitamins and minerals (vitamins C and D, calcium, zinc), and even hormones (e.g., estrogen, progesterone, cortisol). Which means that measuring what exactly is in our sweat, using an arm or finger patch, has alluring potential to lend insight into our overall health without drawing blood.

There are some sweat-sensing devices currently on the market, like the Gx Sweat Patch, but they can measure electrolytes and metabolites only. These devices are primarily marketed to athletes, who can use them to analyze sweat during workouts and optimize their rehydration strategies.

“Sweat is this noninvasive window into the body,” says Tyler Ray, PhD, a mechanical engineering professor at the University of Hawaii and a scientific advisor for Epicore Biosystems, the creator of the Gx Sweat Patch. His lab has created a sweat-sensing device generated by a 3D printer to stick to your forearm. “It allows us to collect sweat very precisely—as it’s coming out from the body over a continuous phase—so we can look at what’s happening in sweat in real time,” Ray says. (For now, it’s used only in research contexts.)

Wei Gao, PhD, a medical engineering professor at the California Institute of Technology, has published data showing the potential for the stress hormone cortisol to be measured with a sweat-sensing patch. His study suggests that cortisol levels in sweat correlate with cortisol levels in blood, validating the potential for this hormone (and others) to be accurately measured by sweat-sensing devices.

Earlier this year, Gao’s lab was the first to publish data measuring estradiol—a form of estrogen—using a sweat-sensing device. Gao says that this finding shows a potential to change women’s health: Frequently monitoring hormone fluctuations throughout the menstrual cycle or during perimenopause and menopause, for example, could provide data that would expand our current knowledge and view of these physiological phases. There’s also potential for sweat-sensing devices to help diagnose and treat infectious diseases, brain and mental health conditions, hormone imbalances, and other health concerns.

But developing this technology doesn’t come without challenges. “Sweat, of course, has its own limitation,” Gao says. The size of proteins and hormones must be considered—it’s easier to measure small molecules from sweat than larger ones because smaller ones diffuse through the skin’s pores more freely.

Scientists also need enough sweat to measure these biomarkers effectively. “The challenge is that there is typically a hundredfold dilution in what is measured in sweat versus what you could measure in blood,” Ray says. That means it’s much harder to detect the same biomarkers that would be present in blood, and a certain volume of sweat is needed to do that.

Creating sweat sensors to measure various biomarkers poses additional challenges, but the researchers I talked to are focused on their vision. “Being able to fully monitor and understand what’s happening with your body in real time—when you want it and when you need it—is going to be really transformative,” Ray says.