Wearable Sensors Provide Real-Time Measurements of Sweat Rate and Electrolytes and Metabolites in Sweat

University of California, Berkeley, CA

Researchers developed wearable skin sensors that can detect what’s in a person’s sweat. Using the sensors, monitoring perspiration could bypass the need for more invasive procedures like blood draws and provide real-time updates on health problems such as dehydration or fatigue. The sensor design can be rapidly manufactured using a roll-to-roll processing technique that essentially prints the sensors onto a sheet of plastic.

The sensors were used to monitor the sweat rate and the electrolytes and metabolites in sweat from volunteers who were exercising and others who were experiencing chemically induced perspiration. The sensors are reliable, reproducible, and can be fabricated to scale so multiple sensors can be placed in different spots of the body.

The sensors can be rapidly manufactured using a roll-to-roll processing technique that prints the sensors onto a sheet of plastic. (Image: Antti Veijola, VTT)

The new sensors contain a spiraling microscopic tube, or microfluidic, that wicks sweat from the skin. By tracking how fast the sweat moves through the microfluidic, the sensors can report how much a person is sweating or their sweat rate. The microfluidics are also outfitted with chemical sensors that can detect concentrations of electrolytes like potassium and sodium and metabolites like glucose. Roll-to-roll processing enables high-volume production of disposable patches at low cost.

To better understand what sweat can say about the real-time health of the human body, the researchers first placed the sweat sensors on different spots on volunteers’ bodies — including the forehead, forearm, underarm, and upper back — and measured their sweat rates and the sodium and potassium levels in their sweat while they rode an exercise bike. They found that local sweat rate could indicate the body’s overall liquid loss during exercise, meaning that tracking sweat rate might be a way to give athletes a heads-up when they may be pushing themselves too hard.

Using these wearable devices, researchers can continuously collect data from different parts of the body to understand, for example, how local sweat loss can estimate whole-body fluid loss. They also used the sensors to compare sweat glucose levels and blood glucose levels in healthy and diabetic patients, finding that a single sweat glucose measurement cannot necessarily indicate a person’s blood glucose level.

For more information, contact Kara Manke at This email address is being protected from spambots. You need JavaScript enabled to view it.; 510-643-7741.