Sweat Patch Could Help People Track Their Health

The answer to tracking your health could be in your sweat.

Scientists at the University of Illinois at Urbana-Champaign have created a microfluidic skin patch that is capable of collecting and analyzing sweat. The patch was worn during a 104-kilometer bike race to test its durability.

The patch, or sweat sensor, collects sweat via a tiny tubing system. Different sections of the sensor slowly change color as they react to different levels of certain chemicals found within the sweat.

“This is radically different from current-generation wearable devices that are a block of electronics strapped to the body,” said John Rogers, a physical chemist and materials scientist at the University to Spectrum. “This allows a clinical-like precision measurement of health markers that physicians know how to interpret.”

The sensor pairs with a smartphone app to interpret the color changes and biochemistry of the sweat as certain health signs by simply taking a picture. Rogers said the biggest challenge was finding a balance between making the sensor comfortable enough to wear while remaining functional.

Researchers ensured that the device created a water-tight seal with the surface of the skin so it remained in place during high-intensity exercise. Another challenge the researchers faced was including how to make the sensor functional without using cheap, rigid electronics or flexible, expensive electronics.

The tubing system was their solution – by channeling the sweat toward different absorbent sections capable of chemically reacting to the presence of different sweat components.

“Our device uses microfluidic, lab-on-a-chip type approaches in sweat capture and analysis, and simple colorimetric chemistries for detection,” Rogers said. “Much different than previous approaches that rely on less sophisticated fluid capture schemes and more expensive electronic-based readout schemes.”

Readings collected by the sweat sensor seemed comparable to the current lab-based standards during a trial that involved a nine volunteers who participated in an indoor cycling exercise. Health readings included the volunteers’ sweat rate, sweat loss, pH, concentrations of lactate, glucose and chloride.

The sensor can hold sweat for around 125 hours after being peeled off the skin as long as all the sensor channel openings are sealed. With open channels, captured sweat remains for almost 75 hours after removed from the skin.

Rogers and his collaborators hope to turn the sensor into cost-efficient, disposable commercial devices. A disposable or recyclable design could avoid complications like cleaning or possible contamination. Their goal is to evolve the sensor into a device that would only cost $1 or $2.

The sensor has grabbed the attention of many different companies, including cosmetics company L’Oreal. The company is interested in using the sweat sensors to replace the bulkier research tools for understanding sweat chemistry and odor to develop new products.

“As a cosmetics company, they’re basically a skin company when you think about it,” Rogers said.

An unnamed biomedical company has also been in talks with Rogers’ lab about how the sweat sensors could eventually enable bloodless pre-screening for diabetes. The U.S. Air Force has also tested more advanced versions of the sweat sensors as worn by active-duty airmen.