A two-part system created by researchers at Stanford University and the University of California-Berkeley detects and analyzes a profile of chemicals in sweat. The flexible sensors and flexible circuit board stick to the skin and provide a health-monitoring device that continuously tracks a user's health at the molecular level.

The wearable sensors measure skin temperature in addition to glucose, lactate, sodium, and potassium in sweat. Integrated circuits analyze the data and transmit the information wirelessly to a smartphone or other device.

Other noninvasive sweat biosensors either monitor only a single molecule at a time or lack signal processing that can adjust for temperature effects or interactions among different molecules. The new device, tested on a team of volunteers, is a fully-integrated “perspiration analysis system” that binds to the skin and measures certain sweat metabolites and electrolytes; the system calibrates its readings based on skin temperature.

In the future, the wearable biosensor could be used to alert athletes and patients to fatigue, dehydration, overheating, and other health problems.