“I grew up in a small village in Xuzhou, China. When I was a child I saw a lot of people around me dying of different diseases. Many people don’t realize there’s a problem until it’s too late. I thought, in the future I should design a wearable electronic device to monitor health and tell us what’s going on and what’s going wrong before it gets bad.

“Our body is generating data all the time. There are so many wearable devices now—the Apple watch, the Fitbit—but they mainly track physical activities or vital signs. They can’t provide information at the molecular level.

“It came into my mind: what about sweat?”

This year, Gao made a sweatband that combines sensors with electronic processors and a Bluetooth transmitter on a flexible printed circuit board. If you wear the band, it wirelessly transmits data about what’s in your sweat to a cell phone running an app.

Gao’s device has sensors that interact with chemicals including glucose and lactate, causing a detectable change in their electrical current. Other sensors change their voltage in response to sodium or potassium. A recent addition includes sensors that can pick up on toxic heavy metals excreted in the sweat.

The challenge now is to figure out whether and how these measurements correspond to meaningful changes in health. So Gao is working with exercise physiologists on clinical studies to look for correlations that will help spot signs of trouble before it’s too late.

—Katherine Bourzac