Staying hydrated isn’t always easy—whether you’re out on a run or just working at your desk, it’s easy to forget to drink enough water.
But a new wearable sweat sensor developed by researchers at the University of California, Berkeley, could soon help solve that problem.
This small, comfortable device can track hydration levels and stress by analyzing your sweat, giving you a simple way to know when it’s time to take a break, have some water, or even relax.
The research, recently published in Nature Electronics, shows how the device uses electrodermal activity (EDA)—a measurement of how easily electricity passes through the skin—to monitor hydration.
EDA has long been used to measure mental stress, but scientists hadn’t considered it reliable for tracking physical activity or hydration.
That’s because sweat can collect under traditional sensors and interfere with readings.
The UC Berkeley team solved this problem with a clever design.
Their new sensor uses breathable, water-permeable electrodes that allow sweat to pass through, preventing buildup and helping the device maintain a clear connection to the skin.
According to study co-leader Seung-Rok Kim, the sensor is thin, soft, and comfortable enough to wear all day and can be built right into the back of a smartwatch or fitness tracker.
This makes it easy for users to get real-time updates on how their body is doing—whether they’re exercising, working, or just going about their day.
For example, athletes can avoid dehydration during training, while students or office workers can monitor their stress and manage their focus more effectively.
To test the sensor, the team built and evaluated three versions of their breathable electrodes using different materials: micro-lace, spiral wire, and carbon fiber fabric.
They placed the sensors on different parts of the body and had participants perform both physical tasks, like cycling, and mental tasks, like solving puzzles.
By comparing EDA signals with sweat measurements and body weight changes, they were able to confirm that the sensor accurately tracked hydration levels and could tell the difference between stress caused by physical activity and stress caused by mental effort.
Graduate researcher Yifei Zhan, another co-lead author, said the ultimate goal is to make health monitoring more accessible and personal. “This technology empowers people to make better choices about when to exercise, when to rest, and how to manage their mental well-being,” he said.
The researchers plan to continue refining the sensor by studying how temperature, humidity, and individual skin types affect the results. They hope their work will lead to the next generation of wearable health devices that can help people stay healthy and in balance, every day.
