Wearable fitness trackers have been developed to monitor everything from heart rate to sleep quality to the number of steps you take in a day. But researchers have now developed a device that measures sweat chemicals, which could alert users to dehydration, fatigue, and more.

The wearable sweat monitor measures glucose, lactate, sodium, and potassium in sweat, according to its creator Ali Javey, a professor of electrical engineering and computer science at the University of California-Berkeley, Medical News Today reports.

According to a study of the device, the tracker is the first fully integrated electronic system that can continuously and simultaneously monitor multiple sweat chemicals.

"Human sweat contains physiologically rich information, thus making it an attractive body fluid for non-invasive wearable sensors," said Javey, who reported on the device in the journal Nature. "However, sweat is complex and it is necessary to measure multiple targets to extract meaningful information about your state of health."

"In this regard, we have developed a fully integrated system that simultaneously and selectively measures multiple sweat analytes, and wirelessly transmits the processed data to a smartphone. Our work presents a technology platform for sweat-based health monitors."

The prototype device consists of a flexible circuit board containing 10 circuit chips, connected to five sensors that monitor glucose, lactate, sodium, potassium and body temperature.

The signals are then wirelessly transmitted to a smartphone app developed by the team, which syncs the data.

"The idea is to have this thumbs-up or thumbs-down device that will give real-time information: it could provide an alarm that you need to take some medication, or that you're getting dehydrated and need to drink some water," said Javey.

While blood tests are currently the "gold standard" when it comes to measuring metabolites and electrolytes in the body, George Brooks, a professor of integrative biology at UC-Berkeley, says the Javey device has the potential to be an effective non-invasive alternative.

"Having a wearable sweat sensor is really incredible because the metabolites and electrolytes measured by the Javey device are vitally important for the health and well-being of an individual,” he said.