New Wearable Sweat Sensor Can Tell You When You're Dehydrated Or Fatigued

“Human sweat contains physiologically rich information, thus making it an attractive body fluid for non-invasive wearable sensors,” explains Ali Javey, the principle investigator of the study published in Nature, in a statement. “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.”

^{The sensors are so thin and flexible, they can be integrated into wristbands. Wei Gao/UC Berkeley}

Previous sensors developed to measure sweat have only managed to track a single compound at a time, or were too large and bulky to be able to integrate into a single band. But the new research has been able to pack five sensors into a thin, flexible circuit board that can easily be incorporated into wristbands or headbands. These sensors can measure the metabolites glucose and lactate, the electrolytes sodium and potassium, and skin temperature, with the power lasting around an hour before the need to recharge. By combining the readings of these different measurements, the band can track how your body is responding to the exercise.

“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,” says Ali Javey of the University of California, Berkeley.

When the sensors are in contact with sweat, an electrical signal is generated that is then amplified and filtered, and finally calibrated via skin temperature. Then if, for example, the levels of lactate are high, it would be an indication that your muscles are fatigued. But it is this need for continual contact with sweat that some people see as problematic, as often this cannot be maintained and gaps appear between the skin and the sensors.

The tech is still in its infancy, and Javey is currently seeking patents for the design, but there are still other challenges to deal with, such as what happens when people stop sweating. Javey, however, has his sights set on developing it further, adding more sensors to the device so that it could become an invaluable medical tool. One day, for example, he suggests the technology could help detect certain compounds that might be biomarkers for mental illness.