Inexpensive Wearable Patches Monitor Sweat and the Data It Contains

Your sweat can tell you a lot about your body and its current condition. At the most obvious level, you can tell how hot you are or how much you’re exerting yourself based on how much you’re sweating. But the composition of your sweat also contains valuable information about your body, and that changes quickly based on factors like hydration and muscle fatigue. To gather information about your sweat and take advantage of it, researchers from the University of California, Berkeley have developed an affordable new wearable patch.

This patch can be worn comfortably for long periods of time in order to collect sweat and analyze it. The data gathered by the patch could be useful in applications ranging from training athletes to monitoring a diabetes sufferer’s glucose levels. To achieve that, each patch is equipped with a spiraling microfluidic tube. That tiny tube wicks sweat away from the skin as the wearer perspires. Sensors on the patch detect how quickly the sweat is moving through the tube in order to monitor sweat rate, and additional chemical sensors are used to detect the concentration levels of sodium, potassium, lactate, and glucose.

Those chemical sensors weren’t chosen arbitrarily, and each substance they’re designed to detect can provide important information about the wearer’s conditions. Lactate levels, for example, are correlated with muscle fatigue. Sodium and potassium readings correspond to hydration levels. Glucose is very important for determining when someone with diabetes needs insulin. The wearable patch connects to a processing board that can transmit the collected data wirelessly to a smartphone, making it easy to keep logs of the wearer’s condition over time.

The patches are also inexpensive to manufacture, thanks to a “roll-to-roll” fabrication technique. In a process similar to lamination, the sensors are rolled onto a flexible sheet of plastic. That makes it possible to make large quantities of the sensors affordably. The only downside is that the data collected varies from person to person. That’s why the researchers hope to use their new sensors in studies to find accurate ways to analyze individuals’ data.