Sensors applied to the skin hold promise for a non-invasive and low-cost method of identifying key biomarkers in sweat, which could help clinicians make earlier and more accurate diagnoses. Up until now, however, sensors could identify the presence of biomarkers but lacked the ability to accurately detect their concentration in the presence of erratic, intermittent and unpredictable sweat production.

To solve this problem, a team of Penn State researchers has developed a sensor that accurately detects biomarker concentrations in sweat samples. Their work was published in Advanced Science.

While researchers had previously created a sensor that could detect amounts of glucose and other biomarkers, the sensors lacked a way to accurately detect the volume of sweat, meaning the concentration of the biomarkers was unknown.

“One particular challenge is to quantify that biomarker and sweat rate in an accurate manner, because the different conditions that cause us to sweat—exercise, warm weather, eating spicy foods—can all have different rates of sweating that may be more consistent or may be on-and-off sweating,” said Huanyu “Larry” Cheng, the James L. Henderson, Jr. Memorial Associate Professor of Engineering Science and Mechanics at Penn State.

“That makes it challenging to measure the volume of sweat, which we need to know if we want to quantify the biomarker concentration.”

To assess this information, the researchers designed a sensor with two channels for capturing sweat: one that will measure the amount of the biomarker, and one that will measure the volume of sweat. The sensor relies on a dye to signal the presence of the biomarker and can be read with the naked eye, making it inexpensive and easy to use.