Wearable sweat sensor able to diagnose cystic fibrosis

Researchers at the Stanford University School of Medicine—in collaboration with the University of California-Berkeley—have developed a wearable sweat sensor that can diagnose cystic fibrosis, a genetic chronic disease that affects the lungs and digestive system.



Sweat contains valuable information, according to Sam Emaminejad, a former Stanford postdoctoral scholar who is now an assistant professor of electrical engineering at UCLA. In particular, sodium and chloride levels in sweat are diagnostic markers for cystic fibrosis, which causes mucus to build up in the lungs, pancreas and other organs, he says.

“Sweat is a very rich source of information that includes glucose, lactate, sodium and potassium ions,” observes Emaminejad.

He notes that the problem with traditional methods for diagnosing cystic fibrosis require that patients visit a specialized center and sit still while electrodes stimulate sweat glands in their skin. However, Emaminejad says the research team’s wearable system of flexible sensors and microprocessors is more accessible and does not require patients to sit still for a long time while sweat is gathered in collectors.

The portable device, which adheres to the skin, stimulates the sweat glands and then detects the presence of different molecules and ions based on their electrical signals. The sensor measures the molecular content of the sweat and electronically transmits the data by way of a Bluetooth-enabled cellphone to a cloud-based server for analysis.

Work on the device at Stanford University was supported by a National Institutes of Health grant, while work at UC-Berkeley was supported by the National Science Foundation.

Results of a new study were published April 17 in the Proceedings of the National Academy of Sciences demonstrating that the sensor detected the elevated sweat electrolyte content of cystic fibrosis patients compared with that of healthy control subjects.

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But, cystic fibrosis is not the only application for the sensor. Emaminejad says he and his research colleagues have also measured glucose levels in sweat, making the device potentially useful for monitoring pre-diabetes and diabetes.

“We showed that it can be used as a diagnostic tool for cystic fibrosis,” contends Emaminejad. “And, we also used it as a clinical investigation tool to show that there potentially could be correlations between glucose levels in sweat and in blood.”

“Our results indicate that oral glucose consumption in the fasting state is followed by increased glucose levels in both sweat and blood,” researchers write in their study. “Our solution opens the possibility for a broad range of noninvasive diagnostic and general population health monitoring applications.”

However, Emaminejad hastens to add that larger scale clinical studies are needed to examine correlations between sweat-sensor readings and overall health. “We need to do much more experiments to establish this, but now we have the platform that can facilitate large-scale investigations.”