Scientists have developed a wearable, battery-free sweat sensor that can continuously track multiple health biomarkers by regenerating its sensing surface and drawing power wirelessly from a smartphone or reader, potentially changing how long-term health monitoring is done outside clinics.

The device, developed by researchers at the University of California, Irvine, is called IREM-W2MS3 (In-Situ Regeneratable, Environmentally Stable, Multimodal, Wireless, Wearable Molecular Sweat Sensing System). It is a flexible skin patch designed to analyze sweat in real time and measure key health-related molecules.

Unlike existing wearables that often degrade over time, this system is built to work for long durations without losing accuracy. It can also trigger sweat production on demand, removing the need for exercise or external stimulation.

The system connects wirelessly to a smartphone or a small wrist-worn reader using near-field communication. It does not rely on a traditional battery. Instead, it uses the electromagnetic field from the reader to power its sensing functions.

Self-cleaning sensor core

The key innovation lies in its regenerating sensing surface. The device applies a low voltage to refresh its sensing layer, removing accumulated molecules that normally reduce accuracy in long-term biosensors.

“The regenerative capability of the IREM-W2MS3 addresses one of the biggest obstacles in long-term wearable biosensing, which is sensor surfaces that lose performance after repeated measurements because molecules remain bound to the sensing layer,” said Rahim Esfandyar-pour, senior author of the study.

The system simultaneously tracks four biomarkers in sweat: cortisol, glucose, lactate, and urea. These markers are linked to stress, metabolism, physical exertion, and kidney function, giving a broad view of health conditions over time.

Because sweat is collected non-invasively, researchers say it could support continuous monitoring in daily life without clinical visits or blood tests.

Multi-signal health tracking

The patch integrates molecular sensing with environmental stability improvements that allow it to function under changing temperature, humidity, and pH conditions. It was tested continuously for 21 days without measurable signal degradation.

The device also solves a long-standing challenge in wearable health tech: generating sweat without requiring physical activity. By activating a hydrogel through wireless energy transfer, the system can induce sweat production when needed for measurement.

“Despite rapid progress in the field, existing wearable devices have consistently fallen short in several critical areas,” said Esfandyar-pour. “They lack environmental stability for real-world, outside-the-lab use; they cannot regenerate their sensing surfaces for repeated, long-term use; and they are largely incapable of simultaneously detecting multiple molecular biomarkers with high precision.”

Researchers say the combination of regeneration, wireless power, and multi-biomarker sensing could make long-term health tracking more practical for conditions such as diabetes, stress disorders, kidney disease, and metabolic monitoring.

The team has filed a patent through UC Irvine’s Beall Applied Innovation office and is now working toward further development and possible commercialization.

The study was published in Nature Biomedical Engineering.