Caltech's Low-Cost Sweat Sensor Tracks Stress Through Cortisol Levels

Researchers at the California Institute of Technology (Caltech) have developed a sweat sensor that, they claim, can measure a wearer's stress levels — and are looking at not only using the device on Earth but taking it into space.

The idea of measuring people's health by analyzing their sweat isn't new: Researchers have developed sensors which analyze sweat for everything from exercise tracking to diabetes monitoring — and Caltech believes the same technology can be used as a non-invasive stress level monitor.

"Depression patients have a different circadian pattern of cortisol than healthy individuals do," explains Gao of how the sweat sensor operates. "With PTSD patients, it's another different one. Our analysis time could be only a few minutes. Typically, a blood test takes at least one to two hours and requires stress-inducing blood draw. For stress monitoring, time is very important."

The cortisol-tracking sensor is claimed to be mass producible at low cost, and operates in near-real-time — a major advantage over traditional means of measuring cortisol levels like taking blood samples. In testing, the sensor appeared to accurately track the user's cortisol levels — and, in doing so, their stress levels, at least in response to exercise and plunging their hands in icy water.

While the stress sensor has considerable applications on Earth, Caltech has confirmed that Gao is one of the research teams participating in a series of studies into the health impact of deep-space missions — and the new sensor will be key. "We aim to develop a wearable system that can collect multimodal data, including both vital sign and molecular biomarker information," Gao explains, "to obtain the accurate classification for deep space stress and anxiety."

The full paper is available in the journal Matter under open access terms.