Researchers at Stanford University have developed a stretchy wearable patch that can measure cortisol levels in sweat. The researchers hope that the technology could help doctors diagnose adrenal or pituitary problems, and help to assess stress levels in young or non-verbal children who cannot communicate with mental health professionals.
Levels of the hormone cortisol can spike in response to stress, but it can also fluctuate significantly during the day. Abnormal cortisol levels can indicate problems with the adrenal glands or the pituitary gland. Current lab tests can take several days, by which point cortisol levels have likely changed, creating a diagnostic dilemma.
The Stanford group set out to develop a wearable non-invasive cortisol sensor, which assesses cortisol levels in the sweat, potentially allowing people to monitor their cortisol levels at home. “We are particularly interested in sweat sensing, because it offers non-invasive and continuous monitoring of various biomarkers for a range of physiological conditions,” said Onur Parlak, a researcher involved in the study. “This offers a novel approach for the early detection of various diseases and evaluation of sports performance.”
The research team developed a stretchy sensor that can be affixed to the skin, and which draws sweat into a reservoir passively. “I always get excited about a device, but the sweat collection system that Onur devised is really clever,” said Alberto Salleo, another researcher involved in the study. “Without any active microfluidics, he’s able to collect enough sweat to do the measurements.”
The sweat reservoir is topped with a cortisol-sensitive membrane, which specifically binds cortisol, but which allows charged ions present in the sweat, such as potassium, to pass through unless they are blocked by the membrane-bound cortisol. If the sweat contains a lot of cortisol, the membrane will allow very few of the ions through, and an electrochemical sensor measures these ions that are backed up in the sweat reservoir. This provides an indirect measurement of the amount of cortisol in the sweat.
To use the sensor, a user will need to be sweating somewhat, so it may be best used during or after exercise. So far, the patches have provided similar results to gold-standard laboratory tests. However, the researchers are working on making it more reliable and want to adapt it to measure other biomarkers in the sweat. One possibility is that the patch could measure several biomarkers at once, helping to provide an in-depth look at someone’s health status.
Via: Stanford University…