Wearable sensor measures stress levels and sports performance via sweat

 

A group of material scientists led by Dr Alberto Saleo of Stanford University has developed a wearable sensor that can measure cortisol levels through sweat. Cortisol is also known as the stress hormone and its levels peak in relation to stress. It is also an indicator of athletic performance since it reflects the working of pituitary or Adrenal glands. The cortisol tests inform treatment for certain medical conditions. But the current lab tests take days to get the results and it is a high probability that the test results cannot be equated to current levels.

The Cortisol Challenge

Keeping all this in mind, the scientists

have developed a flexible, tiny, wearable sensor that measures cortisol levels through the sweat. The majority of the biosensors work by measuring the positive and negative charges of the molecules. But cortisol has no charge and is a major obstacle to measure its levels. So, the scientists designed a flexible patch with a cortisol sensitive membrane. The patch is waterproof and has holes in the bottom.

How they overcome the cortisol obstacle?

The sweat passes passively through the patch and the charged molecules like sodium and potassium are sent out of the membrane. Only the cortisol molecules are retained in the membrane. Then if you connect the patch to a device, it would give the results in seconds. However there is a catch, the membrane doesn’t function if it is saturated with the sweat.

Validation of the sensor

To test the accuracy of the results, the team recruited two volunteers and let them run for 20 minutes with the patches tied to their arms. The lab tests and real-world tests are quite similar indicating the reliability of the patch. The prototype patch also worked multiple times unless it is saturated with sweat. The researchers are now looking to measure the cortisol levels via saliva so that the patients no longer needed to sweat. Further, the team hopes to measure multiple biomarkers at a time which would offer a clearer picture of what’s going inside the body.

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