Stanford scientists created an elastic patch that can collect sweat from the skin and assess the amount of cortisol a person is producing, he said in a study published in the journal Science Advances.
Clinical tests that measure cortisol can be an indicator of the emotional or physical stress of the subjects studied and help doctors determine whether a patient's adrenal glands or pituitary are functioning properly.
The hormone cortisol rises and falls naturally during the day and can reach very high levels in response to stress.
Current methods to measure cortisol levels require a wait of several days to obtain laboratory results. If the prototype version of this device becomes a reality, it could allow people with imbalances to monitor their levels at home and obtain results in seconds.
This rapid test could reveal the emotional state of a young child who otherwise would not be able to communicate that he feels stress, the study said.
"This offers an innovative approach to the early detection of different diseases and to assess athletic performance," said Onur Parlak, a postdoctoral fellow at the Alberto Salleo laboratory at Stanford University and lead author of the study.
The team built a rectangular and elastic sensor around a membrane that binds only to cortisol.
The patch can passively absorb sweat through the holes in the bottom and sweat builds up in a reservoir, the study says.
Charged ions like sodium and potassium from sweat can pass through the membrane unless they are blocked by cortisol.
The sensor detects the charged ions instead of the cortisol itself and in addition to this there is a waterproof layer that protects the patch from contamination.
In the future, researchers could test the sensor in saliva, which would prevent patients from having to sweat.