New York, Aug 6 (IANS): Researchers have developed a biosensor that uses a chemical stimulant to produce sweat even when the patient is relaxed and cool.

Testing sweat, an important factor in understanding the hormones or chemicals, has several possible benefits over blood, according to the the findings published in the journal Lab on a Chip.

Blood analysis is considered the gold standard for biometric analysis. But biometric testing with blood is invasive and often requires the use of a lab. It is far more difficult for the doctors to perform continuous monitoring of blood over hours or days.

Sweat provides a noninvasive alternative, with chemical markers that are more useful in monitoring health than saliva or tears, said Jason Heikenfeld, Professor at the University of Cincinnati.

"People for a long time ignored sweat because although it can be a higher-quality fluid for biomarkers, you can't rely on having access to it," Heikenfeld said.

"Our goal was to achieve methods to stimulate sweat whenever needed -- or for days," Heikenfeld added.

For the study, the researchers applied sensors and a gel containing carbachol, a chemical used in eyedrops, to their subject's forearm for 2.5 minutes.

They then recorded data obtained from the subject's sweat for 30 minutes using sensors that measured concentrations of sweat electrolytes.

Carbachol was effective at inducing sweating under the sensor for as long as five hours.

A subsequent experiment successfully generated sensor results for several days, using this process to stimulate sweat, Heikenfeld said

"This work represents a significant leap forward in sweat-sensing technology."

"Imagine being able to monitor cardiac patients after they have been released from the hospital, or preventing dehydration in athletes or even helping ensure that your body is getting the exact right concentrations of a prescription drug," Heikenfeld said.