Possibly offering a new method to track health and fitness, Northwestern University researchers have developed a skin patch that can test sweat droplets during exercise and relay results to their the user's smartphone.

Led by John Rogers of Northwestern University's Center for Bio-Integrated Electronics, the researchers said they created the first of its kind skin patch because sweat contain biochemical components that can provide information about physiological health.

Experts say it can help a lot during physical activities. For instance, it can provide an early warning that it is time to replenish electrolytes before a runner or bicyclist starts to feel dehydrated.

Stanford University Prof. Zhenan Bao, who wasn't involved in the study, said, "It seems really practical . such a patch allows people to now have an opportunity to understand their health and how it changes depending on activities."

A study found that the experimental gadget successfully worked on sweaty bicyclists, remaining stuck even during a long-distance bicycle race in Arizona.

Prof. Rogers and his colleagues reported the first-of-its-kind health tracking skin patch in the latest edition of the journal Science Translational Medicine.