Wearable skin patch monitors health using your sweat

The device will be on a patch applied to the skin near sweat glands.

It consists of a small vial containing multiple chambers that has a hydrophobic -- water repelling -- valve near the opening made of silicone rubber.

The channel has a hydrophilic -- water attracting -- coating for easy collection of the sweat.

Unlike other devices that require two openings, the single opening reduces the amount of evaporation, leading to longer storage time for later analysis, said the team from Pennsylvania State University and Xiangtan University who developed the wearable device.

"We want to be able to analyze the sweat from daily exercise or from the heat of the sun because in sweat we have a lot of biomarkers like pH and glucose that will be a really nice indicator for disease progression or diagnostics," said Huanyu 'Larry' Cheng, assistant professor of engineering science and mechanics, Penn State.

The pH or glucose level can be read by the naked eye or a photo taken with a smartphone.

Also, the researchers can analyze the sweat at different time points using different chambers -- called chrono-sampling.

"The two-valve device is more complicated and requires using a clean-room technique called photolithography. Our simpler one-valve device can be made without expensive equipment utilizing micromachining," Cheng said in a paper that appeared in the journal Lab on a Chip.

The device will be of interest to the healthcare industry, and particularly in athletics, where it can be used to monitor overheating or to adjust exercise levels for optimum performance, said the researchers.