Scientists at North Carolina State University created a wearable tech that can be attached to the upper arm to harvest body heat and turn it into electricity. Although these are just prototypes, the new design is lightweight, able to conform to any body shape and is able to generate more electricity than other wearable tech.

“Wearable thermoelectric generators (TEGs) generate electricity by making use of the temperature differential between your body and the ambient air,” says study author Daryoosh Vashaee, an associate professor of electrical and computer engineering at the university. “Previous approaches either made use of heat sinks — which are heavy, stiff and bulky — or were able to generate only one microwatt or less of power per centimeter squared (μW/cm2). Our technology generates up to 20 μW/cm2 and doesn’t use a heat sink, making it lighter and much more comfortable.”

The researchers created a layer of material that conducts heat then topped it with a polymer layer to prevent the heat from transferring to the air.

wearable tech

Study co-lead Haywood Hunter shows off the TEG-embedded T-shirt at work. Credit: North Carolina State University

The body heat passes through the TEG and the heat that was converted into electricity has to pass through the TEG into an outer layer of material that can dissipate heat. Overall, the layers are only two millimeters thin.

The researchers say that they can make the prototype larger. They also discovered that the best location for heat harvesting is on the upper arm.

When they placed the TEG into shirts, they found that the device generated 6 μW/cm2. If the person is running while wearing the shirt, the electricity generated can go as high as 6 μW/cm2.

Although wearing T-shirt TEGS is also a good way to generate power, the shirts are not simply as efficient as upper arm bands.

Once they finally perfected their product, they could create devices that can monitor health, including one’s heart and even the factors that can lead to asthma attacks.