Researchers Develop New Wearable Technology Capable of Converting Body Heat to Electricity

A team of researchers from North Carolina State University has developed a new lightweight, wearable technology capable of harvesting body heat and converting it to electricity to power other wearable devices.

The experimental prototypes of the new technology, described in a paper published in the journal Applied Energy, can easily conform to the shape of the body and can produce far more electricity than previous lightweight heat harvesting technologies.

"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," explained Daryoosh Vashaee, an associate professor of electrical and computer engineering at NC State and corresponding author of a paper on the work, in a press release.

The wearable thermoelectric generators (TEGs) work by making use of the temperature differential between the body and the ambient air. Using a layer of thermally conductive material, which is topped with a polymer layer, the researchers were able to prevent the heat from dissipating to the outside air, forcing the body heat to pass through a centrally-located TEG.

For their experimental designs, the researchers found that the upper arm was the optimal location for heat harvesting. They also discovered that the skin temperature around the wrist is higher than the rest of the body. However, the irregular contour of the wrist limited the contact of between the skin and TEG band.

When the researchers incorporated the TEGs into T-shirts, they found that T-shirt TEGS were still able to generate 6 μW/cm2 -- or as much as 16 μW/cm2 if a person is running, making it viable option for powering wearable technologies.

With their new device, the researchers takes one step closer in developing a reliable lightweight and reusable power source for wearable technologies that is being used for long-term health monitoring.