They did it again, and not by accident. A team of North Carolina State University engineers focuses on harvesting heat energy from the human body to power wearable electronics. They recently attained even greater efficiency than we reported in 2020. Mehmet Ozturk, NC State professor of electrical and computer engineering was the lead author of a paper in npj Flexible Electronics that describes the technology’s improved heat retention.

Ozturk and his team continue to refine a flexible wrist-worn body heat harvester. The NCSU technology is a thermoelectric generator (TEG) that converts body heat to electricity. The purpose of the development is to provide a self-powered energy source for wearables so users can forget about changing or charging batteries.

In 2017, the NC State team argued for flexible TEGs because of the technology’s superior skin contact, comfort, and ergonomic factors compared to rigid designs. When we covered the NCSU TEG in 2020, the news was about an improved silicone elastomer that encapsulated the TEG’s graphene flakes, gallium, and iridium alloy. The elastomer — a type of thermal conductive rubber — increased puncture resistance but the greater win was that it bumped up the heat transfer rate by a factor of six.

Clearly not one to rest on the laurels of its own advances, the NC State team has continued to push for even greater efficiency in its TEG design. The most recent paper describes the latest innovation: Orkut et al added aerogel flakes to the silicone elastomer. The latest addition to the mix cut elastomer heat loss in half. By retaining more heat in the device, the TEG is able to increase power output.

We can expect to hear more about the NCSU TEG. Orkut states specifically in the report that his team will continue to work on increased efficiency of the devices. Some day in the future when we can all wear self-powering wristbands to continuously monitor our vital signs, we’ll owe a big tip of the hat to Team Orkut.