Research and developments in energy harvesting to power implants and wearables continues to explore fascinating technologies. We’ve written about harvesting energy from human knee motion at the Chinese University of Hong Kong and from carbon nanotube yarn filaments in garments at the University of Texas and Hangyang University in South Korea. In 2017 we reported on research at North Carolina State University connecting tiny, rigid thermoelectric components with liquid metal in a non-toxic metal alloy used with wearables to generate power from body heat.

NC State is back in the news this year demonstrating an improved thermoelectric generator (TEG) that university engineers claim “surpasses all other flexible harvesters that use body heat at the sole energy source.” Flexible materials with superior skin contact may be favored for wearable comfort, but until now, flexible harvesters have been less efficient than rigid designs.

In a paper published in Applied Energy, NC State professor of electrical and computer engineering Mehmet Ozturk explained that the latest alloy used in NC State’s flexible TEG “is significantly better than other flexible devices reported to date and is approaching the efficiency of rigid devices.”

Key to the improved performance is the use of a new silicone elastomer. It encapsulates the graphene flakes and gallium and iridium alloy (EGaln), but also increases the rate of heat transfer by a factor of six. The elastomer also is mechanically robust which will make it more resistant to puncture or other damage.

Ozturk and his colleagues are focused on increasing the efficiency of the flexible TEGs even further. To date, the NC State team has boosted their TEG’s thermal conductivity by 600%. A reliable and efficient way to harvest body heat to power wearable sensors and other devices could be a major help in making such wearables more convenient and effective.