A New Chemical Mix Delivers Carbon Nanotube Yarn for Powering Wearables From Body Heat

Researchers from the Nara Institute of Science and Technology (NAIST) have come up with a more efficient approach to powering wearable devices — by creating fabrics out of carbon nanotubes that can serve as energy harvesters, turning the wearer's body heat into electrical energy.

"We introduce a low-cost, fast, and environmentally friendly method for the development of flexible and fabric-type wearable thermoelectric devices," says project lead Masakazu Nakamura of the team's work into making wearables more self-sufficient. "The key to high performance is to unravel the entanglement of the raw CNT [Carbon Nanotube] material and increase the degree of CNT orientation when spun from the dispersion."

Designed for powering sensors and other wearables, the team's creation is a yarn with carbon nanotubes that act as a soft and flexible thermoelectric generator — turning the wearer's waste body heat into electrical energy to drive the wearable device. It's not a novel concept, but previous attempts have struggled with the carbon nanotubes become tangled — something Nakamura and colleagues claim to have resolved by using glycerol and polyoxyethylene(50) stearyl ether during the manufacturing process.

The viscous glycerol, the team explains, works to effectively disperse the carbon nanotubes, while the ether works as a surfactant to prevent the carbon nanotubes from clumping together. By tuning the concentration of the chemicals, the team was able to produce a carbon nanotube-infused yarn with highly-aligned bundles — delivering three times the power factor of previous approaches.

The team's work has been published in the journal ACS Applied Nano Materials under open-access terms.