Nanotube-based Yarns Harvest Energy From Twisting and Stretching

An international team of researchers led by researchers at the University of Texas (UT) at Dallas—where they have been working on making carbon nanotube-based yarns for well over a decade—has devised a way to make these carbon nanotube yarns into devices that can harvest energy from stretching or twisting them.

In research described in the journal Science, the initial results show promise for immediate use in powering small sensor nodes in Internet of Things (IoT) applications. The team says its nanotube yarns could produce larger amounts of energy by flexing and twisting in response to the movement of ocean waves.

While it appears as though these nanotube yarns are exploiting a piezoelectric effect, in which a material can generate an electric charge in response to applied mechanical stress, the yarn’s behavior makes it more closely tied to so-called electroactive polymers (EAPs), which are a kind of artificial muscle.

“Basically what’s happening is when we stretch the yarn, we’re getting a change in capacitance of the yarn. It’s that change that allows us to get energy out,” explains Carter Haines, associate research professor at UT Dallas and co-lead author of the paper describing the research, in an interview with IEEE Spectrum.