Harvesting continuous rotational mechanical energy using coiled sheath-core carbon nanotube yarn

Twisted and coiled carbon nanotube (CNT) yarns utilize the capacitance change induced by mechanical deformation to convert mechanical energy into electrical energy without requiring a bias voltage. Improved techniques are needed for improving the energy generation of a single yarn. Here we report a sheath-core CNT yarn harvester (SCCH) using a twisted CNT sheath and a polymer fiber core, which increases the energy conversion efficiency to 6.1 %, up from 1.7 % for the neat coiled yarn. The SCCH generated a 2.2 times peak power density (233 W kg−1) than neat CNT yarn when cyclic stretched at 15 Hz. Additionally, the twistron was coated with gel electrolytes to create a sensor capable of monitoring human motion. The twistron was further employed to harness continuous rotational energy in diverse environments where fluid flow is present, facilitating the operation of temperature or humidity-sensing electronic devices.