Thermally Responsive Torsional and Tensile Fiber-actuator Based on Graphene Oxide.

Graphene based actuators are of practical interest because of their relatively low cost compared with other nano-carbon materials, such as carbon nanotubes. We demonstrate the simple fabrication of graphene oxide (GO)-based fibers with infiltrated Nylon-6,6 polymer by wet-spinning. These fibers could be twisted to form torsional actuators and further coiled to form tensile actuators. By control the relative twisting and coiling direction of the GO/Nylon fiber, we were able to realise reversible contraction or elongation actuation with strokes as high as -80% and 75%, respectively, when the samples were heated to 200oC. The tensile actuation showed remarkably little hysteresis. Moreover, this GO/Nylon actuator could lift loads over 100 times heavier than itself, and generate stable actuation at high temperatures over the melting point of the polymer. This novel kind of GO-based actuator, which has multi-directional actuation, have potential for a wide range of applications such as artificial muscles, robotics, and temperature sensing.