Graphene fibers are lightweight, flexible, and strong. As such, they are ideal candidates for incorporation into “smart materials” that change shape in response to stimuli.

Liangti Qu and his team, Beijing Institute of Technology, China, have prepared graphene/graphene oxide (G/GO) nanofibers by scanning a laser beam over freshly spun GO fibers to result in the formation of asymmetric areas of graphene. These G/GO fibers are flexible and have a high tensile strength.

The oxygen-rich nature of graphene oxide means that it has a higher affinity for water than graphene does. Exposure to water vapor, therefore, results in the reversible expansion/contraction of the GO layers, but not the G layers, and thus the fibers reversibly bend in the presence of moist air with a relative humidity of 80 %.

As the laser reduction can be used to make fibers with precisely defined G regions, the researchers successfully designed and produced systems that can reversibly form “hooks” and “S” shapes. They also fabricated a G/GO fiber “walker” that moves through a narrow slit upon “on” and “off” states of applied moisture, and even wove the fibers to produce a responsive textile structure. The team hopes that these fibers can be used in the development of woven devices and smart textiles.

• Graphene Fibers with Predetermined Deformation as Moisture-Triggered Actuators and Robots,
  Huhu Cheng, Jia Liu, Yang Zhao, Chuangang Hu, Zhipan Zhang, Nan Chen, Lan Jiang, Liangti Qu,
  Angew. Chem. Int. Ed. 2013, 52, 10482–10486.
  DOI: 10.1002/anie.201304358