Liquid-Metal-Enhanced Wire Mesh as a Stiffness Variable Material for Making Soft Robotics

Stiffness variable materials are of great interests to many fields, especially in soft robotics. However, most materials require external voltage or high temperature to trigger the stiffness regulation process, which limits their applications in many situations, such as underwater. Herein, an easy-operating low-melting-point-metal enhancer is proposed, which can discretionarily regulate the stiffness of copper (Cu) wire mesh and greatly improve the performances of the target network-organized material. The mechanical property is improved through swift stiffness variations in a large scale, from completely soft to high hardness. Over the experiments, such liquid-metal enhancer can also work as a “glue,” meaning it can glue several individual meshes together in arbitrary shapes just by organizing them in proper positions. The bonding force produced by the enhancer permits a four-layer mesh combination (0.8 mm thickness) to successfully afford a load of 2 kg. In addition, the electrical resistance of the copper wire mesh decreases 10% after treated by the enhancer. Based on the results, the grabber and support structure are designed and built by the enhanced meshes and achieving the designed function. This study opens up a brand new method for fast fabrication of reconfigurable modular soft robotics that can tolerate large external forces.