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

Abstract

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 easyoperating 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.

Liquid Metal Smart Materials toward Soft Robotics

“…Previous studies have shown that liquid metal has desirable wettability with other materials (e.g., Cu mesh), [169][170][171][172] thereby ensuring that the liquid metal can be closely attached to these soft solid materials while retaining the ability to be shaped. [173] Such a solid-liquid coupling strategy can help achieve the standing and shaping of liquid metal. In addition, the fast and controllable liquid metal solid-liquid phase changes are considered as beneficial for its standing and shaping.…”

Tuning Flexibility–Rigidity Conversion of Liquid Metal/Polyurethane Composites by Phase Transition for Potential Shape Memory Application

“…Also, this special feature may provide a new strategy to reduce the shape recovery temperature. [21,22] This article describes 3D elastic polyurethane (PU) with metallic coating that can be programmed into stable, temporary shapes at body temperature. The shape of the 3D PU recovers rapidly and elastically when heated due to the ability of the coating to undergo a solid-liquid phase transition.…”

“…Also, this special feature may provide a new strategy to reduce the shape recovery temperature. [ 21,22 ]…”

Ga Based Particles, Alloys and Composites: Fabrication and Applications

“…In particular, Galinstan has been used, for example, as a coolant [2][3][4], a soft electronic material [5,6] and a lubricant [7,8]. EGaIn has been widely used in many areas, such as non-destructive contact in large-area junctions [9][10][11], nanomedicine carriers in drug delivery systems [12,13] and soft robotics [14][15][16]. To further enrich their functionalities, LM composites have been synthesized to build new material systems in which LMs/alloys are suspended as nanodroplets within a soft polymer matrix or mixed with other inorganic nanoparticles.…”