Stretchable and Recyclable Liquid Metal Droplets Embedded Elastomer Composite with High Mechanically Sensitive Conductivity

Liquid metal (LM)-based elastomers have received growing interest for a wide range of applications such as soft robotics and flexible electronics. This work reports a stretchable and bendable liquid metal droplets embedded elastomer (LMDE) composite, which consists of liquid metal droplets (LMDs) filler and carbonyl iron particles (CIPs)/polydimethylsiloxane (PDMS) hybrid matrix. The reversible switching of the composite from an insulator to a conductor can be realized through the contact and noncontact process between the LMDs. The mechanism of constructing the controllable conductive path between the droplets under external deformations has been systematically studied, and this result also provides a basis model for analyzing the conductive networks in traditional LM-based flexible composites. The composites exhibit stable mechanical and electrical performance under different tensile strains and bending angles. Moreover, the fluidic nature of LM endows the composite with good electrically healing capability. The valuable LM can be easily recycled at a high recovery rate of 98%. Finally, the composite can be developed as a sensor for the detection of both compressive force and magnetic field, demonstrating a broad promising in flexible electronics, actuators, and wearable devices.