Liquid Metal Hybrid Composites with High-Sensitivity\nand Large Dynamic Range Enabled by Micro- and Macrostructure Engineering

Abstract

Conductive elastic composites composed\nof conductive fillers and\npolymer matrices are showing an increasing number of applications\nin the fields of flexible sensors, wearable devices, and stretchable\nelectronics. Under mechanical deformation, the conductive filler network\nin the matrix shifts to change the conductive pathway among particles\nand thus, electrical conductivity of the composite. For most conductive\ncomposites, their conductivity changes monotonically with strain.\nHere, we report a composite that exhibits an unconventional strain\nresponse; its electrical conductivity increases sharply under both\ncompressive and tensile loads. The Ecoflex-based composite contains\nspike-shaped nickel microparticles and liquid metal microdroplets.\nBecause of the elastomeric mechanical properties of Ecoflex, the composite\nhas an extremely high stretchability and pressure sensitivity, which\nis ideal for tactile sensing and mechanical responsiveness. On the\nbasis of a composite film with a grooved or pyramidal surface structure,\nwe demonstrate a pressure-controlled intelligent heating film and\na pressure sensor with extremely high sensitivity and dynamic range.