Flexible and lightweight microcellular RGO@Pebax composites with synergistic 3D conductive channels and microcracks for piezoresistive sensors

Piezoresistive sensors with high flexibility, lightweight and high sensitivity are crucial in variable conductors and wearable devices. Herein, microcellular poly(ether-block-amide) beads coated with reduced graphene oxide (RGO@Pebax) composites with synergistic 3D conductive channels and microcracks were fabricated via the supercritical CO2 foaming followed by dip-coating hydrogen bond assembly, compression moulding and in-situ reduction. The microcellular RGO@Pebax composites exhibit high flexibility (up to 50% compressibility) and low mass density (down to 0.2 g/cm3) due to the incorporation of microcellular structures and 3D interconnected channels. The resultant microcellular RGO@Pebax composites-based piezoresistive sensors exhibit excellent sensing capacity due to the synergistic effect of double mechanisms: “disconnect-connect” transition of microcracks and increased contact area in the 3D conductive channels. Moreover, the piezoresistive sensors exhibit outstanding reliability and stability during the long-term repeated compression strain. Functional applications of the piezoresistive sensors have been demonstrated, indicating their excellent application potentials in variable conductors and wearable devices.