Highly compressible graphene/polyurethane sponge with linear and dynamic piezoresistive behavior

Abstract

A high-elastic graphene/polyurethane (PU) nanocomposite with excellent electromechanical properties was fabricated by a facile ice-templated assembly strategy. The resulting PU-reinforced graphene sponges (PGS) not only possess a combination of low density (18 ± 5 mg cm⁻³) and adjustable sensitivity (0.75 to 3.08 kPa⁻¹) but can also withstand large strain without permanent deformation. The pressure-sensitive sensors based on our sponge exhibit a negative piezoresistive effect, and the resistance can change from 5 kΩ to 25 Ω under 99% strain. We have also designed a novel device to investigate the delay ratio and fast piezoresistive response with different loading frequencies. Owing to its rapid response (14 ms), high flexibility and facile fabrication, this graphene strain sensor presents great potential for cost-effective artificial skins, which are urgently needed in soft robotic systems. Moreover, this effective assembly strategy provides a route to fabricating novel functional materials by embedding porous graphene inside another porosint.