A skin-inspired multifunctional soft actuator based on PVDF/MXene with fast response, large deformation, and high stability

Soft actuators are widely emphasized for their applications in artificial intelligence, human prosthesis, and intelligent robotics. Among them, piezoelectric actuators stand out due to good mechanical properties and fast response performance. However, it remains a major challenge to endow them with large deformation capability and stability. Inspired by human skin, we proposed a novel strategy to construct multifunctional soft actuators based on polyvinylidene difluoride (PVDF) and MXene via gradient strain mismatch. Polyethylene terephthalate (PET) with Young's modulus provides stable support for the actuator, and PVDF/MXene with small Young's modulus and excellent inverse piezoelectricity endows it with large deformation. Due to the modification of MXene, larger proportion of β crystalline phase in PVDF can be induced to amplify the deformation capability. Under synergies of inverse piezoelectric effect and gradient strain mismatch, the actuator can realize fast response (104 ms), large deformation (16 mm), and high stability (> 3000 testing cycles). Thereon, a bionic electronic hand, a soft gripper, and a dragonfly-like robot integrated with high-performance actuators are successively constructed to demonstrate their versatility and superior performance. Hence, this work offers a paradigm to fabricate multifunction soft actuators with great potentials in human-machine interaction, electronic protheses, and soft robots.