Light-driven locomotive soft actuator and multi-functional sensors based on asymmetric PVA/carbon/PE bilayer film

Soft actuators and micro-robots receive significant attention for their potential applications in transportation, photovoltaic conversion devices, clinical care, and other fields. In this work, a polyvinyl alcohol/Chinese ink mixture was uniformly coated on polyethylene film for preparing structure-stabilized bilayer soft actuators. Due to the significant difference in thermal expansion coefficients between the two layers, the actuator can achieve a large bending deformation with a fast response speed under xenon light. A large amplitude of bending angle of 1260° was achieved in 6 s. A soft-body robot similar to an inchworm was constructed by changing the intensity of xenon or near-infrared light combined with the bionic structure design of an inchworm. The robot can realize various forms of movements (such as crawling and pushing boxes) on different surfaces (such as paper and leaves). Light-driven applications such as hands capable of grasping objects (grasping objects 14 times their weight), cats exhibiting variable expressions, elephant trunks performing curling and retraction, and bionic flowers realizing flowering and closing can be realized. In addition, based on the good photothermal conversion and pressure sensing performance of the bilayer actuator, it is able to monitor daily human activities (such as joint flexion, abdominal breathing, water swallowing, and other movements) and integrate with photoelectric conversion devices. This versatile and diverse drive-mode soft robot exhibits significant potential for applications such as wearable devices, transportation, photovoltaic conversion devices, and clinical therapies.