Novel multi-responsive soft actuator assembled with a graphene oxide nanoribbons doped strain hydrogel sensor with high sensitive and NIR-triggered performances

Effectively integrating multiple properties of hydrogel materials for expanding the application field of soft materials is highly desirable. In this work, a fast initiation system was used to prepare hydrogels. Based on the dynamic hydrogen bonding interactions between two-dimensional graphene oxide nanoribbons (GONRs), polymer chains and metal ions, the hydrogel exhibited excellent mechanical properties, great sensing performance and great self-healing property. Especially, the hydrogel exhibited sensitive response performance to near-infrared (NIR) light. A bilayer hydrogel actuator was assembled by combining the hydrogel with the temperature-sensitive Poly-N-isopropylacrylamide (PNIPAM) hydrogel. The bilayer hydrogel actuator exhibited stable responses to temperature, pH, and NIR light. The bilayer hydrogel could achieve bending close to 360° with good cycling stability in these three environments. As a proof-of-concept, the bilayer hydrogel was used as an identifiable fluid valve with selective passage which released fluids of different properties into corresponding containers. At the same time, the self-healing properties of the hydrogel and the actuation performance of the bilayer hydrogel were successfully used to simulate the wagging motion of the tail of puppy. The developed self-healing and sensing hydrogel and the assembled bilayer hydrogel actuator are expected to open new application fields in the health monitoring and soft robotics.