4D-Printed Bionic Soft Robot with Superior Mechanical Properties and Fast Near-Infrared Light Response

Inspired by natural organisms, a four-dimensional (4D)-printed starfish-like bionic soft robot (SBSR) was effectively prepared by integrating three-dimensional (3D) printing with smart hydrogels. The body of the SBSR is composed of a reduced graphene oxide-poly(N-isopropylacrylamide) hydrogel (rGO-PNH) with superior mechanical properties. In addition, the enhanced photothermal conversion effect was obtained by the reduction of graphene oxide nanosheets after the 3D printing process. Cylindrical actuators prepared using rGO-PNH exhibited bending and orientation toward the light source within 20 s of exposure to near-infrared light, thus demonstrating the rapid photoresponsivity of rGO-PNH. Furthermore, the 4D-printed SBSR showcased effective grasping, lifting, and releasing of objects by mimicking the predatory behavior of starfish. This study would provide insights into the development of responsive materials in 4D printable bionic soft robots and their applications in areas such as biomimetic devices and artificial muscles.