Multi-responsive and programmable actuators made with nacre-inspired graphene oxide-bacterial cellulose film.

In recent years, graphene oxide (GO)-based multi-responsive actuators have attracted great interest due to their board application in soft robots, artificial muscles, and intelligent mechanics. However, most GO-based actuators suffer from low mechanical strength. Inspired by the natural nacre, a graphene oxide-bacterial cellulose (GO-BC) film with a "brick and mortar" structure is constructed. Compared with the pure GO film, the tensile strength of the GO-BC film is increased by about 2 times. Benefiting from the rich oxygen-containing functional groups of GO sheets and BC nanofibers, the cracked GO-BC films can be pasted together with the help of water, which can be used to construct GO-BC films with multi-dimensional complex structures. Subsequently, a GO-BC/polymer actuator capable of responding to various stimuli is successfully developed through a complementary strategy of "active layer and inert layer". Further, based on the water-assisted pasting properties of GO-BC films, a series of GO-BC/polymer actuators with 3D complex deformations can be fabricated by pasting together two or more GO-BC/polymer actuators. Finally, the potential applications of multi-response GO-BC/polymer actuators in flexible robots, artificial muscles, and smart devices are demonstrated through a series of applications such as bionic sunflowers, octopus-inspired soft tentacles, and smart curtains.