Multi-stimuli-responsive Ti3C2TX MXene-based actuators actualizing intelligent interpretation of traditional shadow play

For smart devices, there is a growing demand for multi-functional soft actuators, nevertheless, well-developed actuators always respond to single stimulus, and it is still challenging to achieve the application diversity standards. Herein, a bidirectional multi-stimuli responsive soft actuator based on Ti3C2TX MXene-cellulose nanowhiskers (CNWs)-polyvinyl alcohol (PVA)/polydimethylsiloxane (PDMS) multilayer membranes is proposed (MXCP-P). By grafting CNWs onto MXene nanosheets, a freestanding composite film with gradient layered structure was prepared. Due to the hygroscopicity among MXene nanosheets, increased interlayer space is in favor of adsorption/desorption of water molecules, causing invertible shape change and humidity-driven deformation with a rapid response. Based on high photothermal conversion capacity of MXene and large difference of coefficient of thermal expansion between PDMS and MXene, the MXCP-P achieves an ultra-large amplitude and fast response driven by natural light. A Venus flytrap soft robot is constructed with good actuation behaviors. The MXCP-P film was employed as actuators in the opera of The Male Phoenix Pursui from Han Dynasty and in shadow puppetry "Monkey King Subdus the White-Bone Demon" of China, both exhibiting excellent performances towards humidity and light stimuli synchronously. This paper inspires a new strategy for multi-stimuli responsive soft bionic robots and intelligent traditional shadow play.