Bio-inspired rotary flight of light-driven nanocomposite films

Abstract Light-driven photoactuators are promising in a wide range of applications. However, it is still challenging to apply them in flying devices owing to their slow response, small deflection/force and low frequency response. Herein, inspired by the structure of vine maple seeds, we report a nanocomposite film-based soft photoactuator, which exhibits an unprecedented ‘helicopter’-like rotary flight behavior in response to near-infrared (NIR) light (0.6 W/cm2) with ultrafast rotation (~7200 revolutions per minute) and rapid response (~650 ms). This photoactuator is operated based on a fundamentally different mechanism that harnesses the outcome of a series of sequential synergistic interactions between the ternary constituents, i.e., the aerodynamic favorable ‘airscrew’ formation of the hygroscopic agar/silk fibroin film followed by the jet propulsion, which is caused by the photothermal effect of the embedded graphene in the actuator. The soft helicopter-like device exhibits controlled flight and steering behaviors, making it promising for applications in soft robotics, controlled cargo delivery, and other miniature devices.