Bio-Inspired High Sensitivity of Moisture-Mechanical GO Films with Period-Gradient Structures

Moisture actuators can accomplish humidity-triggered energy-conversion process, through material screening and structural design. Inspired by natural caterpillars and the hydrophilic properties of graphene oxide (GO), this work proposes a geometrical design of period-gradient structures in GO films for fabricating moisture actuators. These novel period-gradient-structured GO films exhibit excellent dynamic performance that they could deform at 1000° with a small radius in several seconds at a high relative humidity (RH ≈ 80%). The properties of fast actuating speed and high response to deformation are achieved through the structural designing of the sole GO film by a one-step formation process. A mechanics-based theoretical model combined with the finite element simulation is presented to demonstrate the actuating mechanism in geometry, moisture, and mechanics, which lays the foundation for potential applications of GO films in remote control, environmental monitoring, and man-machine interactions.