Asymmetric flexible graphene oxide papers for moisture-driven actuators and water level indicators.

Smart actuators have shown great potential for a range of industries, including artificial muscles, sensors, and smart devices. However, traditional actuators often suffer from small deformation and complex materials and manufacturing processes. Graphene oxide (GO) has emerged as an ideal candidate for moisture-responsive actuators due to its excellent moisture sensitivity. In this study, we present the development of a moisture-responsive actuator using a simple and straightforward approach based on a monolayer graphene oxide (GO) paper. By utilizing the different affinity of its two sides for water, the graphene oxide actuator demonstrates excellent performance in response to humidity gradients, achieving a large bending amplitude with a curvature of 3 cm⁻¹. Furthermore, the graphene oxide actuator was used as a humidity-sensitive switch to perform on and off switch movements, demonstrating its capability for autonomous detection for real-time humidity monitoring. This work provides a new avenue for the development of moisture-responsive materials and their potential applications in the design of intelligent control systems, actuators, soft robots, artificial muscles, and switches. [Display omitted] • The paper introduces a novel moisture-responsive actuator made of a single layer of graphene oxide paper. • The actuator exploits the different water affinity of its two sides to bend in response to humidity changes. • The actuator can also function as a humidity-sensitive switch, enabling autonomous and real-time humidity detection. • The paper demonstrates the potential of graphene oxide as a material for smart actuators, sensors, and devices. [ABSTRACT FROM AUTHOR]