Journal Article

MXene/Carboxymethyl Chitosan Moisture Responsive Soft Actuator with Diode‐Like Actuation for Versatile Applications Driven by Human Metabolism

Xu, Liangliang, Ling, Yangyang, Hu, Ying, Chang, Longfei, Li, Xiaoxia, Li, Ziqing, Peng, Qingyu, Xu, Xinyu

2026

Overview

Moisture responsive soft actuators are receiving increasing attention due to their unique potential in reducing external energy dependence and carbon footprint. For the conventional moisture responsive soft actuators, their bending deformation under moisture stimulation is usually bidirectional, and the orientation of the bending axis is random. Achieving a moisture responsive monolithic actuator with controllable unidirectional deformation remains a challenge. Here, a Ti3C2Tx MXene/carboxymethyl chitosan composite film actuator with thickness gradient along length direction is fabricated via a vacuum‐assisted “tilt‐filtration” approach. The actuator exhibits a “diode‐like” controllable unidirectional deformation behavior under moisture gradient, and its deformation direction is strictly correlated to its thickness gradient direction and moisture source direction. Based on this highly correlated actuation behavior with internal structural asymmetry, a self‐sustained oscillator under a constant moisture gradient is achieved. Besides, various multifunctional applications based on this actuator driven by human metabolism are also demonstrated, including non‐contact switch with unidirectional conductivity, intelligent keyboard for non‐contact character input, biomimetic crawling robot, wearable intelligent thermal management clothing, and a self‐powered respiratory sensor. This work paves the way for the realization of moisture responsive soft actuators with unidirectional controllable deformation, and further promotes the development of sustainable intelligent materials in soft robotics and electronics. A MXene‐based actuator with gradient thickness is fabricated by a novel and simple vacuum‐assisted “tilt‐filtration” approach. The actuator exhibits a “diode‐like” controllable unidirectional deformation behavior under moisture gradient, and its deformation direction is strictly correlated to its thickness gradient direction and moisture source direction. Based on this actuator, a series of versatile applications driven by human metabolism are demonstrated.

• Publisher: John Wiley & Sons, Inc,Wiley
• Subject: asymmetric structure / Asymmetry / Composite materials / Deformation / diode deformation / Fourier transforms / Humidity / Metabolism / Microscopy / moisture responsive / Robotics / soft actuator / soft robotics / Spectrum analysis / Sustainable materials