Flexible MXene-Nb ₂ CT _<i>x</i> /Bacterial Cellulose Film for Rapid Humidity Response and Multifunctional Biomimetic Applications

Humidity-responsive actuators, which can directly convert ambient humidity changes into controllable mechanical deformation, exhibit broad application potential in fields such as bionic robotics, smart wearable devices, and human-machine interactive systems. MXenes have emerged as ideal humidity-responsive materials due to their unique two-dimensional layered structure, exceptional surface hydrophilicity and electrical conductivity. However, their poor environmental stability severely limits their application in humidity-driven actuators. In this study, we designed a composite film (MXBC) based on MXene-Nb₂CT_<i>x</i> and bacterial cellulose (BC), where a three-dimensional layered-fiber interwoven structure synergistically enhances humidity-driven performance through a hydrogen-bonding network. The MXBC film demonstrates an ultrafast response of 536° within 0.5 s under ΔRH = 50%, along with remarkable cycling stability over 3000 cycles, while maintaining robust mechanical properties. Leveraging these advantages, we successfully developed various intelligent bionic devices, including biomimetic flytraps, artificial flowers, smart switches, and adaptive clothing. This study not only provides a new strategy for developing highly stable and multifunctional smart actuating materials but also expands the application of MXenes in environmentally adaptive soft robotics and interactive wearable systems.