Gradient-Structured Hydrogel with Integrated Actuation and Strain Sensing for Biomimetic Robotics

The development of soft robotics that integrates autonomous motion and real-time sensing remains challenging due to the irreconcilability of these functions in homogeneous materials. Inspired by natural symbiotic systems, a conductive nanocomposite hydrogel is developed that achieved a synergistic combination of magnetic actuation and built-in strain-sensing capabilities through a facile magnetic-field-induced assembly strategy that creates a gradient distribution of Fe 3 O 4 @MXene nanohybrids within the hydrogel network. The resulting hydrogel exhibits a comprehensive set of properties underpinning this synergy: good conductivity (2.6 mS cm −1 ), high strain sensitivity (gauge factor of 6), a broad strain response range (0–580%), and excellent fatigue resistance (500 cycles), along with a fast magnetic actuation speed of 30° s −1 . The core advance is that actuation and sensing work in concert within a single material, allowing it to execute programmed deformation while simultaneously monitoring its own motion in real-time, which is vividly showcased through biomimetic applications, such as a gripper that adjusts its grip upon sensing and a crawler that can track its own movement. This work provides a paradigm for creating intelligent soft matter with innate feedback loops, opening transformative avenues in adaptive soft robotics, biomedicine, and human-machine interaction.