High-strength lignin-based polyurethane with multilayer integrated structure: A flexible protective layer for intelligent robot perception and energy supply.

As robotic technologies continue to advance, the growing demand for integrated protection, sensing, and energy-supply functions in outdoor robotic systems can scarcely be satisfied by single-functioned materials. Herein, a sandwich-structured multifunctional intelligent material is developed, wherein lignin-based polyurethane (LPU) serves as the mechanical support layer, acrylic-based eutectic gel as the conductive sensing layer, and MXene as the photothermal/infrared stealth layer. Through the incorporation of acylsemicarbazide (ASC)-derived hydrogen-bond arrays into the lignin-based polyurethane network, LPU is endowed with high mechanical strength (the tensile strength increased from 45.6 MPa to 81 MPa), self-healing property, and recyclability, as well as excellent impact resistance and photothermal properties, providing reliable structural support for the entire material. As the conductive adhesive layer, the acrylic-based eutectic gel enables reliable monitoring of both large-scale human motions and subtle movements while maintaining intimate conformal contact with skin joints for precise signal transduction. MXene, as the photothermal energy supply and infrared stealth layer on the surface, can achieve an output voltage of nearly 0.3 V under 8.0 W cm-2 light irradiation. This integrated structure effectively addresses the inherent drawbacks of including module interference, poor structural compatibility, and low integration levels. Moreover, it provides a novel approach for the construction of lightweight and multifunctional wearable sensing devices.