A High-Sensitivity MXene/PVDF Flexible Piezoelectric Sensor for Intelligent Tunnel Lighting.

Polyvinylidene fluoride (PVDF), one of the most promising flexible piezoelectric polymers bridging mechanical compliance and infrastructure-scale sensing, suffers from low intrinsic β-phase content that limits energy conversion efficiency. Two-dimensional MXene nanosheets offer a compelling solution, inducing β-phase crystallization through interfacial hydrogen bonding while preserving essential flexibility, yet conventional fabrication methods lack precise control over dipole alignment and suffer from percolation leakage at functional loadings. Herein, we report a process-structure synergistic strategy that combines EHD printing with an optimized serpentine structure to reconcile piezoelectric sensitivity with mechanical durability. By precisely tuning the MXene loading to 0.75 wt% (near but below the percolation threshold), the composite achieves a β-phase content of 71.91% and a piezoelectric sensitivity of 18.09 mV/kPa, while the serpentine design delivers a tensile strength of 21.97 MPa and 17.46% elongation at break. As a proof-of-concept, the sensor is deployed in a vehicle-responsive tunnel lighting system, withstanding cyclic heavy loads and achieving a 95.04% energy-saving rate compared to continuous operation. This work advances high-performance flexible piezoelectric composites for intelligent infrastructure applications.