Hierarchically Engineered Interfaces in Flexible Piezoelectric Composite Films for Broad-Range Pressure Sensing

Broad-range pressure sensing remains challenging for flexible piezoelectric sensors since deformation becomes restricted under high compressive loads, often causing premature response saturation. Here, a flexible piezoelectric composite film featuring a nacre-inspired hierarchically engineered interfacial architecture was fabricated by a facile solvent exchange-induced self-assembly process. Graphene oxide lamellae are preferentially aligned at the interfaces between a quasi-interconnected piezoceramic framework and thermoplastic polyurethane matrix, forming a mechanically robust architecture that can withstand high compressive loads (megapascal regime) and facilitate efficient stress transfer and interfacial polarization. Consequently, the optimized piezoelectric film exhibits the quasi-static piezoelectric charge coefficient d₃₃ of 52.2 pC N^-1 and the voltage constant g₃₃ of 74.8 mV m N^-1, and the device demonstrates stable signal output across a broad pressure range from 8.95 kPa to 3.06 MPa, along with a rapid response time of 18.1 ms and excellent durability over 10,000 cycles. A seven-channel integrated sensing system based on the film is developed for distributed lower-limb biomechanical monitoring, highlighting its potential for wearable health management. This work provides a practical route toward flexible piezoelectric sensors for broad-range pressure sensing and wearable biomechanical monitoring.