High-Temperature and Flexible Piezoelectric Sensors for Lamb-Wave-Based Structural Health Monitoring

Piezoelectric sensors can be utilized in Lamb-wave-based structural health monitoring (SHM), which is an effective method for aircraft structural damage detection. However, due to the inherent stiffness, brittleness, weight, and thickness of piezoelectric ceramics, their applications in aircraft structures with complex curved surfaces are seriously restricted. Herein, we report a flexible, light-weight, and high-performance BaTiO₃:Sm₂O₃/SrRuO₃/SrTiO₃/mica film sensor that can be used in high-temperature SHM of aircraft. Enhanced ferroelectric Curie temperature (487 °C) and piezoelectric coefficient d₃₃ (120-130 pm/V) are achieved in BaTiO₃, which can be attributed to the tensile strain developed by stiff Sm₂O₃ nanopillars. Stable ferroelectricity and piezoelectricity are retained up to 150 °C. The flexible BaTiO₃:Sm₂O₃/SrRuO₃/SrTiO₃/mica film is validated as an ultrasonic sensor with high sensitivity and stability for damage monitoring on aircraft structures with the curved surface ranging from 25 to 150 °C. Our work demonstrates that flexible and light-weight BaTiO₃:Sm₂O₃/SrRuO₃/SrTiO₃/mica film sensors can be employed as high-temperature piezoelectric sensors for real-time SHM of aircraft structures with complex curved surfaces.