A flexible piezoelectric sensor based on a piezoelectric composite film with high sensitivity and excellent thermal stability for multi-scenario applications†

Abstract

With the development of basic facilities around the world, irregular curved structures are continuously emerging, so it is of great significance to conduct flexible sensing studies on complex curved surfaces. However, the traditional piezoelectric ceramics are seriously restricted in their application to structures with curved surfaces due to their inherent stiffness, brittleness, and low Curie temperature. Herein, we report a flexible piezoelectric composite film based on BiScO₃–PbTiO₃–(Sr_0.7Bi_0.2)TiO₃ (BS–PT–SBT) piezoelectric ceramic particles and a polyimide (PI) matrix. The as-fabricated film shows a large voltage output of ∼112 V, a maximum current output of ∼454 nA, a high sensitivity of 6.56 V N⁻¹, and good temperature stability at 30–210 °C. In practical applications, it can serve as a functional component in a strain sensor, ultrasonic sensor, and acoustic emission sensor. Of particular significance is that the devices can monitor the water flow change process in a circular pipe, act as a vehicle counter on a curved road, and also be applied to the health monitoring of curved concrete and pipeline structures under high-temperature environments. This work demonstrates that the BS–PT–SBT–PI composite film exhibits enormous potential for sensing applications in multiple scenarios.