Preparation of ZnO/PVA flexible piezoelectric films for sensing dynamic-static superimposed loads under varying temperatures.

Flexible thin-film sensors exhibit considerable application potential in the structural health monitoring of bridges under complex traffic scenarios, owing to their capability of rapidly responding to dynamic loads, static loads, and dynamic-static coupled loads. In this study, following the evaporation crystallization method, ZnO/PVA was deposited on the substrate to form a 10-μm-thick film by adjusting the material ratio (m(ZnO):m(PVA) = 4:1) and solution environment (pH = 12). After cutting and packaging, the flexible piezoelectric film sensor was obtained. The sensing characteristics of the ZnO/PVA film sensor under quasi-static, vibratory, and coupled-force loads were analyzed using a dynamic data acquisition system, revealing excellent response feedback in detecting these three stress states. The sensitivity, stability, and response time were 2.34, 0.34, and 12.41 mV/N; 90.6, 94.4, and 92.3%; and 41, 5, and 8 ms, respectively. Temperature-dependent tests (10-60 °C) demonstrated significant signal stability after implementing a curve-fitting compensation algorithm. This temperature correction mechanism addresses the critical challenge of environmental fluctuations in practical bridge monitoring scenarios where static stresses and dynamic vibrations coexist.