An island-bridge packaging piezoelectric sensor for structural health monitoring in high-strain environments

Piezoelectric sensor failure triggered by high structural strain is a critical problem in structural health monitoring (SHM) that cannot be neglected. Thus, a novel island-bridge packaging piezoelectric sensor for SHM in high-strain environments is proposed in this paper. The trapezoidal-section island-bridge structure of the new sensor greatly optimizes the high-strain survivability of the piezoelectric layer. Additionally, good impedance matching characteristics between the monitored structure and the sensor guarantee the transmission strength of high-frequency dynamic sensing signals. The feasibility of the structure and the principle of operation for the novel sensor were demonstrated via theory, simulation and experiment. Besides, an established analytical model and its simulation and experimental verification results displayed that the structural parameters of the sensor could significantly adjust the strain-bearing capacity. Under a specific parameter configuration, the strain transfer coefficient of the novel sensor was only 0.087, which was 12.1% of the conventional sensor, thus could safely operate in the monitoring structure environment of 10,000 με. On the other hand, the proposed sensor’s impedance signal strength was satisfactory in the SHM frequency range of 10–110 kHz, where its average impedance value was as high as 397.7 Ω. Moreover, the optimized signal demonstrated very good stability, reliability, and strength in the test, thus ensuring the effective monitoring of crack propagation via the new sensor. Therefore, this work is a good complement to the existing piezoelectric sensors SHM technique.