Electromechanical impedance spectra investigation of impedance-based PZT and cement/polymer based piezoelectric composite sensors

Electromechanical impedance (EMI) technology based on piezoelectric sensor has potential application in structural health monitoring. PZT piezoelectric ceramic and cement/polymer based piezoelectric composites with different connectivities were used as sensing elements to fabricate the piezoelectric sensors in this study. The electromechanical impedance characteristic of the piezoelectric sensors before and after coupling with structure was also investigated. The research indicates that the electric impedance–frequency spectra for different kinds of piezoelectric sensors show the similar variation rule after coupling with structure. Comparing with piezoelectric composite sensors, PZT piezoelectric ceramic sensor has more resonant peaks as well as larger peak value. However, the piezoelectric composite sensors are more sensitive to the effects of mechanical damping of the coupled structures. Therefore, the cement/polymer based piezoelectric composites have potential advantage in EMI technology for concrete damage detection.