Dynamic characterization of piezoelectric paint sensors under biaxial strain

A piezoelectric paint film has been designed to be used as a strain sensor. The composite is a suspension of milled lead zirconate titanate (PZT) ceramic powder in a polymer binder (water-based acrylic). The sensitivity of the sensor was estimated as the electric displacement (electric charge per electrode area) generated by the sensor relative to the strain experienced by the substrate surface, under the hypothesis that the electric charge generated is proportional to the sum of the principal strains. The piezoelectric constant d31 (conventionally used to characterize piezoelectric sensor materials for structural vibration measurement) has also been obtained. The sensor linearity has been demonstrated over a strain range of ±200 μɛ and the sensor sensitivity is shown to be flat to within ±2 dB over a frequency range of 5–500 Hz, ranges typically required for structural vibration monitoring applications.