Sensitivity analysis of piezoelectric paint sensors made up of PZT ceramic powder and water-based acrylic polymer

A strain sensor based on piezoelectric paint film has been designed to be used in structural vibration monitoring applications. The piezoelectric paint film can be considered as a piezoelectric composite constituted by two phases: lead zirconate titanate (PZT) ceramic powder (active phase) homogeneously distributed in a water-based acrylic polymer (passive phase). Two electrodes placed to both sides of the film are required to measure the electric charge generated by the sensor. Because PZT is a ferroelectric material, the film must be polarized with a high electric field across the electrodes prior to use.The sensor sensitivity, defined in this work as the electric displacement relative to the biaxial strain of the substrate surface in which the sensor is attached, has been analyzed as a function of various parameters: the electric field applied to polarize the sensor; the time during which the electric field is applied; the film thickness; the electrode area; and the concentration of PZT by weight. From the analysis of the experimental results a mathematical model has been proposed which defines the sensor sensitivity as a function of the previously mentioned parameters.