Novel Characterization Procedure for Single Piezoelectric Fibers

The characterization of the ferroelectric properties of piezoelectric ceramic fibers is paramount for optimizing their manufacturing processes, for quality control purposes, and for modeling the response of components and structures. Until now, fibers were generally characterized by measuring the so-called 1-3 composites, fiber arrays embedded in a polymer matrix. The fiber properties can then be extracted, provided the volume fraction and stiffness of each phase, the fiber piezoelectric charge constant as a function of the electrical field strength, and the matrix permittivity are known. This implies a large amount of time and experimental effort. This article presents a comprehensive procedure for the direct characterization of single piezoelectric ceramic fibers in terms of butterfly and polarization loops, as well as their blocking force. The experimental setup is composed of a waveform generator, a high-voltage amplifier, a dynamic mechanical analyzer, a current/charge measuring circuit, and an oscilloscope. The active circuitry used for reliably collecting the charge generated by a single fiber is presented in full detail. The very good repeatability of the measurements showed the proposed procedure to be robust. The comparison between single fiber measurements and the investigation of 1-3 composites revealed both procedures to be equal, at 99.9%, in determining the average strain and polarization properties. In addition, the single fiber measurement provides an estimation of the variation in fiber properties within a single production batch. This information is essential to understand how to optimize processing routes and build robust devices.