Piezoelectric fiber-composite-based cantilever sensor for electric-field-induced strain measurement in soft electroactive polymer

Polymeric materials have been widely used in electronic and electromechanical transducer applications. Because of their low elastic modulus, it is quite challenging to accurately characterize the electric-field-induced strain and elastic modulus by conventional contact methods. In this paper, a piezoelectric lead zirconate titanate (PZT) fiber-composite- based cantilever strain sensor has been investigated to accurately characterize the electric-field-induced strain response in the out-of-plane direction of soft electroactive polymer samples. By choosing appropriate substrate material and the thickness ratio of the fiber composite to the substrate, this strain sensor can be optimized to provide high sensitivity and high flexibility simultaneously. The high voltage sensitivity can be attributed to partial decoupling of the longitudinal and transverse piezoelectric responses, the improved piezoelectric coefficient and small dielectric permittivity. The high flexibility is due to the reduced flexural spring constant of the composite-based cantilever device. Both theoretical modeling of the PZT fiber-composite-based cantilever device and experimental verification are performed in this work. The results indicate that the piezoelectric PZT fiber-composite-based cantilever strain sensor can accurately characterize the electric-field-induced small strain in electroactive soft polymers with high reliability.