Flexible energy harvester based on aligned PZT/SMPU nanofibers and shape memory effect for curved sensors

Abstract

The popularity of flexible energy harvesters has grown rapidly in recent decades because of their high flexibility for application in wearable and implantable devices. Flexibility and functionality are key issues for their use in wider engineering applications. In this study, we present a multifunctional flexible energy harvester based on aligned lead zirconate titanate (PZT)/shape memory polyurethane (SMPU) nanofibers and applying its shape memory properties for use with surfaces with curved and/or complex structures. Mechanical and thermomechanical analyses and energy harvesting tests were performed on random and aligned nanofibers to investigate the influence of nanofiber orientation and its shape memory properties. Our results showed that, compared with random nanofibers, 0° aligned PZT/SMPU nanofibers (the nanofibers’ direction is parallel to the tensile direction) demonstrated higher mechanical, shape memory and energy harvesting properties. In particular, the energy harvesting properties (output voltages) were increased by 5.4 times. In addition, taking advantage of the shape memory effect, the PZT/SMPU energy harvester can be deformed into various curved shapes to match complex structures while maintaining its original piezoelectric characteristics, which resulted in enhanced energy harvesting from curved surfaces. The developed energy harvester realized better piezoelectricity as a result of its nanofiber arrangement, and offers a flexible ability to match various surfaces with complex structures to achieve more effective energy harvesting.