Enhanced Piezoelectricity of PVDF-TrFE Nanofibers by Intercalating with Electrosprayed BaTiO₃

Over the past few decades, flexible piezoelectric devices have gained increasing interest due to their wide applications as wearable sensors and energy harvesters. Poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE), as one of piezoelectric polymers, has caught considerable attention because of its high flexibility, high thermal stability, and biocompatibility. However, its relatively lower piezoelectricity limits its broader applications. Herein, we present a new approach to improving the piezoelectricity of PVDF-TrFE nanofibers by integrating barium titanate (BTO) nanoparticles. Instead of being directly dispersed into PVDF-TrFE nanofibers, the BTO nanoparticles were electrosprayed between the nanofiber layers to create a sandwich structure. The results showed that the sample with BTO sandwiched between PVDF-TrFE nanofibers showed a much higher piezoelectric output compared to the sample with BTO uniformly dispersed in the nanofibers, with a maximum of ∼ 457% enhancement. Simulation results suggested that the enhanced piezoelectricity is due to the larger strain induced in the BTO nanoparticles in the sandwich structure. Additionally, BTO might be better poled during electrospraying with higher field strength, which is also believed to contribute to enhanced piezoelectricity. The potential of the piezoelectric nanofiber mats as a sensor for measuring biting force and as a sensor array for pressure mapping was demonstrated.