Enhanced flexoelectricity in PVDF/AgNbO₃ composite films for flexible sensor

Flexible polymers have garnered significant interest in the field of flexoelectricity due to their capacity to endure substantial strain gradients. However, the flexoelectric coefficients of these polymers are generally lower than those of ferroelectric ceramics, thereby restricting their application potential in sensor technologies. In this study, we propose a method to augment the flexoelectric coefficients of polyvinylidene fluoride (PVDF) films through the incorporation of silver niobate (AgNbO₃) nanoparticles and nanofibers. Owing to the enhancement in dielectric constant resulting from the introduction of AgNbO₃, the flexoelectric coefficients of the PVDF composite films increased with the concentration of AgNbO₃ achieving a maximum value of 20.6 nC/m, which represents a 2.6-fold increase compared to pure PVDF. Based on this, a multilayer flexible sensor embedded with the PVDF composite films was designed for monitoring human joint motion. The measured flexoelectric current was found to increase with the finger bending angle, and the result was in good agreement with the theoretical prediction. This research provides an effective method for enhancing the flexoelectric response of flexible PVDF-based polymer films and offers novel insights into the development of wearable flexible electronic devices.