Experimental decoupling of cylindrical flexoelectric coefficients

Flexoelectricity is a property of all dielectric materials in which they polarize in response to deformation gradients such as those produced by pressing, bending, or twisting, and knowledge of flexoelectric coefficients is essential when considering the applications of flexoelectricity. Here, we describe an experimental approach to the measurement of cylindrical flexoelectric coefficients of polyvinylidene fluoride. Two specimens are designed to generate and decouple the corresponding strain gradients. Theoretical and finite element analyses are developed and simplified, and specimen designs are then tested to obtain multiple strain-gradient-coupled electric polarization charges. The flexoelectric coefficients μ_φzρρ and μ_φzzρ are then decoupled, using two independent equations together with the experimental data. This work provides an experimental method that can be used to obtain multiple unknown flexoelectric coefficient tensor components by imposition of a twisting load, and it reveals the potential for the application of flexoelectricity in irregular structures in complex environments.