Measuring inverse flexoelectric effect at the macro scale and flexoelectric actuator

Abstract The flexoelectric effect is a two-way mechanical-electrical coupling. The dielectric is polarized when subjected to bending moments, and inversely, the electric field can also induce strain gradients within the dielectric. Although equally important, research on the inverse flexoelectric effect has lagged far behind that on the direct effect, and investigations of the inverse effect on a macroscopic scale are noticeably lacking. This dilemma impedes the design of flexoelectric actuators. To go out of the dilemma, in this work, we design an experimental method to achieve inverse flexoelectricity and propose a method to measure the inverse flexoelectric effect with a lower voltage at the macroscopic scale. The result shows that the flexoelectric coefficient of SrTiO 3 (STO) single crystal from the inverse flexoelectric experiment has the same order of magnitude as that of the direct flexoelectric experiments. Furthermore, this method can be utilized to design an STO flexoelectric actuator on a macroscopic scale. The displacement resolution of flexoelectric actuators is as low as 0.42 pm V −1 , which is three orders of magnitude lower than that of piezoelectric actuators. This type of flexoelectric actuator is important for precise driving and positioning.