Flexoelectricity
is the electromechanical coupling between mechanical
strain gradient and electric polarization or vice versa. This unique
effect becomes considerable as the material dimension decreases and
is found in a wide range of materials. In this review, flexoelectric
effects in different dielectric materials and their characterization
methods have been summarized. Also, the different mechanical structures
for the measurement of electric outputs corresponding to different
components of strain gradient are discussed. We have also discussed
in detail the recent theoretical models developed in the field of
flexoelectricity. Furthermore, the factors contributing to the effect
such as various mechanisms of the flexoelectric response in ferroelectrics
and affecting the effective flexoelectric coefficient have been highlighted.
Along with providing a broad material choice, it has found vast potential
applications in sensors, actuators, transducers, etc., and thus, a
flexoelectric nanogenerator has proven to be an energy harvesting
technique. The recent advances in flexoelectric energy harvesting
techniques have been reviewed. Apart from these applications, we have
given a brief report on the recent developments and other applications
of the flexoelectric effect. Moreover, the recent discoveries in flexoelectricity
that claim that this effect may promote the development of nanoelectronics
have been summarized. At the end of the review, the future perspective
of flexoelectric-based applications has been discussed.