An actuation method by a biconcave beam structure with converse flexoelectric effect

Abstract

Converse flexoelectricity describes the linear relationship between an electric field gradient and the mechanical stress in dielectric materials. It is not restricted by the Curie temperature limit, does not require advanced electrical poling and a wide range of candidate materials exist; hence, there is growing interest in converse flexoelectricity for application in actuators. In this work, a biconcave beam structure and actuation method based on the converse flexoelectric effect is presented. Theoretical and finite element analyzes were developed for the relationship between the electric field gradient and the geometric parameters. A non-piezoelectric dielectric material, polyvinylidene fluoride, was experimentally applied to validate the designed effect. The experimental results show that the designed structure outputs markedly larger displacements magnitudes than the control specimens. This work provides a design method for converse flexoelectric actuators and further enhances the application prospects of converse flexoelectricity in all solid dielectric materials.

Comprehensive Review on Flexoelectric Energy Harvesting Technology: Mechanisms, Device Configurations, and Potential Applications

“…With decreasing actuator size, the field gradient increased and a smaller thickness of the actuator, for a given external radius, could result in a larger electric field gradient and induced greater stress; this indicates that the flexoelectric mechanism has a strong size effect. The displacement of the actuator had a precise value of 1.0 × 10 −9 m and a range of 6.36 × 10 −8 m at a voltage of 3 × 10 3 V. Wu et al 143 proposed a design method based on converse flexoelectric actuators, and PVDF was used for validation of the method. The proposed design could provide a nonuniform structure for generating an electric field gradient and can act as an actuator due to the converse flexoelectric effect.…”

An analytical model for nanoscale flexoelectric doubly curved shells

“…The direct flexoelectric effect bridges strain gradient and electrical polarization, which is applied in energy harvesters [11][12][13][14] and sensors [15][16][17][18]. On the contrary, the converse flexoelectric effect links mechanical stresses and electric field gradients, which has a high practical value in actuators [19][20][21][22]. The flexoelectric effect breaks the limitation that piezoelectricity solely occurs in crystals which are not centrosymmetric [2], thus significantly broadening the range of materials suitable for electromechanical coupling.…”

Ultrahigh flexoelectric effect of 3D interconnected porous polymers: modelling and verification

“…The flexoelectricity has demonstrated its broad application prospects in areas of sensing 16,17 , mechanical actuating 18,19 , energy harvesting 20 and high-density data storage 21 .…”