Tunable Flexoelectricity of Elastomers

Stretchable materials are expected in next-generation devices as examples of soft electronics and wearable healthcare. Elastomers are stretchable and well-applied in various electromechanical applications as substrate and functional materials. Elastomers are believed to have substantial electromechanical response of flexoelectricity, due to their large deformation range and hence large strain gradient capability. Flexoelectricity is an electromechanical coupling effect in dielectrics, describing the linear relation between its strain gradient and its induced electric polarization. In this work, we propose a phenomenological model to study the flexoelectricity of elastomers, where cross-linking density is the key. The flexoelectric coefficient is increased by enlarging the cross-linking density of the elastomer. This model is experimentally verified by measuring transverse flexoelectric response of two typical elastomers. This work shows a fundamental understanding on tunable flexoelectricity of elastomers, and opens up possibilities in material designs for flexoelectric-based applications with elastomers.