Programmable electric-field-induced bending shapes of dielectric liquid crystal elastomer sheets

The nematic director of dielectric liquid crystal elastomers (DLCEs) can be rotated by electric field, which makes the DLCE macroscopically deformed. In this paper, the electric-field-induced bending of DLCE sheets with director orientation gradient in thickness are investigated theoretically. The results reveal that the flat DLCE sheets in response to electric fields can deform to surfaces with zero, positive, or negative Gaussian curvature. Bending shapes of DLCE sheets can be encoded by patterning the nematic director field. Specifically, bending shapes with zero and positive Gaussian curvatures caused by unidirectional and multidirectional bending, respectively, are encoded by the splay–bend and splay–twist–bend director alignments, while the bending shape with negative Gaussian curvature is encoded by the twist or splay–twist–bend​ director alignments. Moreover, for each of these bending shapes, the Gaussian curvature and principal curvatures can also be maximized and optimized by adjusting the initial director alignments. The results imply that it is possible to program more complex bending shapes such as human face, in surface topography engineering, and this work provides a theoretical basis for promoting the application of LCEs as the electrically-triggered actuators and sensors.