Dynamically Switchable 3D Shape-Morphing and Rotation from Liquid Crystal Elastomer Actuators.

Polymer-based soft actuators capable of responsive shape morphing hold great potential for developing untethered soft robotics with dexterous motion under complex surroundings. To realize this potential, achieving fast, dynamically tunable shape morphing that can generate sufficient mechanical force is essential. Here, soft actuators composed of liquid crystal elastomer (LCE) bilayer film are constructed via direct ink writing (DIW), which exhibit rapid and sequential 3D-to-3D́ morphological reconfiguration within seconds under temperature stimulus. The dynamic shape morphing is facilitated by the bidirectional bending of the LCE film, which possesses anisotropic mesogen orientation and distinct phase transition temperatures. By balancing the two LCE layers in terms of differential contraction, layer sequence, and two-dimensional (2D) geometry, its bending directions, amplitude, and sequence can be programmed, thus enabling diverse three-dimensional (3D) shape reconfigurations, such as biomimetic "orchid" blooming and "palm" gesture switching. Beyond shape morphing, the LCE actuator is capable of converting shape morphing into rotational kinetic energy in different directions. As a prototype, it generates sufficient torque to drive the rotation of an LCE rotor, exhibiting switchable clockwise, "self-oscillating", and anticlockwise motions. With the merits of dynamic shape morphing and mechanical energy harvesting, the LCE actuator presents a promising platform for advancing soft robotics with adaptive and diverse locomotion for performing tasks in complex environments.