Transforming machines capable of continuous 3D shape morphing and locking

Inspired by natural species that leverage morphological changes to realize multiple locomotion modes, diverse multimodal robots have been reported. While developments of small-scale actuators with continuous shape morphing and locking capabilities controlled by the same energy source are crucial for miniaturization of untethered multimodal robots, it remains elusive. We introduce a synergistic design concept of small-scale continuously morphable actuators (CMAs) that harness precisely programmable actuation deformation of liquid crystal elastomer to achieve continuous shape morphing and high stiffness variation of shape memory polymer to lock geometric configuration, both through electrothermal control. Lego-inspired design strategy allows customized construction of complexly shaped CMAs (for example, ‘transformer’, ‘aircraft’ and ‘turtle’) through rational assembly of elementary actuator units with different ranges of accessible geometric configurations. The powerful shape morphing and locking capabilities, as well as the relatively high load-bearing capacity of the CMAs, allow for developments of versatile exoskeletons that can integrate a diversity of functional components. Demonstrations of unique small-scale transforming machines, such as morphable displays with a rich diversity of three-dimensional geometries, a wheeled microrobot capable of transformation among ‘sports car’, ‘winged car’ and ‘van’, and a lightweight untethered terrestrial–aerial microrobot, suggest a broad spectrum of applications.