Programmable thermochromic soft actuators with “two dimensional” bilayer architectures for soft robotics

Soft robots have unique advantages in the fields including human-machine interaction and bionics, yet there remain persistent challenges in developing multifunctional, programmable, and high-performance soft actuators. Here, we introduce a class of programmable thermochromic soft actuators (PTSAs) through liquid–vapor phase transitions, which can deform greatly through extreme volume change accompanying reversible liquid-vapor phase transition of embedded low boiling point fluid, and change several colors through reversible reactions of embedded thermochromic microcapsules. Using a "two dimensional" architecture, the initial shape and deformation type of the actuator with three different modes can be easily programmed. Respond to multiple stimuli, PTSAs have a variety of optional actuating methods including external heating, Joule heating, magnetic induction heating, and magnetic actuating. The suitable operating temperature and stretchability allows PTSAs to be used in wearable devices. Using PTSAs, a range of applications including color-shifting curly biomimetic maple leaves, color-shifting twisting biomimetic vines, zero-power holding and visually temperature sensing soft grippers, untethered magnetically actuated camouflage soft robots, and blood pressure sensing wristband are demonstrated, illustrating their broad prospects for applications in soft robotics, wearable devices, camouflage, and bionics. • Propose multifunctional, programmable and stretchable thermochromic soft actuators based on liquid-vapor phase transitions. • Shape and deformation of the actuator can be programmed conveniently and flexibly due to a “two dimensional” architecture. • Thermochromic capabilities of the actuator enrich its functions including bionics, camouflage, and visually sensing. • Multi-stimuli responses endow the actuator with multiple actuating methods. • The safe voltage, suitable operating temperature and stretchability allow the actuator to be used in wearable devices.