Continuum soft actuators based on reprogrammable geometric constraints

Although numerous soft actuators have been developed to generate diverse and dexterous morphing such as branching, bending, and twisting, continuum manipulation with increased degrees of freedom still relies on the coactivation of multiple actuators. We demonstrate continuum soft actuators that exhibit a higher number of deformation modes in a single actuating unit. Our devices consist of an elastomer composite embedded with micro liquid droplets and an array of resistive heating elements to locally drive the liquid–vapor phase change of adjacent liquid droplets. The elastomer composite body only inflates in the vicinity of a resistive heating element in the on-state while other segments, including those near inactive elements, serve as rigid constraints, such that the bending direction can be systemically changed depending on the state of the individual resistive heating elements in the embedded array. We show that our continuum soft actuators permit fully continuous motions, including rotations, via a simple operating scheme.