Motorizing the buckled blister for rotary actuation

Snap-through bistability was widely exploited for rapid hopping in micro-electro-mechanical systems and soft robots. However, considerable energy input was required to trigger the transition between discrete buckling states blocked by potential wells. Here a dynamic buckling mechanism of a buckled blister constrained inside an outer ring is explored for eliciting rotary actuation via a localized change of curvature in the blister. Due to rotational invariance of the buckled blister, lower energy supply is required to initiate the snap-through of buckling compared to conventional bistable mechanism. The controllability in rotational speed and output torque of the bimetallic blister-based rotator inside a rigid stator is exhibited, and the locomotion is demonstrated with two elastic rings via localized pneumatic actuators. With broad choices of stimulus and material for rings, the findings illustrate the promising potential of two nested rings to create active motions for diverse applications including gearless motors, peristaltic pumps, and locomotive robots.