Variable-stiffness suction cups with adjustable adhesion based on solid-to-liquid phase transition

A vacuum suction cup is a typical adhesion device based on negative pressure adhesion, which has extensive applications, like gripping and transporting objects on demand. However, it often fails to reach the theoretical maximum adhesion force in practice. This is because the edge of the suction cups will flex during the detachment process, leading to leakage of the sealing chamber and premature detachment of the suction cup. In this work, a Field's metal ring is embedded in the suction cup with the purpose of adjusting the edge stiffness through solid-to-liquid phase transition. The adhesion force reaches its maximum at 32.20 N in the strong adhesion state and diminishes to 17.34 N in the weak adhesion state. This study provides a new structure design to realize adjustable adhesion based on negative pressure adhesion.