A Bioinspired Adhesive Sucker with Both Suction and Adhesion Mechanisms for Three-Dimensional Surfaces

There are significant advantages to investigate underwater attachments,which would be valuable in providing inspirations and design strategies for multi-functional surfaces and underwater robots.Here,an abalone-inspired sucker integrating an elastic body and a membrane structure is proposed and fabricated filled with rigid quartz particles to adjust the backing stiffness of the contact like abalone.The membrane is used to conform and contact surfaces well,the center area of which can be pulled in exposed to a negative pressure differential,to create a suction cavity.The pulling experiments indicate that the sucker can adhere to three-dimensional surfaces with both suction and adhesion mechanisms in both dry and liquid environments.The switching between soft/hard contact states leads to the change of adhesive strength over 30 times.Furthermore,we provide theoretical analysis on how the sucker work well in both dry and liquid environments.Finally,the developed sucker can easily lift up smooth planar objects and 3D objects,and can grip objects both smaller and larger than the size of the sucker,which have a difficulty for conventional suckers or friction-based grippers.The potential application of the sucker in flexible transfer robot is demonstrated on various surfaces and environments,paving the way for further bio-inspired adhesive designs for both dry and wet scenarios.