Surface-Tension-Controlled Molding of Large Suction Cup Arrays for Adaptive Adhesion

In this paper, we present a scalable and low-cost fabrication process that uses surface-tension-controlled (STC) molding to generate suction cups, enabling adaptive adhesion of soft robotic surfaces through large suction cup arrays. The STC molding process leverages the surface tension of liquid rubbers to form fillets, or menisci, around open molds and fixtures. The menisci create smooth and curved surfaces that are used as both the molding surfaces and the bodies of suction cups, allowing us to generate both push-on and vacuum-powered suction cups in large arrays. This STC molding process allows us to create larger numbers of suction cups in a single array, supported by a soft underlying body without complex or manually intensive molding processes. Direct integration of suction cups into a soft underlying body and vacuum manifold can allow the arrays to adapt to irregular, compliant, and deforming surfaces. We explore the potential uses of STC molding for applications like bio tagging, manipulation, and locomotion by prototyping a sheet with 70 push-on suction cups, a 19 -cup vacuum-powered grasper, and a tube feet array with 20 suction cups on their tips. The fully soft underlying body and vacuum manifold allows the large arrays of suction cups to conform and thus adapt to irregular, compliant, and deforming surfaces.