Wet Adhesion of Soft Curved Interfaces With Micro Pattern

Abstract

Previous research reveals that a flat micropatterned soft pad, which mimics the structure of tree-frog's toes, increases adhesion when gripping an object in a wet environment. However, soft interfaces may change shape to adapt to curved environments, therefore, it is necessary to clarify the mechanics of wet adhesion in such cases. In this letter, we propose a method for evaluation of the adhesive ability of a soft curved interface with a specific micropattern in a concave contact interface. We focused on wet adhesion force in the normal direction on the contact interface in different contact scenarios. The micropattern soft pad used in this analysis has 3600 cells, each has 85 $\mu$ m × 85 $\mu$ m separated by grooves 15 $\mu$ m in width ×44 $\mu$ m in depth. This micropattern soft pad may deform to fit a concave surface. We also compared this micropattern soft pad with a similar soft pad without a micropattern in term of adhesion ability at the interface between the pad and the substrate. Obtained results have good agreement with the estimations, demonstrating that the surface of the micro-patterned pad enhanced contact force at the interface approximately 1-2 times than the non-parttern surface. This approach can be utilized in evaluation of wet adhesion in grasping objects with curved surface using soft pads with patterned surfaces.