Self-modifying percolation governs detachment in soft suction wet adhesion.

Abstract

Aquatic animals such as octopuses use soft suction cups to solve the persistent challenge of wet attachment on rough surfaces. Detachment has long been described as smooth drainage governed by a Reynolds-type pressure gradient. Combining spatiotemporal pressure mapping with confocal imaging of the fluid layer between a suction cup-substrate interface, we reveal a two-stage, nonequilibrium pathway for pressure equalization that challenges this conventional view. Suction-induced elastic deformation dynamically remodels the interfacial fluid, producing a self-coupled pressure channel system. Stage I is governed by an outward-moving invasion-percolation suction front with diffusion-like scaling. When internal suction falls below a critical value, the network opens globally, and stage II follows classical Poiseuille drainage. This mechanism defines a self-modifying percolation in which the flow remodels its own pathways, which advances our understanding of biological suction and viscous adhesion and suggests design principles for long-lived wet adhesives and hydrogel microfluidics.