A review of adhesion mechanisms of mushroom-shaped microstructured adhesives

Very recently, both experimental and theoretical investigations have shown that micro-structured surfaces covered with mushroom shaped micropillars present strongly enhanced adhesive properties if compared to standard flat surfaces made of the same material. However, different geometries lead to different adhesive performance, and finding the optimal solution has become of utmost importance. In this review we summarize the main detachment mechanisms of flat-topped and mushroom-topped soft micro pillars and show how the geometry of the pillars should be designed in order to obtain the best adhesive performances. We also discuss the effect of air entrapment at the interface between the pillar and the substrate and investigate the influence of the non uniform pillar height and thermal fluctuations on pull-off force.