Friction Contribution to Bioinspired Mushroom-Shaped Dry Adhesives

Bioinspired mushroom-shaped micropillar recently has attracted considerable interest from researchers on adhesion-functionalized artificial surface due to its prominent dry adhesive property. Understanding the interface behavior and further exploring the physical mechanism are of significance for properly designing the structure dimension with enhanced performance. However, the friction contribution to such type of adhesive structures is mostly overlooked in previous investigations. In this paper, by revisiting the detachment behavior associated with the calculation of the critical dynamic crack size making the contact interface destabilized, it is demonstrated that the friction force does work in the detachment process of mushroom-shaped micropillars. The calculated maximum pull-off forces are in good agreement with experimental results and the friction force contribution can reach up to about 41% of the total adhesive force when the tip diameter is 2.6 times the diameter of the supporting pillar. The present model provides a deeper insight into the mushroom-shaped dry adhesives and may be helpful in future bioinspired dry adhesives designs.