Measurement of adhesion ability. (a) Diagram and digital images of the bioinspired multifunctional MNs adhering to the knuckle of the thumb when the knuckle is bent to 90°. The thickness of the MNs was 2 mm. The scale bar is 1.5 cm. (b) Diagrams and optical images of four different MNs: normal MNs (i), PDA-based MNs (ii), suction-cup MNs (iii), and multifunctional MNs (iv). The scale bars are all 300 μm. (c) Representative time-dependent profiles of peeling forces for multifunctional MNs in dry and wet conditions. (d) Dry and wet adhesion performances of the four different MNs. (e) Repeating cycles of the dry and wet adhesion performances of multifunctional MNs.