Fig. 2: Characterization of underwater capillary adhesion.
a Schematic drawing and the scanning electron microscopic (SEM) images of the dual-scale structured Al plate with hybrid wettability. The scale bars in the SEM images are both 10 μm. b Optical photos of Al plate with hybrid wettability in air and underwater. When being immersed in water, the outer superhydrophobic region of the hybrid Al plate is screened by the uniform air ring, while the inner superhydrophilic region is completely wetted by water. The scale bar is 1 cm. c Selected snapshot images comparing underwater adhesion of samples with different surface wettability. Scale bar: 1 cm. d The time evolution of the force generated between two plates under a stretching speed of 200 μm s−1. The adhesion force of plates with hybrid wettability is ~1.5 and ~39.0 times of that with homogeneous superhydrophobicity and superhydrophilicity, respectively. e The cycling test of the encapsulated water bridge-enhanced underwater adhesion, where an average adhesion force of 2.75 N is sustained over 10 cycles. Here, the error bars are the standard deviations of five measurements.
