Figure 2

<p>(a) Representative textured pattern mimicking the surface of legs of the wharf roach <i>Ligia exotica</i>. The right and left paths mimic the central and edge regions, while the middle path is a hybrid of central and edge textures. The length of “podite” is designed to be mm (or 3.4 mm), which is comparable to a typical size of podite in real legs. The sizes in the illustrations are expressed in the unit mm. (b) A snapshot of capillary rise on the reference surface. The imbibition fronts are shown by the horizontal arrows. The vertical arrows indicate velocities with reflecting relative magnitudes. (c) Height of the rise renormalized by vs elapsed time obtained from the reference surface. The labels, -, correspond to the labels in (b). (d) vs , obtained from the reference surface. The solid and thin lines with Labels “init.” and “final” are those fitting the data in the initial and final regions of the front in the central region of the HT path labeled in (b). (e) and (f): the same plots as the plot in (d) but for substrates different from the reference.</p

Figure 1

<p>(a)–(b) SEM images of a leg of the wharf roach <i>Ligia exotica</i>. A path for water transport on the leg seen in (a) is covered with small blades. In a simplified view, wide blades cover the central-texture (CT) region and narrow blades the edge-texture (ET) region, as seen in the image in (b) showing the boundary between the central and edge regions with a higher magnification. The height of the blades are about 50 m. (c) A leg of the wharf roach used for the imbibition experiment. (d) Height of the rising water front, renormalized by the length of the lowest podite in (c), as a function of the elapsed time . The labels in the plot correspond to those in (c). Label in (c) corresponds to the origin of the plot.</p

Figure 3

<p>(1a)–(1d) Texture-parameter dependences of the imbibition dynamics on the CT paths, with the insets giving those on the ET paths. (1a) The coefficient , a measure of the rising speed, vs the length at for CT and for ET. (1b) vs at for CT and for ET. (1c) vs at for CT and for ET. (1d) Comparison of the data with the theory. All the data collected from (1a) - (1c), together with other three data, are well on a straight line as predicted in Eq. (6). The straight line shown in the plot is obtained by numerical fitting. The curved lines in (1a)–(1c) and those in the inset are based on the theory in Eq. (6) with and determined by the straight line in (1d). (2a)–(2d) Texture-parameter dependences of the “initial” imbibition dynamics in the central region of the HT paths with the edge region specified by the set . (2a) vs at . (2b) vs at . (2c) vs at . (2d) Comparison of the data with the theory. All the data collected from (2a)–(2c) are well on the straight solid line, obtained by numerical fitting. The curved solid lines in (2a)–(2c) are based on the theory in Eq. (6) with and determined by the straight solid line in (2d). The insets to (2a)–(2c) quantify speed-up by the edge effect, showing the ratios of average values of in the main plots of (2a)–(2c) to those in (1a)–(1c), demonstrating the dynamics in the central region on the HT paths are clearly faster than those on the corresponding CT paths, except for two exceptional cases. The dashed lines in (2a)–(2d) are the solid lines in (1a)–(1d), respectively, confirming the edge effect in different ways.</p