Fig. 1.

(A) Shark denticle shows a divergent shape with an asymmetry in the wall-normal and streamwise directions. Adapted with permission from ref. 17. (B and C) Microscopy images of the micropillar arrays presented in this study, which have a similar asymmetric shape. (Scale bars: $100\mathrm{\mu }\text{m}$.) The height and tip diameter of each element are $85\mathrm{\mu }\text{m}$ and $75\mathrm{\mu }\text{m}$, whereas the stalk diameter is $40\mathrm{\mu }\text{m}$. The center-to-center distance between the pillars is $120\mathrm{\mu }\text{m}$.