Figure 1. Heterogeneous surfaces structures to tailor bubble nucleation.

SEM images of (a), Uniformly dense ZnO nanostructures. (b) 150–500 μm heterogeneous surface configuration. (c) Plain polymer dot, 150 μm in diameter. (d) Cross-sectional area of interface between ZnO nanostructures and polymer dot. (e) Schematic of downhill capillary wicking mechanism on the heterogeneous surface. The downhill scheme promotes the flow of liquid to the lower-level polymer site where nucleation has occurred to efficiently lift-off bubbles and allow for subsequent bubble nucleation.