Dual length scales: Chocolate (Cu) chip cookies
Nature often seems to use more than one length-scale of roughness - the Lotus leaf has small bumps on large bumps. Using photolithographic techniques and electrodeposition, it is possible to overlay large scale textured surfaces with small-scale roughness and see whether surfaces with multiple length scales shed water more effectively. In one experiment a "chocolate" chip cookie pattern was created using copper. Read more about the process in the publication below.
Dual-scale roughness produces unusually water repellent surfaces,
Adv. Maters. 16 (21) (2004) 1929-1932.
View postprint pdf
Wetting and wetting transitions on copper-based super-hydrophobic surfaces,
Langmuir 21 (3) (2005) 937-943.
Via ACS server