Path-guided wrinkling of nanoscale metal films.

Surface wrinkling instability is typically caused by compressive stresses in layered systems. In a bilayer system with a stiff surface layer on a drastically more compliant substrate, spontaneous wrinkle patterns emerge as a result of the wrinkling instability. The wrinkle patterns can be controlled to form ordered surface structures, offering an unconventional method for microfabrication. [ 1–22 ] Several methods have been developed to control wrinkle patterns: by introducing bas-relief patterns into substrates, [ 1 , 9 , 10 ] by locally modifying mechanical properties of substrates, [ 12 , 14 , 15 ] by placing patterned PDMS mold on the surface, [ 13 ] by applying anisotropic stress or strain, [ 2 , 5 , 11 , 17 ]