Stiff thin fi lms on soft substrates are both ancient and
commonplace in nature; for instance, animal skin comprises
a stiff epidermis attached to a soft dermis. Although more
recent and rare, artifi cial skins are increasingly used in a broad
range of applications, including fl exible electronics1
, tunable
diff raction gratings2,3, force spectroscopy in cells4
, modern
metrology methods5
, and other devices6–8. Here we show that
model elastomeric artifi cial skins wrinkle in a hierarchical pattern
consisting of self-similar buckles extending over fi ve orders of
magnitude in length scale, ranging from a few nanometres to a
few millimetres. We provide a mechanism for the formation of
this hierarchical wrinkling pattern, and quantify our experimental
fi ndings with both computations and a simple scaling theory. Th is
allows us to harness the substrates for applications. In particular,
we show how to use the multigeneration-wrinkled substrate for
separating particles based on their size, while simultaneously
forming linear chains of monodisperse particles.