The present invention provides, in one embodiment, an apparatus. The apparatus, without limitation, may include a substrate with a surface, and a polymer layer attached to a region of the surface. The apparatus may further include a plurality of nanostructures, a first end of each nanostructure being in the polymer layer and a second end of each nanostructure protruding through the polymer layer, wherein the nanostructures are configured to move from a first position to a second position in response to a change in thickness of the polymer layer from a first thickness to a second thickness.