Miniaturization of surface patterns in soft elastic film over patterned substrates

Abstract

In this experimental study results reveal the formation of miniaturized surface morphologies over a soft thin elastic film of micron range thickness (h), when cast on various patterned substrates created from: naturally available intrinsically rough water lily leaves, commercially available sinusoidally patterned compact disks and cubic boxes created by electron beam lithography. The evolving surface patterns formed had varying structures of columns to labyrinth to cavities during the adhesion and debonding cycle, irrespective of which the engendered dominant wavelength (λ) remained at a minuscule length scale that was found to be much less than that obtained on flat substrates. It was observed experimentally that the length scales of the patterns formed decreased linearly with increase in substrate amplitude and regardless of the substrate pattern geometry used depended solely on its RMS roughness such that λ/h = 2.96−18.2*(RMS/h). The study indicates the redundancy in creating very costly regular geometrical patterned substrates for miniaturization and instead advocates the use of intrinsically rough natural surface replicas to be used as patterned substrates for cost-effective fabrication of miniaturized surface patterns at such soft interfaces.