title: Self-organized meso-patterning of soft solids by controlled adhesion: elastic contact lithography.
abstract: The surface of a soft elastic film becomes unstable and deforms when a rigid flat plate is brought into its contact proximity, without application of any external pressure. These isotropic undulations have a characteristic wavelength, lambda approximately 3H, where H is the film thickness. The wavelength is independent of the adhesive interactions and the mechanical properties of the film. We present here a mini-review of our recent work on techniques of aligning, modulating, and ordering the instability structures by the use of simple 1-D patterned stamps, by changing the stamp-surface separation, by slow shearing of a flat stamp and by confining the instability in soft narrow channels. The generality of the technique for different soft materials is illustrated by patterning cross-linked polydimethylsiloxane (PDMS), aluminum coated PDMS and hydrogels films. Use of a flexible stamp such as a metal foil provides enhanced conformal contact by adhesive forces, which aids large area patterning without critically maintaining a parallel configuration and uniform pressure between the stamp and the film. The technique has the potential to develop into a new soft lithography tool--"Elastic Contact Lithography" suitable for rapid, large area micron and sub-micron self-organized patterning of a variety of soft materials without any special equipments.
authors.affiliation: Department of Chemical Engineering, Indian Institute of Technology, Kanpur 208016, India.
authors.forename: Ashutosh
authors.initials: A
authors.lastname: Sharma
authors.forename: Manoj
authors.initials: M
authors.lastname: Gonuguntla
authors.forename: Rabibrata
authors.initials: R
authors.lastname: Mukherjee
authors.forename: Subash A
authors.initials: SA
authors.lastname: Subramanian
authors.forename: Ravindra C
authors.initials: RC
authors.lastname: Pangule
mesh_terms: D003460:Crystallization / Q000379:methods*; D004129:Dimethylpolysiloxanes / Q000737:chemistry*; D004548:Elasticity; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D036103:Nanotechnology / Q000379:methods*; D010316:Particle Size; D012828:Silicones / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D004129:Dimethylpolysiloxanes; D046911:Macromolecular Substances; D012828:Silicones; C013830:baysilon