Soft lithography meets self-organization: Some new developments in meso-patterning

Abstract

This is a brief review of our recent and ongoing work on simple, rapid, room temperature, pressure-less and large area (~ cm 2 ) imprinting techniques for high fidelity meso-patterning of different types of polymer films. Examples include soft solid polymer films and surfaces like cross-linked polydimethylsiloxane (PDMS) and polyacrylamide (PAA) based hydrogels, thermoplastics like polystyrene (PS), polymethylmethacrylate (PMMA) etc both on planar and curved surfaces. These techniques address two key issues in imprinting: (i) attainment of large area conformal contact with the stamp, especially on curved surfaces, and (ii) ease of stamp detachment without damage to the imprinted structures. The key element of the method is the use of thin and flexible patterned foils that readily and rapidly come into complete conformal contact with soft polymer surfaces because of adhesive interfacial interactions. The conformal contact is established at all length scales by bending of the foil at scales larger than the feature size, in conjunction with the spontaneous deformations of the film surface on the scale of the features. Complex two-dimensional patterns could also be formed even by using a simple one-dimensional master by multiple imprinting. The technique can be particularly useful for the bulk nano applications requiring routine fabrication of templates, for example, in the study of confined chemistry phenomena, nanofluidics, bio-MEMS, micro-imprinting, optical coatings and controlled dewetting.

Pattern formation in thin polymer films by spatially modulated electric fields

“…A number of these film destabilization mechanisms have been investigated for their usefulness in lithography. [1][2][3][4][5][6][7][8][9] Film destabilization induced by electric fields is promising because the magnitude of the destabilizing force can be easily varied, providing excellent control over the emerging pattern. [10][11][12][13][14][15] Initial theoretical descriptions of this effect focused on pattern formation in homogenous electric fields, which were later extended towards heterogeneous electric fields.…”

Fabrication of bioinspired omnidirectional and gapless microlens array for wide field-of-view detections

“…In recent years, several strategies have been developed for non-planer microfabrications. [6][7][8][9][10] Although these techniques demonstrate the ability to produce microstructures on the curvilinear surfaces, they are high-cost, complex, and require long processing time. There is still an unmet need for a simple and cost-effective method.…”

Polymeric Nanomaterials in Biomineralization

“…20 Mainly, a low-cost patterning method for any random curved or nonplanar surface is still hard to achieve as most of the available techniques are for planar surfaces. 21 On the other hand complex nanoscale structures can be realized with biological self-assemblies such as the tobacco mosaic virus, 22 collagen, capsid proteins, 23 tubulin, 24 or actin.…”