Micropatterned arrays of functional materials by self-organized dewetting of ultrathin polymer films combined with electrodeposition

Abstract

Large area ordered dewetting offers a new approach to in situ mask generation for selective decoration with functional materials for bio-sensing and lab-on-chip applications, as demonstrated in this work with zinc oxide, copper oxide and nickel hydroxide. The ZnO structures were grown within the pores of partially dewetted polystyrene (PS) films on gold-coated surfaces by electrochemical deposition using the zinc nitrate hexahydrate precursor. The morphology of these ZnO structures is governed by the spatial confinement, i.e., membrane thickness and diameter of the mask opening and the deposition time of ZnO. Vertical and lateral confinement offered by a masking film is found to greatly affect the assembly of the growth. The morphology of microstructures and their evolution are studied to understand the process development. This work establishes controlled dewetting as a route for spatially defined growth of functional materials such as ZnO micro/nano structures which further provide strong binding sites for other functional molecules such as thiol-modified DNA. Ordered arrays of these functional microstructures are deposited over large areas by combining dewetting with a simple lithographic technique, Capillary Force Lithography (CFL). We explore liquid immersion dewetting of a thin polymer film as a lithographic method to template spatially defined growth of zinc oxide (ZnO) micro and nano-structures in the form of hierarchically organized ZnO nano-crystals. The methodology of large area patterning for selective deposition/growth promises to be a facile approach to micro/nano fabrication.