Abstract
This paper presents an overview on three major fabrication techniques developed in our laboratory for achieving complex polymeric structures using nanoimprint lithography (NIL), namely reversal imprinting, combinatorial-mould imprinting and sequential imprinting. The key strategy employed by all three techniques is the use of conventional two-dimensional (2D) molds to achieve greater degrees of complexity than are ordinarily achievable with conventional imprinting techniques. For example, reversal imprinting combined with colloidal self-assembly allows for structures that have variations with depth as well as scale. Combinatorial-mould imprinting enables the fabrication of three-dimensional (3D) structures that have variations in length, width as well as depth. Sequential imprinting enables hierarchical structures that have scale-dependent variations and complexity. 3D structures, hierarchical structures, and combinations thereof are obtained in fewer processing steps and without the use of a sacrificial component or process.