Fabrication of micro-/nano-scale patterns using polydimethylsiloxane (PDMS) mold and its applications

Abstract

In this thesis, micro-/nano-scale patterns were fabricated using an elastomeric polydimethylsiloxane (PDMS) mold via various routes, and the applications using the fabricated patterns have been demonstrated. Moreover, the novel technique for patterning of colloidal crystals were presented using the PDMS mold and the electrophoretic deposition method. In chapter 2.1, we have investigated a novel soft-imprint technique for fabrication of submicron scale polymer structures that can be simply performed at room temperature by polymerization with an elastomeric polydimethylsiloxane (PDMS) mold. The proposed technique is a simple, cheap and reproducible method for the patterning of large areas, and that allows the transfer of polymer patterns at the submicron scale without high pressures. The PDMS mold is placed on a fluid mixture of prepolymer and monomer after a brief UV exposure, full polymerization follows, and then the mold is removed. SEM and AFM observations confirm that the submicron scale polymer structures are produced without any defect or distortion and with good pattern fidelity over large area. In chapter 2.2, to prevent the swelling of the PDMS mold by the monomer during polymerization procedure, the mold surface is coated with an amorphous fluoropolymer Teflon AF. By using the surface modified PDMS mold, the submicron scale polymer structures are successfully generated with good pattern fidelity, and are also fabricated over large areas through the UV based soft-imprint technique. In chapter 3, We also presented a novel microfabrication technique for multilevel microstructures via the soft-imprint technique using a PDMS mold attached with a screen mask, TEM grid. The prepolymer and monomer mixture after short UV exposure rises only into the open spot of TEM grid, sequentially into the groove of PDMS mold. Moreover, the conformal contact of PDMS mold with TEM grid prevents the permeation of sticky prepolymer into the interface of PDMS mold and TEM grid...