Fabrication of optical grayscale masks for tapered microfluidic devices

In this paper we report a process using electron beam lithography (EBL) to provide high-resolution prototyping of sub-wavelength patterned grayscale masks. The fabrication of such masks and the characterisation of grayscale patterning in thick optical resist are described. In addition, the application of these masks for the creation of three-dimensional tapered microstructures for use as masters in soft lithography for microfluidic devices is demonstrated. (C) 2008 Elsevier B.V. All rights reserved.