The past 25 years have seen considerable progress in the development of microfabricated systems for use in the chemical and biological sciences.Interest in microfluidic technology has driven by concomitant advances in the areas of genomics, proteomics, drug discovery,high-throughput screening and diagnostics, with a clearly defined need to perform rapid measurements on small sample volumes.At a basic level, microfluidic activities have been stimulated by the fact that physical processes can be more easily controlled when instrumental dimensions are reduced to the micron scale.1 The relevance of such technology is significant and characterized by a range of features that accompany system miniaturization.Such features include the ability to process small volumes of fluid, enhanced analytical performance, reduced instrumental footprints, low unit costs, facile integration of functional components within monolithic substrates and the capacity to exploit atypical fluid behaviour to control chemical and biological entities in both time and space.