An investigation into separation enhancement methods for miniaturised planar capillary electrophoresis devices

摘要

The analytical capability of field-portable instruments and in-situ devices is often limited due to cost, complexity and spatial restrictions. With powerful analytical methods incorporated onto miniaturised sensor platforms, in-depth sample and environmental examinations become feasible. There has been significant research reported in the literature for improving miniaturised capillary electrophoresis systems alongside lab-on-a-chip applications. The work presented in this thesis discusses the development of novel methods to improve the separation resolution of capillary electrophoresis on microfluidic devices without compromising device size. Further to this, complex chemical buffering systems have been avoided since they tend to make the end device highly application specific.The separation resolution of capillary electrophoresis can be enhanced by dynamic control of the electroosmotic flow. This is achieved through control of the zeta-potential, which can be modified by applying a potential to an electrode close to the surface of the separation channel. The separation enhancement methods increase the effective channel length and therefore can be used to aid the incorporation of capillary electrophoresis into both portable field instruments and for in-situ systems.Computational models have been developed for an in-depth investigation into the proposed separation enhancement routines. Where possible, these models have been experimentally verified. The operation limits of the enhancement methods have been investigated, and related to the composition of the sample to infer design criteria.