Electroosmotic flow in composite microchannels and implications in microcapillary electrophoresis systems

The electroosmotic flow in laminated excimer laser-ablated microchannels ha s been studied as a function of the depth of the rectangular channels, and particular emphasis has been given to the difference in the g-potentials be tween the lamination layer and the ablated substrate. Experimental electroo smotic flow follows the tendency predicted by a recently published model. T he g-potentials of lamination and ablated surfaces were determined for poly (ethylene terephthalate) and poly(carbonate) substrates by fitting the expe rimental data with a numerical implementation of this model. In the experim entally investigated range of channel cross sections, a linear fit to the d ata gives a good approximation of the zeta -potentials for both materials. Moreover, a flow injection analysis of fluorescein dye has been performed t o show the severe loss in numbers of theoretical plates, caused by Taylor d ispersion, when such microchannels, dedicated to microcapillary electrophor esis, are used.