Miniaturized chemical analysis systems based on electroosmotic flow

In electrophoresis, the number of theoretical plates obtained per unit time depends on capillary diameter. High speed and efficiency, however, usually require small injection and detection volumes. These features can easily be arranged on a photolithographically etched microstructure, avoiding virtually any dead volumes. Micromachining and microsystem technology have expanded into separation science for a number of years now. The results seem promising, the number of applications is increasing, and additional research groups enter the field. Main advantages include the use of short capillaries giving high speed separations, the application of high electric field strengths keeping the plate numbers reasonable, and the possibility of integrated multiplexing or hyphenation. For design and fabrication of a chip structure, a few thoughts and calculations may be helpful before deciding the dimensions. This presentation will give some background theory on the miniaturization, and an example, how a microstructure has been optimized.