The analysis of liquid mixtures, as e.g. encountered in environmental monitoring, food safety analysis, the development of novel pharmaceutical compounds, etc... is usually carried out using chromatogaphic separatoin techniques. Theoretical calculations have shown that the efficiency of these techniques can be strongly enhanced if they would be carried out in perfectly ordered chromatographic beds, in stead of the randomly packed tubes filled with spherical particles as used today. In the present work, the various details of the fabrication processes needed to produce such perfectly ordered chromatographic beds (on-chip HPLC columns) have been analyzed and solutions have been proposed. Lithographic etching protocols, based on the use of Bosch-etching process have been optimized to produce ordered arrays of micro-pillars over long column lengths. Optimized turn structures were developed to arrange very long (up to 3m) columns on the surface of a 4 inch wafer. Various coupling techniques, to connect the on-chip HPLC columns with a minimum of coupling losses were developed. In addition, a novel experimental set-up and procedure were developed to study the flow processes, and especially the radial dispersion process in on-chip HPLC-columns in great detail. This work lead to a novel correlation for the velocity dependency of the radial dispersion in ordered and disordered beds of cylindrical micro-pillars.
|Award date||25 Oct 2013|
|Place of Publication||Enschede|
|Publication status||Published - 25 Oct 2013|