Structured Microgroove Columns as a Potential Solution to Obtain Perfectly Ordered Particle Beds

We report on a novel concept to produce ordered beds of spherical particles in a suitable format for liquid chromatography. In this concept, spherical particles are either positioned individually (single-layer column) or stacked (multi-layer column) in micromachined pockets that form an interconnected array of micro-grooves acting as a perfectly ordered chromatographic column. As a first step towards realizing this concept, we report on the breakthrough we realized by obtaining a solution to uniformly fill the micro-groove arrays with spherical particles. We show this can be achieved in a few sweeps using a dedicated rubbing approach wherein a particle suspension is manually rubbed over a silicon chip. In addition, numerical calculations of the dispersion in the newly introduced column format have been carried out and demonstrate the combined advantage of order and reduced flow resistance the newly proposed concept has over the conventional packed bed. For fully-porous particles and a zone retention factor of k’’ = 2, the hmin decreases from hmin = 1.9 for the best possible packed bed column to around hmin =1.0 for the microgroove array, while the interstitial velocity-based separation impedance Ei (a direct measure for the required analysis time) decreases from 1450 to 200. The next steps will focus on the removal of occasional particles remaining on the sides of the micro-pockets, the addition of a cover substrate to seal the column and the subsequent conduction of actual chromatographic separations.