Glass microchips are fabricated to demonstrate two-dimensional spatial confinement of ions and fluids using electrokinetic forces. Neutral and charged molecular samples can be electrokinetically focused to widths as narrow as 3.3 μm in a 18 μm long by 18 μm wide chamber. The electrokinetic focusing characteristics are tested using cationic, neutral, and anionic samples to evaluate the influence of electric fields on the sample stream. Focusing is achieved using electrophoresis, electrophoresis, or a combination of the two. In addition, concentration enhancement is observed in the focusing chamber by employing sample stacking, and the focusing chamber is multiplexed to confine spatially more than one sample stream simultaneously.
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