FACETED DESIGN OF MICROSCALE CHANNELS FOR ELECTROKINETIC FLOWS

摘要

A novel methodology for designing microfluidic channels for low-dispersion, electrokinetic flows is presented. The technique relies on trigonometric relations that apply for ideal electrokinetic flows, allowing faceted channels to be designed using common drafting software and a hand calculator. Flows are rotated and stretched along the abrupt interface between adjacent regions having differing specific permeability. Two-interface systems are used to eliminate hydrodynamic rotation of bands injected into channels. Regions bounded by interfaces form faceted flow "prisms" with uniform velocity fields that can be combined with other prisms to obtain a wide range of turning angles and expansion ratios. Lengths of faceted prisms can be varied arbitrarily, simplifying chip layout and allowing the ability to select time-of-flight for a given faceted prism. The method is tested using combined experimental and computational demonstrations of flow displacers. Designs are demonstrated using two-dimensional numerical solutions of the Laplace equation. Experimental flow visualization is performed using standard epi-fluorescence microscopy techniques.