William Chiang

Electrohydrodynamic Pumps for High-Density Microfluidic Arrays

We have developed electrohydrodynamic (EHD) pumps for fluid delivery in high-density microfluidic arrays as part of a drug discovery collaboration with Orchid Biocomputer, Inc. and SmithKline Beecham Pharmaceuticals. The multi-layer array structures are fabricated in glass and silicon, and have no moving parts. Each pump is comprised of two planar-processed, conductive via electrodes that are in contact with fluid inside the array. Typical applied voltages (300–500 V) result in pressures on the order of inches of water. EHD pumping in microfluidic array chips has been demonstrated and characterized for flow direction and relative pumping efficiency with more than one hundred different organic solvents and solvent-reagent compounds. A basic theory for the phenomena is presented, and quantitative velocity measurements for some representative solvents are shown.