Microchip Coulter particle counter

Abstract

This paper presents a micro device employing the Coulter principle for counting and sizing of living cells and particles in liquid suspension. The microchip Coulter particle counter (/spl mu/CPC) has been employed in a planar silicon structure covered with glass, which enables detailed observation during operation. By sheathing of a nonconductive liquid on either side of an electrolyte, it is possible to optimize the sensitivity to a specific cell-size. A method for measuring the relative flow-rates between liquid phases with different conductivity is presented. The method utilizes the laminar flow and short contact time of liquids in microchannels. As a result, the width of the liquids can be controlled without knowing the actual flow rates. The /spl mu/CPC has been fabricated by standard microfabrication techniques, including RIE, wet silicon etching, metalization and anodic bonding.