S054015 Flow property near a solid-liquid interface in a microchannel

Abstract

The velocity profiles of dilute polymer solutions, surfactant solution and distilled water near the wall surface in a microchannel was clarified by using evanescent wave illumination. Fluorescent particles with the diameter of 20 nm and 100 nm were used as tracer particles. Polymer solutions were aqueous solutions of polyethylene-glycol (PEG8000 and PEG20000) and polyethylene-oxide (SE15 and SE70) at 5 ppm. Surfactant solution was aqueous solution of Oleyl bis-(2-hydroxyethyl) methyl ammonium chloride (trade name : Ethoquad 0/12) at 500 ppm with sodium salicylate. The results obtained for the velocity profiles basically fitted with plane Poisuille flow, except for surfactant solution whose velocity profile significantly decreased compared with that of distilled water. The resolution of the velocity profile near the wall surface was improved from the conventional result.