Particle transport across bi-fluid interface using acoustic radiation force

Abstract

A bi-fluid micro-flow system is proposed for separating particles from its original solvent and re-diluting them into another solvent simultaneously. In this micro-flow system, two different miscible solvents flow parallel to each other through a 2-inlet-2-outlet micro-channel, where an acoustic standing wave is set up. Due to the differences in acoustic properties of these solvents, the pressure node of the acoustic wave is shifted from the middle line of the channel. Under the action of the acoustic radiation force, particles with positive φ-factors are extracted from their original solvent and re-suspended into the other solvent, wherein the pressure node resides. Particles suspended in the new solvent are collected at one of the two outlets downstream. Experiments were conducted on a prototype using two aqueous solutions: deionized water and 40% glycerin aqueous solution with polystyrene micro-particles. The results show that under the action of the acoustic standing wave, most of the particles were successfully transported from its original solvent to the other solvent and collected at the outlet. © 2010 World Scientific Publishing Company.