Macroscale angled ultrasonic standing waves: A novel approach for particle manipulation

Abstract

Macro scale acoustophoretic devices use radiation forces to trap particles inside a standing wave to separate them from a mixture in a continuous fashion. However, these devices are limited by factors such as flow rates, residence times, and temperature rise which could be detrimental for certain applications. A novel method of separating, sorting and differentiating various particles using bulk angled ultrasonic standing waves is presented. This technique offers very sensitive separation capability with respect to size and acoustic contrast of particles. Universal curves are developed for particle deflection from the bulk flow direction at all wave angles as a function of a non-dimensional parameter defined by the ratio of acoustic radiation force to viscous drag force. Both CFD (Computational Fluid Dynamics) and model test data verify the analytical predictions. New macro-scale, ultrasonic separator concepts are presented that use the angle wave technology to effectively deflect and/or separate microcarrier beads from a flowing mixture at high speeds when compared to conventional ultrasonic separators. Model test data verify the ability to move, differentiate, separate, or fractionate particles in suspension by size and acoustic contrast.