Particle Manipulation and Separation Using Macro-Scale Bulk Angled Standing Waves

A novel method of separating, sorting and differentiating various particles using macroscale bulk ultrasonic standing waves oriented at an angle relative to the fluid velocity is presented. This technique offers a sensitive separation capability with respect to size and acoustic contrast of particles. An analytical model for particle deflection is presented and universal curves are developed for all possible wave angles as a function of a non-dimensional parameter, M, defined by the ratio of acoustic radiation force to viscous drag force. Using this parameter, deflection angle can be accurately predicted for any particle of known properties. Experimental results verify the analytical model and the universal curve for different M parameters. The angled wave system shows 90+% efficiency in separating Jurkat T-cells and calibrated beads.