Model for tracing the path of microparticles in continuous flow microfluidic devices for 2D focusing via standing acoustic waves

An, experimentally validated, two-dimensional dynamic model for tracing the path of microparticles in a microfluidic layered transducer is developed. The model is based on Newton's 2nd law and considers forces due to inertia, gravity, buoyancy, virtual mass and acoustics; it is solved using finite difference method. Microparticles' trajectory consists of transient and steady state phases. All operating and geometric parameters are influential during the transient phase. The final levitation height is independent of the radius and initial vertical location of the microparticle as well as volumetric flow rate; however, dependent on the acoustic energy density and wavelength. There exists a threshold acoustic energy density for levitating microparticles from a specific initial vertical displacement; analytical equation for determining this acoustic energy density is provided. (C) 2015 Elsevier B.V. All rights reserved.