Modeling of Microfluidic Acoustophoretic Motion of Cells and Particles for Identification of Vibro-Acoustic Properties

date March 8, 2013
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Friday, March 8, 2013 4:00 p.m. in ETC 4.150

Professor Yong-Joe Kim
Department of Mechanical Engineering
Texas A&M University

Microfluidic, acoustophoretic cell/particle separation has gained significant interest recently. In order to analyze the motion of cells/particles in the acoustophoretic separation, a one-dimensional (1-D) analytical model in a “static” fluid medium has been widely used, while the effects of acoustic streaming, viscous boundary layers, and 2‑D and 3‑D geometries are usually not considered. Therefore, it is not sufficient to accurately predict the cell/particle motion. Thus, a numerical modeling procedure for analyzing the acoustophoretic microparticle motion in microfluidic channels is presented to include the aforementioned effects.  Here, the mass and momentum conservation equations and the state equation are decomposed into zeroth‑, first‑, and second‑order governing equations by using a perturbation method.  Then, zeroth‑, first‑, and second‑order acoustic fields are calculated by applying a sixth‑order finite difference method to the decomposed governing equations.  The acoustophoretic force calculated by integrating the acoustic pressure over the surface of a rigid microparticle along with viscous drag force is then applied to the Newton’s equation of motion to analyze the acoustophoretic motion of the microparticle.  Since the acoustophoretic motion depends on the vibro-acoustic properties (e.g., density, compressibility, and size) of particles/cells, the vibro-acoustic properties can be estimated by optimally fitting the experimental and simulated trajectories. The properties obtained from experimental results with polystyrene beads and cancer cells show good agreement with the data reported in literature.