Particle Trajectories and Transverse Dispersion in Acoustic Microfluidic Devices

The difference in residence time spent by particles in acoustic separator devices correlates to the values of the efficiency and purity coefficients. Although the particle trajectories and the required flow speeds have been investigated in theoretical and numerical studies, most of the existing studies overlook the effect of transverse flow profiles. More complex sorter methods, such as tilted-angle or frequency-modulated methods however can be better understood by applying analysis based on flow profiles. A numerical integration scheme is used here to obtain axial particle trajectories for arbitrary flow profiles with residence time differences of up to 20% for simple time-of-flight sorting. For more complex phase modulated techniques, a non-monotonous dependence of residence time on particle size is observed, with differences up to 27%.