Design and modelling of a standing surface acoustic wave-based microdevice for whole blood cell separation

Standing surface acoustic wave (SSAW)-based acoustofluidics are widely used due to their compatibility with soft materials and polymer structures. In the presence of the acoustic field, particles move either toward pressure node or pressure anti node according to their contrast factor. Using this technique, blood cells with a certain characteristic can be oriented in different stream lines in microchannel. Combination of appropriate inlet velocity ratio of buffer solution to blood, frequency, voltage, and channel geometry are essential keys of separation in these microdevices. In this study, simultaneous separation of white blood cells, red blood cells, and platelets at one stage is proposed using numerical simulation. Linear constitutive equation for the piezoelectric substrate, Helmholtz equation for the acoustic field, and Navier-stokes equation for fluid mechanics are solved simultaneously to precisely capture the blood cell behavior in the SSAW-based device. Results show that whole blood cells separation can be achieved by a velocity ratio of 6.25, a resonance frequency of 8.28 MHZ, and a voltage of 8.5v through the proposed five-outlet channel microchip.