Cell/particle manipulation using Bulk Acoustic Waves (BAWs) on centrifugal microfluidic platforms: A mathematical study

This study presents an integrated acoustic-aided centrifugal microfluidic system to focus and separate microparticles. A 3D numerical simulation was conducted to analyze microparticle movement by exploiting the simultaneous imposition of centrifugal forces and bulk acoustic waves (BAWs) on an electrified lab-on-a-disc device (eLOD). Accordingly, the movement of microparticles was analyzed in a radially positioned rectangular microchannel at various rotation speeds. The effect of physical parameters, including the distance of the microchannel to the center/radius, tilting angle (α), the oscillation amplitude of BAWs, the microchannel's dimension, and the particles’ diameter on particle trajectories and focusing efficiency, was studied. It was found that properly adjusting the microchannel's placement at α = 30° made it possible to direct the focused stream of microparticles toward the desired outlet. Higher values of applied oscillation amplitude of BAWs (0.3 nm) led to perfect focusing of microparticles toward the middle outlet in a 200-µm width microchannel at 80 rad/s rotation. Furthermore, the system's ability to separate the circulating tumor cells (CTC) from white blood cells (WBC) was also simulated. The results showed that a successful size-based separation of these bioparticles is achievable by adequately adjusting the microchannel's position or tilting angle at 286 rpm.