Acoustic Radiation Forces Produced by Sharp-Edge Structures in Microfluidic Systems.

We study sharp-edge structures that are used in microfluidic systems for particle and cell manipulation. Experiments show that oscillating sharp edges can attract or repel particles suspended in a microfluidic channel. This effect is caused by acoustic radiation forces induced by sharp edges. We propose an analytical theory that allows one to evaluate the acoustic radiation force produced by a sharp-edge structure on elastic particles and to study which parameters govern the interaction of particles with a sharp-edge structure, forcing them to be attracted in one situation and to be repelled in another situation. The proposed theory gives foundations for the design of microfluidic systems making use of sharp edges for particle trapping. We also provide experimental data to validate the theory.