Two-Dimensional Mapping Separating the Acoustic Radiation Force and Streaming in Microfluidics

Abstract

In microscale fluids, fields of physical force and streaming play central roles in manipulating and tweezing objects, but it is difficult to disentangle and obtain accurate pictures of them. We develop a multiradius microparticle image velocimetry (MRμPIV) protocol to solve this problem in miniaturized spaces. By using several monodisperse suspensions of spherical particles, each with its own specific particle radius, two-dimensional (2D) mapping separating the fields of radiation force and streaming is demonstrated in a microfluidic chamber driven by standing or focused surface acoustic waves, while motorized scanning is unnecessary and no special assumptions need to be made about the driving field. The results also allow the extraction of other physical parameters such as the acoustic pressure amplitude. The principle of MRμPIV relies on a quasiequilibrium assumption for the particle motion and a linear dependence of the field force on particle volume. Therefore, it is also applicable to tweezing techonologies using optical, dielectrophoretic, and magnetic forces, constituting an extension of the PIV technique impactful for microscale physics in general.

Rotational manipulation of massive particles in a 2D acoustofluidic chamber constituted by multiple nonlinear vibration sources

“…[32][33][34] The differences in and applications of these two acoustic effects have been elaborated in a series of references. [35][36][37] In recent years, to obtain sophisticated distributions of acoustic radiation forces and acoustic streaming fields, immense numbers of concrete research studies of acoustofluidic fields have been carried out for applications in particle patterning, tissue/organ engineering, and other physico-chemical and biomedical reactions. [29,30,38,39] Considering that the spatial variations in sound intensity and Reynolds stress in the Navier-Stokes equations are the results of time averaging of the sound field distribution, the acoustic radiation force and acoustic streaming field are significantly influenced by the input frequency, oscillation amplitude, and initial phase differences of multiple vibration sources, the acoustofluidic characteristics of different media, and the shape and distribution of fluid-solid interfaces.…”

Profiling Cell–Matrix Adhesion Using Digitalized Acoustic Streaming

“…Acoustofluidics − may be an alternative solution for addressing the challenges in measuring CTC–matrix interaction. By introduction of bulk acoustic waves or surface acoustic waves into a microfluidic channel/chamber, the acoustofluidic technique normally uses acoustic radiation force and Stokes drag force induced by acoustic streaming to manipulate biological particles or fluids. − Because of the unique nature of acoustic waves, the acoustofluidic technique can achieve various biomanipulations in a label-free, contactless, and highly biocompatible manner. The acoustic radiation force has been used to pattern, transport, separate, and sort cells and particles − for broad application in tissue engineering, regenerative medicine, drug screening, and disease detection and treatment.…”