Microparticle enrichment and steering via frequency-controlled acoustic bubble array

Manipulation of microscopic objects plays an essential role in broad applications. Microparticle enrichment and steering in microfluidic channels have been widely used in cell sorting and bio-analysis. However, there still lacks a method satisfying the requirements of good biocompatibility and alternative functions. Here, we propose an efficient method to achieve microparticle enrichment and steering via frequency-controlled acoustic bubble array. An aligned oscillating bubble array trapped by the side openings has been employed. The enrichment and steering direction of the target microparticles can be switched conveniently by altering the excitation frequency. Both experimental investigations and numerical modeling have been conducted, confirming the correctness and robustness of the method. The introduced mechanisms and methods pave the way for optimized cytometer sorting and biomedical analysis.