Multifunctional acoustofluidic centrifuge device using tri-symmetrical design for particle enrichment and separation and multiphase microflow mixing

Effective enrichment and separation of particles and mixing of multiphase microflows can be technically challenging in microfluidic sample processing and analysis. Acoustofluidic techniques have advantages such as high biocompatibility, versatility, and simple device design to meet these demands. Here, we present a novel tri-symmetrical acoustofluidic centrifuge based on traveling surface acoustic waves (TSAWs), achieving particle enrichment and bidirectional size-based separation, pushing away the larger particles while enriching the smaller ones, in a rapid time (<6 s). A microfluidic chamber was designed for further extraction of treated particles and cells. Experimental results show that our device can achieve enrichment of particles in a range of sizes and high purity separation (e.g. >90 % in 5 µm and 40 µm sample), demonstrating its sample processing capabilities. The acoustic treatment did not affect cells (consistent with the control group above 80 %). TSAW-induced acoustic streaming enabled efficient mixing (mixing efficiency χ >85 %) of fluorescent multi-phase microflows within a short time (<0.5 s). The underlying physical mechanisms have been verified by numerical simulations.