A Microfluidic System for Particle Enrichment by Integrating an Acoustic Field with Oscillatory Flow

The enrichment of biological particles has significant applications in biomedical detection, environmental monitoring and chemical analysis. Although various external fields used individually or in combination have been widely implemented to achieve particle enrichment, balancing enrichment efficiency with preservation of biological activity remains one of the bottleneck issues. In this study, we designed a novel microfluidic enrichment strategy by integrating an acoustic field with oscillatory flow. An integrated microfluidic system was constructed, comprising an acoustic actuation module, an oscillatory flow generation module, and a real-time observation module on a single chip, along with an external miniaturized power supply. Numerical simulations were performed to systematically study the effects of the acoustic field and oscillatory flow on particle motion in the microchannel, providing a theoretical foundation for the design of the enrichment system. Comprehensive experiments were then conducted to examine the influence of acoustic field intensity and frequency, as well as oscillatory flow parameters, on particle enrichment behavior. Results demonstrated that increasing the acoustic driving voltage enhanced the enrichment effect, while frequency adjustment allowed control over the enrichment position. In terms of oscillatory flow, enrichment efficiency correlated positively with driving frequency, whereas voltage amplitude had no significant impact. These findings advance the understanding of particle enrichment mechanisms under coupled acoustic and oscillatory flow fields, and offer important theoretical guidance for developing portable, low-cost microfluidic particle enrichment systems.