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

The enrichment of biological particles has important applications in biomedical detection, environmental monitoring, and chemical analysis. Although various external fields applied individually or in combination have been widely employed to achieve particle enrichment, balancing high enrichment efficiency with the preservation of biological activity remained a critical bottleneck. In this study, a novel microfluidic particle enrichment strategy was developed by integrating an acoustic field with oscillatory flow. An integrated microfluidic system was constructed, consisting of an acoustic actuation module, an oscillatory flow generation module, and a real-time observation region on a single chip, coupled with a miniaturized external programmable power supply. Comprehensive experiments were conducted to explore the influences of acoustic intensity and frequency, as well as key oscillatory flow parameters, on particle enrichment behavior. The results demonstrated that increasing the acoustic driving voltage enhanced the enrichment effect, while frequency tuning allowed control over the enrichment position. For oscillatory flow, enrichment efficiency exhibited a positive correlation with the driving frequency, whereas the voltage amplitude showed no significant influence. These findings deepened the understanding of particle enrichment mechanisms under coupled acoustofluidic fields and offered important theoretical guidance for the development of prototypes with relatively low hardware costs, showing potential for further miniaturization and portable operation.