A particle suspended in a fluid within a microfluidic channel experiences a direct acoustic radiation force (ARF) when traveling surface acoustic waves (TSAWs) couple with the fluid at the Rayleigh angle, thus producing two components of the ARF. Most SAW‐based microfluidic devices rely on the horizontal component of the ARF to migrate prefocused particles laterally across a microchannel width. Although the magnitude of the vertical component of the ARF is more than twice the magnitude of the horizontal component, it is long ignored due to polydimethylsiloxane (PDMS) microchannel fabrication limitations and difficulties in particle focusing along the vertical direction. In the present work, a single‐layered PDMS microfluidic chip is devised for hydrodynamically focusing particles in the vertical plane while explicitly taking advantage of the horizontal ARF component to slow down the selected particles and the stronger vertical ARF component to push the particles in the upward direction to realize continuous particle separation. The proposed particle separation device offers high‐throughput operation with purity >97% and recovery rate >99%. It is simple in its fabrication and versatile due to the single‐layered microchannel design, combined with vertical hydrodynamic focusing and the use of both the horizontal and vertical components of the ARF.

中文翻译：

---

通过向上迁移进行颗粒的垂直流体动力聚焦和连续声流分离

当表面声波 (TSAW) 与流体以瑞利角耦合时，悬浮在微流体通道内流体中的颗粒会受到直接声辐射力 (ARF)，从而产生 ARF 的两个分量。大多数基于 SAW 的微流体装置依靠 ARF 的水平分量在微通道宽度上横向迁移预聚焦粒子。尽管ARF的垂直分量的大小是水平分量的两倍以上，但由于聚二甲基硅氧烷（PDMS）微通道制造的限制以及粒子沿垂直方向聚焦的困难，它长期以来被忽略。在目前的工作中，设计了一种单层 PDMS 微流控芯片，用于在垂直平面中流体动力学聚焦颗粒，同时明确利用水平 ARF 分量减慢所选颗粒的速度，并利用更强的垂直 ARF 分量将颗粒向上推动实现颗粒连续分离的方向。所提出的颗粒分离装置提供高通量操作，纯度>97%，回收率>99%。由于采用单层微通道设计，结合垂直流体动力聚焦以及 ARF 水平和垂直组件的使用，其制造简单且用途广泛。