The enrichment and focusing of the nano-/submicroparticle (e.g., 150–1000 nm microvesicle shed from the plasma membrane) in the viscoelastic fluid has great potentials in the biomedical and clinical applications such as the disease diagnosis and the prognostic test for liquid biopsy. However, due to the small size and the resulting weak hydrodynamic force, the efficient manipulation of the nano-/submicroparticle by the passive viscoelastic microfluidic technology remains a major challenge. For instance, a typically long channel length is often required to achieve the focusing or the separation of the nano-/submicroparticle, which makes it difficult to be integrated in small chip area. In this work, a microchannel with gradually contracted cross-section and high aspect ratio (the ratio of the height to the average width of channel) is utilized to enhance the hydrodynamic force and change the force direction, eventually leading to the efficient enrichment of nano-/submicroparticles (500 and 860 nm) in a short channel length (2 cm). The influence of the flow rate, the particle size, the solid concentration, and the channel geometry on the enrichment of the nano-/submicroparticles are investigated. With simple structure, small footprint, easy operation, and good performance, the present device would be a promising platform for various lab-chip microvesicle-related biomedical research and disease diagnosis.

中文翻译：

---

粘弹性流体中纳米/亚微米粒子的高效微流体富集

粘弹性流体中纳米/亚微米颗粒（例如，从质膜脱落的150-1000 nm微泡）的富集和聚焦在疾病诊断和液体活检预后测试等生物医学和临床应用中具有巨大潜力。然而，由于尺寸小且产生的流体动力较弱，被动粘弹性微流体技术对纳米/亚微米粒子的有效操纵仍然是一项重大挑战。例如，通常需要较长的通道长度来实现纳米/亚微米颗粒的聚焦或分离，这使得难以集成在小芯片区域中。在这项工作中，利用横截面逐渐收缩和高纵横比（通道高度与平均宽度之比）的微通道来增强流体动力并改变力方向，最终导致纳米/亚微米颗粒的有效富集（ 500 和 860 nm），通道长度较短（2 cm）。研究了流速、粒径、固体浓度和通道几何形状对纳米/亚微米颗粒富集的影响。该装置结构简单、占地面积小、操作方便、性能好，将成为各种实验室芯片微泡相关生物医学研究和疾病诊断的有前景的平台。最终导致纳米/亚微米颗粒（500 和 860 nm）在短通道长度（2 cm）中的有效富集。研究了流速、粒径、固体浓度和通道几何形状对纳米/亚微米颗粒富集的影响。该装置结构简单、占地面积小、操作方便、性能好，将成为各种实验室芯片微泡相关生物医学研究和疾病诊断的有前景的平台。最终导致纳米/亚微米颗粒（500 和 860 nm）在短通道长度（2 cm）中的有效富集。研究了流速、粒径、固体浓度和通道几何形状对纳米/亚微米颗粒富集的影响。该装置结构简单、占地面积小、操作方便、性能好，将成为各种实验室芯片微泡相关生物医学研究和疾病诊断的有前景的平台。