The preferential concentration or reduction of cells in the suspension media has numerous application in disease diagnostics, drug delivery, and bio-analysis. The development of micro-scale systems provides controlled manipulation of cells, rapid analysis, and point-of-care solutions. In this study, we present preferential manipulation of platelets in the blood plasma on a microfluidic platform. Extensive experiments were performed with several blood samples comprising various levels of blood dilutions, and whole blood samples with various initial red blood cells (RBCs) to platelets ratio, at flow rate range of 0.05–0.4 ml/min on a constriction–expansion microchannel. The manipulation of platelets in the plasma exploits numerous hemodynamic phenomenon, hydrodynamic and geometrical effects in the microchannel. Extensive experimental study provides insights of flow physics of blood and advantages of hydrodynamic collision of blood cells for the manipulation of platelets in the plasma. Next, we investigated effect of various governing parameters such as inlet flow rates, inlet blood dilution levels and initial concentration of blood cells on the preferential movement of platelets assisting concentration or reduction of platelets in the plasma. This understanding led to the development of a microdevice yielding both platelet-rich plasma and platelet-poor plasma from the same microdevice, depending on the flow conditions, which can further spur the development of an on-chip aggregometer. In addition, the proposed microfluidic system has practical potential for the isolation, enrichment and depletion of blood cells applicable for diseases diagnostics, and regenerative medicine.

悬浮介质中细胞的优先浓缩或减少在疾病诊断、药物输送和生物分析中有许多应用。微型系统的开发提供了细胞的受控操作、快速分析和即时护理解决方案。在这项研究中，我们在微流体平台上优先处理血浆中的血小板。在收缩-膨胀微通道上以 0.05–0.4 ml/min 的流速范围内，对包含不同浓度血液稀释液的几种血液样本和具有各种初始红细胞 (RBC) 与血小板比率的全血样本进行了广泛的实验。血浆中血小板的操作利用了微通道中的许多血液动力学现象、流体动力学和几何效应。广泛的实验研究提供了血液流动物理学的见解和血细胞流体动力学碰撞的优势，用于操纵血浆中的血小板。接下来，我们研究了各种控制参数（例如入口流速、入口血液稀释水平和血细胞初始浓度）对血小板优先运动的影响，这些参数有助于血浆中血小板的浓缩或减少。这种理解导致了微型设备的开发，根据流动条件，可以从同一微型设备中产生富含血小板的血浆和贫血小板血浆，这可以进一步促进片上聚集计的发展。此外，所提出的微流体系统具有分离、富集和消耗血细胞​​的实际潜力，适用于疾病诊断，