Spiral microchannels have shown promising results for separation applications. Hydrodynamic particle–particle interactions are a known factor strongly influencing focusing behaviors in inertial devices, with recent work highlighting how the performance of bidisperse mixtures is altered when compared with pure components in square channels. This phenomenon has not been previously investigated in detail for spiral channels. Here, we demonstrate that, in spiral channels, both the proportion and deformability of larger particles (13 μm diameter) impact upon the recovery (up to 47% decrease) of small rigid particles (4 μm). The effect, observed at low concentrations (volume fraction <0.0012), is attributed to the hydrodynamic capture of beads by larger cells. These changes in particles focusing behavior directly impede the efficiency of the separation—diverting beads from locations expected from measurements with pure populations to co-collection with larger cells—and could hamper deployment of technology for certain applications. Similar focusing behavior alterations were noted when working with purification of stem cell end products.

中文翻译：

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螺旋微通道在异质混合物中分离颗粒的局限性：颗粒尺寸和变形能力的影响。

螺旋微通道在分离应用中显示出有希望的结果。流体动力学粒子 - 粒子相互作用是强烈影响惯性装置中聚焦行为的已知因素，最近的工作强调了与方形通道中的纯组分相比，双分散混合物的性能如何改变。这种现象以前没有详细研究过螺旋通道。在这里，我们证明了，在螺旋通道，两者的比例和更大的颗粒（13的变形 μ在小刚性粒子的回收率（高达47％的减少）米直径）的影响（4  μ米）。在低浓度（体积分数 <0.0012）下观察到的效果归因于较大细胞对珠子的流体动力学捕获。粒子聚焦行为的这些变化直接阻碍了分离的效率——将珠子从纯种群测量预期的位置转移到与更大细胞的共同收集——并可能阻碍某些应用的技术部署。在纯化干细胞终产物时，也注意到了类似的聚焦行为改变。