近年來在生物和醫學的研究領域中，如何從異質混合物分離出細胞一直是重要的目標，而細胞分離更是許多臨床診斷和治療的必要步驟，對於細胞分離的需求也正擴展到分離某些稀有的靶細胞群，例如循環腫瘤細胞等，然而許多研究團隊發現循環腫瘤細胞不僅與主要腫瘤細胞擁有相似的生物特徵，亦可用於監測癌症治療的成效。然而，在血液的組成中，白血球細胞的直徑與循環腫瘤細胞極為相近，因此增加分離出循環腫瘤細胞的難度，故本研究將利用特殊的流體動力學設計，透過控制磁性人工纖毛不同的擺動模式，精準的調控流場剪應力及壁面效應，搭配粒子在微流體環境的移動特性，透過模擬方法研究直徑15與20 µm的粒子在微流體裝置中因人工纖毛擺動而產生的移動差異，藉由量化粒子在通過人工纖毛後的位置分佈，可以得到粒子最終平衡位置與雷諾數以及斯特勞克數的趨勢關係，更進一步說明尺度相似的粒子可以產生10 %的軌跡差異，進而找出最佳的流體參數以實現高效率的細胞分類，再透過實驗觀測粒子在流場中受磁性人工纖毛擺動所產生的移動軌跡，並利用微粒子影像測速儀進行流體動力學分析，驗證不同大小粒子的軌跡差異與模擬結果趨勢相同。本研究成功透過人工纖毛轉動達到調控流場剪切梯度作用力之目標，未來期待將此技術運用在生物醫學等領域作為分離循環腫瘤細胞的基礎。

Recent years have witnessed an unprecedented effort from the scientific society towards separating specific cells from the heterogeneous mixture of cells for various biological and medical purposes. Such an example is capturing circulating tumor cells (CTCs) from the other blood cells. However, separating CTCs from the whole blood is hydrodynamically a difficult task as the size of other blood cells such as leukocyte have a similar dimensional features. In this aspect, we are investigating the migrating behavior of leukocytes and circulating tumor cells induced by magnetic artificial cilia within microfluidic environment through the precise control of flow-induced shear gradient and wall surface effect via numerical analysis. By quantifying the position distribution of the particles after passing the artificial cilia, the relations between the final equilibrium position of the particles and two non-dimensional number (Reynolds number and Strouhal number) can be obtained, further indicating that the particles with similar dimensions can produce a trajectory difference over 10%. In the experimental section, the particle trajectory induced by different rotational modes of magnetic artificial cilia can also be observed by micro-particle image velocimetry to verify that the experimental results are consistent with the simulation results. This study shows that the equilibrium position of particles with similar dimensions still can be manipulated into different positions through the precise control of the flow shear gradient by changing the frequency and amplitude of artificial cilia rotation. It is expected that this technology will be applied in the biomedical fields as the basis for separating circulating tumor cells.

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