Precise manipulation of cells within water-in-oil emulsion droplets has the potential to vastly expand the type of cellular assays that can be conducted in droplet-based microfluidics systems. However, achieving such manipulation remains challenging. Here, we present an in-droplet label-free cell separation technology by utilizing different dielectrophoretic responses of two different cell types. Two pairs of angled planar electrodes were utilized to generate positive or negative dielectrophoretic force acting on each cell type, which results in selective in-droplet movement of only one specific cell type at a time. A downstream asymmetric Y-shaped microfluidic junction splits the mother droplet into two daughter droplets, each of which contains only one cell type. The capability of this platform was successfully demonstrated by conducting in-droplet separation from a mixture of Salmonella cells and macrophages, two cell types commonly used as a bacterial pathogenicity analysis model. This technology enable the precise manipulation of cells within droplets, which can be exploited as a critical function in implementing broader ranges of droplet-based microfluidics cellular assays.

中文翻译：

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基于双极介电泳响应的液滴内细胞分离，以促进细胞液滴测定。

精确控制油包水型乳剂液滴中的细胞具有极大地扩展可在基于液滴的微流体系统中进行的细胞测定类型的潜力。然而，实现这种操纵仍然是挑战。在这里，我们提出了一种利用两种不同细胞类型的不同介电电泳响应的无液滴内无标签细胞分离技术。利用两对成角度的平面电极来产生作用于每种细胞类型的正或负介电泳力，从而导致一次仅一种特定细胞类型的选择性液滴内运动。下游的不对称Y形微流体连接将母滴分成两个子滴，每个子滴仅包含一种细胞类型。沙门氏菌细胞和巨噬细胞是两种细胞类型，通常用作细菌致病性分析模型。这项技术能够对液滴内的细胞进行精确操作，可将其用作实施更广泛的基于液滴的微流控细胞分析的关键功能。