Inertial migration of particles to a characteristic lateral equilibrium position in laminar micro-flows has been investigated under various aspects during the last decades. The majority of the studies deal with the equilibrium position of rigid particles and viscous droplets. Here, we compare the equilibrium velocity of viscoelastic cells and rigid polystyrene spheres in flow by applying the method of spatially modulated emission. The technique allows the precise determination of the equilibrium velocity of an object in flow, which has been found to depend on object characteristics like size in earlier studies. Here, we first show that the deformable cells move at higher equilibrium velocity than rigid polystyrene particles, thus revealing that a particle’s equilibrium velocity is related to its deformability—in addition to size. In a second set of experiments, we treat cells with the cytostatic agent colchicine, which results in a systematic decrease of the equilibrium velocity that is attributed to cell stiffening. This study thus provides evidence that the parameter cell deformability can be extracted from the equilibrium velocity based on spatially modulated emission, which opens up an alternative way for high-throughput cell-deformability characterization.

在过去的几十年中，已经研究了粒子在层状微流中向特征性横向平衡位置的惯性迁移。大多数研究涉及刚性颗粒和粘性液滴的平衡位置。在这里，我们通过应用空间调制发射的方法比较了粘弹性单元和刚性聚苯乙烯球在流动中的平衡速度。该技术可以精确确定物体在流动中的平衡速度，这已被发现取决于物体特性，如早期研究中的尺寸。在这里，我们首先显示可变形单元的平衡速度要比刚性聚苯乙烯颗粒高，从而揭示了颗粒的平衡速度与其可变形性有关（大小除外）。在第二组实验中，我们用细胞抑制剂秋水仙碱处理细胞，这导致平衡速度的系统性下降，这归因于细胞变硬。因此，这项研究提供了证据，可以基于空间调制发射从平衡速度中提取参数细胞变形能力，这为表征高通量细胞变形能力开辟了另一种途径。