International Iberian Nanotechnology Laboratory, Braga, Portugal.
Lab Chip. 2018 Aug 21;18(17):2593-2603. doi: 10.1039/c8lc00486b.
We report the design and characterization of a lateral and vertical hydrodynamic focusing feature for whole cell detection on a miniaturized flow cytometer. The developed system, based on magnetic sensing, incorporates spin valve sensors on the bottom of the microfluidic channels that detect cells labeled with magnetic beads. An adaptable 3D hydrodynamic focusing system was developed that pushes labeled cells towards the bottom of the microchannel, closer to the sensors, allowing increased signal amplitude for cells labeled with magnetic beads and enhanced discrimination of labeled cells. Fluorescence microscopy indicates that the lateral and vertical hydrodynamic focusing effect was adequately implemented, consistent with simulation predictions. The sensitivity of the system to detect labeled cells was improved by at least two-fold. By estimating the coverage of magnetic beads on cells, the signal from labeled cells could be predicted using a mathematical model, which also demonstrated the sensitivity of the signal to the height of the cells relative to the sensor. The system is versatile allowing interchangeable flow rates for cells with different diameters.
我们报告了一种横向和纵向流体动力学聚焦特征的设计和特性，用于微型流动细胞仪上的全细胞检测。该系统基于磁传感，在微流道的底部配备了自旋阀传感器，用于检测用磁珠标记的细胞。开发了一种适应性强的 3D 流体动力学聚焦系统，可将标记的细胞推向微通道的底部，更接近传感器，从而增加了带有磁珠标记的细胞的信号幅度，并增强了对标记细胞的区分。荧光显微镜表明，横向和纵向流体动力学聚焦效果得到了充分的实现，与模拟预测一致。通过至少两倍地提高了系统检测标记细胞的灵敏度。通过估计细胞上的磁珠覆盖率，可以使用数学模型预测标记细胞的信号，该模型还表明信号对细胞相对于传感器的高度的灵敏度。该系统具有通用性，允许不同直径的细胞使用可互换的流速。
