Deterministic-hydrodynamic Size-, Shape- and Density Fractionation of Polydisperse Microparticles

在过去的几年里，对直径小于10μm的微颗粒的工业应用分馏方法的需求一直在稳步增长。在传统的筛分、过滤、沉降、离心和筛选等方法被推向极限的地方，微流控分离方法能够在层流条件下对微微米和亚微米颗粒施加高的水动力。特别是被动微流控分离过程可以设计成非常紧凑和并行的方式来提高吞吐量。最成功的微流控系统是多孔流体分馏（MOFF）、微流控蛇形通道分馏和确定性横向位移分馏（DLDF）。在资助期1，这些成功地用于模型颗粒的大小和密度分选，也适用于多维分离。然而，通过上述方法根据大小、密度和形状等多种特征分离实际颗粒的方法仍然知之甚少。为了更好地了解这些过程，将在资助期2进行补充性的数值和实验研究。计划项目的中心目标是通过目标模型粒子和真实粒子实验的结合，首次实现小于1µm粒子的多维分离。为此，现有的通道几何形状将配备多个水流出口，以分离和分析分馏后的部分水流。这也允许与其他项目伙伴合作测试多级分馏过程。在第一个资助期内成功建立了所需的数值和实验方法。它们允许以时间和空间分辨的方式研究微粒的复杂运动动力学。由于分离方法的复杂性和实验对几种通道几何形状的限制，在第二个资助期也需要模拟和实验之间的密切合作。这包括系统中主导强迫机制的数值敏感性研究，也包括数值辅助实验设计和结果评估。与第一个资助期相比，只需要适度扩展数值和实验技术，就可以促进布朗分子运动下小于1 μ m颗粒的分馏动力学研究。考虑到未来的工业应用，重点研究了在更高通量和更高颗粒浓度下的分馏，以量化颗粒相互作用对分离程度和选择性的影响。

Throughout the last years the demand for industrially applicable fractionation methods for microparticles of less than 10μm diameter has been steadily growing. Where conventional approaches such as sieving, filtering, sedimentation, centrifugation and screening are pushed to its limits, microfluidic separation methods are capable to exert high hydrodynamic forces on micro- and submicron particles under laminar flow conditions. Especially passive microfluidic separation processes can be designed in a very compact and parallelized manner to increase throughput rates.The most successful microfluidic systems for size fractionation of microparticles are the Multi Orifice Fluid Fractionation (MOFF), fractionation in microfluidic serpentine channels and the Deterministic Lateral Displacement Fractionation (DLDF). In funding period 1, these were successfully used for size and density fractionation of model particles and are also suitable for multidimensional separation. Nevertheless, the separation of real particles according to multiple characteristics such as size, density and shape via aforementioned methods is still little understood. To gain a better understanding of these processes, complementary numerical and experimental studies shall be performed in funding period 2. A central goal of the planned project is to realize for the first time multidimensional separation of particles smaller than 1µm by a combination of targeted model particle and real particle experiments. For this purpose, existing channel geometries will be equipped with multiple flow outlets to separate and analyze partial streams after fractionation. This also allows testing multi-stage fractionation processes in cooperation with other project partners.Required numerical and experimental methods were successfully established in the first funding period. They allow studying the complex motion dynamics of microparticles in a temporally and spatially resolved manner. The complexity of the separation methods and the experimental restrictions to a few channel geometries require a close cooperation between simulation and experiment also in the second funding period. This includes numerical sensitivity studies of dominant forcing mechanisms in the systems but also numerically assisted designing of experiments and evaluation of results. Compared to the first funding period, only moderate extensions of numerical and experimental techniques are necessary to facilitate studies of the fractionation dynamics of particles smaller than 1 µm under Brownian molecular motion. In view of future industrial applications, fractionation under increasing throughput rates and higher particle concentrations is studied in particular to quantify the influence of particle interaction on the separation degree and the selectivity.