Colloidal dispersions have been frequently encountered in a wide range of industrial applications, such as foods, paints, and Li-ion electrode slurries. Therefore, it is essential to understand the rheological and flow characteristics of colloidal dispersions to improve the quality and optimize the processing conditions of colloidal products. The shear viscosity of a colloidal dispersion deviates from Newtonian behavior, exhibiting shear thinning and/or shear thickening as the volume fraction of the colloidal particles increases. However, there are not many reports on the non-Newtonian flow phenomena caused by the normal stress differences of colloidal dispersion due to their small magnitude. Recently, these normal stress differences in colloidal dispersions with a constant shear viscosity lead to a single-line focused streams of micron-sized particles along the centerline of microchannels. In this study, the lateral migration of single micron-sized particles suspended in poly (N-isopropylacrylamide) microgel dispersions with a shear-thinning viscosity was investigated. The micron-sized particles migrated toward the centerline or between the centerline and wall of a microchannel depending on the volume fraction of the colloidal particles and the flow conditions. The current findings are expected to contribute to our understanding of the non-Newtonian fluid dynamics in colloidal dispersions and flow-induced particle segregation phenomenon.

胶体分散体在广泛的工业应用中经常遇到，例如食品、油漆和锂离子电极浆料。因此，了解胶体分散体的流变学和流动特性对提高胶体产品的质量和优化加工条件至关重要。胶体分散体的剪切粘度偏离牛顿行为，随着胶体颗粒的体积分数增加，表现出剪切变稀和/或剪切增稠。然而，由于胶体弥散的法向应力差异引起的非牛顿流动现象的量级较小，关于非牛顿流动现象的报道并不多。最近，具有恒定剪切粘度的胶体分散体中的这些法向应力差异导致沿着微通道中心线的微米级颗粒的单线聚焦流。在这项研究中，悬浮在聚 (研究了具有剪切稀化粘度的N-异丙基丙烯酰胺）微凝胶分散体。根据胶体颗粒的体积分数和流动条件，微米级颗粒向中心线或中心线与微通道壁之间迁移。目前的研究结果有望有助于我们理解胶体分散体中的非牛顿流体动力学和流动引起的粒子偏析现象。