Drop-in additives for suspension manipulation: Colloidal motion induced by sedimenting soluto-inertial beacons
Drop-in additives for suspension manipulation: Colloidal motion induced by sedimenting soluto-inertial beacons
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DOI：
10.1103/physrevfluids.5.073701
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发表时间：
2020-07-02
影响因子：
2.7
通讯作者：
Squires, Todd M.
中科院分区：
文献类型：
--
作者：
Banerjee, Anirudha;Tan, Huanshu;Squires, Todd M.
溶液-惯性（SI）悬浮液相互作用涉及非平衡胶体在毫米范围内的迁移，由建立持久化学梯度的“信标”驱动。SI概念的先前演示仅限于固定的圆柱形信标，这些信标可以在受控的二维几何形状中维持溶质通量。在这里，我们研究了通过悬浮液沉积的球形信标建立的解-惯性相互作用。沉淀的信标留下一个拖尾的溶质尾迹，其通量驱动邻近悬浮物的运动。实验表明，尾迹可以吸引或排斥粒子，这取决于溶质-胶体对，在悬浮液中产生富含或缺乏粒子的局部区域。理论描述准确地捕捉实验观察，并提供预测能力，以衡量这些相互作用的强度在设计参数方面。我们预计，由“滴入式”信标添加剂驱动的远距离大块悬浮液相互作用将使稀悬浮液的按需絮凝和胶体混合物的分离成为可能。
Soluto-inertial (SI) suspension interactions involve nonequilibrium colloidal migration over millimeters, driven by "beacons" that establish long-lasting chemical gradients. Previous demonstrations of the SI concept were restricted to fixed, cylindrical beacons that would sustain solute fluxes in controlled two-dimensional geometries. Here we examine soluto-inertial interactions established by a spherical beacon that sediments through a suspension. The sedimenting beacon leaves a trailing solute wake, the flux from which drives the motion of neighboring suspended objects. Experiments reveal wakes that can attract or repel particles, depending on the solute-colloid pair, creating local regions in the suspension that are enriched in or devoid of particles. Theoretical descriptions accurately capture experimental observations and provide predictive ability to gauge the strength of these interactions in terms of the design parameters. We anticipate that long-range, bulk suspension interactions driven by "drop-in" beacon additives will enable on-demand flocculation of dilute suspensions and separation of colloidal mixtures.