Acoustically actuated sessile bubbles can be used as a tool to manipulate microparticles, vesicles, and cells. In this work, using acoustically actuated sessile semicylindrical microbubbles, we demonstrate experimentally that finite-sized microparticles undergo size-sensitive migration and trapping toward specific spatial positions in three dimensions with high reproducibility. The particle trajectories are successfully reproduced by passive advection of the particles in a steady three-dimensional streaming flow field augmented with volume exclusion from the confining boundaries. For different particle sizes, this volume exclusion mechanism leads to three regimes of qualitatively different migratory behavior, suggesting applications for separating, trapping, and sorting of particles in three dimensions.

中文翻译：

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尺寸依赖的粒子在三维微气泡流中的迁移和捕集

声驱动的无泡可以用作操纵微粒，囊泡和细胞的工具。在这项工作中，使用声学驱动的无柄半圆柱形微气泡，我们通过实验证明了有限尺寸的微粒经历了尺寸敏感的迁移，并以高可复制性向着三维的特定空间位置捕集。通过在稳定的三维流动流场中对粒子进行被动对流，成功地重现了粒子轨迹，该流场中的体积被排除在边界之外。对于不同的粒径，这种体积排阻机制导致了三种在性质上不同的迁移行为，这建议在三个维度上分离，捕获和分类颗粒。