The manipulation of micro- and nanoparticles at fluid interfaces is central to optofluidics, microfluidics, and colloidal assembly. While capillarity-driven migration and ordering are well established, achieving stable and reconfigurable particle trapping remains a challenge. Here, we demonstrate that a neck-shaped meniscus formed around a vertically actuated rod acts as a dynamically tunable capillary well, enabling reversible particle confinement, directed migration, and release. Furthermore, elliptical rods create anisotropic meniscus curvature that guides particles toward regions of higher curvature; we identify an optimal aspect ratio of the rod cross-section that maximizes trapping efficiency. Experiments supported by simulations confirm the predicted critical meniscus height and quasistationary regime velocity. These findings establish a geometry-controlled, field-free strategy for robust and reconfigurable particle manipulation at fluid interfaces, extending the principles of curvature-guided assembly.

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• Capillary interactions
• Contact line dynamics
• Surface tension effects
• Wetting