Flow Topology during Multiplexed Particle Manipulation Using a Stokes Trap

Anish Shenoy, Dinesh Kumar, Sascha Hilgenfeldt, Charles M. Schroeder

Research output: Contribution to journalArticlepeer-review


Trapping and manipulation of small particles underlies many scientific and technological applications. Recently, the precise manipulation of multiple small particles has been demonstrated using a Stokes trap that relies only on fluid flow, without the need for optical or electric fields. Active flow control generates complex flow topologies around suspended particles during the trapping process, yet the relationship between the control algorithm and the flow structure is not well understood. In this work, we characterize the flow topology during active control of particle trajectories using a Stokes trap. Our results show that optimal control of two particles unexpectedly relies on flow patterns with zero or one stagnation points, as opposed to positioning two particles using two distinct stagnation points. We characterize the sensitivity of the system with respect to the parameters in the control objective function, thereby providing a systematic understanding of the trapping process. Overall, these results will be useful in guiding applications involving the controlled manipulation of multiple colloidal particles and the precise deformation of soft particles in defined flow fields.

Original languageEnglish (US)
Article number054010
JournalPhysical Review Applied
Issue number5
StatePublished - Nov 5 2019

ASJC Scopus subject areas

  • General Physics and Astronomy


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