Ultrasound-controlled stream splitting in a microfluidic coflow

Fuente: arXiv
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Main Authors: Ghosh, D., Hoque, S. Z., Sujith, T., Satpathi, N. S., Malik, L., Sen, A. K.
Format: Preprint
Published: 2026
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author Ghosh, D.
Hoque, S. Z.
Sujith, T.
Satpathi, N. S.
Malik, L.
Sen, A. K.
author_facet Ghosh, D.
Hoque, S. Z.
Sujith, T.
Satpathi, N. S.
Malik, L.
Sen, A. K.
contents Precise control of multiphase microfluidic flows underpins applications ranging from chemical processing to biomedical diagnostics. We investigate the response of a liquid--liquid coflow in a rectangular microchannel to an externally applied standing acoustic field. Acoustic excitation destabilizes an otherwise stable interface, giving rise to a sequence of reversible interfacial regimes: waviness, splitting, relocation, and stream-droplet breakup. Remarkably, a distinct splitting regime emerges, where a continuous stream partially splits into droplets at tunable locations while retaining a thin residual stream. Unlike conventional droplet breakup, this regime avoids complete disruption of the main flow, enables droplet generation at high capillary numbers, and allows spatial control over droplet formation. Extending across a broad range of capillary numbers, we examine how variations in flow conditions and applied acoustic power influence these regimes. Combining experiments, numerical simulations, and theoretical scaling, we elucidate the mechanisms governing this droplet generation mode and the associated regime transitions. Systematic measurements show that droplet size and residual stream thickness are governed primarily by hydrodynamic parameters, whereas the acoustic field controls the onset and spatial location of the breakup. These results establish a simple avenue for stream splitting and drop generation on-demand in a microfluidic coflow, opening new possibilities for spatially programmable manipulation of multiphase flows.
format Preprint
id arxiv_https___arxiv_org_abs_2604_05419
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Ultrasound-controlled stream splitting in a microfluidic coflow
Ghosh, D.
Hoque, S. Z.
Sujith, T.
Satpathi, N. S.
Malik, L.
Sen, A. K.
Fluid Dynamics
Precise control of multiphase microfluidic flows underpins applications ranging from chemical processing to biomedical diagnostics. We investigate the response of a liquid--liquid coflow in a rectangular microchannel to an externally applied standing acoustic field. Acoustic excitation destabilizes an otherwise stable interface, giving rise to a sequence of reversible interfacial regimes: waviness, splitting, relocation, and stream-droplet breakup. Remarkably, a distinct splitting regime emerges, where a continuous stream partially splits into droplets at tunable locations while retaining a thin residual stream. Unlike conventional droplet breakup, this regime avoids complete disruption of the main flow, enables droplet generation at high capillary numbers, and allows spatial control over droplet formation. Extending across a broad range of capillary numbers, we examine how variations in flow conditions and applied acoustic power influence these regimes. Combining experiments, numerical simulations, and theoretical scaling, we elucidate the mechanisms governing this droplet generation mode and the associated regime transitions. Systematic measurements show that droplet size and residual stream thickness are governed primarily by hydrodynamic parameters, whereas the acoustic field controls the onset and spatial location of the breakup. These results establish a simple avenue for stream splitting and drop generation on-demand in a microfluidic coflow, opening new possibilities for spatially programmable manipulation of multiphase flows.
title Ultrasound-controlled stream splitting in a microfluidic coflow
topic Fluid Dynamics
url https://arxiv.org/abs/2604.05419