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Focusing capillary jets close to the continuum limit

Nature Physics volume 3, pages 737–742 (2007)Cite this article

Abstract

The demand for techniques that can reliably deliver and control nanometre-scale volumes of liquid is a growing priority in biotechnology and medicine. Capillary jets are capable of supplying a steady stream of monodisperse liquid droplets. But because of the increasing forces and pressures needed to counteract surface tension for droplets of decreasing size, reaching the nanoscale with such an approach is difficult. One way of overcoming such limitations is to electrostatically focus a jet as it emerges from a capillary. Another, which we report here, is to focus such a jet by hydrodynamic means, a double flow-focusing arrangement that involves a manifold capillary that delivers a second immiscible fluid jet that envelopes and guides the jet from an inner capillary. Under the appropriate working conditions, this enables the generation of continuous steady capillary fluid jets down to submicrometre diameter—approaching the ultimate continuum limit, which is supported by a proposed theory.

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Figure 1: The double fluidic focusing arrangement.
Figure 2: Pictures of the different fluid combinations used.
Figure 3: Pilot Ink droplets dispersed in SOII by co-flow focusing.
Figure 4: Photographs of mercury droplets obtained using a mercury–silicon oil II–air combination at different experimental conditions.
Figure 5: Plot of the jetting–dripping transition location in the capillary number–viscosity ratio plane.

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Acknowledgements

This work is supported by the Ministry of Education and Science, Project no. DPI2004-07197, and by the Junta de Andalucía, Excellence Project no. TEP 1190.

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Authors and Affiliations

  1. Department of Aerospace Engineering and Fluid Mechanics, ESI, Universidad de Sevilla, 41092 Sevilla, Spain

    Alfonso M. Gañán-Calvo, Román González-Prieto, Pascual Riesco-Chueca & Miguel A. Herrada

  2. Ingeniatrics Tecnologías S.L., c/Trovador 3, 5A, 41018 Sevilla, Spain

    María Flores-Mosquera

Authors
  1. Alfonso M. Gañán-Calvo
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  3. Pascual Riesco-Chueca
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Contributions

A.M.G.C.: project planning, experimental work, data analysis, theoretical work, article writing; R.G.P.: experimental work, data analysis; P.R.C.: theoretical work, article writing; M.A.H.: numerical work; M.F.M.: project planning.

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Correspondence to Alfonso M. Gañán-Calvo.

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Gañán-Calvo, A., González-Prieto, R., Riesco-Chueca, P. et al. Focusing capillary jets close to the continuum limit. Nature Phys 3, 737–742 (2007). https://doi.org/10.1038/nphys710

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