Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

Controlled drop emission by wetting properties in driven liquid filaments

Nature Materials volume 10, pages 367–371 (2011)Cite this article

Subjects

Abstract

The controlled formation of micrometre-sized drops is of great importance to many technological applications1,2,3,4,5. Here we present a wetting-based destabilization mechanism of forced microfilaments on either hydrophilic or hydrophobic stripes that leads to the periodic emission of droplets. The drop emission mechanism is triggered above the maximum critical forcing at which wetting, capillarity, viscous friction and gravity can balance to sustain a stable driven contact line. The corresponding critical filament velocity is predicted as a function of the static wetting angle, which can be tuned through the substrate behaviour, and shows a strong dependence on the filament size. This sensitivity explains the qualitative difference in the critical velocity between hydrophilic and hydrophobic stripes, and accounts for previous experimental results of splashing solids6. We demonstrate that this mechanism can be used to control independently the drop size and emission period, opening the possibility of highly monodisperse and flexible drop production techniques in open microfluidic geometries.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Liquid microfilaments forced on chemical stripes of a given static angle, θe, and varying capillary number, Ca.
Figure 2: Schematic diagram of filament mid-section.
Figure 3: Critical capillary number, Ca* , as a function of the static contact angle, θe , at different values of the length-scale-separation parameter, ε .
Figure 4: Dimensionless radius and period of the emitted drop.
Figure 5: Experimental observation of wetting-controlled drop emission.

Similar content being viewed by others

References

  1. Atencia, J. & Beebe, D. J. Controlled microfluidic interfaces. Nature 437, 648–655 (2005).

    Article  CAS  Google Scholar 

  2. Song, H., Chen, D. L. & Ismagilov, F. Reactions in droplets in microfluidic channels. Angew. Chem. Int. Ed. 45, 7336–7356 (2006).

    Article  CAS  Google Scholar 

  3. Song, H., Tice, J. D. & Ismagilov, F. A microfluidic system for controlling reaction networks in time. Angew. Chem. Int. Ed. 42, 767–772 (2003).

    Google Scholar 

  4. Edd, J. F. et al. Controlled encapsulation of single-cells into monodisperse picolitre drops. Lab Chip 8, 1262–1264 (2008).

    Article  CAS  Google Scholar 

  5. Prakash, M. & Gershenfeld, N. Microfluidic bubble logic. Science 315, 832–835 (2007).

    Article  CAS  Google Scholar 

  6. Duez, C., Ybert, C., Clanet, C. & Bocquet, L. Making a splash with water repellency. Nature Phys. 3, 180–183 (2007).

    Article  CAS  Google Scholar 

  7. Anna, S. L., Bontoux, N. & Stone, H. A. Formation of dispersions using ‘flow focusing’ in microchannels. Appl. Phys. Lett. 82, 364–366 (2003).

    Article  CAS  Google Scholar 

  8. Link, D. R., Anna, S. L., Weitz, D. A. & Stone, H. A. Geometrically mediated breakup of drops in microfluidic devices. Phys. Rev. Lett. 92, 054503 (2004).

    Article  CAS  Google Scholar 

  9. Xu, J. H., Luo, G. S., Li, S. W. & Chen, G. G. Shear force induced monodisperse droplet formation in a microfluidic device by controlling wetting properties. Lab Chip 6, 131–136 (2006).

    Article  CAS  Google Scholar 

  10. Pannacci, N. et al. Equilibrium and nonequilibrium states in microfluidic double emulsions. Phys. Rev. Lett. 101, 164502 (2008).

    Article  Google Scholar 

  11. Kataoka, D. E. & Troian, S. M. Patterning liquid flow at the microscopic scale. Nature 402, 794–797 (1999).

    Article  CAS  Google Scholar 

  12. Rauscher, M., Dietrich, S. & Koplik, J. Shear flow pumping in open micro- and nanofluidic systems. Phys. Rev. Lett. 98, 224504 (2007).

    Article  Google Scholar 

  13. Bonn, D., Eggers, J., Indekeu, J., Meunier, J. & Rolley, E. Wetting and spreading. Rev. Mod. Phys. 81, 739–805 (2009).

    Article  CAS  Google Scholar 

  14. Snoejier, J. H., Ziegler, J., Andreotti, B., Fermigier, M. & Eggers, J. Thick films of viscous fluid coating a plate withdrawn from a liquid reservoir. Phys. Rev. Lett. 100, 244502 (2008).

    Article  Google Scholar 

  15. Sebilleu, J., Limat, L. & Eggers, J. Flow separation from a stationary meniscus. J. Fluid Mech. 633, 137 (2009).

    Article  Google Scholar 

  16. Succi, S. The Lattice Boltzmann Equation for Fluid Dynamics and Beyond (Oxford Univ. Press, 2001).

    Google Scholar 

  17. Eggers, J. Hydrodynamic theory of forced dewetting. Phys. Rev. Lett. 93, 094502 (2004).

    Article  Google Scholar 

  18. Aarts, D. G. A. L., Schmidt, M. & Lekkerkerker, H. N. W. Direct visual observation of thermal capillary waves. Science 304, 847–850 (2004).

    Article  CAS  Google Scholar 

  19. Qian, T., Wang, X-P. & Sheng, P. A variational approach to moving contact line hydrodynamics. J. Fluid Mech. 564, 333–360 (2006).

    Article  CAS  Google Scholar 

  20. Chevalier, C., Ben Amar, M., Bonn, D. & Lindner, A. Inertial effects on Saffman–Taylor viscous fingering. J. Fluid Mech. 552, 83–97 (2006).

    Article  Google Scholar 

  21. Duez, C., Ybert, C., Clanet, C. & Bocquet, L. Wetting controls separation of inertial flows from solid surfaces. Phys. Rev. Lett. 104, 084503 (2010).

    Article  Google Scholar 

  22. Ohzono, T., Monobe, H., Shiokawa, K., Fujiwara, M. & Shimizu, Y. Shaping liquid on a micrometre scale using microwrinkles as deformable open channel capillaries. Soft Matter 5, 4658–4664 (2009).

    Article  CAS  Google Scholar 

  23. Cubaud, T. Wetting and lubricating film instabilities in microchannels. Phys. Fluids 21, 091103 (2009).

    Article  Google Scholar 

Download references

Acknowledgements

We are grateful to the authors of ref. 6 for kindly providing their experimental data and for useful discussions, to G. McHale for providing superhydrophobic cards and to A. Cabot and J. Yeomans for useful discussions. We acknowledge financial support from Dirección General de Investigación (Spain) under projects FIS 2009-12964-C05-02 and FIS 2008-04386, and DURSI projects SGR2009-00014 and SGR2009-634. R.L-A. acknowledges support from Conacyt (Mexico), Fundación Carolina (Spain) and EPSRC grant EP/D050952/1. The computational work herein was carried out in the MareNostrum Supercomputer at Barcelona Supercomputing Center.

Author information

Authors and Affiliations

  1. Departament d’Estructura i Constituents de la Matèria, Universitat de Barcelona, Avinguda Diagonal 647, E-08028 Barcelona, Spain

    R. Ledesma-Aguilar, R. Nistal & A. Hernández-Machado

  2. The Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road, Oxford OX1 3NP, UK

    R. Ledesma-Aguilar

  3. Departament de Física Fonamental, Universitat de Barcelona, Avinguda Diagonal 647, E-08028 Barcelona, Spain

    I. Pagonabarraga

Authors
  1. R. Ledesma-Aguilar
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. R. Nistal
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. A. Hernández-Machado
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. I. Pagonabarraga
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

R.L-A., A.H-M. and I.P. planned the research, developed the theoretical model and experimental design, carried out data analysis and interpretation, and wrote the manuscript. R.L-A. carried out the numerical simulations. R.N. carried out the microfluidic experiments, and processed and analysed the experimental data.

Corresponding author

Correspondence to R. Ledesma-Aguilar.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary Information (PDF 528 kb)

Supplementary Movie

Supplementary Movie (AVI 7131 kb)

Supplementary Movie

Supplementary Movie (AVI 3781 kb)

Supplementary Movie

Supplementary Movie (AVI 5247 kb)

Supplementary Movie

Supplementary Movie (MPG 200 kb)

Supplementary Movie

Supplementary Movie (MPG 198 kb)

Rights and permissions

Reprints and permissions

About this article

Cite this article

Ledesma-Aguilar, R., Nistal, R., Hernández-Machado, A. et al. Controlled drop emission by wetting properties in driven liquid filaments. Nature Mater 10, 367–371 (2011). https://doi.org/10.1038/nmat2998

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nmat2998

This article is cited by

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing