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.

  • Article
  • Published:

Anisotropic particle synthesis in dielectrophoretically controlled microdroplet reactors

Abstract

The miniaturization of chemical and biological processes in microfluidic devices and bioarrays is a major technological achievement. Microchips performing multiphase material synthesis operations could be a future step in this trend of miniaturizing technology. Here we show how electrically controlled chips can be used for the synthesis and manipulation of new types of particles with advanced structure. The method is based on a technique that allows freely suspended droplets and particles to be entrapped and transported using electric fields. The fields that hold and guide the droplets and particles are applied through arrays of electrodes submerged in the oil. Each of the microdroplets suspended on the surface of fluorinated liquid serves as a microscopic reactor, where the particles are formed by solidification of the carrier droplets. Controlled on-chip assembly, drying, encapsulation and polymerization were used to make anisotropic 'eyeball' and striped particles, polymer capsules and semiconducting microbeads.

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

Access options

Rent or buy this article

Prices vary by article type

from$1.95

to$39.95

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

Figure 1: Droplet and particle entrapment on chips with addressable electrode arrays.
Figure 2: Anisotropic 'eyeball' supraparticle assembly by the evaporation of droplets from binary suspension.
Figure 3: Formation of 'striped' multilayer particles by the evaporation of droplets from ternary particle mixtures.
Figure 4: Polymer-based and polymer-encapsulated particles.

Similar content being viewed by others

References

  1. Velev, O. D., Furusawa, K. & Nagayama, K. Assembly of latex particles by using emulsion droplets as templates. 1. Microstructured hollow spheres. Langmuir 12, 2374–2384 (1996).

    Article  CAS  Google Scholar 

  2. Dinsmore, A. D. et al. Colloidosomes: Selectively permeable capsules composed of colloidal particles. Science 298, 1006–1009 (2002).

    Article  CAS  Google Scholar 

  3. Velev, O. D. & Nagayama, K. Assembly of latex particles by using emulsion droplets 3. Reverse (water in oil) systems. Langmuir 13, 1856–1859 (1997).

    Article  CAS  Google Scholar 

  4. Boker, A. et al. Hierarchical nanoparticle assemblies formed by decorating breath figures. Nature Mater. 3, 302–306 (2004).

    Article  Google Scholar 

  5. Wang, D. Y. & Möhwald, H. Template-directed colloidal self-assembly—the route to 'top-down' nanochemical engineering. J. Mater. Chem. 14, 459–468 (2004).

    Article  CAS  Google Scholar 

  6. Noble, P., Cayre, O. J., Alargova, R. G., Velev, O. D. & Paunov, V. N. Fabrication of 'Hairy' colloidosomes with shells of polymeric microrods. J. Am. Chem. Soc. 126, 8092–8093 (2004).

    Article  CAS  Google Scholar 

  7. Velev, O. D., Lenhoff, A. M. & Kaler, E. W. A class of microstructured particles through colloidal crystallization. Science 287, 2240–2243 (2000).

    Article  CAS  Google Scholar 

  8. Manoharan, V. N., Elsesser, M. T. & Pine, D. J. Dense packing and symmetry in small clusters of microspheres. Science 301, 483–487 (2003).

    Article  CAS  Google Scholar 

  9. Yi, G. R. et al. Generation of uniform colloidal assemblies in soft microfluidic devices. Adv. Mater. 15, 1300–1304 (2003).

    Article  CAS  Google Scholar 

  10. Moon, J. H., Yi, G. R., Yang, S. M., Pine, D. J. & Bin Park, S. Electrospray-assisted fabrication of uniform photonic balls. Adv. Mater. 16, 605–609 (2004).

    Article  CAS  Google Scholar 

  11. Manoharan, V. N. & Pine, D. J. Building materials by packing spheres. Mater. Res. Soc. Bull. 29, 91–95 (2004).

    Article  CAS  Google Scholar 

  12. Song, H., Rice, J. D. & Ismagilov, R. F. A microfluidic system for controlling reaction networks in time. Angew. Chem. Int. Edn 42, 768–772 (2003).

    Article  CAS  Google Scholar 

  13. Shestopalov, I., Tice, J. D. & Ismagilov, R. F. Multi-step synthesis of nanoparticles performed on millisecond time scale in a microfluidic droplet-based system. Lab Chip 4, 316–321 (2004).

    Article  CAS  Google Scholar 

  14. Pollack, M. G., Fair, R. B. & Shenderov, A. D. Electrowetting-based actuation of liquid droplets for microfluidic applications. Appl. Phys. Lett. 77, 1725–1726 (2000).

    Article  CAS  Google Scholar 

  15. Jones, T. B., Gunji, M., Washizu, M. & Feldman, M. J. Dielectrophoretic liquid actuation and nanodroplet formation. J. Appl. Phys. 89, 1441–1448 (2001).

    Article  CAS  Google Scholar 

  16. Jones, T. B. Liquid dielectrophoresis on the microscale. J. Electrostat. 51, 290–299 (2001).

    Article  Google Scholar 

  17. Pollack, M. G., Shenderov, A. D. & Fair, R. B. Electrowetting- based actuation of droplets for integrated microfluidics. Lab Chip 2, 96–101 (2002).

    Article  CAS  Google Scholar 

  18. Cho, S. K., Moon, H. J. & Kim, C. J. Creating, transporting, cutting, and merging liquid droplets by electrowetting-based actuation for digital microfluidic circuits. J. Microelectromech. Syst. 12, 70–80 (2003).

    Article  Google Scholar 

  19. Velev, O. D., Prevo, B. G. & Bhatt, K. H. On-chip manipulation of freely suspended droplets. Nature 426, 515–516 (2003).

    Article  CAS  Google Scholar 

  20. Schwartz, J. A., Vykoukal, J. V. & Gascoyne, P. R. C. Droplet-based chemistry on a programmable micro-chip. Lab Chip 4, 11–17 (2004).

    Article  CAS  Google Scholar 

  21. Jones, T. B. Electromechanics of Particles (Cambridge Univ. Press, Cambridge, 1995).

    Book  Google Scholar 

  22. Fuhr, G. et al. Radio-frequency microtools for particle and live cell manipulation. Naturwissencschaften 81, 528–535 (1994).

    Article  CAS  Google Scholar 

  23. Hughes, M. P. Nanoelectromechanics in Engineering and Biology (CRC, London, 2003).

    Google Scholar 

  24. Slot, J. W. & Geuze, H. J. A new method of preparing gold probes for multiple-labeling cyto-chemistry. Eur. J. Cell Biol. 38, 87–93 (1985).

    CAS  Google Scholar 

Download references

Acknowledgements

We thank David Woolard for assistance with some of the experiments. This study was supported by the National Science Foundation (USA; CTS-0238636 and CTS-0403462).

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Orlin D. Velev.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Millman, J., Bhatt, K., Prevo, B. et al. Anisotropic particle synthesis in dielectrophoretically controlled microdroplet reactors. Nature Mater 4, 98–102 (2005). https://doi.org/10.1038/nmat1270

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nmat1270

This article is cited by

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