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.
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References
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).
Dinsmore, A. D. et al. Colloidosomes: Selectively permeable capsules composed of colloidal particles. Science 298, 1006–1009 (2002).
Velev, O. D. & Nagayama, K. Assembly of latex particles by using emulsion droplets 3. Reverse (water in oil) systems. Langmuir 13, 1856–1859 (1997).
Boker, A. et al. Hierarchical nanoparticle assemblies formed by decorating breath figures. Nature Mater. 3, 302–306 (2004).
Wang, D. Y. & Möhwald, H. Template-directed colloidal self-assembly—the route to 'top-down' nanochemical engineering. J. Mater. Chem. 14, 459–468 (2004).
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).
Velev, O. D., Lenhoff, A. M. & Kaler, E. W. A class of microstructured particles through colloidal crystallization. Science 287, 2240–2243 (2000).
Manoharan, V. N., Elsesser, M. T. & Pine, D. J. Dense packing and symmetry in small clusters of microspheres. Science 301, 483–487 (2003).
Yi, G. R. et al. Generation of uniform colloidal assemblies in soft microfluidic devices. Adv. Mater. 15, 1300–1304 (2003).
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).
Manoharan, V. N. & Pine, D. J. Building materials by packing spheres. Mater. Res. Soc. Bull. 29, 91–95 (2004).
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).
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).
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).
Jones, T. B., Gunji, M., Washizu, M. & Feldman, M. J. Dielectrophoretic liquid actuation and nanodroplet formation. J. Appl. Phys. 89, 1441–1448 (2001).
Jones, T. B. Liquid dielectrophoresis on the microscale. J. Electrostat. 51, 290–299 (2001).
Pollack, M. G., Shenderov, A. D. & Fair, R. B. Electrowetting- based actuation of droplets for integrated microfluidics. Lab Chip 2, 96–101 (2002).
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).
Velev, O. D., Prevo, B. G. & Bhatt, K. H. On-chip manipulation of freely suspended droplets. Nature 426, 515–516 (2003).
Schwartz, J. A., Vykoukal, J. V. & Gascoyne, P. R. C. Droplet-based chemistry on a programmable micro-chip. Lab Chip 4, 11–17 (2004).
Jones, T. B. Electromechanics of Particles (Cambridge Univ. Press, Cambridge, 1995).
Fuhr, G. et al. Radio-frequency microtools for particle and live cell manipulation. Naturwissencschaften 81, 528–535 (1994).
Hughes, M. P. Nanoelectromechanics in Engineering and Biology (CRC, London, 2003).
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).
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).
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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
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DOI: https://doi.org/10.1038/nmat1270
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