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Geometry-induced electrostatic trapping of nanometric objects in a fluid


The ability to trap an object—whether a single atom or a macroscopic entity—affects fields as diverse as quantum optics1, soft condensed-matter physics, biophysics and clinical medicine2. Many sophisticated methodologies have been developed to counter the randomizing effect of Brownian motion in solution3,4,5,6,7,8,9,10, but stable trapping of nanometre-sized objects remains challenging8,9,10. Optical tweezers are widely used traps, but require sufficiently polarizable objects and thus are unable to manipulate small macromolecules. Confinement of single molecules has been achieved using electrokinetic feedback guided by tracking of a fluorescent label, but photophysical constraints limit the trap stiffness and lifetime8. Here we show that a fluidic slit with appropriately tailored topography has a spatially modulated electrostatic potential that can trap and levitate charged objects in solution for up to several hours. We illustrate this principle with gold particles, polymer beads and lipid vesicles with diameters of tens of nanometres, which are all trapped without external intervention and independently of their mass and dielectric function. The stiffness and stability of our electrostatic trap is easily tuned by adjusting the system geometry and the ionic strength of the solution, and it lends itself to integration with other manipulation mechanisms. We anticipate that these features will allow its use for contact-free confinement of single proteins and macromolecules, and the sorting and fractionation of nanometre-sized objects or their assembly into high-density arrays.

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Figure 1: Pictorial overview of the device and experimental set-up.
Figure 2: Transverse and axial confinement of a 100-nm gold particle by pocket nanostructures.
Figure 3: Electrostatic potential in a topographically structured fluidic nanoslit.
Figure 4: Trapping single lipid vesicles.


  1. Chu, S. Cold atoms and quantum control. Nature 416, 206–210 (2002)

    Article  ADS  CAS  Google Scholar 

  2. Grier, D. G. A revolution in optical manipulation. Nature 424, 810–816 (2003)

    Article  ADS  CAS  Google Scholar 

  3. Ashkin, A. Acceleration and trapping of particles by radiation pressure. Phys. Rev. Lett. 24, 156–159 (1970)

    Article  ADS  CAS  Google Scholar 

  4. Gosse, C. & Croquette, V. Magnetic tweezers: micromanipulation and force measurement at the molecular level. Biophys. J. 82, 3314–3329 (2002)

    Article  CAS  Google Scholar 

  5. Chiou, P. Y., Ohta, A. T. & Wu, M. C. Massively parallel manipulation of single cells and microparticles using optical images. Nature 436, 370–372 (2005)

    Article  ADS  CAS  Google Scholar 

  6. Soyka, F., Zvyagolskaya, O., Hertlein, C., Helden, L. & Bechinger, C. Critical Casimir forces in colloidal suspensions on chemically patterned surfaces. Phys. Rev. Lett. 101, 208301 (2008)

    Article  ADS  Google Scholar 

  7. Cordovez, B., Psaltis, D. & Erickson, D. Electroactive micro and nanowells for optofluidic storage. Opt. Express 17, 21134–21148 (2009)

    Article  ADS  CAS  Google Scholar 

  8. Cohen, A. E. & Moerner, W. E. Suppressing Brownian motion of individual biomolecules in solution. Proc. Natl Acad. Sci. USA 103, 4362–4365 (2006)

    Article  ADS  CAS  Google Scholar 

  9. Yang, A. H. J. et al. Optical manipulation of nanoparticles and biomolecules in sub-wavelength slot waveguides. Nature 457, 71–75 (2009)

    Article  ADS  CAS  Google Scholar 

  10. Juan, M. L., Gordon, R., Pang, Y. J., Eftekhari, F. & Quidant, R. Self-induced back-action optical trapping of dielectric nanoparticles. Nature Phys. 5, 915–919 (2009)

    Article  ADS  CAS  Google Scholar 

  11. Jo, K. et al. A single-molecule barcoding system using nanoslits for DNA analysis. Proc. Natl Acad. Sci. USA 104, 2673–2678 (2007)

    Article  ADS  CAS  Google Scholar 

  12. Reisner, W., Larsen, N. B., Flyvbjerg, H., Tegenfeldt, J. O. & Kristensen, A. Directed self-organization of single DNA molecules in a nanoslit via embedded nanopit arrays. Proc. Natl Acad. Sci. USA 106, 79–84 (2009)

    Article  ADS  CAS  Google Scholar 

  13. Kukura, P. et al. High-speed nanoscopic tracking of the position and orientation of a single virus. Nature Methods 6, 923–927 (2009)

    Article  CAS  Google Scholar 

  14. Jacobsen, V., Klotzsch, E. & Sandoghdar, V. in Nano Biophotonics (eds Masuhara, H., Kawata, S. & Tokunaga, F.) 143–160 (Elsevier, 2007)

    Google Scholar 

  15. Eichmann, S. L., Anekal, S. G. & Bevan, M. A. Electrostatically confined nanoparticle interactions and dynamics. Langmuir 24, 714–721 (2008)

    Article  CAS  Google Scholar 

  16. Hansen, P. M., Bhatia, V. K., Harrit, N. & Oddershede, L. Expanding the optical trapping range of gold nanoparticles. Nano Lett. 5, 1937–1942 (2005)

    Article  ADS  CAS  Google Scholar 

  17. Israelachvili, J. Intermolecular and Surface Forces (Academic, 1992)

    Google Scholar 

  18. Kramers, H. A. Brownian motion in a field of force and the diffusion model of chemical reactions. Physica 7, 284–304 (1940)

    Article  ADS  MathSciNet  CAS  Google Scholar 

  19. Kaplan, P. D., Faucheux, L. P. & Libchaber, A. J. Direct observation of the entropic potential in a binary suspension. Phys. Rev. Lett. 73, 2793–2796 (1994)

    Article  ADS  CAS  Google Scholar 

  20. Tessier, F. & Slater, G. W. Effective Debye length in closed nanoscopic systems: a competition between two length scales. Electrophoresis 27, 686–693 (2006)

    Article  CAS  Google Scholar 

  21. Dubois, M. et al. Osmotic pressure and salt exclusion in electrostatically swollen lamellar phases. J. Chem. Phys. 96, 2278–2286 (1992)

    Article  ADS  CAS  Google Scholar 

  22. Maxwell, J. C. A Treatise on Electricity and Magnetism Vol. 1, 116 (Dover, 1954)

    Google Scholar 

  23. Adamczyk, Z. & Warszynski, P. Role of electrostatic interactions in particle adsorption. Adv. Colloid Interface Sci. 63, 41–149 (1996)

    Article  CAS  Google Scholar 

  24. Krishnan, M., Monch, I. & Schwille, P. Spontaneous stretching of DNA in a two-dimensional nanoslit. Nano Lett. 7, 1270–1275 (2007)

    Article  ADS  CAS  Google Scholar 

  25. Krishnan, M., Petrasek, Z., Moench, I. & Schwille, P. Electrostatic self-assembly of charged colloids and macromolecules in a fluidic nanoslit. Small 4, 1900–1906 (2008)

    Article  CAS  Google Scholar 

  26. Polin, M., Grier, D. G. & Han, Y. Colloidal electrostatic interactions near a conducting surface. Phys. Rev. E 76, 041046 (2007)

    Article  Google Scholar 

  27. Lu, H. P., Xun, L. Y. & Xie, X. S. Single-molecule enzymatic dynamics. Science 282, 1877–1882 (1998)

    Article  ADS  CAS  Google Scholar 

  28. Stebe, K. J., Lewandowski, E. & Ghosh, M. Oriented assembly of metamaterials. Science 325, 159–160 (2009)

    Article  CAS  Google Scholar 

  29. Jamshidi, A. et al. Dynamic manipulation and separation of individual semiconducting and metallic nanowires. Nature Photon. 2, 85–89 (2008)

    Article  ADS  CAS  Google Scholar 

  30. MacDonald, M. P., Spalding, G. C. & Dholakia, K. Microfluidic sorting in an optical lattice. Nature 426, 421–424 (2003)

    Article  ADS  CAS  Google Scholar 

  31. Behrens, S. H. & Grier, D. G. The charge of glass and silica surfaces. J. Chem. Phys. 115, 6716–6721 (2001)

    Article  ADS  CAS  Google Scholar 

  32. Loeb, A. L., Wiersma, P. H. & Overbeek, J. T. G. The Electrical Double Layer Around a Spherical Colloidal Particle (MIT Press, 1961)

    Google Scholar 

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We thank A. Alt for expert assistance in electron-beam lithography and the staff of the Center for Micro- and Nanoscience (FIRST), ETH Zurich, for clean-room support; H. Ewers for assistance in producing lipid vesicles; M. Celebrano and A. Renn for experimental input; M. Agio for discussions; and E. Petrov and R. Klemm for reading the manuscript. M.K. acknowledges a Marie Curie Intra-European Fellowship for Career Development of the European Commission, and greatly appreciates the support of B. Eichler, I. Mönch and P. Schwille in the early stages of the project.

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Authors and Affiliations



M.K. conceived the research, designed the experiments and performed the theoretical analysis. N.M. and M.K. performed the experiments and analysed the data. P.K. and V.S. provided expertise on iSCAT. M.K. and V.S. wrote the manuscript.

Corresponding author

Correspondence to Madhavi Krishnan.

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The authors declare no competing financial interests.

Supplementary information

Supplementary Information

This file contains Supplementary Figure 1 with a legend and legends for Supplementary Movies 1-7. (PDF 129 kb)

Supplementary Movie 1

This movie shows guided diffusion of a gold particle along a groove – see Supplementary Information file for full legend. (AVI 716 kb)

Supplementary Movie 2

The movie shows gold particles trapped by pocket nanostructures – see Supplementary Information file for full legend. (AVI 129 kb)

Supplementary Movie 3

This movie shows gold particles trapped by pocket nanostructures – see Supplementary Information file for full legend. (AVI 572 kb)

Supplementary Movie 4

This movie shows Stable trapping of a single gold particle – see Supplementary Information file for full legend. (AVI 704 kb)

Supplementary Movie 5

This movie shows stiff trapping of single gold particles – see Supplementary Information file for full legend. (AVI 129 kb)

Supplementary Movie 6

This movie shows stable trapping of single lipid vesicles – see Supplementary Information file for full legend. (AVI 185 kb)

Supplementary Movie 7

This movie shows trapping single polystyrene particles along arbitrary contours – see Supplementary Information file for full legend. (AVI 288 kb)

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Krishnan, M., Mojarad, N., Kukura, P. et al. Geometry-induced electrostatic trapping of nanometric objects in a fluid. Nature 467, 692–695 (2010).

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