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.
Subscribe to Journal
Get full journal access for 1 year
only $3.90 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
Chu, S. Cold atoms and quantum control. Nature 416, 206–210 (2002)
Grier, D. G. A revolution in optical manipulation. Nature 424, 810–816 (2003)
Ashkin, A. Acceleration and trapping of particles by radiation pressure. Phys. Rev. Lett. 24, 156–159 (1970)
Gosse, C. & Croquette, V. Magnetic tweezers: micromanipulation and force measurement at the molecular level. Biophys. J. 82, 3314–3329 (2002)
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)
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)
Cordovez, B., Psaltis, D. & Erickson, D. Electroactive micro and nanowells for optofluidic storage. Opt. Express 17, 21134–21148 (2009)
Cohen, A. E. & Moerner, W. E. Suppressing Brownian motion of individual biomolecules in solution. Proc. Natl Acad. Sci. USA 103, 4362–4365 (2006)
Yang, A. H. J. et al. Optical manipulation of nanoparticles and biomolecules in sub-wavelength slot waveguides. Nature 457, 71–75 (2009)
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)
Jo, K. et al. A single-molecule barcoding system using nanoslits for DNA analysis. Proc. Natl Acad. Sci. USA 104, 2673–2678 (2007)
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)
Kukura, P. et al. High-speed nanoscopic tracking of the position and orientation of a single virus. Nature Methods 6, 923–927 (2009)
Jacobsen, V., Klotzsch, E. & Sandoghdar, V. in Nano Biophotonics (eds Masuhara, H., Kawata, S. & Tokunaga, F.) 143–160 (Elsevier, 2007)
Eichmann, S. L., Anekal, S. G. & Bevan, M. A. Electrostatically confined nanoparticle interactions and dynamics. Langmuir 24, 714–721 (2008)
Hansen, P. M., Bhatia, V. K., Harrit, N. & Oddershede, L. Expanding the optical trapping range of gold nanoparticles. Nano Lett. 5, 1937–1942 (2005)
Israelachvili, J. Intermolecular and Surface Forces (Academic, 1992)
Kramers, H. A. Brownian motion in a field of force and the diffusion model of chemical reactions. Physica 7, 284–304 (1940)
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)
Tessier, F. & Slater, G. W. Effective Debye length in closed nanoscopic systems: a competition between two length scales. Electrophoresis 27, 686–693 (2006)
Dubois, M. et al. Osmotic pressure and salt exclusion in electrostatically swollen lamellar phases. J. Chem. Phys. 96, 2278–2286 (1992)
Maxwell, J. C. A Treatise on Electricity and Magnetism Vol. 1, 116 (Dover, 1954)
Adamczyk, Z. & Warszynski, P. Role of electrostatic interactions in particle adsorption. Adv. Colloid Interface Sci. 63, 41–149 (1996)
Krishnan, M., Monch, I. & Schwille, P. Spontaneous stretching of DNA in a two-dimensional nanoslit. Nano Lett. 7, 1270–1275 (2007)
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)
Polin, M., Grier, D. G. & Han, Y. Colloidal electrostatic interactions near a conducting surface. Phys. Rev. E 76, 041046 (2007)
Lu, H. P., Xun, L. Y. & Xie, X. S. Single-molecule enzymatic dynamics. Science 282, 1877–1882 (1998)
Stebe, K. J., Lewandowski, E. & Ghosh, M. Oriented assembly of metamaterials. Science 325, 159–160 (2009)
Jamshidi, A. et al. Dynamic manipulation and separation of individual semiconducting and metallic nanowires. Nature Photon. 2, 85–89 (2008)
MacDonald, M. P., Spalding, G. C. & Dholakia, K. Microfluidic sorting in an optical lattice. Nature 426, 421–424 (2003)
Behrens, S. H. & Grier, D. G. The charge of glass and silica surfaces. J. Chem. Phys. 115, 6716–6721 (2001)
Loeb, A. L., Wiersma, P. H. & Overbeek, J. T. G. The Electrical Double Layer Around a Spherical Colloidal Particle (MIT Press, 1961)
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.
The authors declare no competing financial interests.
This file contains Supplementary Figure 1 with a legend and legends for Supplementary Movies 1-7. (PDF 129 kb)
This movie shows guided diffusion of a gold particle along a groove – see Supplementary Information file for full legend. (AVI 716 kb)
The movie shows gold particles trapped by pocket nanostructures – see Supplementary Information file for full legend. (AVI 129 kb)
This movie shows gold particles trapped by pocket nanostructures – see Supplementary Information file for full legend. (AVI 572 kb)
This movie shows Stable trapping of a single gold particle – see Supplementary Information file for full legend. (AVI 704 kb)
This movie shows stiff trapping of single gold particles – see Supplementary Information file for full legend. (AVI 129 kb)
This movie shows stable trapping of single lipid vesicles – see Supplementary Information file for full legend. (AVI 185 kb)
This movie shows trapping single polystyrene particles along arbitrary contours – see Supplementary Information file for full legend. (AVI 288 kb)
About this article
Cite this article
Krishnan, M., Mojarad, N., Kukura, P. et al. Geometry-induced electrostatic trapping of nanometric objects in a fluid. Nature 467, 692–695 (2010). https://doi.org/10.1038/nature09404
Microsystems & Nanoengineering (2021)
Nature Materials (2020)
Stand-off trapping and manipulation of sub-10 nm objects and biomolecules using opto-thermo-electrohydrodynamic tweezers
Nature Nanotechnology (2020)
Interferometric scattering microscopy reveals microsecond nanoscopic protein motion on a live cell membrane
Nature Photonics (2019)
Pseudomonas aeruginosa orchestrates twitching motility by sequential control of type IV pili movements
Nature Microbiology (2019)