A Landau-Squire Nanojet

ORAL

Abstract

Fluid jets are found in nature at all length scales -- microscopic to cosmological. Here we report on what may be the smallest liquid jet ever observed: an electroosmotically driven flow from a single glass nanopore about 75 nm in radius with a maximum flow rate of about 30 pL/s. A novel anemometry technique allows us to map out the vorticity and velocity fields which show excellent agreement with the classical Landau-Squire solution of the Navier Stokes equations for a point jet. We observe a phenomenon that we call flow rectification: an asymmetry in the flow rate with respect to voltage reversal. Such a nanojet could potentially find applications in gene delivery, nano patterning, and as a diode in microfluidic circuits.

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Authors

  • Sandip Ghosal

    Dept. of Mech. Eng. \& (by courtesy) Eng. Sci. Appl. Math., Northwestern University, USA, Department of Mechanical Engineering and (by courtesy) Engineering Science \& Applied Mathematics, Northwestern University

  • Nadanai Laohakunakorn

    Dept. of Physics, Cambridge University, UK

  • Benjamin Gollnick

    Centro Nacional de Biotecnologia, Spain

  • Fernando Moreno-Herrero

    Centro Nacional de Biotecnologia, Spain

  • Dirk G.A.L. Aarts

    Dept. of Chemistry, Oxford University, UK

  • Roel P.A. Dullens

    Dept. of Chemistry, Oxford University, UK

  • Ulrich F. Keyser

    Dept. of Physics, Cambridge University, UK