Thursday, October 17, 2013

A Landau-Squire nanojet

Nadanai Laohakunakorn , Benjamin Gollnick , Fernando Moreno-Herrero , Dirk Aarts , Roel P.A. Dullens , Sandip Ghosal , and Ulrich F Keyser
Fluid jets are found in nature at all length scales – microscopic to cosmological. Here we report on an electroosmotically driven jet from a single glass nanopore about 75 nm in radius with a maximum flow rate ~ 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 micro manipulation, nano patterning, and as a diode in microfluidic circuits.
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