Nanometer scale resolution, multi-channel separation of spherical particles in a rocking ratchet with increasing barrier heights

Abstract

We present a nanoparticle size-separation device based on a nanofluidic rocking Brownian motor. It features a ratchet-shaped electrostatic particle potential with increasing barrier heights along the particle transport direction. The sharp drop of the particle current with barrier height is exploited to separate a particle suspension into multiple sub-populations. By solving the Fokker--Planck equation, we show that the physics of the separation mechanism is governed by the energy landscape under forward tilt of the ratchet. For a given device geometry and sorting duration, the applied force is thus the only tunable parameter to increase the separation resolution. For the experimental conditions of 3.5 V applied voltage and 20 s sorting, we predict a separation resolution of $\sim 2$ nm, supported by experimental data for separating spherical gold particles of nominal 80 and 100 nm diameters.

arXiv comment5 pages, 4 figures plus supplemental material

References in corpus (7)

• Artificial Brownian motors: Controlling transport on the nanoscale
• The Charge of Glass and Silica Surfaces
• Advanced scanning probe lithography
• Nanofluidic Rocking Brownian Motors
• Experimental observation of current reversal in a rocking Brownian motor
• Deterministic Deposition of Nanoparticles with Sub-10 nm Resolution
• In-situ contrast calibration to determine the height of individual diffusing nanoparticles in a tunable confinement

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