Experimental observation of current reversal in a rocking Brownian motor

Abstract

A reversal of the particle current in rocking Brownian motors was predicted more than 20 years ago; however, an experimental verification and a deeper insight into the underlying mechanisms remained elusive. Here, we investigate the high frequency behaviour of a rocking Brownian motor for charged nanoparticles based on electrostatic interactions in a 3D shaped nanofluidic slit and electro-osmotic forcing of the particles. A sub ms temporal and $\approx 10$nm spatial resolution of the 60 nm gold spheres allows us to measure the time-resolved and frequency dependent evolution of the particle probability density in-situ. At 250 Hz the particle current changes sign, in agreement with a theoretical model based on the time-dependent Fokker-Planck equation. From this fit-parameter free description and its excellent agreement with the observed behaviour, we trace the origin of the current reversal to the asymmetric and increasingly static probability density at high frequencies.

arXiv comment6 pages, 4 figures, SM: 14 pages, 14 figures

References in corpus (11)

• Artificial Brownian motors: Controlling transport on the nanoscale
• Advanced scanning probe lithography
• Nanofluidic Rocking Brownian Motors
• Hydrodynamic and entropic effects on colloidal diffusion in corrugated channels
• Observation of Flux Reversal in a Symmetric Optical Thermal Ratchet
• High efficiency deterministic Josephson Vortex Ratchet
• Experimental Control of Transport and Current Reversals in a Deterministic Optical Rocking Ratchet
• Rectifying fluctuations in an optical lattice
• Vortex motion rectification in Josephson junction arrays with a ratchet potential
• ac-driven Brownian motors: a Fokker-Planck treatment
• In-situ contrast calibration to determine the height of individual diffusing nanoparticles in a tunable confinement

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