Concentration Dependent Diffusion of Self-Propelled Rods

Arshad Kudrolli
Phys. Rev. Lett. 104, 088001 – Published 23 February 2010

Abstract

We examine the persistent random motion of self-propelled rods (SPR) as a function of the area fraction ϕ and study the effect of steric interactions on their diffusion properties. SPR of length l and width w are fabricated with a spherocylindrical head attached to a beaded chain tail, and show directed motion on a vibrated substrate. The mean square displacement (MSD) on the substrate grows linearly with time t for ϕ<w/l, before displaying caging as ϕ is increased, and stops well below the close packing limit. Direction autocorrelations decay progressively slower with ϕ. We describe the observed decrease of SPR propagation speed c(ϕ) with a tube model. Further, MSD parallel to the SPR collapse with τ=l/c(ϕ) and scales as (lt/τ)2, and MSD in the perpendicular direction grows progressively slower than l2t/τ with ϕ, consistent with dynamics inside a thinning tube.

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  • Received 28 August 2009

DOI:https://doi.org/10.1103/PhysRevLett.104.088001

©2010 American Physical Society

Authors & Affiliations

Arshad Kudrolli

  • Department of Physics, Clark University, Worcester, Massachusetts 01610, USA

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Issue

Vol. 104, Iss. 8 — 26 February 2010

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