Active elastic dimers: self-propulsion and current reversal on a featureless track

TL;DR

This paper introduces a Brownian inchworm model for a self-propelled elastic dimer that explains propulsion and current reversal mechanisms without external potential, unifying various biological and physical systems.

Contribution

It presents an analytical model linking key nonequilibrium features and predicts current reversals, validated by simulations, applicable to diverse biological and physical systems.

Findings

Analytical results match numerical simulations.

Current reversals observed in the model.

Unifies propulsion mechanisms across systems.

Abstract

We present a Brownian inchworm model of a self-propelled elastic dimer in the absence of an external potential. Nonequilibrium noise together with a stretch-dependent damping form the propulsion mechanism. Our model connects three key nonequilibrium features -- position-velocity correlations, a nonzero mean internal force, and a drift velocity. Our analytical results, including striking current reversals, compare very well with numerical simulations. The model unifies the propulsion mechanisms of DNA helicases, polar rods on a vibrated surface, crawling keratocytes and Myosin VI. We suggest experimental realizations and tests of the model.