Transport and Energetics of Bacterial Rectification

TL;DR

This study combines experiments, simulations, and theory to analyze bacterial rectification through asymmetric structures, revealing optimal geometries and energetic principles of active matter transport.

Contribution

It introduces a parameter-free microscopic model that explains bacterial rectification and predicts optimal geometries for maximum efficiency.

Findings

Quantitative agreement between model, experiments, and simulations.

Identification of optimal funnel geometries for rectification.

Establishment of a relationship between time irreversibility and extractable work.

Abstract

Randomly moving active particles can be herded into directed motion by asymmetric geometric structures. Although such a rectification process has been extensively studied due to its fundamental, biological, and technological relevance, a comprehensive understanding of active matter rectification based on single particle dynamics remains elusive. Here, by combining experiments, simulations, and theory, we study the directed transport and energetics of swimming bacteria navigating through funnel-shaped obstacles -- a paradigmatic model of rectification of living active matter. We develop a microscopic parameter-free model for bacterial rectification, which quantitatively explains experimental and numerical observations and predicts the optimal geometry for the maximum rectification efficiency. Furthermore, we quantify the degree of time irreversibility and measure the extractable work associated with bacterial rectification. Our study provides quantitative solutions to long-standing questions on bacterial rectification and establishes a generic relationship between time irreversibility, particle fluxes, and extractable work, shedding light on the energetics of non-equilibrium rectification processes in living systems.