Fluctuations and Rheology in Active Bacterial Suspensions

We probe non-equilibrium properties of an active bacterial bath through measurements of correlations of passive tracer particles and the response function of a driven, optically trapped tracer. These measurements demonstrate violation of the fluctuation-dissipation theorem and enable us to extract t...

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Bibliographic Details
Published inarXiv.org
Main Authors Chen, D T N, Lau, A W C, Hough, L A, Islam, M F, Goulian, M, Lubensky, T C, Yodh, A G
Format Paper Journal Article
LanguageEnglish
Published Ithaca Cornell University Library, arXiv.org 10.09.2007
Subjects
Bacteria
Correlation analysis
Physics - Soft Condensed Matter
Response functions
Rheological properties
Rheology
Stress concentration
Tracer particles
Variation
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Summary:We probe non-equilibrium properties of an active bacterial bath through measurements of correlations of passive tracer particles and the response function of a driven, optically trapped tracer. These measurements demonstrate violation of the fluctuation-dissipation theorem and enable us to extract the power spectrum of the active stress fluctuations. In some cases, we observe \(1/\sqrt{\omega}\) scaling in the noise spectrum which we show can be derived from a theoretical model incorporating coupled stress, orientation, and concentration fluctuations of the bacteria.
ISSN:2331-8422
DOI:10.48550/arxiv.0709.1465