A micrometre-sized heat engine operating between bacterial reservoirs

Krishnamurthy, Sudeesh and Ghosh, Subho and Chatterji, Dipankar and Ganapathy, Rajesh and Sood, AK (2016) A micrometre-sized heat engine operating between bacterial reservoirs. In: Nature Physics, 12 (12). 1134+.

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Abstract

Artificial microscale heat engines are prototypical models to explore the mechanisms of energy transduction in a fluctuation-dominated regime(1,2). The heat engines realized so far on this scale have operated between thermal reservoirs, such that stochastic thermodynamics provides a precise framework for quantifying their performance(3-6). It remains to be seen whether these concepts readily carry over to situations where the reservoirs are out of equilibrium(7), a scenario of particular importance to the functioning of synthetic(8,9) and biological(10) microscale engines and motors. Here, we experimentally realize a micrometre-sized active Stirling engine by periodically cycling a colloidal particle in a time-varying optical potential across bacterial baths characterized by different degrees of activity. We find that the displacement statistics of the trapped particle becomes increasingly non-Gaussian with activity and contributes substantially to the overall power output and the effciency. Remarkably, even for engines with the same energy input, differences in non-Gaussianity of reservoir noise results in distinct performances. At high activities, the effciency of our engines surpasses the equilibrium saturation limit of Stirling effciency, the maximum effciency of a Stirling engine where the ratio of cold to hot reservoir temperatures is vanishingly small. Our experiments provide fundamental insights into the functioning of micromotors and engines operating out of equilibrium.

Item Type:	Journal Article
Publication:	Nature Physics
Publisher:	NATURE PUBLISHING GROUP, MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND
Additional Information:	Copy right for this article belongs to the NATURE PUBLISHING GROUP, MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit Division of Physical & Mathematical Sciences > Physics
Date Deposited:	04 Jan 2017 05:30
Last Modified:	04 Jan 2017 05:30
URI:	http://eprints.iisc.ac.in/id/eprint/55857

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