Author: Krishnamurthy, S.; Ghosh, S.; Chatterji, D.; Ganapathy, R.; Sood, A.K.
Description: Artificial microscale heat engines are prototypical models to explore the mechanisms of energy transduction in a fluctuation-dominated regime1,2. 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 performance3,4,5,6. It remains to be seen whether these concepts readily carry over to situations where the reservoirs are out of equilibrium7, a scenario of particular importance to the functioning of synthetic8,9 and biological10 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 efficiency. Remarkably, even for engines with the same energy input, differences in non-Gaussianity of reservoir noise results in distinct performances. At high activities, the efficiency of our engines surpasses the equilibrium saturation limit of Stirling efficiency, the maximum efficiency 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.
Subject Headings: Heat engine; Bacterial reservoirs; Micrometre
Keywords: A micrometre-sized heat engine operating between bacterial reservoirs
Publication year: 2016
Journal or book title: Nature Physics
Volume: 12
Issue: 12
Pages: 1134-1138
Find the full text : https://www.nature.com/articles/nphys3870
Find more like this one (cited by): https://scholar.google.com/scholar?cites=17008665446969087550&as_sdt=1000005&sciodt=0,16&hl=en
Type: Journal Article
Serial number: 2526