A micrometre-sized heat engine operating between bacterial reservoirs
By S. Krishnamurthy, Subho Ghosh, D. Chatterji, R. Ganapathy, A. Sood. Nature Physics, 2016
214 citations recorded by the source corpus.
A colloidal particle connected to suspensions of motile bacteria forms a model system for studying microscale engines in contact with active baths. The engine outperforms its passive counterparts due to the presence of non-Gaussian fluctuations. 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.
Subfields: Computational Mechanics, Physical and Theoretical Chemistry, Statistical and Nonlinear Physics
View Paper: https://www.semanticscholar.org/paper/7336b9743cf9eec50f1790c5af0673a464ffbc19
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Citations in the corpus
- Experiments in Stochastic Thermodynamics: Short History and Perspectives (2017, background): “This simple example shows that fluctuations of the injected and dissipated power may be relevant not only in microscopic but also in macroscopic systems such as hydrodynamic flows [26], granular media [27–30], mechanical systems [31], and more recently on self-propelling particles [32,33].”
- Irreversibility in Active Matter Systems: Fluctuation Theorem and Mutual Information (2018, background): “Further potential applications of our results include the exploration of features in ∆Σ and ∆I which are characteristic for the different phases of active matter [20], the analysis of linear response under small external perturbations and its potential for probing properties of the active bath [126]”