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Living systems are intrinsically nonequilibrium: They use metabolically derived chemical energy to power their emergent dynamics and self-organization. A crucial driver of these dynamics is the cellular cytoskeleton, a defining example of an active material where the energy injected by molecular motors cascades across length scales, allowing the material to break the constraints of thermodynamic equilibrium and display emergent nonequilibrium dynamics only possible due to the constant influx of energy. Notwithstanding recent experimental advances in the use of local probes to quantify entropy production and the breaking of detailed balance, little is known about the energetics of active materials or how energy propagates from the molecular to emergent length scales. Here, we use a recently developed picowatt calorimeter to experimentally measure the energetics of an active microtubule gel that displays emergent large-scale flows. We find that only approximately one-billionth of the system’s total energy consumption contributes to these emergent flows. We develop a chemical kinetics model that quantitatively captures how the system’s total thermal dissipation varies with ATP and microtubule concentrations but that breaks down at high motor concentration, signaling an interference between motors. Finally, we estimate how energy losses accumulate across scales. Taken together, these results highlight energetic efficiency as a key consideration for the engineering of active materials and are a powerful step toward developing a nonequilibrium thermodynamics of living systems.
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Organization and Self-Assembly Away from Equilibrium: Toward Thermodynamic Design Principles
Studies of biological systems and materials, together with recent experimental and theoretical advances in colloidal and nanoscale materials, have shown how nonequilibrium forcing can be used to modulate organization in many novel ways. In this review, we focus on how an accounting of energy dissipation, using the tools of stochastic thermodynamics, can constrain and provide intuition for the correlations and configurations that emerge in a nonequilibrium process. We anticipate that the frameworks reviewed here can provide a starting point to address some of the unique phenomenology seen in biophysical systems and potentially replicate them in synthetic materials.
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- PAR ID:
- 10311992
- Date Published:
- Journal Name:
- Annual Review of Condensed Matter Physics
- Volume:
- 12
- Issue:
- 1
- ISSN:
- 1947-5454
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1146/annurev-conmatphys-031218-013309
