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Updated: May 28, 2026

Patterning of Microorganisms and Microparticles through Sequential Capillarity-assisted Assembly
Published on: November 4, 2021
Effective interactions between colloidal particles suspended in a bath of swimming cells
L Angelani1, C Maggi, M L Bernardini
1CNR-IPCF, UOS Roma c/o Dip. di Fisica Università "Sapienza", Italy.
Abstract:
The dynamics of passive colloidal tracers in a bath of self-propelled particles is receiving a lot of attention in the context of nonequilibrium statistical mechanics. Here we demonstrate that active baths are also capable of mediating effective interactions between suspended bodies. In particular we observe that a bath of swimming bacteria gives rise to a short range attraction similar to depletion forces in equilibrium colloidal suspensions. Using numerical simulations and experiments we show how the features of this interaction arise from the combination of nonequilibrium dynamics (peculiar of bacterial baths) and excluded volume effects.
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A solution is a homogeneous mixture composed of a solvent, the major component, and a solute, the minor component. The physical state of a solution—solid, liquid, or gas—is typically the same as that of the solvent. Solute concentrations are often described with qualitative terms such as dilute (of relatively low concentration) and concentrated (of relatively high concentration).
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