Sedimentation and Effective Temperature of Active Colloidal Suspensions

Condensed Matter journal club

Sedimentation and Effective Temperature of Active Colloidal Suspensions

  • Event time: 11:30am
  • Event date: 10th February 2012
  • Speaker: Rim Harich (Formerly School of Physics & Astronomy, University of Edinburgh)
  • Location: Room 2511,

Event details


In this Letter, we investigate experimentally the nonequilibrium steady state of an active colloidal suspension under gravity field. The active particles are made of chemically powered colloids, showing self propulsion in the presence of an added fuel, here hydrogen peroxide. The active suspension is studied in a dedicated microfluidic device, made of permeable gel microstructures. Both the microdynamics of individual colloids and the global stationary state of the suspension under gravity are measured with optical microscopy. This yields a direct measurement of the effective temperature of the active system as a function of the particle activity, on the basis of the fluctuation-dissipation relationship. Our work is a first step in the experimental exploration of the out-of-equilibrium properties of active colloidal systems.
PRL vol. 105, article 088304 (2010)
pdf version of paper


Jeremie Palacci, Cecile Cottin-Bizonne, Christophe Ybert, and Lyderic Bocquet