Activity Induced Rigidity of Liquid Droplets

Kaili Xie (1) , Benjamin Gorin (1) , Rory Cerbus (1) , Laura Alvarez (2) , Jean-Michel Rampnoux (1) , Hamid Kellay (1)

1 LOMA - Laboratoire Ondes et Matière d'Aquitaine
2 CRPP - Centre de Recherche Paul Pascal

Here we show that encapsulating active Janus particles within a drop renders it more resistant to deformation. This drop is deformed under the action of an extensional flow. Such deformation is primarily resisted by the drop interfacial tension. When the particles are active under the action of laser illumination, the deformation decreases signaling an increase in effective tension or Laplace pressure. This increase is attributed to the activity of the particles. Our results using numerous drop sizes, particle number densities, and active velocities show that the obtained increase agrees surprisingly well, over an extended range, with a standard expression for the pressure engendered by an ensemble of active particles, proposed years ago but not tested yet in three dimensions.

Domaines: Matière Molle [cond-mat.soft]; Mécanique statistique [cond-mat.stat-mech]

Kaili Xie, Benjamin Gorin, Rory Cerbus, Laura Alvarez, Jean-Michel Rampnoux, et al.. Activity Induced Rigidity of Liquid Droplets. Physical Review Letters, 2022, 129 (13), pp.138001. ⟨10.1103/physrevlett.129.138001⟩. ⟨hal-03789264v2⟩