Paper Number
PO20 

Session
Poster Session

Title
Spontaneous self-propulsion and nonequilibrium shape fluctuations of a droplet enclosing active particles

Presentation Date and Time
October 12, 2022 (Wednesday) 6:30

Track / Room
Poster Session / Riverwalk A

Authors (Click on name to view author profile)

  1. Kokot, Gasper (Jožef Stefan Institute)
  2. Faizi, Hammad A. (Northwestern University)
  3. Pradillo, Gerardo M. (Georgetown University)
  4. Snezhko, Alexey (Argonne National Lab)
  5. Vlahovska, Petia M. (Northwestern University)

Author and Affiliation Lines (in printed abstract book)
Gasper Kokot1, Hammad A. Faizi2, Gerardo M. Pradillo3, Alexey Snezhko4 and Petia M. Vlahovska2
1Jožef Stefan Institute, Ljubljana, Slovenia; 2Northwestern University, Evanston, IL 60208; 3Georgetown University, Washington, DC; 4Argonne National Lab, Lemont, IL

Speaker / Presenter 
Faizi, Hammad A.

Keywords
active matter; colloids; directed systems; suspensions

Text of Abstract
Active particles, such as swimming bacteria or self-propelled colloids, spontaneously assemble into large-scale dynamic structures. Geometric boundaries often enforce different spatio-temporal patterns compared to unconfined environment and thus provide a platform to control the behavior of active matter. Here, we report collective dynamics of active particles enclosed by soft, deformable boundary, that is responsive to the particles’ activity. We reveal that a quasi two-dimensional fluid droplet enclosing motile colloids powered by the Quincke effect (Quincke rollers) exhibits strong shape fluctuations with a power spectrum consistent with active fluctuations driven by particle-interface collisions. A broken detailed balance confirms the nonequilibrium nature of the shape dynamics. We further find that rollers self-organize into a single drop-spanning vortex, which can undergo a spontaneous symmetry breaking and vortex splitting. The droplet acquires motility while the vortex doublet exists. Our findings provide insights into the complex collective behavior of active colloidal suspensions in soft confinement.