Seminar über aktuelle Fragen zur Dynamik komplexer Fluide: Rheotaxis of active droplets in microconfinements

Seminar über aktuelle Fragen zur Dynamik komplexer Fluide

  • Date: Apr 23, 2021
  • Time: 10:15 AM - 11:15 AM (Local Time Germany)
  • Speaker: Ranabir Dey
  • IIT Hyderabad, India
  • Location: Max-Planck-Institut für Dynamik und Selbstorganisation (MPIDS)
  • Room: Video conference at, Meeting ID: 980 3913 9623, Passcode: 050762
  • Host: MPIDS/DCF
  • Contact:
Biological microswimmers navigate upstream of an external flow (positive rheotaxis) in trajectories ranging from linear, spiral to oscillatory. Such rheotaxis stems from the interplay between the complex shapes of the microswimmers- specifically the chirality of the rotating flagella, the shear flow characteristics, and the activity-induced hydrodynamic interaction with a confining surface. Here, we show that an active droplet microswimmer exhibits a unique oscillatory rheotaxis in a micro-confinement despite its symmetric spherical geometry. The translational velocity, swimming orientation, and the chemical trail of the active droplet undergo periodic variations between the confining walls during the oscillatory navigation. Using a hydrodynamic model and concepts of dynamical systems, we demonstrate that the oscillatory rheotaxis emerges primarily from the interplay between the activity-induced simultaneous hydrodynamic interaction of the finite-sized microswimmer with all the walls of the microconfinement, and the shear flow characteristics. Such oscillatory rheotactic behavior is different from the directed motion near a planar wall observed previously for artificial microswimmers in shear flows. Our results provide a realistic understanding of the behaviour of spherical active particles in confined microflows, as will be encountered in majority of the envisioned applications like targeted drug delivery.
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