Regensburg 2019 – wissenschaftliches Programm
DY 44.2: Vortrag
Donnerstag, 4. April 2019, 10:15–10:30, H19
Tuning propulsion modes in active emulsions — •Corinna C. Maass, Babak Vajdi Hokmabad, and Kyle A. Baldwin — Max-Planck-Institut für Dynamik und Selbstorganisation
Single cell organisms show a variety of swimming behaviours: e.g. persistent, helical, run-and-tumble or switch-and-flick, all dependent on intricate biophysical machinery and serving various strategies of navigation, e.g. persistence against external flow, efficiency of gradient sensing or expanding their range of exploration. Their locomotion has to adapt to low Reynolds numbers, highly viscous or non-Newtonian environments. An important aspect to the construction of biomimetic model swimmers is to mimic as many of those strategies as possible, based on simple principles of non equilibrium physics without requiring intricate biochemical machinery. Here, we investigate the dynamics of active droplets dependent on the viscosity of the bulk phase. We can tune their propulsion from almost ballistic persistence over a quite diffusive ``run-and-spiral'' mode to a ``stop-and-go'' behaviour that is noisy on short, but persistent on long time scales, simply by changing the composition of the bulk phase with a varying fraction of glycerol. Such unsteady swimming is caused by a dynamic instability in the chemical and hydrodynamic fields around the droplets which we have mapped simultaneously via multichannel fluorescent video microscopy.