Soft and Living Matter Seminar Series: Friday, February 28th, 2020 -- Role of friction in ciliary beating

Event Date: 

Friday, February 28, 2020 - 1:30pm

Event Location: 

  • Elings 1601
  • Soft and Living Matter Seminar Series

Ciliary oscillations driven by molecular motors cause fluid motion at micron scale. Naturally, the system operating in low Reynolds number regime is expected to be governed by the ambient fluid friction. However, the role of hydrodynamics is highly debated in flagellar synchronization of live cells and collective behavior of ciliary carpets. Therefore, to ascertain the role of fluid friction in ciliary beating, we simultaneously measure the waveform and flow field of isolated (cell-free) and reactivated cilia as well as cilia anchored on single celled microalgae Chlamydomonas. Apart from the conventional waveform measurement, which only allows us to understand the passive elastic forces, the flow field enables us to directly measure the external viscous drag force acting on the cilia. We show that this simultaneous measurement provides vital information on ciliary mechanisms that cannot be obtained from waveform measurements alone. For example, in the case of isolated cilia, we show it is not the fluid friction but a friction internal to the filament which controls the dynamical steady state in ciliary oscillations, close to the instability threshold of periodic beating. Similar measurements on swimming cells confined by hard walls illustrate novel motility and flow behavior.