Synchronization Transitions and Collective Flow Dynamics in the Bacterial Carpet
Yi-Teng Hsiao1*, Kuan-Ting Wu1, Chia-Chun Chan1, Wei-Yen Woon1
1Department of Physics, National Central University, Jungli, Taiwan
* presenting author:Yi-Teng Hsiao ,
We investigate the synchronization transitions in array formed by self-propelling particle (SPP) under low Reynolds number (Re) condition. Bacteria, as a kind of self-propelling particles, possess molecular motors that are able to perform highly efficient flagellum rotation even under low Re condition. Bacterial carpets consist of randomly anchored uni-polar-flagellated sodium-motive bacteria matrix are prepared by flow deposition. Collective flow dynamics across the bacterial carpets are probed with optical tweezers-microsphere assay. The vertical force measurement shows the force magnitudes increase abruptly at sodium-motive driving over a critical value, suggesting a threshold-like transition of hydrodynamic synchronization across bacterial carpet. Implementing a high temporal resolution position sensitive photodiode enables us to investigate what kinds of the synchronization transition it is. The transition types are dependent on the characteristic of single bacteria and the quality of bacterial carpet. We further explore the behavior of the different kind carpets by using different strain of bacteria and different condition of flow deposition process. The sharp or gradual synchronization transition may be observed in the different kind carpets.

Keywords: Synchronization, Collective Flow, Bacterial Carpet, Optical Tweezers