Research Progress

Hydrodynamics-Induced Long-Range Attraction between Plates in Bacterial Suspensions

SourceSeminar Oct 10,2023
As a collaborative work between Institute of Physics, Chinese Academy of Sciences, Institute of Theoretical Physics, Chinese Academy of Sciences and University of Chinese Academy of Sciences, we perform optical-tweezer experiments and mesoscale fluid simulations to study the effective interactions between two parallel plates immersed in bacterial suspensions. The plates are found to experience a long-range attraction, which increases linearly with bacterial density and decreases with plate separation. The higher bacterial density and orientation order between plates observed in the experiments imply that the long-range effective attraction mainly arises from the bacterial flow field, instead of the direct bacterium-plate collisions, which is confirmed by the simulations. Furthermore, the hydrodynamic contribution is inversely proportional to the squared interplate separation in the far field. Our findings highlight the importance of hydrodynamics on the effective forces between passive objects in active baths,providing new possibilities to control activity-directed assembly. 


Contact: Fanlong Meng

Institute of Theoretical Physics, CAS