Bending Dynamics of Magnetic Filaments at a Curved Bacterial Bath Interface

The bending dynamics of microscopic filaments play a crucial role in various mechanical and biological processes. While thermal fluctuations typically have a minor effect, active fluctuations can provide sufficient mechanical energy to alter bending deformations in these systems. In this work, we investigate how active noise influences the bending dynamics of a self-assembled chain of magnetic particles at a curved liquid-air interface in the presence of swimming <i>E. coli</i> bacteria. We analyze the bending behavior of semiflexible chains under a lateral gravitational force and compare their response in passive and active baths. In a passive bath, the chain remains bent, fluctuating slightly around its deformed configuration due to thermal noise. However, in an active bath, strong bacterial activity suppresses the average bending deformation, causing the chain to fluctuate around a nearly straight configuration. These findings highlight the impact of active fluctuations on self-assembled microstructures and demonstrate a simple yet effective approach to studying the mechanical dynamics of microscopic filaments.