Dynamics of a Model Microswimmer in the Vicinity of a Liquid Droplet

Microorganisms in viscous fluids are known to exhibit complex swimming motions in the presence of boundaries. In this study, we investigate the dynamics of microswimmers near a drop with a soft, deformable, penetrable surface. Three distinct swimming modes, including penetrating, bouncing, and sliding, are observed when the microswimmers approach the surface of the drop. The critical trapping angle and the influence of the radius of the droplet are analyzed in detail, showing a correlation with the swimming strength. The effect of viscosity differences between the fluids inside and outside the drop is also studied. Our findings contribute to a deeper understanding of the dynamics of microswimmers in complex fluid systems and may have implications for physiological and biological phenomena, such as oilmicrobe interactions and marine ecosystems.