Microorganisms like bacteria and even sperm have to be excellent swimmers in order to navigate the environments they frequent.
Now, researchers from Tokyo Metropolitan University have uncovered the mechanisms that allow microorganisms to maneuver through fluids with a gel-like consistency.
Microorganisms need fluids with the right kind of viscosity to swim around effectively, but previous research that focused on how microorganisms swim paid little attention to the fluids themselves.
The results of the most recent study, published in the journal Europhysics Letters, show that changes in the microorganism’s features invoke different responses from the fluid around it and that the size of the structure of the fluid and microorganism impacts movement.
Researchers studying the swimming movements of microorganisms use a model called a three-sphere-microswimmer, which is a string of three microscopic spheres attached to a string. The model propels itself forwards by pumping its arms.
For this study, the researchers immersed the three-sphere model in a polymer gel.
The model was able to achieve motion through two mechanisms. The first involved breaking something called time-reversal symmetry and the other mechanism required that the arms of the model change the amplification of their propelling motion.
Movement was also impacted by the structure of the fluid itself, and if the microspheres were larger than the components of the fluid, there was more resistance against the swimmer.
The study could help provide insight into the movement of bacteria and cells and could even be used to create robots that can maneuver through debris after a flood or landslide.