Mechanical characterization of bio-inspired flagella interaction*

Locomotion of bacteria and other microbes has been investigated since their discovery, particularly their movement in low Reynolds flow. Bacteria use flagella-driven mechanisms to swim and turn, such as buckling, bundling, and tumbling. Researchers have used different techniques to investigate these locomotion modes, from numerical modeling to biological experiments and scaled-up setups. While there have been successful measurements of forces on biological flagella, comprehensive analysis of forces resulting from the interaction of multiple elastic flagella remains limited. This research focuses on the role of flagella elasticity, forces involved in fluid-structure interactions, and potential applications in medical microbots. We use the Discrete Elastic Rod (DER) method to model the flagella as Kirchhoff's elastic rods, coupled with the Regularized Stokeslet Segments (RSS) method for the hydrodynamics and the implicit contact model (IMC) for a physical contact simulation. An experimental setup with high precision is developed to measure forces in a viscous medium, and the results are compared to mathematical models to ensure model accuracy. We present a characterization map of propulsive force based on various elastic flagella interactions by varying their number, spacing distance, and motion pattern.