Collaborative Research: Exploring Flagellar Mechanics to Advance Bacterial Locomotion and Nanorobotic Propulsion

Many bacteria swim using slender, spiral-shaped filaments called flagella, which are rotated by molecular motors to generate propulsion. This movement allows bacteria to navigate complex environments, seek nutrients, and interact with host organisms. The mechanical properties of these flagella, especially their stiffness, play a crucial role in how efficiently bacteria can swim and reorient. This project will investigate how the stiffness of bacterial flagella influences swimming behaviors and turning maneuvers. Beyond biology, these insights are relevant to the development of nanorobots that use bacterial flagella for propulsion. Improved understanding of flagellar mechanics could enable better design and control of nanorobots for applications such as targeted drug delivery, microsurgery, and microscale fabrication. This research supports the progress of science and national health by contributing fundamental knowledge with wide-reaching impact, from microbiology and ecological function to biomedical innovation and soft robotics. It will also provide training opportunities in biophysics, computational modeling, and microscopy for students at multiple levels, helping to build a skilled scientific workforce. This study will advance fundamental understanding of flagellar deformability by overcoming limitations in existing models. Prior research often relied on simplified force equations, inadequate representations of the surrounding fluid flow, and low-resolution image-based geometry extractions. This project will integrate high-precision experiments on tethered flagella with advanced image processing algorithms to reconstruct the three-dimensional geometry of flagella in motion with subpixel accuracy. Using the method of regularized Stokeslets, the study will incorporate hydrodynamic interactions with nearby surfaces to better model bending mechanics. These approaches will allow for improved characterization of bending stiffness, including nonlinearities. The results will clarify how mechanical properties affect motility in bacteria and propulsion efficiency in flagella-powered nanorobots. Together, this project will deliver new theoretical and experimental tools to the biomechanics community and contribute critical insights into the design principles of biologically inspired locomotion systems. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.