Characterization and modeling of micro swimmers with helical tails and cylindrical heads inside circular channels

Micro swimming robots offer many advantages in biomedical applications, such as delivering potent drugs to specific locations in targeted tissues and organs with limited side effects, conducting surgical operations with minimal damage to healthy tissues, treatment of clogged arteries, and collecting biological samples for diagnostic purposes. Reliable navigation techniques for micro swimmers need to be developed to improve the localization of robots inside the human body in future biomedical applications. In order to estimate the dynamic trajectory of magnetically propelled micro swimmers in channels, that mimic blood vessels and other conduits, fluid-micro robot interaction and the effect of the channel wall must be understood well. In this study, swimming of one-link robots with helical tails is modeled with Stokes equations and solved numerically with the finite element method. Forces acting on the robot are set to zero to enforce the force-free swimming and obtain forward, lateral and angular velocities that satisfy the constraints. Effects of the number of helical waves, wave amplitude, relative size of the cylindrical head of micro swimmer and the radial position on angular and linear velocity vectors of micro swimmer are presented.