Motion Dynamics of Magnetically Actuated Rod-Like Softrobots Swimming in Viscous Fluids

Soft and flexible structures made of hydrogel polymer have garnered a lot of excitement and promise in mesoscale (milli- and microscale) soft robotics, as they can be loaded with magnetic materials for actuation, biosensors for sensing, and are already commonly used in areas such as tissue engineering, drug delivery, and micromanipulation. Here, we present experimental and numerical investigations of the locomotion of magnetically actuated hollow, rod-like softrobots in Newtonian fluids. We report propulsion and boundary rolling in Newtonian fluids with different viscosities for soft rod-like swimmers actuated by an externally applied uniform rotating magnetic field. The propulsion is only observed in some Newtonian fluids, and we numerically test if that can be explained by time-dependent deformations, by simulating the dynamics of the deformed shape using Kirchhoff rod theory.