Tetherless magnetic helical devices (TMHDs), including helix-, screw-, and twist-shaped variants, exhibit considerable potential in biomedical applications, particularly for their capacity to be remotely controlled to navigate deep tissues within the human body. The goal of Zhengya Zhang’s thesis is to achieve stable and effective navigation of TMHDs in physiological environments, thereby laying the groundwork for their integration into biomedical applications such as targeted drug delivery and material removal. To accomplish this goal, the thesis explores the development of TMHD actuation systems and the implementation of TMHD motion control within physiological environments.
The magnetic field produced by electromagnet- and permanent magnet-based robotic systems is a viable option as an external stimulus to enable the motion of a TMHD in physiological environments. In this thesis, a permanent magnet-based robotic system is developed with an open configuration using two synchronized rotating permanent magnets to generate time-varying rotating magnetic fields. These fields are used to apply torque on a TMHD in physiological environments. The configuration of the system is vertically symmetric, allowing the permanent magnets to exert gradient-free space within the center of the workspace. Such a feature allows us to focus on the directional control of a TMHD without needing to account for the magnetic gradient force acting on the TMHD within the gradient-free space, thereby optimizing and streamlining TMHD motion control. The experimental results demonstrate the capability of our robotic system to control a TMHD moving along prescribed trajectories in three-dimensional space.
