An Optimal Design of an Electromagnetic Actuation System towards a Large Homogeneous Magnetic Field and Accessible Workspace for Magnetic Manipulation

Abstract

Untethered nano-/microrobots have been appealing to biomedical applications under magnetic guidance. Numerous actuation systems are specifically designed to generate either uniform or non-uniform fields which are unable to support all actuating mechanisms of magnetic robots. The size of their accessible space does not enable applications in life sciences (e.g., placing around human parts for tasks or an in vivo experiment in animals). Moreover, homogeneity of uniform magnetic fields is limited in a small region. Here, we propose an electromagnetic coil system that is optimally designed based on numerical simulation investigations to derestrict the mentioned constraints. The built-up system provides a large bore in which magnetic field generation by passing a 10 A current is strong enough for nano-/micromanipulation switchable between uniformity in a large-homogeneous region about 50-mm-wide along the x- and y-axes and 80-mm-wide along the z-axis, and with a non-uniformity of about 12 mT with 100 mT/m. It experimentally carries out potential and versatile controls to manipulate several commonly used microrobots that require a particular type of magnetic field to perform multi-DOF locomotion in diverse viscous environments. (e.g., helical propulsion by rotating magnetic field in the 3D-large workspace and in the complex network path, side-to-side sweeping-slip locomotion by oscillating fields, translation and rocking-slip locomotion by gradient-based fields). Besides, the system can be reproduced into any accessible space size regarding the square coil size to support diverse applications and guarantee the result in both uniformity of magnetic field in the large homogeneous region and a sufficiently strong gradient over the workspace.

On the Workspace of Electromagnetic Navigation Systems

“…For a discrete set of tasks, each task in the set must be tested individually to find the minimum in (28). A similar case can be constructed for an ellipsoid using (23). For a polytope, the tasks to be tested are composed of the vertices of the polytope.…”

A Review of Soft Microrobots: Material, Fabrication, and Actuation

“…[191,224,225] Within different magnetic fields, microrobots show different motion modes, such as spiral motion generated within a rotating magnetic field, drag translation generated within a gradient magnetic field, and fluctuation generated within an oscillating magnetic field. [221,226] As a widely used propulsion method for • Require suitable environment and conditions • Lifetime is short microrobots, magnetic actuation has also been used for the 3D navigation of soft microrobots. [34,68,97,155,191,227,228] With the actuation and navigation of a magnetic field, the submillimeterscale continuous microrobot fabricated by Kim et al using programmable ferromagnetic soft materials shows omnidirectional steering ability to realize accurate control in complex and constrained environments.…”

Investigation of Swimming Behavior and Performance of the Soft Milli-Robots Embedded with Different Aspects of Magnetic Moments

“…In order to generate magnetic energy to manipulate the robots, magnetic actuation systems were specifically designed in diverse configurations with a variety of control techniques (e.g. magnetic navigation in a large workspace) [3]. Once the actuation system generated magnetic field, the magnetic property of the robots as called magnetization responded with such that actuation through magnetic alignment.…”