Localization and Actuation for MNPs Based on Magnetic Field-Free Point: Feasibility of Movable Electromagnetic Actuations

Abstract

Targeted drug delivery (TDD) based on magnetic nanoparticles (MNPs) and external magnetic actuation is a promising drug delivery technology compared to conventional treatments usually utilized in cancer therapy. However, the implementation of a TDD system at a clinical site based on considerations for the actual size of the human body requires a simplified structure capable of both external actuation and localization. To address these requirements, we propose a novel approach to localize drug carriers containing MNPs by manipulating the field-free point (FFP) mechanism in the principal magnetic field. To this end, we devise a versatile electromagnetic actuation (EMA) system for FFP generation based on four coils affixed to a movable frame. By the Biot–Savart law, the FFP can be manipulated by appropriately controlling the gradient field strength at the target area using the EMA system. Further, weighted-norm solutions are utilized to correct the positions of FFP to improve the accuracy of FFP displacement in the region of interest (ROI). As MNPs, ferrofluid is used to experiment with 2D and 3D localizations in a blocked phantom placed in the designed ROI. The resultant root mean square error of the localizations is observed to be approximately 1.4 mm in the 2D case and 1.6 mm in the 3D case. Further, the proposed movable EMA is verified to be capable of simultaneously scanning multiple points as well as the actuation and imaging of MNPs. Based on the success of the experiments in this study, further research is intended to be conducted in scale-up system development to design precise TDD systems at clinical sites.

Optimization of Field-Free Point Position, Gradient Field and Ferromagnetic Polymer Ratio for Enhanced Navigation of Magnetically Controlled Polymer-Based Microrobots in Blood Vessel

“…The region of interest (ROI) in our system is . This nine-coil EMA setup not only generates higher gradient fields but also provides the gradient field in the z -direction, thus minimizing the use of a mechanical microstage in most conventional four-coil EMA setups and can control the microrobots in 5-DOFs [ 34 ]. The detailed parameters of the EMA coil system are summarized in Table 1 .…”

A Review of Microrobot’s System: Towards System Integration for Autonomous Actuation In Vivo

“…MPI is an imaging method based on magnetic particles that can be actuated and functionally targeted for microrobots in drug delivery and situ sensing applications [ 68 , 69 ]. Le et al [ 70 ] have designed a real-time 2D MPI for electromagnetic navigation, which monitored Resovist particles at 45 to 65 nm (5 nm core) in real-time ( Figure 7 D).…”

Multimodal Locomotion and Active Targeted Thermal Control of Magnetic Agents for Biomedical Applications

“…Thus, recently, researchers are working on developing multifunctional electromagnetic systems capable not only of magnetic locomotion control for magnetic microrobots but also the ability to track their position when inside the human body. [ 28 , 29 ]…”