A New Drive System for Microagent Control in Targeted Therapy Based on Rotating Gradient Magnetic Fields

Using magnetically powered microagents as precise delivery carriers is a promising technology for targeted therapy. It is a significant challenge to converge microagents to the desired position without sufficient support of real-time imaging feedback. Herein, a new drive solution is proposed, which generates a rotating gradient-based magnetic field by sequentially energizing each coil of the electromagnetic coil system. With this method, a high magnetic field gradient concentrated onto a specific target site is generated, which will attract microagent swarms to automatically converge to the target site from different directions. Based on the established model of rotating gradient magnetic field actuation, the relationship between the current inputs of coils and the location of the aggregation center is characterized, so that the target site can be adjusted in the entire workspace by changing the coil current inputs. The method drives microagents to rotate while moving forward, thereby reducing the viscous resistance and friction on microagents. It does not rely on specific trajectory planning and real-time visual guidance to navigate microagents, and can drive magnetic microagents with different characteristics such as size, shape, and materials. This research provides a basis for using microagent delivery in clinical applications and precision-targeted therapy.