Magnetically actuated soft robots may improve the treatment of disseminated intravascular coagulation. Significant progress has been made in the development of soft robotic systems that steer catheters. A more challenging task, however, is the development of systems that steer sub-millimeter-diameter guidewires during intravascular treatments; a novel microrobotic approach is required for steering. In this article, we develop a novel, magnetically actuated, soft microrobotic system, increasing the steerability of a conventional guidewire. The soft microrobot is attached to the tip of the guidewire, and it is magnetically steered by changing the direction and intensity of an external magnetic field. The microrobot is fabricated via replica molding and features a soft body made of polydimethylsiloxane, two permanent magnets, and a microspring. We developed a mathematical model mapping deformation of the soft microrobot using a feed-forward approach toward steering. Then, we used the model to steer a guidewire. The angulation of the microrobot can be controlled from 21.1° to 132.7° by using a magnetic field of an intensity of 15 mT. Steerability was confirmed by two-dimensional in vitro tracking. Finally, a guidewire with the soft microrobot was tested by using a three-dimensional (3D) phantom of the coronary artery to verify steerability in 3D space.

Alzheimer's disease (AD) is the most prevalent age-related neurodegenerative disease, pathologically characterized by the accumulation of aggregated amyloid beta (Aβ) in the brain. Here, we describe for the first time the development of a new, pioneering nanotechnology-based drug delivery approach for potential therapies for neurodegenerative diseases, particularly AD. We demonstrated the delivery of fluorescent carboxyl magnetic Nile Red particles (FMNPs) to the brains of normal mice using a functionalized magnetic field (FMF) composed of positive- and negative-pulsed magnetic fields generated by electromagnetic coils. The FMNPs successfully reached the brain in a few minutes and showed evidence of blood–brain barrier (BBB) crossing. Moreover, the best FMF conditions were found for inducing the FMNPs to reach the cortex and hippocampus regions. Under the same FMF conditions, dextran-coated Fe₃O₄ magnetic nanoparticles (MNPs) loaded with osmotin (OMNP) were transported to the brains of Aβ_1–42-treated mice. Compared with native osmotin, the OMNP potently attenuates Aβ_1–42-induced synaptic deficits, Aβ accumulation, BACE-1 expression and tau hyperphosphorylation. This magnetic drug delivery approach can be extended to preclinical and clinical use and may advance the chances of success in the treatment of neurological disorders like AD in the future.

Magnetic nanoparticles (MNPs) are effective drug carriers. By using electromagnetic actuated systems, MNPs can be controlled noninvasively in a vascular network for targeted drug delivery (TDD). Although drugs can reach their target location through capturing schemes of MNPs by permanent magnets, drugs delivered to non-target regions can affect healthy tissues and cause undesirable side effects. Real-time monitoring of MNPs can improve the targeting efficiency of TDD systems. In this paper, a two-dimensional (2D) real-time monitoring scheme has been developed for an MNP guidance system. Resovist particles 45 to 65 nm in diameter (5 nm core) can be monitored in real-time (update rate = 2 Hz) in 2D. The proposed 2D monitoring system allows dynamic tracking of MNPs during TDD and renders magnetic particle imaging-based navigation more feasible.

Magnetically driven microrobots have been widely studied for various biomedical applications in the past decade. An important application of these biomedical microrobots is heart disease treatment. In intravascular treatments, a particular challenge is the submillimeter-sized guidewire steering; this requires a new microrobotic approach. In this study, a flexible microrobot was fabricated by the replica molding method, which consists of three parts: (1) a flexible polydimethylsiloxane (PDMS) body, (2) two permanent magnets, and (3) a micro-spring connector. A mathematical model was developed to describe the relationship between the magnetic field and the deformation. A system identification approach and an algorithm were proposed for steering. The microrobot was fabricated, and the models for steering were experimentally validated under a magnetic field intensity of 15 mT. Limitations to control were identified, and the microrobot was steered in an arbitrary path using the proposed model. Furthermore, the flexible microrobot was steered using the guidewire within a three-dimensional (3D) transparent phantom of the right coronary artery filled with water, to show the potential application in a realistic environment. The flexible microrobot presented here showed promising results for enhancing guidewire steering in percutaneous coronary intervention (PCI).