Strategies for Navigating Magnetic Microrobots in Neurovascular Networks: A Numerical Analysis.

First-line therapy for ischemic stroke relies on the systemic administration of thrombolytics for dissolving clots affecting brain perfusion. However, because conservative dosages are used to avoid off-target toxicity and side effects, the systemic route is often unable to deal with large clots in a timely manner. Targeted delivery of thrombolytics could be the solution if microrobots carrying the drugs could be navigated through the patient's neurovascular network to locally administer them directly to the clot. Herein, the steering of magnetic microrobots along a patient-specific neurovascular network is numerically studied, for optimizing the navigation of the microrobots to target vessels often obstructed in ischemic stroke. It is found that spatially constant magnetic gradients can be used to navigate the microrobots to the target vessels and describe various navigation strategies that can be used by health professionals to reach different positions in the vasculature. Equations are developed to predict the required magnetic gradients as a function of the microrobot diameter, which are key for the development of magnetic navigation systems that can autonomously navigate microrobots through neurovascular networks. These findings open exciting possibilities for exploring targeted drug delivery approaches in clinical settings.