This paper introduces a two-dimensional (2-D) autonomous navigation strategy of a 750-μm steel microrobot along a complex fluidic vascular network inside the bore of a clinical 3.0T magnetic resonance imaging (MRI) scanner. To ensure successful magnetic resonance navigation of a microrobot along consecutive channels, the design of autonomous navigation strategy is needed, taking into account the major MRI technological constraints and physiological perturbations, e.g., nonnegligible pulsatile flow, limitations on the magnetic gradient amplitude, MRI overheating, and susceptibility artifacts uncertainties. An optimal navigation planning framework based on Pareto optimality is proposed in order to deal with this multiple-objective problem. Based on these optimal conditions, a dedicated control architecture has been implemented in an interventional medical platform for real-time propulsion, control, and imaging experiments. The reported experiments suggest that the likelihood of controlling autonomously untethered 750-μm magnetic microrobots is rendered possible in a complex 2-D centimeter-sized vascular phantom. The magnetic microrobot traveled intricate paths at a mean velocity of about 4 mms ^-1 with average tracking errors below 800 μm with limited magnetic gradients ±15 mTm ^-1 , which is compatible with clinical MRI scanners. The experiments demonstrate that it is effectively possible to autonomously guide a magnetic microrobot using a conventional MRI scanner with only a software upgrade.

This paper presents the endovascular navigation of a ferromagnetic microdevice using magnetic resonance imaging (MRI)-based predictive control. The concept was studied for the future development of...

This paper presents a preoperative microrobotic surgical simulation and planning application. The main contribution is to support computer-aided minimally invasive surgery (MIS) procedure using untethered microrobots that have to navigate within the arterial networks. We first propose a fast interactive application (with endovascular tissues) able to simulate the blood flow and microrobot interaction. Second, we also propose a microrobotic surgical planning framework, based on the anisotropic fast marching method (FMM), that provides a feasible pathway robust to biomedical navigation constraints. We demonstrate the framework performance in a case study of the treatment of peripheral arterial diseases.

This paper presents real-time MRI-based control of a ferromagnetic microcapsule for endovascular navigation. The concept was studied for future development of microdevices designed to perform minimally invasive interventions in remote sites accessible through the human cardiovascular system. A system software architecture is presented illustrating the different software modules to allow navigation of a microdevice in blood vessels, namely: (i) vessel path planner, (ii) magnetic gradient steering, (iii) tracking and (iv) closed-loop navigation control. First, the position recognition of the microrobot into the blood vessel is extracted using Frangi vesselness filtering from the pre-operation images. Then, a set of minimal trajectory is predefined, using FMM, to guide the microrobot from the injection point to the tumor area through the anarchic vessel network. Based on the pre-computed path, a GPC is proposed for robust time-multiplexed navigation along a 2D path in presence of pulsative flow. The simulation results suggest the validation of the proposed image processing and control algorithms. A series of disturbances introduced in the presence and absence of closed-loop control affirms the robustness and effectiveness of this predictive control system.

Navigating in bodily fluids to perform targeted diagnosis and therapy has recently raised the problem of robust control of magnetic microrobots under real endovascular conditions. Various control approaches have been proposed in the literature but few of them have been experimentally validated. In this paper, we point out the problem of navigation controllability of magnetic microrobots in high viscous fluids and under pulsatile flow for endovascular applications. We consider the experimental navigation along a desired trajectory, in a simplified millimeter-sized arterial bifurcation, operating in fluids at the low-Reynolds-number regime where viscous drag significantly dominates over inertia. Different viscosity environments are tested under a systolic pulsatile flow compatible with heart beating. The control performances in terms tracking, robustness and stability are then experimentally demonstrated.