Advantages and limitations of the various magnetic manipulation methods of untethered agents in the human body

Magnetic manipulation of untethered agents is likely to play a critical role in several interventions conducted in the human body. Such interventions ranging from surgeries to drug deliveries require magnetic manipulation methods with characteristics that are best suited for the type of interventions being considered. The main characteristics include but are not limited to the magnetic field strength, the magnitude of the magnetic gradients, the rate at which such directional gradients can vary, the degree-of-freedom (DOF) being supported, appropriateness of the imaging modality for real-time positional assessments of the agents being manipulated, the total workspace, and the duty cycle or the period of time that such magnetic manipulation can be performed without interruption. Since no single existing magnetic manipulation method is optimized for all of the above characteristics, emphasizes the need to select the appropriate method that will offer the best required characteristics for a given type of interventions. Here, a study and review of such main magnetic manipulation methods and systems with the corresponding characteristics and the related preferred type of interventions are provided.