'Magnetic bandages' for targeted delivery of therapeutic agents

We investigate planar periodically magnetized structures for use in targeting or controlling the delivery of therapeutic agents attached to small magnetic particles, and derive simple analytic expressions for the relevant magnetostatic forces. We show that improved particle trapping or confinement characteristics are possible relative to those that can be obtained with more conventional ( i. e. uniformly magnetized) structures. These improvements include forces that are larger at close range ( for equivalent magnetization densities) and that are both unidirectional and uniform over arbitrarily large areas parallel to the magnet surface. Expressions for the magnetostatic forces exerted on point- like magnetic particles in the vicinity of long rods ( with circular and ellipsoidal cross sections) uniformly magnetized perpendicular to their axes are summarized in an appendix.