Unidirectional Propulsion of Planar Magnetic Nanomachines

Artificial magnetic micro- and nanomachines, and their steering by weak rotating magnetic fields, have been extensively studied for biomedical applications, such as drug delivery. This work theoretically investigates the driven propulsion of planar magnetic microstructures that can be mass-produced by standard photolithography, and thus are of practical interest. Actuation by a conically rotating magnetic field (in contrast to a planar rotating field) can yield efficient unidirectional propulsion of a two-dimensional \ensuremath{\bigvee}-shaped sructure magnetized in its plane. Surprisingly, even though the symmetrical \ensuremath{\bigvee} rotates with the actuating field, its propulsion velocity is frequency-independent.