Abstract
Microscale swimming robots have been envisaged for many biomedical applications such as targeted drug delivery, where the microrobot will be expected to navigate in a fluid environment while carrying a payload. We show that such a payload does not have to be physically bound to the swimmer, but may be instead manipulated by the microrobot through hydrodynamic interaction. We consider a magnetically actuated artificial microswimmer, whose locomotion induces a disturbance velocity field in the fluid, which moves a cargo particle in its vicinity. The problem investigated in this paper is therefore one of coupled locomotion-manipulation of two bodies in a fluid. The swimmer is actuated by a uniform, rotating magnetic field of constant strength leading to net motion in the direction perpendicular to the plane of rotation if the frequency associated with the periodic magnetic field is above a critical frequency. Below this critical frequency, the swimmer tumbles in place without net locomotion. Controlled motion of the particle and swimmer is achieved by switching the planes of rotation of the magnetic field and the frequency of the magnetic field above and below the critical frequency. The results of this paper show that microswimmers can be utilized as mobile manipulators of microparticles in a fluid.
