Magnetic confinement of paramagnetic micro and nano-particles away from solid walls

In many biological processes, like medical diagnostic, using paramagnetic micro or nanosized particles, adherence of these particles to the walls is a major drawback to the efficiency of the process. Usually, one tries to use electrostatic repulsion and/or special wall chemical treatment to reduce the number of particles sticking to the walls. Another way of keeping the particles away from the walls, based upon magnetic repulsion, is presented here. The advantage is that it does not require changing the chemical composition of the fluid/walls, it acts only externally on the magnetic colloid. The method is first described by numerical simulation using a finite element approach. Then an experimental confirmation of the principle is shown.