Abstract: The methods and apparatus disclosed herein allow for the controlling of the suspension of particles in a liquid medium. The method comprises intermittently magnetically causing at least a portion of a device immersed in the fluid medium (i) to rotate from a rest position about an approximately horizontal axis to a second position at an angle not greater than about 135 degrees from the rest position and (ii) to return to a rest position. The frequency of movement of the device is sufficient to control the suspension of particles in the medium. The method is particularly applicable to controlling a suspension of cells, for example, erythrocytes, in a liquid medium with a minimization of lysis.