A method of mixing magnetic particles (3) in a reaction chamber (2) that is part of a microfluidic device and that contains the said particles in suspension, comprises the steps: (a) providing an elecA method of mixing magnetic particles (3) in a reaction chamber (2) that is part of a microfluidic device and that contains the said particles in suspension, comprises the steps: (a) providing an electromagnetic means (1,1 ',6, 7) to generate magnetic field sequences having polarity and intensity that vary in time and a magnetic field gradient that covers the whole space of the said reaction chambtromagnetic means (1,1 ',6, 7) to generate magnetic field sequences having polarity and intensity that vary in time and a magnetic field gradient that covers the whole space of the said reaction chamber (2); (b) applying a first magnetic field sequence to separate or confine the particles (3) so the particles occupy a sub-volume in the volume of the reaction chamber (2); (c) injecting a defined voer (2); (b) applying a first magnetic field sequence to separate or confine the particles (3) so the particles occupy a sub-volume in the volume of the reaction chamber (2); (c) injecting a defined volume of the said reagent in the reaction chamber; and (d) applying a second magnetic field sequence to leads the particles (3) to be homogenously distributed and dynamically moving over a substantiallume of the said reagent in the reaction chamber; and (d) applying a second magnetic field sequence to leads the particles (3) to be homogenously distributed and dynamically moving over a substantialportion of the whole reaction chamber volume.portion of the whole reaction chamber volume.