An embodiment of the invention relates to a device comprising (1) an array of electromagnetic elements comprising coils, metal cores, and metal core heads, and (2) a controller that is adapted to control a current for one or more coils individually, to vary the current for said one or more coils individually, to reverse the current for one or more coils individually, and to generate a specific magnetic flux distribution and gradient across two or more coils; wherein the metal core head is at one end of the coil and the metal core head has a geometry to create a desired magnetic flux, intensity and gradient, in a region of interest between two adjacent coils; further wherein the device is functionally coupled to a fluidic device to concentrate and transport magnetic particles in a fluid without fluidic movement of the fluid.