The invention relates to a magnetic sample-processing device, particularly a sensor device (100), that comprises two electromagnets (110, 120) for generating a magnetic field (B) in a first and a second sample chamber (SC1, SC2) located adjacent to each other in an x-direction. The poles of the electromagnets are disposed below the first and the second sample chamber (SC1, SC2), respectively, next to each other in a perpendicular y-direction. Moreover, the electromagnets are individually controlled by a control unit (130). In a preferred embodiment, the distance between the electromagnets (110, 120) in x-direction is so large that magnetic cross talk can be neglected. In another embodiment, said distance is close, and the electromagnets are operated in a synchronized way.