Attraction and repulsion of magnetic or magnetizable objects to and from a sensor surface

The present invention provides a magnetic sensor device a first magnetic field generating means for attracting magnetic or magnetizable objects, e.g. magnetic particles, to a sensor surface and a second magnetic field generating means for, in combination with the first magnetic field, repelling magnetic or magnetizable objects, e.g. magnetic particles, from the sensor surface. The magnetic fields generated by the first and second magnetic field generating means have substantially anti-parallel directions. The present invention furthermore provides a method for attracting and repelling magnetic or magnetizable objects, e.g. magnetic particles, to and from a sensor surface. [on SciFinder (R)]