The magnetic field sensitive MOSFET (MAGFET) is used as a sensor to convert the magnetic field applied perpendicular to the channel to an electrical signal, like current, voltage, or frequency [143]. Integrated magnetic field sensor arrays can detect variations of the magnetic field in a small area. Such sensor arrays are used, e.g., to determine fringing fields in electrical motors or to detect defaults in metallic pipes [144]. Magnetic sensor arrays have been fabricated up to sizes of about and are also used to detect non-magnetic quantities like currents by their surrounding magnetic field, displacement of magnets, or the movement of membranes to which magnetic dipoles have been applied [145]. Thus, two different applications can be distinguished: