(color online) The lithography pattern transferred to the film to fabricate the central Hall bar, 10 mm long, contacted by 64 gold lines and contact pads. The doping gradient is generated by the COMBE synthesis technique with a single Sr source at a shallow angle. The Hall bar is aligned along the direction determined by the doping gradient. The current runs from contact I+ to I−and the voltages are measured between contact pairs like 1 and 3 or 1 and 2, to determine longitudinal or Hall resistances, respectively. All pixels (30 for longitudinal and 31 for Hall resistance) can be measured simultaneously.