Researchers of MESA+, the research institute for nanotechnology of the University of Twente, in cooperation with researchers of the University of Strasbourg and Eindhoven University of Technology, are the first to successfully create perfect one-dimensional molecular wires of which the electrical conductivity can almost entirely be suppressed by a weak magnetic field at room temperature. The underlying mechanism is possibly closely related to the biological compass used by some migratory birds to find their bearings in the geomagnetic field. This spectacular discovery may lead to radically new magnetic field sensors, for smartphones for example.