Electrically tunable magnetic sensor for satellite-free global positioning

Navigation and positioning technologies play a key role in modern human activities. Currently, navigation devices are mostly dependent on the global navigation satellite systems, for example, the global positioning system (GPS). However, it is known that GPS signals can be jammed or spoofed or otherwise fail. As the need for GPS independent navigation increases in some practical application scenarios, novel navigation techniques based on the geomagnetic field have been developed. A main task of geomagnetic navigation is to obtain the amplitude and direction of the geomagnetic field accurately. Here, we introduce an alternative scheme for vectorial measurements of the local geomagnetic field for magnetic positioning based on the biological ferric sulfide cluster, which exists in the magnetoreceptor protein/cryptochrome complex in certain avian species. We find that by observing the number of peaks and the proportional rate of spectrum on resonance, both the direction and intensity of the magnetic field can be determined. Therefore, our findings may provide a fresh insight into magnetic field measurement and also suggest further guidelines for the design and operation of satellite-free navigation systems based on the electrically tunable inorganic biological molecules.