High-Sensitivity magnetic field sensor shielded from the effect of earth's magnetism

To realize a general-purpose magnetic field sensor having a detection sensitivity of the order of 10-12 T/√Hz at room temperature, a problem of removing the effect of the Earth's magnetism from the sensor must be solved because its magnitude is 4.5 × 104 times larger than that in the range to be detectable. For this purpose, a well-known approach of exciting the sensor in the opposite direction to the Earth's magnetism to cancel out the value has been adopted. This paper aims at realizing a magnetic field sensor free from the Earth's magnetism by introducing a method called 'zero magnetic field.' In practice, such a sensor was developed and the tested results confirmed that the detection performance was maintained without losing the high sensitivity.