A demagnetization method for reducing the residual field of the magnetic shielding box with door gap

Weak magnetic fields are essential environmental conditions for sensors used in magnetic biological measurements. However, traditional demagnetization method proves insufficient in reducing the unidirectional residual field inside magnetic shielding box caused by the gap in the door seam. This paper proposes a novel demagnetization method incorporating DC bias adjustment and optimizing the demagnetization coil design to effectively suppress the residual field. Experimental results demonstrate a 34.4% reduction in the residual field compared to the traditional demagnetization method. The proposed approach is well-suited for enhancing magnetic shielding performance in applications requiring ultra-low magnetic environments.