基于硬磁薄膜材料的GMI传感器偏置磁场分布模拟

Simulation of the bias magnetic field distribution of GMI sensor based on permanent magnetic film

由于GMI效应对磁场的对称性特点，在传感器设计中，通常采用引入偏置磁场的方法来提高GMI传感器的灵敏度。而采用硬磁薄膜材料作为GMI传感器的偏置磁场源，可在提供80～160A／m的偏置磁场的前提下，实现GMI传感器的低功耗和微型化。运用COMSOL软件对薄膜材料的空间磁场分布进行了模拟，研究了薄膜材料特性及其尺寸对空间磁场分布的影响，并对影响有限元分析结果可靠性的因素进行了探讨。研究结果表明，硬磁薄膜材料的剩余磁化强度为0.3～0．7MA／m、长度为5～7mm、厚度为7～13μm时可以为GMI传感器敏感元件提供符合要求的偏置磁场源。

Because of the GMI effect＇s symmetrical impedance characteristics with the externally applied fields, the sensor is usually designed by adding a bias magnetic field to improve its sensitivity. Using permanent magnetic film to provide bias magnetic field, could not only meet the condition of 80-160 A/m bias field, but also benefit the miniaturization and the low-power dissipation of the sensor. A permanent magnetic film material model is established to simulate the field distribution of the film material to study the influence of the film property and size on magnetic field the film produces, and analyze the factors affecting the reliability of the FEM solution. The results show that film with remanent magnetization of 0.3 to 0.7 MA/m, length of 5 to 7mm and thickness of 7 to 13 μm can provide a bias field meeting the requirement for GMI senser.