退磁场对磁致伸缩应力耦合谐振磁传感器灵敏度的影响研究

Influence of the Demagnetizing Field Effect on the Sensitivity of the Resonant Magnetic Field Sensor based on Magnetostrictive Stress Coupling

将磁致伸缩材料与石英音叉谐振器复合的谐振式磁传感器具有高灵敏度、高分辨率、高Q值等优良性能。然而,磁性敏感材料的退磁场效应导致磁传感器的灵敏度随敏感材料的尺寸而变化。采用退磁因子计算经验公式与Maxwell电磁仿真相结合,分析了相同截面积、不同长度铁镓(FeGa)磁致伸缩合金的退磁因子,并将退磁因子代入非线性磁致伸缩模型,分析并预测了退磁场对FeGa合金磁致伸缩性能和FeGa/石英音叉谐振器复合谐振式磁场传感器灵敏度的影响。采用10.6 mm、20 mm和30 mm三种不同长度FeGa合金与石英音叉谐振器复合,制备器件实验表明:退磁因子和传感器灵敏度随FeGa合金长度增加而分别减小和增加,最优偏置点的灵敏度分别为3.7 Hz/Oe,5.8 Hz/Oe和9 Hz/Oe,实验结果和理论分析结果较为吻合。

The resonant magnetic sensors composed of magnetostrictive alloy and quartz tuning fork resonator feature the performances of high sensitivity,high resolution and high Q-factor.However,the sensitivity of the magnetic sensor changes with the size of the magnetostrictive material due to demagnetizing effect.The demagnetization factors of FeGa magnetostrictive alloys with the same cross-sectional area and different lengths are analyzed by using the empirical formula of demagnetization factor and Maxwell electromagnetic simulation.By substituting the demagnetization factor into the nonlinear constitutive model of magnetostrictive material,the influences of demagnetization on the magnetostrictive properties of FeGa alloy and the sensitivity of the resonant magnetic sensor are analyzed and predicted.The experimental results show that the demagnetization factor decreases and the sensitivity increases with the increase of the length of FeGa alloy,respectively.The sensitivity values of the sensors composed of quartz tuning fork resonator and FeGa magnetostrictive alloys with different lengths of 10.6 mm,20 mm and 30 mm are 3.7 Hz/Oe,5.8 Hz/Oe and 9 Hz/Oe,respectively.The experimental results are in good agreement with the theoretical analysis results.