Bi Ran, Zhang Huiquan, Pan Shi, Liu Xinting, Chen Ruiying, Wu Shilin, Hu Jun
Department of Electrical Engineering, Tsinghua University, Beijing 100084, China.
Sensors (Basel). 2025 Jul 31;25(15):4739. doi: 10.3390/s25154739.
Measuring weak magnetic fields proposes significant challenges to the sensing capabilities of magnetic field sensors. The magnetic field detection capacity of tunnel magnetoresistance (TMR) sensors is often insufficient for such applications, necessitating targeted optimization strategies to improve their performance in weak-field measurements. Utilizing magnetic flux concentrators (MFCs) offers an effective approach to enhance TMR sensitivity. In this study, the finite element method was employed to analyze the effects of different MFC geometric structures on the uniformity of the magnetic field in the air gap and the magnetic circuit gain (MCG). It was determined that the MCG of the MFC is not directly related to the absolute values of its parameters but rather to their ratios. Simulation analyses evaluated the impact of these parameter ratios on both the MCG and its spatial distribution uniformity, leading to the formulation of MFC design optimization principles. Building on these simulation-derived principles, several MFCs were fabricated using the 1J85 material, and an experimental platform was established to validate the simulation findings. The fabricated MFCs achieved an MCG of 7.325 times. Based on the previously developed TMR devices, a detection sensitivity of 2.46 nT/Hz @1Hz was obtained. By optimizing parameter configurations, this work provides theoretical guidance for further enhancing the performance of TMR sensors in magnetic field measurements.
测量弱磁场对磁场传感器的传感能力提出了重大挑战。隧道磁电阻（TMR）传感器的磁场检测能力在这类应用中往往不足，因此需要有针对性的优化策略来提高其在弱场测量中的性能。利用磁通量集中器（MFC）是提高TMR灵敏度的有效方法。在本研究中，采用有限元方法分析了不同MFC几何结构对气隙磁场均匀性和磁路增益（MCG）的影响。结果表明，MFC的MCG与其参数的绝对值没有直接关系，而是与其比值有关。仿真分析评估了这些参数比值对MCG及其空间分布均匀性的影响，从而得出了MFC设计优化原则。基于这些从仿真得出的原则，使用1J85材料制作了几个MFC，并建立了一个实验平台来验证仿真结果。制作的MFC实现了7.325倍的磁路增益。基于之前开发的TMR器件，在1Hz时获得了2.46 nT/Hz的检测灵敏度。通过优化参数配置，这项工作为进一步提高TMR传感器在磁场测量中的性能提供了理论指导。
