MEMS铁磁磁场传感器的研究

Study on MEMS ferromagnetic magnetic field sensors

提出了一种新型的基于Si压阻效应的铁磁体MEMS磁场传感器结构,其结构由制作在硅桥敏感膜表面的惠斯通电桥和在膜中间旋涂环氧胶沾上铁磁体制成。铁磁体在外磁场中磁化产生磁力,磁力耦合到硅桥敏感膜上会产生应力使膜上的惠斯通电桥产生电压输出以达到测量磁场的目的。文章先通过有限元软件对铁磁体在磁场中的受力大小和磁场传感器在磁力下的输出进行了仿真,然后对该结构进行了测试,仿真结果和实验结果较接近。实验测得该传感器最大灵敏度为70 mV/T,分辨率为330μT。该磁场传感器结构简单、工艺成熟、成本低,易于大批量生产。

A novel MEMS magnetic field sensor is proposed based on piezoresistive effect, which is composed of a silicon sensitivity diaphragm of silicon bridge, an embedded piezoresistive Wheatstone bridge and a ferromagnetic magnet adhered on the silicon diaphragm. When the bridge is subjected to an external magnetic field to be measured, the magnetic force bends the silicon sensitive diaphragm, thereby produces a stress that causes a piezoresistance change in the Wheatston bridge. So the magnetic field intensity can be measured by the output voltage of the Wheatstone bridge. The sensor has been simulated using finite element software tool. The paper compares the result obtained from the simulation with the response from the test. Experiment results demonstrate that the maximum sensitivity and resolution of the sensor are 70 mV/T and 330μT, respectively. The proposed magnetic field sensor features simply principle, mature technology, low cost and easy to be put into cost-effective batch fabrication.