中文摘要：

利用三端式磁通门传感器测量微弱低频弱磁信号原理,设计了磁通门测磁系统用于测量不同质量的磁性材料.该系统可以直接测量一定质量的磁纳米粒子感应磁场强度并将其转化为直流值电压,然后让电压值与质量建立对应关系.在分析三端式磁通门传感器的工作原理的基础上,基于二次谐波法,设计了包含差分放大、选频放大、带通滤波、相敏检波和低通滤波的测量电路,然后在此基础上设计了差分式双探头磁通门传感器弱磁测量系统,最后通过实验测试和数据采集与分析,证明利用此种原理设计的测量系统可以检测不同质量的磁性材料.

英文摘要：

Using three terminal fluxgate sensor for measuring weak magnetic signal of low frequency, the fluxgate mag- netic measurement system for measuring magnetic materials of different quality is designed. The system can directly measure the magneticfield strength of magnetic nanoparticles and converted it to dc value, and establish corresponding relationship with the quality and the dc value. The working principle of the fluxgate sensor is analyzed, and a measurement circuit inclu- ding the differential amplifier, select frequency amplifier, Band-pass filter, phase sensitive detection, low pass filter are de- signed based on second harmonic method. Finally measurement system is proved could be used to measure the mass of mag- netic nanoparticles through the experiment.