To implement a fast location of metallic foreign body in human body and fast preoperative or postoperative detection of surgical instruments, a portable device based on gradient measurement of fluxgate sensors was designed. Two working modes based on remnant magnetic effect and eddy current effect were proposed for locating two different kinds of metal, thereby solving the problem that nonferromagnetics could not be sensed by fluxgate. Metglas ribbon and modified race-track core were chosen and digital signal processor was utilized to implement harmonic extraction and cross correlation algorithm, which could mean a better fluxgate performance. Database of the depth information was established to provide the ability of analyzing the depth in human body. The locating experiments of 15 foreign body patients has demonstrated the effectiveness of the proposed portable device in clinic applications.%为实现患者体内金属异物的准确定位及术前术后手术器械的快速排查,设计了基于磁通门梯度测量方式的便携式装置.提出基于剩磁效应的铁磁性金属定位方法和基于电涡流效应的非铁磁性金属定位模式,用以解决传统磁通门无法感应非铁磁性金属的问题.采用改进的跑道型磁芯结构,选择钴基非晶合金Metglas2705M作为磁芯材料,以数字信号处理器为核心进行谐波提取和互相关滤波处理,提高了磁通门性能.通过建立信息数据库使该装置具有一定深度分析能力.15例异物患者临床实验证明,该技术便捷有效,有良好的临床应用前景.
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