多电极血液流速仪励磁系统优化研究

Simulation research on excitation system of multi-electrode blood flow meter

为了实现对人体血液流量测量及流速分布的监测,基于多电极电磁测量设计了血液流速仪,通过测量皮肤表面的感应电动势,实现对动、静脉血液流速的测量。首先,模仿人体肢体结构,包括皮肤、脂肪、骨骼、肌肉、动脉和静脉的尺寸和相对位置,建立COMSOL仿真模型。然后,以赫姆霍兹线圈、C型铁芯线圈为基础,仿真研究了多种励磁结构和励磁方式在肢体测量截面处激励的电磁感应强度分布,提出了励磁线圈的优化设计方案,最后,对不同结构、不同激励方式的励磁系统进行了优化对比。结果表明,两对正交布置并且采用同向激励电流的赫姆霍兹线圈磁场呈中心对称,磁场强度和均匀性均优于其他励磁系统,能够有效增强感应电动势数值,更适用于非轴对称流的多电极电磁测量。研究结果验证了励磁系统优化方案的可行性,以及其均匀性对于提高速度重构精度的积极作用。

In order to monitor human blood flow rate and flow velocity distribution,a blood flow meter based on multi-electrode electromagnetic measurement has been proposed to measure the flow velocity of the arteriovenous blood by obtaining the induced voltage on the skin surface.The COMSOL 3-D model has been built to simulate the physical structure of the human limb,including the size and relative position of skin,fat,bones,muscles,arteries and veins.Based on the Helmholtz coil and C-type coil,the electromagnetic induction intensity distribution of excitation structures and methods is simulated which is imposed through the body measurement section.The optimal design scheme of the excitation coil is proposed.Different excitation systems of different structures and different incentive methods are compared.The result shows that the two pairs of Helm-holtz coils of orthogonal layout with syntroph excitation current has better uniformity,field center symmetry and stronger magnetic field strength,and effectively enhances the value of induction electromotive force,showing it is more suitable for multielectrode electromagnetic measurement of non-axisymmetric flow.The research result proves that the optimization scheme of excitation system is feasible,and its uniformity plays a positive role in improving the accuracy of velocity reconstruction.