适用于穿戴式EIT系统的3种Howland电流源电路性能对比研究  

Comparison study of three Howland current source circuits for wearable EIT systems

作　　者：伏丹晨 付峰 史学涛 刘本源 杨滨 马航 李蔚琛 夏军营 FU Dan-chen;FU Feng;SHI Xue-tao;LIU Ben-yuan;YANG Bin;MA Hang;LI Wei-chen;XIA Jun-ying(School of Biomedical Engineering,Air Force Medical University,Xi'an 710032,China)

机构地区：[1]空军军医大学军事生物医学工程学系

出　　处：《医疗卫生装备》2020年第1期1-6,20,共7页Chinese Medical Equipment Journal

基　　金：国家自然科学基金重点项目(51837011);军队重大项目(AWS14C006);空军军医大学医学提升计划(2018HKTS10)

摘　　要：目的:对比标准Howland电流源电路、带缓冲反馈的Howland电流源电路和桥式Howland电流源电路在穿戴式电阻抗测量要求下的性能差异,为选择出一种更加适合于穿戴式电阻抗成像(electrical impedance tomography,EIT)系统的电流源电路提供参考。方法:在对3种电流源电路结构进行分析对比的基础上,利用Multisim仿真软件对3种电流源电路的输出阻抗、恒流特性以及动态输出范围进行仿真分析,结合课题组设计的穿戴式EIT系统进行实测分析并与仿真结果进行对比。结果:仿真实验中,桥式Howland电流源电路在输出阻抗、恒流特性以及动态输出范围3个方面都明显优于标准Howland电流源电路和带缓冲反馈的Howland电流源电路,当施加50 kHz的激励信号时,桥式Howland电流源电路的输出阻抗可以达到6 MΩ以上;带缓冲反馈的Howland电流源电路的动态输出范围大于标准Howland电流源电路,而输出阻抗和恒流特性不如标准Howland电流源电路,这与电路分析的结果一致。实际电路测量中,桥式Howland电流源电路的恒流特性优于标准Howland电流源电路和带缓冲反馈的Howland电流源电路,输出阻抗大于标准Howland电流源电路和带缓冲反馈的Howland电流源电路,50 kHz输出阻抗实测能达到800 kΩ。结论:相对于其他2种电流源电路,桥式Howland电流源电路更加适合应用于穿戴式EIT系统。Objective To study the performances of standard Howland current source circuit,Howland current source circuit with buffered feedback path and Howland current source circuit with bridge configuration under wearable application requirements,and to provide references for choosing a suitable current source circuit model for wearable EIT systems.Methods Based on the analyses of their circuit structures,stimulation tests were performed with Multisimoutput resistance,constant current property and output dynamic range.With the wearable EIT system designed actual measurement was carried out and the results were compared with those from the simulation tests.Results In stimulation tests,Howland current source circuit with bridge configuration had advantages over the other two in aspects of output resistance,constant current property and output dynamic range and could reach an output resistance of over 6 MΩat 50 kHz.Howland current source circuit with buffered feedback path was superior to the standard Howland current source circuit in aspects of dynamic output range while was inferior in aspects of output resistance and constant current property,which was consistent with circuit analyses.In actual measurement,Howland current source circuit with bridge configuration performed better than the other two configurations in output resistance and constant current property and could get an output resistance of 800 kΩat 50 kHz.Conclusion Compared with standard Howland current source circuit and Howland current source circuit with buffered feedback path,Howland current source circuit with bridge configuration is a better choice for wearable application.

关 键 词：电阻抗断层成像 穿戴式 Howland电流源 输出阻抗 恒流特性 动态输出范围 

分 类 号：R318[医药卫生—生物医学工程]