数字化生物电阻抗测量平台研究
发布时间：2018-10-12 18:47
【摘要】：人体组织器官具有独特的电特性(阻抗、导纳、介电常数等),在新陈代谢过程中出现生理和病理状态改变就会引起相应电特性的改变。生物电阻抗技术(Electrical Bioimpedance Technology)是利用生物组织与器官的电特性及其变化提取相关信息的无损伤检测技术。其最大优势在于提取与人体生理病理状态相联系的功能性或前瞻性信息,具有无创、廉价、安全、无毒无害和信息丰富的特点,广泛应用于心、脑、肺血管及循环系统功能检测,肿瘤的早期发现和诊断,胃动力学检测,人体组成成份测定,电阻抗断层成像(Electrical Impedance Tomography, EIT)等。 本研究在总结生物电阻抗技术的研究进展和测量理论发展的基础上,针对多频、复阻抗生物电阻抗测量的要求,研究以FPGA芯片为核心通用型数字化生物电阻抗测量实验平台,具体工作如下： 1、分析生物电阻抗技术的发展动态,提出数字化多频、复阻抗测量系统这一研究目标,基于FPGA的数字系统开发与设计方法,设计实验平台的结构框图,并规划各模块的功能。 2、基于FPGA和DDS技术设计了输出频率为6.1KHz～1562.5KHz的数字信号发生器,采用改进的Howland电路由THS4021芯片构建恒流激励源,其输出阻抗有较好的频率稳定性,在6.1KHz～97.7KHz的范围内输出阻抗维持在200KΩ附近,当频率为390.6KHz时输出阻抗可保持在170KΩ。 3、采用基于FPAG的数字技术,依据生物阻抗信号的正交解调方法,构建了高质量正交解调和串口通信等模块。能同时获取被测阻抗信号的实部和虚部信息,完成数据采集和传送等功能,用于复阻抗全信息测量。 4、进行了电阻、电容和三元件模型的测试实验和误差分析,验证了本研究平台的有效性和准确性；基于16电极盐水槽实验系统,采用相邻激励-相邻测量模式进行了EIT盐水槽成像实验,初步验证了本研究平台用于EIT测量的可行性。 最后对研究工作进行了总结,并对今后进一步完善研究平台提出了建议。
[Abstract]:Human tissues and organs have unique electrical properties (impedance, admittance, dielectric constant, etc.). The changes of physiological and pathological state in metabolic process will cause the corresponding changes of electrical properties. Bioelectrical impedance (Electrical Bioimpedance Technology) is a nondestructive detection technique which uses electrical properties and changes of biological tissues and organs to extract relevant information. Its greatest advantage lies in the extraction of functional or forward-looking information related to the physiological and pathological state of the human body. It has the characteristics of non-invasive, cheap, safe, non-toxic and informative, and is widely used in the heart and brain. Detection of pulmonary vascular and circulatory function, early detection and diagnosis of tumor, gastric dynamics, composition of human body, electrical impedance tomography (Electrical Impedance Tomography, EIT), etc. On the basis of summarizing the research progress of bioelectric impedance technology and the development of measurement theory, aiming at the requirement of multi-frequency and complex impedance bioelectrical impedance measurement, this paper studies the FPGA chip as the core and general digital experimental platform for bioelectrical impedance measurement. The main work is as follows: 1. The development trend of bioelectric impedance technology is analyzed. The research goal of digital multi-frequency and complex impedance measurement system is put forward. The development and design method of digital system based on FPGA is presented. The structure block diagram of the experimental platform is designed, and the functions of each module are planned. 2. Based on FPGA and DDS technology, the digital signal generator with output frequency of 6.1KHz~1562.5KHz is designed. The improved Howland circuit is used to construct the constant current excitation source from THS4021 chip. The output impedance has good frequency stability. In the range of 6.1KHz~97.7KHz, the output impedance is kept around 200K 惟, and when the frequency is 390.6KHz, the output impedance can be kept at 170K 惟. 3. The digital technique based on FPAG is used. According to the quadrature demodulation method of biological impedance signal, the high quality quadrature demodulation and serial communication module are constructed. It can simultaneously obtain the real and imaginary part information of the impedance signal under test, complete the functions of data acquisition and transmission, and be used to measure the full information of complex impedance. 4. The testing experiment and error analysis of resistance, capacitance and three-element model are carried out. The validity and accuracy of the research platform are verified. Based on the 16-electrode salt flume experimental system, the EIT salt flume imaging experiment is carried out by using adjacent excitation-adjacent measurement mode, and the feasibility of using this platform for EIT measurement is preliminarily verified. Finally, the research work is summarized and some suggestions are put forward to further improve the research platform in the future.
【学位授予单位】：北京协和医学院
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：R318.0
本文编号：2267211
[Abstract]:Human tissues and organs have unique electrical properties (impedance, admittance, dielectric constant, etc.). The changes of physiological and pathological state in metabolic process will cause the corresponding changes of electrical properties. Bioelectrical impedance (Electrical Bioimpedance Technology) is a nondestructive detection technique which uses electrical properties and changes of biological tissues and organs to extract relevant information. Its greatest advantage lies in the extraction of functional or forward-looking information related to the physiological and pathological state of the human body. It has the characteristics of non-invasive, cheap, safe, non-toxic and informative, and is widely used in the heart and brain. Detection of pulmonary vascular and circulatory function, early detection and diagnosis of tumor, gastric dynamics, composition of human body, electrical impedance tomography (Electrical Impedance Tomography, EIT), etc. On the basis of summarizing the research progress of bioelectric impedance technology and the development of measurement theory, aiming at the requirement of multi-frequency and complex impedance bioelectrical impedance measurement, this paper studies the FPGA chip as the core and general digital experimental platform for bioelectrical impedance measurement. The main work is as follows: 1. The development trend of bioelectric impedance technology is analyzed. The research goal of digital multi-frequency and complex impedance measurement system is put forward. The development and design method of digital system based on FPGA is presented. The structure block diagram of the experimental platform is designed, and the functions of each module are planned. 2. Based on FPGA and DDS technology, the digital signal generator with output frequency of 6.1KHz~1562.5KHz is designed. The improved Howland circuit is used to construct the constant current excitation source from THS4021 chip. The output impedance has good frequency stability. In the range of 6.1KHz~97.7KHz, the output impedance is kept around 200K 惟, and when the frequency is 390.6KHz, the output impedance can be kept at 170K 惟. 3. The digital technique based on FPAG is used. According to the quadrature demodulation method of biological impedance signal, the high quality quadrature demodulation and serial communication module are constructed. It can simultaneously obtain the real and imaginary part information of the impedance signal under test, complete the functions of data acquisition and transmission, and be used to measure the full information of complex impedance. 4. The testing experiment and error analysis of resistance, capacitance and three-element model are carried out. The validity and accuracy of the research platform are verified. Based on the 16-electrode salt flume experimental system, the EIT salt flume imaging experiment is carried out by using adjacent excitation-adjacent measurement mode, and the feasibility of using this platform for EIT measurement is preliminarily verified. Finally, the research work is summarized and some suggestions are put forward to further improve the research platform in the future.
【学位授予单位】：北京协和医学院
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：R318.0
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