【作者】 王斯亮；

【导师】 林凌；

【作者基本信息】 天津大学 ， 生物医学工程， 2008， 硕士

【摘要】 生物电阻抗测量技术是近年来发展起来的一门新兴技术,该技术具有廉价、安全、无毒无害等特点,是一种具有广泛应用前景的无损检测技术,已作为生物医学工程领域的重要研究课题,受到国内外临床医学和生物医学工程学界的广泛重视。近年来生物电阻抗测量技术发展迅速,被广泛应用于生理病理参数监护中,特别是在经络实质的研究中,经络阻抗测量法成为研究经络实质的重要手段之一。然而,目前生物阻抗测量技术还存在一定问题,比如,利用单一频率激励信号测量,得到信息不完整;采用分立式电路,抗干扰性能较差;采用基于欧姆定律的测量原理,对电流源精度依赖性较大;后续软件校准部分的算法简单,占用资源较大,不适合低端控制器。针对上述情况,本文设计了一种基于AD5933的精密生物阻抗谱测量方法。该方法利用了比例测量和DFT解调等高精度测量原理,具有电路集成度高,能实现快速扫频测量,对信号源精度依赖性小等特点。结合AD5933的稳定度和可重复性好的特点,本文设计了软件校准方法,分别对模值和相位进行校准,进一步提高了测量精度,该算法简单,可以在单片机上实现。利用上述方法,设计了基于AD5933的精密生物阻抗谱测量系统,实现了系统的硬件和软件部分,并利用自行设计的系统测量了针灸过程中的经络阻抗谱变化,对试验结果进行了初步分析。实验得到了明显的趋势性现象:行针后,同一激励频率下,随着留针时间的增加,经络阻抗模值先减小后回升,低频时变化的更明显;经络阻抗的相角逐渐减小的,10KHz时变化量最大。更多还原

【Abstract】 Bioelectrical Impedance Measuring Technology (BIMT) is a new technology developed in recent years. Due to the feature of non-invasive, low-cost, safety, nontoxic and harmless, it has extensive application perspective. The special attention is paid to the BIMT technique by the researchers in biomedical engineering and clinical medicine areas. In recent years the BIMT has been widely used in various fields, for instance in the area of meridians and collaterals impedance study.At the same time, the BIMT still has some problems, for example most system use single frequency source that can’t give entire imformation; most systems don’t use integrate circuit which has more anti-interference capability; most systems base on the Ohm’s law, and their accuracy have greater dependence on the current source; most algorithm of software calibration is easy to understand, but it is hard to implement on the low-end CPU.In light of the above, this paper designe a high-accuracy bio-impedance spectrum measurement based on AD5933 which uses high-precision theory such as proportion-measurement and DFT demodulation technique. This method has high integration, and less dependence on the source. And also a method of compensation is proposed on account of the stability of AD5933.The magnitude and phase are compensated separately; and this algorithm can be implemented on the SCM.By designing the hardware and software following the above method, a bio-impedance spectrum system is implemented. This system is used to test the changes of meridians and collaterals impedance spectrum when acupuncturing. The experimental result indicates that when acupuncturing the magnitude pick-up after the first decrease, more in lower frequency and the phase decrease, most at 10KHz.更多还原