【作者】 王越；

【导师】 李刚；

【作者基本信息】 天津大学 ， 生物医学工程， 2006， 硕士

【摘要】 子宫肌层由平滑肌束和弹性纤维组成,在分娩时会出现有规律的电活动。子宫肌电信号能够反映肌肉纤维兴奋的原始过程,提供了有关子宫肌肉活动的辅助信息。由于体表子宫肌电(EHG)的检测是无创检测,是由放置在产妇腹部体表的电极记录到的子宫肌电活动,与目前使用的介入式的产程监护技术相比更适合于临床使用,是一种更理想的产程监护技术。本文首先从子宫细胞与组织水平的肌电活动、子宫体直接记录到的肌电信号与体表记录到的子宫电信号三个层面对子宫肌电信号研究已经取得的成果进行了全面的追踪和介绍。从工程研究的角度回顾了EHG信号研究的发展历程,介绍了EHG研究所采用的一般方法和已经取得的重要结论。对目前研究中仍然存在的一些问题进行了分析和归纳,并提出了本课题的研究内容。在信号的拾取方面,以往的研究大多采用的都是单导联分别记录,由于子宫电信号没有固定的起搏区域,单导联记录必将损失子宫活动的位相信息。也有研究采用多导联数据采集系统,但采用单极电极记录EHG信号,信号被噪声严重污染。本课题设计的16导宫缩检测仪采用双极电极记录,记录的是两个电极下区域的差动信号,因而可以抑制母体心电、母亲活动、电极移动和工频干扰这类共模噪声。整套系统便于携带,使用安全,实现了对信号的高质量采集。本文介绍了实验中用到的16导宫缩检测仪的设计原理,并分析了用于子宫肌电数据采集中现有系统存在的问题(如由于温漂以及子宫肌电采集系统高通截止频率低造成的前置放大器共模抑制比低等)。采用了一种新型的生理电前置放大器设计方案来解决这些问题。电路结构简单,可以在抑制直流干扰的情况下,提供极高的共模抑制比。该电路设计对外围无源器件的参数不敏感,即使采用低成本的常用芯片,无需刻意匹配仍然可以达到良好的性能,尤其适合生理电信号的高精度测量。本文引入了拉普拉斯算法,对采集到的EHG信号进行一定的分析和处理。采用五点电极法,对采集到的多导EHG信号进行拉普拉斯估算,得到EHG信号的拉普拉斯值,使信号更加局部化,减小了不同导联信号间的影响程度,为实现信号的源定位研究提供帮助。同时,提出了一种新型的有源拉普拉斯的电极的设计,为将其应用于临床EHG信号检测做准备。更多还原

【Abstract】 Derived from the electrical activity generated at the muscle fiber lever, uterine EMG provides complementary information on the muscle. During the last 60 years, uterine EMGs have been extensively investigated at the cell and tissue levels, at whole-organ myometrial and abdominal levels. EHG (Electrohysterogram) is the recording of uterine electromyogram with external electrodes located on the abdomen of pregnant woman. It provides complementary information on the muscle, and appears to be very promising techniques for clinical or physiologic investigations of uterine activity, compared with current invasive monitoring.However, until now, most of EHG study was based on only single-lead recordings. Since EHG signal has no fixed pace-making areas, single-lead recordings will lose phase information of uterine activity. Using unipolar electrode, the EHG signal is badly noised by many other signals (remaining of electrocardiogram, electromagnetic noise, electrode movement,…). A new kind of monitor system for the uterine contraction, therefore, is presented in this paper. The main problems involved in the development of a multi-channel EHG data-acquisition system are examined carefully and the respondent approaches to solve the problems are presented.To pick up multi-channel uterine EHGs exactly, a novel multi-channel biopotential amplifier is presented. The proposed circuit has many interesting characteristics regarding simplicity and cost, while achieving high CMRR and effective dc interference suppression without any trimming.The surface Laplacian involves the second derivative of the potential. It will give different and perhaps more localized information concerning the sources that give rise to the surface potential distribution. The surface Laplacian recordings can be obtained indirectly using a five electrodes array. In this article we put forward a new type of electrodes that is called active Laplacian electrode. It Integrates concentric rings electrode with bioelectricity preamplifier and is capable of acquiring localized information. We can local the EHG signals source more easily by using this new electrode.更多还原