Abstract: Cardiovascular disease (CVD) is a leading cause to mortality in the population, accounting for more than 47% of deaths and posing a serious threat to people's health. Electrocardiography (ECG), as the primary method for detecting the cardiac electrical activity, plays a pivotal role in the prediction and diagnosis of CVD. Conventional ECG systems use disposable Ag/AgCl gel wet electrodes, and while these electrodes are capable of acquiring better bioelectrical signals, the drying up of the gel and the irritation with the skin during long-term use seriously affects patients' willingness to use them. Fabric dry electrodes, by virtue of excellent conformability and comfort, as well as their good electrical conductivity and mechanical stability, have a wide range of applications in wearable ECG monitoring. According to the different preparation processes, fabric electrodes can be mainly categorized into woven fabric electrodes, knitted fabric electrodes and embroidered electrodes.
However, the factors affecting the quality of ECG signals involve not only the preparation process of fabric electrodes, but also the contact impedance between the electrodes and the skin as well as the adaptability under dynamic conditions. To investigate the effects of different preparation processes on the quality of ECG signals from fabric electrodes, we utilized silver/nylon yarn as the primary conductive material and prepared eight different types of fabrics through three distinct processes. These fabrics included three woven fabrics, two knitted fabrics, and three embroidered fabrics. By assessing their surface conductivity, we identified the woven fabric (W3), knitted fabric (K2), and embroidered fabric(E3) types that exhibited the best conductivity. For the woven fabrics, the resistance values increased with the distance between the two test points and were approximately equal when the test points were equidistant. The magnitude of the surface resistance of knitted fabrics was closely related to the coil density. The conductivity of embroidered fabrics was affected by the combination (intersection density) of stitch direction and stitch density, etc. We prepared these three fabrics as cardiofabric electrodes and tested them by electrode-copper-plate low-frequency impedance and electrode-skin contact impedance, and concluded that longer floating-length wires, denser coil structure, higher stitch intersection density, and a larger contact area were important factors for lowering the impedance.
After that, we prepared woven, knitted and embroidered fabric electrocardiographic tapes and comprehensively analyzed the factors affecting the quality of dynamic and static electrocardiographic signals, including structural tightness, contact uniformity and dynamic adaptability. The results showed that different preparation processes and fabric structures significantly affected the conductivity of the electrodes and the quality of contact with the skin, which in turn affected the accuracy and stability of the ECG signals. E3 outperformed both W3 and K2 electrodes in terms of structural compactness, contact uniformity, and dynamic adaptability, and was able to acquire the highest quality ECG signals in both dynamic and static states, with the static Pearson correlation coefficient of 0.94 and the dynamic one above 0.91.

Key words: fabric electrodes, ECG bands, skin impedance, ECG, Pearson correlation coefficient

摘要： 为了探究不同制备工艺对织物电极心电信号质量的影响，采用针织、机织和刺绣工艺制备了8种结构的织物电极，并对其进行表面导电性分析，结果发现：机织物表面电阻随测试点距离增加而增加；针织物表面电阻与线圈密度相关；刺绣电极导电性受针迹方向和密度影响，交集密度越大，导电性越好。将表面电阻最小的五枚三飞纬面缎纹机织物、1＋1罗纹9×36结构的针织物和填充针迹的刺绣织物与弹力带集成，分析电极-铜板低频阻抗和电极-皮肤接触阻抗规律，在动静状态下对3种工艺的织物电极进行心电信号测试，结果发现：表面电阻和阻抗与织物的浮长线、线圈密度、针迹交集密度以及接触面积紧密相关。相比于一次性Ag/AgCl凝胶湿电极，3种工艺的织物电极在动静态下均能采集到质量较好的心电信号，刺绣工艺制备的填充织物电极采集到的信号质量最好，静态皮尔逊相关系数为0.94，动态皮尔逊相关系数在0.91以上。

关键词: 织物电极, 心电带, 皮肤阻抗, 心电图, 皮尔逊相关系数