电容耦合非接触电极及心电信号获取
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摘要
电极与皮肤间接触所导致的不适感,是穿戴式心电信号测量系统实际应用中的常见问题。设计了一种非接触心电信号测量系统。采用印刷电路板制作的测量电极,借助电容耦合测量位移电流的方式获取心电信号。采用反接二极管提供测量所需的高阻值偏置电阻,结合高输入阻抗仪表放大器,制作了测量电极信号提取电路。测量系统由两个测量电极与一个直接与测量电路地相连的参考电极组成。选择金属铝板、导电纤维和导电橡胶作为参考电极,实验研究了共模干扰抑制性能与参考电极接触阻抗之间的量化关系。将主元分析与奇异谱分析相结合,提出了一种心电信号处理算法。实验结果表明,该系统可在棉质线衣外侧有效获得满意的心电信号。
In practical applications of wearable electrocardiogram( ECG) monitoring systems,the discomfortness caused by the contact between the electrodes and skin is a common problem. A non-contact ECG measurement system is designed. The sensing electrodes are made from standard printed circuit board(PCB). The ECG signal is obtained by means of displacement current measurement in a capacitive coupling way. A reversely connected diode is used to provide the required high-value bias resistance for the measurement; the pickup circuit for the measurement electrode is implemented with a high input impedance instrumentation amplifier. The measurement system is composed of two measurement electrodes,together with one reference electrode that is directly connected to the measurement circuit ground. Aluminum plate,conductive textile,and conductive polymer are selected as the reference electrode,respectively. The relationship between the common-mode interference suppression performance and the contact impedance of the reference electrode is analyzed quantitatively in experiment. A new ECG signal processing algorithm,which combines principal component analysis(PCA) and singular spectrum analysis(SSA),is proposed. Experiment results show that this system can effectively obtain satisfied ECG signals outside cotton-fiber clothing.
In practical applications of wearable electrocardiogram( ECG) monitoring systems,the discomfortness caused by the contact between the electrodes and skin is a common problem. A non-contact ECG measurement system is designed. The sensing electrodes are made from standard printed circuit board(PCB). The ECG signal is obtained by means of displacement current measurement in a capacitive coupling way. A reversely connected diode is used to provide the required high-value bias resistance for the measurement; the pickup circuit for the measurement electrode is implemented with a high input impedance instrumentation amplifier. The measurement system is composed of two measurement electrodes,together with one reference electrode that is directly connected to the measurement circuit ground. Aluminum plate,conductive textile,and conductive polymer are selected as the reference electrode,respectively. The relationship between the common-mode interference suppression performance and the contact impedance of the reference electrode is analyzed quantitatively in experiment. A new ECG signal processing algorithm,which combines principal component analysis(PCA) and singular spectrum analysis(SSA),is proposed. Experiment results show that this system can effectively obtain satisfied ECG signals outside cotton-fiber clothing.
引文
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[3]梁振虎,古悦,杨春林,等.基于安卓平台的脑-心电远程监控系统[J].国外电子测量技术,2014,33(6):91-94.LIANG ZH H,GU Y,YANG CH L,et al.Remote EEGECG monitoring system based on Android platform[J].Foreign Electronic Measurement Technology,2014,33(6):91-94.
[4]朱凌云,吴宝明,王正国,等.移动心电监护系统QRS波的实时检测算法研究[J].仪器仪表学报,2005,26(6):603-607.ZHU L Y,WU B M,WANG ZH G,et al.A real-time QRS complex detection algorithm for mobile ECG telemonitoring system[J].Instrument Technique and Sensor,2005,26(6):603-607.
[5]UENO A,AKABANE Y,KATO T,et al.Capacitive sensing of electrocardiographic potential through cloth from the dorsal surface of the body in a supine position:A preliminary study[J].Biomedical Engineering,IEEE Transactions on,2007,54(4):759-766.
[6]SULLIVAN T J,DEISS S R,CAUWENBERGHS G.A low-noise,non-contact EEG/ECG sensor[C].Biomedical Circuits and Systems Conference,IEEE,2007:154-157.
[7]BAEK H J,CHUNG G S,KIM K K,et al.A smart health monitoring chair for nonintrusive measurement of biological signals[J].Information Technology in Biomedicine,IEEE Transactions on,2012,16(1):150-158.
[8]ALEKSANDROWICZ A,LEONHARDT S.Wireless and Non-contact ECG Measurement System-the“Aachen Smart Chair”[J].Acta Polytechnica,2007,47(4-5).
[9]FAGGION L,MAHDI A E.Noncontact human electro-physiological measurements using a new displacement current sensor[C].Sensors,IEEE,2011:296-299.
[10]CHI Y M,NG P,KANG E,et al.Wireless non-contact cardiac and neural monitoring[C].Wireless Health2010.ACM,2010:15-23.
[11]周平,汪丰,刘梦星,等.非接触式心电测量的噪声抑制研究[J].仪器仪表学报,2013,34(10):2226-2230.ZHOU P,WANG F,LIU M X,et al.Design of capacitance-based non-contact ECG sensor[J].Instrument Technique and Sensor,2013,34(10):2226-2230.
[12]CHI Y M,CAUWENBERGHS G.Wireless non-contact EEG/ECG electrodes for body sensor networks[C].Body Sensor Networks(BSN),2010 International Conference on.IEEE,2010:297-301.
[13]SPACH M S,BARR R C,HAVSTAD J W,et al.Skinelectrode impedance and its effect on recording cardiac potentials[J].Circulation,1966,34(4):649-656.
[14]GOLYANDINA N,ZHIGLJAVSKY A.Singular spectrum analysis for time series[M].Springer,2013.
[15]ABDI H,WILLIAMS L J.Principal component analysis[J].Wiley Interdisciplinary Reviews:Computational Statistics,2 0 1 0,2(4):4 3 3-4 5 9.
[16]O'Haver T C.An introduction to signal processing in chemical measurement[J].Journal of Chemical Education,1991,68(6):A147.