Capacitive ECG Measurement by Conductive Fabric Tape

Authors: Yue-Der Lin, Ya-Hsueh Chien, Yen-Ting Lin, Shih-Fan Wang, Cheng-Lun Tsai, Ching-Che Tsai

Abstract:

Capacitive electrocardiogram (ECG) measurement is an attractive approach for long-term health monitoring. However, there is little literature available on its implementation, especially for multichannel system in standard ECG leads. This paper begins from the design criteria for capacitive ECG measurement and presents a multichannel limb-lead capacitive ECG system with conductive fabric tapes pasted on a double layer PCB as the capacitive sensors. The proposed prototype system incorporates a capacitive driven-body (CDB) circuit to reduce the common-mode power-line interference (PLI). The presented prototype system has been verified to be stable by theoretic analysis and practical long-term experiments. The signal quality is competitive to that acquired by commercial ECG machines. The feasible size and distance of capacitive sensor have also been evaluated by a series of tests. From the test results, it is suggested to be greater than 60 cm2 in sensor size and be smaller than 1.5 mm in distance for capacitive ECG measurement.

Keywords: capacitive driven-body (CDB) circuit, capacitive electrocardiogram (ECG) measurement, capacitive sensor, conductive fabric tape, power-line interference (PLI).

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1331691

References:

[1] A. J. Lopez and P. C. Richardson, "Capacitive electrocardiographic and bioelectric electrodes," IEEE Trans Biomed. Eng., vol.16, pp. 99, Jan. 1969.
[2] R. J. Prance, A. Debray, T. D. Clark, H. Prance, M. Nock, C. J. Harland and A. J. Clippingdale, "An ultra-low-noise electrical-potential probe for human-body scanning," Meas. Sci. Technol., vol.11, pp. 291-297, Mar. 2000.
[3] C. J. Harland, T. D. Clark, N. S. Peters, M. J .Everitt and P. B. Stiffell, "A compact electric potential sensory array for the acquisition and reconstruction of the 7-lead electrocardiogram without electrical charge contact with the skin," Physiol. Meas. vol.26, pp. 939-950, Dec. 2005.
[4] Y. G. Lim, K. K. Kim and K. S. Park, "ECG measurement on a chair without conductive contact," IEEE Trans. Biomed. Eng., vol.53, pp. 956-959, May 2006.
[5] M. Steffen, A. Aleksandrowicz and S. Leonhardt, "Mobile noncontact monitoring of heart and lung activity," IEEE Trans. Biomed. Circ. Syst., vol.1, pp. 250-257, Dec. 2007.
[6] A. Ueno, Y. Akabane, T. Kato, H. Hoshino, S. Kataoka and Y. Ishiyama, "Capacitive sensing of electrocardiographic potential through cloth from the dorsal surface of the body in a supine position: a preliminary study," IEEE Trans. Biomed., Eng., vol.54, pp. 759-766, Apr. 2007.
[7] M. Oehler, V. Ling, K. Melhorn and M. Schilling, "A multichannel portable ECG system with capacitive sensors," Physiol. Meas., vol.29, pp. 783-793, Jul. 2008.
[8] Y. G. Lim, K. K. Kim and K. S. Park, "ECG recording on a bed during sleep without direct skin-contact," IEEE Trans. Biomed. Eng., vol.54, pp. 718-725, Apr. 2007.
[9] A. Gruetzmann, S. Hanse and J. M├╝ller, "Novel dry electrodes for ECG monitoring," Physiol. Meas., vol.28, pp. 1375-1390, Nov. 2007.
[10] N. V. Thakor and J. G. Webster, "Ground-free ECG recording with two electrodes," IEEE Trans. Biomed. Eng., vol.27, pp. 699-704, Dec. 1980.
[11] B. B. Winter and J. G. Webster, "Driven-right-leg circuit design," IEEE Trans. Biomed. Eng., vol.30, pp. 62-66, Jan. 1983.
[12] M. R. Neuman, "Biopotential amplifiers," in Medical Instrumentation: Application and Design, 2nd ed., J G Webster, Ed. Boston, MA: Houghton Mifflin, 1992, pp. 288-353.
[13] Y. M. Chi, T. P. Jung and G. Cauwenberghs, "Dry-contact and noncontact biopotential electrodes: methodological review," IEEE Rev. Biomed. Eng., vol.3, pp. 106-119, Dec. 2010.