A simple and reproducible capacitive electrode.

Capacitive Electrodes (CE) allow the acquisition of biopotentials through a dielectric layer, without the use of electrolytes, just by placing them on skin or clothing, but demands front-ends with ultra-high input impedances. This must be achieved while providing a path for bias currents, calling for ultra-high value resistors and special components and construction techniques. A simple CE that uses bootstrap techniques to avoid ultra-high value components and special materials is proposed. When electrodes are placed on the skin; that is, with coupling capacitances C(S) of around 100 pF, they present a noise level of 3.3 µV(RMS) in a 0.5-100 Hz bandwidth, which is appropriate for electrocardiography (ECG) measurements. Construction details of the CE and the complete circuit, including a fast recovery feature, are presented.

[1]  S W Smye,et al.  The effect of improved modelling of plasma clearance in paediatric patients with expanded body spaces on estimation of the glomerular filtration rate , 2010, Physiological measurement.

[2]  S. Lanyi.  The noise of input stages with low parasitic capacitance , 2001 .

[3]  Yong Gyu Lim,et al.  Thin and flexible active electrodes with shield for capacitive electrocardiogram measurement , 2010, Medical & Biological Engineering & Computing.

[4]  C. Goodman.  Association for the Advancement of Medical Instrumentation , 1988 .

[5]  T. J. Sullivan,et al.  A Low-Noise, Non-Contact EEG/ECG Sensor , 2007, 2007 IEEE Biomedical Circuits and Systems Conference.

[6]  W. M. Portnoy,et al.  Improved capacitive electrocardiogram electrodes for burn applications , 1979, Medical and Biological Engineering and Computing.

[7]  W. Portnoy,et al.  Insulated electrocardiogram electrodes , 1972, Medical and biological engineering.

[8]  J. Rosell,et al.  An improved buffer for bioelectric signals , 1989, IEEE Transactions on Biomedical Engineering.

[9]  Marcelo Haberman,et al.  Insulating electrodes: a review on biopotential front ends for dielectric skin–electrode interfaces , 2010, Physiological measurement.

[10]  T. D. Clark,et al.  An ultra-low-noise electrical-potential probe for human-body scanning , 2000 .

[11]  Marcelo Haberman,et al.  A capacitive electrode with fast recovery feature , 2012, Physiological measurement.

[12]  T. D. Clark,et al.  Non-contact VLSI imaging using a scanning electric potential microscope , 1998 .

[13]  T. D. Clark,et al.  Electric potential probes - new directions in the remote sensing of the human body , 2002 .

[14]  Tzyy-Ping Jung,et al.  Dry-Contact and Noncontact Biopotential Electrodes: Methodological Review , 2010, IEEE Reviews in Biomedical Engineering.