Low Impedance Carbon Adhesive Electrodes with Long Shelf Life

A novel electrocardiogram (ECG) electrode film is developed by mixing carbon black powder and a quaternary salt with a visco-elastic polymeric adhesive. Unlike traditional wet gel-based electrodes, carbon/salt/adhesive (CSA) electrodes should theoretically have an infinite shelf life as they do not dehydrate even after a prolonged period of storage. The CSA electrodes are electrically activated for use through the process of electrophoresis. Specifically, the activation procedure involves sending a high voltage and current through the electrode, which results in significant reduction of impedance so that high fidelity ECG signals can be obtained. Using the activation procedure, the ideal concentration of carbon black powder in the mixture with the adhesive was examined. It was determined that the optimum concentration of carbon black which minimized post-activation impedance was 10%. Once the optimal carbon black powder concentration was determined, extensive signal analysis was performed to compare the performance of the CSA electrodes to the standard silver–silver chloride (Ag/AgCl) electrodes. As a part of data analysis, electrode–skin contact impedance of the CSA was measured and compared to the standard Ag/AgCl electrodes; we found consistently lower impedance for CSA electrodes. For quantitative data analysis, we simultaneously collected ECG data with CSA and Ag/AgCl electrodes from 17 healthy subjects. Heart rate variability (HRV) indices and ECG morphological waveforms were calculated to compare CSA and Ag/AgCl electrodes. Non-significant differences for most of the HRV indices between CSA and Ag/AgCl electrodes were found. Of the morphological waveform metrics consisting of R-wave peak amplitude, ST-segment elevation and QT interval, only the first index was found to be significantly different between the two media. The response of CSA electrodes to motion artifacts was also tested, and we found in general no difference in the quality of the ECG signal between the two media. Hence, given that CSA electrodes are expected to have a very long shelf-life, with potentially less cost associated with their fabrication, and have ECG signal dynamics nearly identical to those of Ag/AgCl, the new electrodes provide an attractive alternative for ECG measurements.

[1]  A. Gruetzmann,et al.  Novel dry electrodes for ECG monitoring , 2007, Physiological measurement.

[2]  I. Benedek Pressure-Sensitive Adhesives and Applications , 2004 .

[3]  Juliane Junker,et al.  Medical Instrumentation Application And Design , 2016 .

[4]  G. Ruffinia,et al.  First human trials of a dry electrophysiology sensor using a carbon nanotube array interface , 2008 .

[5]  D. Adam,et al.  Assessment of autonomic function in humans by heart rate spectral analysis. , 1985, The American journal of physiology.

[6]  Carmen Vidaurre,et al.  BioSig: The Free and Open Source Software Library for Biomedical Signal Processing , 2011, Comput. Intell. Neurosci..

[7]  Longchun Wang,et al.  PDMS-Based Low Cost Flexible Dry Electrode for Long-Term EEG Measurement , 2012, IEEE Sensors Journal.

[8]  K.Lee Lerner,et al.  The Gale encyclopedia of science , 2004 .

[9]  L. Kirkup,et al.  A direct comparison of wet, dry and insulating bioelectric recording electrodes. , 2000, Physiological measurement.

[10]  R J Cohen,et al.  Beat to beat variability in cardiovascular variables: noise or music? , 1989, Journal of the American College of Cardiology.

[11]  A. Malliani,et al.  Heart rate variability. Standards of measurement, physiological interpretation, and clinical use , 1996 .

[12]  Sang-Hoon Lee,et al.  CNT/PDMS Composite Flexible Dry Electrodesfor Long-Term ECG Monitoring , 2012, IEEE Transactions on Biomedical Engineering.

[13]  R. Cohen,et al.  Power spectrum analysis of heart rate fluctuation: a quantitative probe of beat-to-beat cardiovascular control. , 1981, Science.

[14]  G. Breithardt,et al.  Heart rate variability: standards of measurement, physiological interpretation and clinical use. Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology. , 1996 .

[15]  Charles Sodini,et al.  A long-term wearable electrocardiogram measurement system , 2013, 2013 IEEE International Conference on Body Sensor Networks.

[16]  Ki H. Chon,et al.  Novel Electrodes for Underwater ECG Monitoring , 2014, IEEE Transactions on Biomedical Engineering.

[17]  I. Benedek Pressure-Sensitive Formulation , 2000 .

[18]  K. Park,et al.  Flexible polymeric dry electrodes for the long-term monitoring of ECG , 2008 .