Practical Performance Assessment of Dry Electrodes Under Skin Moisture for Wearable Long-Term Cardiac Rhythm Monitoring Systems
- 1.7k Downloads
The use of wearable dry sensors for long term recordings of electrocardiographic bipolar leads located in comfortable areas of the body, is a requirement for detecting certain heart rhythms. Knowledge of the skin-electrode electrical performance of dry electrodes is necessary when seeking to improve various processing stages for signal quality enhancement. In this paper, methods for the assessment of skin-electrode impedance (Zse) of dry electrodes and its modelling are presented. We need to know the behavior of dry electrodes when they are moistened with skin sweat, either at the time of exercise or when it comes to warm climates, under the following posed hypothesis: the impedance magnitude of dry electrodes under study would be significantly lower after they have been moistened with sweat, and comparatively could reach levels of impedance characteristics presented by standard pre-gelled ECG electrodes. Measurements were carried out on selected dry-electrode materials such as silver, stainless steel, AgCl (dry), polyurethane and iron (Fe). These presented, |Zse| values between 500 kΩ and 1 MΩ within the main ECG frequency range (1–100 Hz), under no sweat conditions, and values of few kiloohms under artificial sweat conditions. However, in spite of the sweat conditions, open bandwidth ECG traces were of similar quality and stability, within tolerance; with dry AgCl electrode material presenting the best ECG trace performance.
KeywordsDry electrodes Moistened skin-electrode impedance Spectroscopy Effect of sweat Arm ECG Wearable monitoring devices Heart rhythm
This research is supported by funding from the European Union (EU): H2020-MSCA-RISE Programme (WASTCArD Project, Grant #645759). Prof Omar Escalona is supported by funds equally from the Ulster Garden Villages Ltd. and the McGrath Trust, UK.
- 1.W.D. Lynn, O.J. Escalona and D.J. McEneaney, “ECG monitoring techniques using advanced signal recovery and arm worn sensors”. IEEE International Conference on Bioinformatics and Biomedicine, IEEE BIBM 2014, pp. 51–55.Google Scholar
- 2.O. Escalona and M. Mendoza, “Electrocardiographic Waveforms Fitness Check Device Technique for Sudden Cardiac Death Risk Screening”. IEEE-EMBC 2016, pp. 3453–3456.Google Scholar
- 3.A. Bosnjak, P. Linares, J. McLaughlin, O.J. Escalona. “Characterizing dry electrodes impedance by parametric modeling for arm wearable long-term cardiac rhythm monitoring”. In Computing in Cardiology 2017, 44:1–4. https://doi.org/10.22489/cinc.2017.130-461.
- 4.Y.H Chen, M.O. Beeck, L. Vanderheyden, et al. “Soft, Comfortable Polymer Dry Electrodes for High Quality ECG and EEG Recording”. Sensors, Vol 14, 2014, pp. 23758–780.Google Scholar
- 5.S. Grimnes, G., Martinsen. “Bioimpedance and Bioelectricity (Basics)”, Third Edition, Elsevier and Academic Press (2015).Google Scholar
- 6.A. Bosnjak, A. Kennedy, P. Linares, M. Borges, J.A.D. McLaughlin, O.J. Escalona, “Performance assessment of dry electrodes for wearable long term cardiac rhythm monitoring: skin-electrode impedance spectroscopy”. In Proceedings of the Annual International Conference of the IEEE-EMBS 8037209, pp. 1861–1864 (2017).Google Scholar
- 7.C. Assambo, R. Dozio, A. Baba and M. J. Burke “Determination of the Parameters of the Skin Electrode Impedance Model for ECG Measurement”. Proc. 6th Int. Conf. on Electronics, Hardware, Wireless and Optical Communications, Corfu, pp. 540–318 (2007).Google Scholar