Electrode–skin impedance imbalance measured in the frequency domain

Type of content
Journal Article
Thesis discipline
Degree name
Publisher
Elsevier BV
Journal Title
Journal ISSN
Volume Title
Language
en
Date
2021
Authors
Fortune BC
Pretty CG
Cameron CJ
McKenzie LR
Chatfield LT
Hayes MP
Abstract

Objective To measure the magnitude and phase imbalance of the electrode-skin interface for silver/silver chloride (Ag/AgCl) and silver (Ag) electrode pairs, highlighting the need to balance both the magnitude and phase of the electrode-skin interface. Methods The electrode-skin impedance imbalance between two electrodes placed on ten healthy subjects was recorded over a frequency range of 1 Hz–100 kHz, using three electrode configurations: Ag/AgCl electrodes without skin preparation (Ag/AgClNSP), Ag/AgCl electrodes with skin preparation (Ag/AgClSP), and Ag electrodes with skin preparation (Ag-SP). A compensation network was developed to simulate impedance imbalance reduction using the experimental data. Results The mean electrode-skin impedance imbalance at 50 Hz was (37.6 ± 47.1) kΩ and (15.0 ± 18.3) degrees using the Ag/AgClNSP electrode configuration; (4.52 ± 7.65) kΩ and (4.6 ± 6.9) degrees using the Ag/AgClSP electrode configuration; and (36.2 ± 45.1) kΩ and (3.4 ± 3.6) degrees using the Ag-SP electrode configuration. The compensation network resulted in a mean reduction in impedance imbalance over the bioelectrical signal range (1 Hz–500 Hz) of 284.3 kΩ and 11.9 degrees; 4.6 kΩ and 6.2 degrees; 86.7 kΩ and 2.5 degrees for the Ag/AgClNSP, Ag/AgClSP and Ag-SP electrode configurations respectively. Conclusion This study confirmed that the electrode-skin impedance imbalance can be large, and varies between subjects. Although abrasive skin preparation reduces the electrode-skin impedance imbalance, it does not guarantee a balanced electrode-skin interface, therefore, balancing the electrode-skin impedance using a compensation network has the potential to decrease bioelectrical signal interference. Significance As bioelectrical signal interference is a function of electrode-skin impedance imbalance, to improve noise immunity of bioelectrical signal recordings, added compensatory impedance is required to balance the electrode-skin interface.

Description
Citation
Fortune BC, Pretty CG, Cameron CJ, McKenzie LR, Chatfield LT, Hayes MP (2021). Electrode–skin impedance imbalance measured in the frequency domain. Biomedical Signal Processing and Control. 63. 102202-102202.
Keywords
Electrode-skin interface, Electrode-tissue interface, impedance, compensation, balancing, crosstalk, sEMG, EMG
Ngā upoko tukutuku/Māori subject headings
ANZSRC fields of research
0903 Biomedical Engineering
0906 Electrical and Electronic Engineering
1004 Medical Biotechnology
Fields of Research::32 - Biomedical and clinical sciences::3206 - Medical biotechnology::320602 - Medical biotechnology diagnostics (incl. biosensors)
Fields of Research::40 - Engineering::4003 - Biomedical engineering::400305 - Biomedical instrumentation
Fields of Research::40 - Engineering::4008 - Electrical engineering::400899 - Electrical engineering not elsewhere classified
Rights
All rights reserved unless otherwise stated