scholarly journals Statistical Estimation of EIT Electrode Contact Impedance Using a Magic Toeplitz Matrix

2011 ◽  
Vol 58 (8) ◽  
pp. 2194-2201 ◽  
Author(s):  
E. Demidenko ◽  
A. Borsic ◽  
Yuqing Wan ◽  
R. J. Halter ◽  
A. Hartov
Keyword(s):  
Toeplitz Matrix ◽  
Statistical Estimation ◽  
Contact Impedance ◽  
Electrode Contact

scholarly journals Textile Electrodes: Influence of Knitting Construction and Pressure on the Contact Impedance

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1578
Author(s):  
Luisa Euler ◽  
Li Guo ◽  
Nils-Krister Persson
Keyword(s):  
Smooth Surface ◽  
Research Field ◽  
Uneven Surface ◽  
Contact Impedance ◽  
Dry Electrodes ◽  
Textile Electrodes ◽  
Human Forearm ◽  
Wet Condition ◽  
Electrode Contact ◽  
Influencing Parameters

Textile electrodes, also called textrodes, for biosignal monitoring as well as electrostimulation are central for the emerging research field of smart textiles. However, so far, only the general suitability of textrodes for those areas was investigated, while the influencing parameters on the contact impedance related to the electrode construction and external factors remain rather unknown. Therefore, in this work, six different knitted electrodes, applied both wet and dry, were compared regarding the influence of specific knitting construction parameters on the three-electrode contact impedance measured on a human forearm. Additionally, the influence of applying pressure was investigated in a two-electrode setup using a water-based agar dummy. Further, simulation of an equivalent circuit was used for quantitative evaluation. Indications were found that the preferred electrode construction to achieve the lowest contact impedance includes a square shaped electrode, knitted with a high yarn density and, in the case of dry electrodes, an uneven surface topography consisting of loops, while in wet condition a smooth surface is favorable. Wet electrodes are showing a greatly reduced contact impedance and are therefore to be preferred over dry ones; however, opportunities are seen for improving the electrode performance of dry electrodes by applying pressure to the system, thereby avoiding disadvantages of wet electrodes with fluid administration, drying-out of the electrolyte, and discomfort arising from a “wet feeling”.

scholarly journals Flexible 3D-Printed EEG Electrodes

Sensors ◽  
2019 ◽  
Vol 19 (7) ◽  
pp. 1650 ◽  
Author(s):  
Andrei Velcescu ◽  
Alexander Lindley ◽  
Ciro Cursio ◽  
Sammy Krachunov ◽  
Christopher Beach ◽  
...  
Keyword(s):  
Silver Chloride ◽  
Eeg Signals ◽  
Contact Impedance ◽  
3D Printed ◽  
Electrode Contact ◽  
Silver Silver ◽  
Silver Silver Chloride ◽  
First Time ◽  
Chloride Coating ◽  
Different Parts

For electroencephalography (EEG) in haired regions of the head, finger-based electrodes have been proposed in order to part the hair and make a direct contact with the scalp. Previous work has demonstrated 3D-printed fingered electrodes to allow personalisation and different configurations of electrodes to be used for different people or for different parts of the head. This paper presents flexible 3D-printed EEG electrodes for the first time. A flexible 3D printing element is now used, with three different base mechanical structures giving differently-shaped electrodes. To obtain improved sensing performance, the silver coatings used previously have been replaced with a silver/silver-chloride coating. This results in reduced electrode contact impedance and reduced contact noise. Detailed electro-mechanical testing is presented to demonstrate the performance of the operation of the new electrodes, particularly with regards to changes in conductivity under compression, together with on-person tests to demonstrate the recording of EEG signals.

Electrode contact impedance sensitivity to variations in geometry

2012 ◽  
Vol 33 (5) ◽  
pp. 817-830 ◽  
Author(s):  
Roberto Cardu ◽  
Philip H W Leong ◽  
Craig T Jin ◽  
Alistair McEwan
Keyword(s):  
Contact Impedance ◽  
Electrode Contact
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