Signal Quality and Electrode-Skin Impedance Evaluation in the Context of Wearable Electroencephalographic Systems

Author(s):  
Zhichun Zhao ◽  
Kamen Ivanov ◽  
Ludwig Lubich ◽  
Olatunji Mumini Omisore ◽  
Zhanyong Mei ◽  
...  
2020 ◽  
Vol 6 (3) ◽  
pp. 139-142
Author(s):  
Jens Haueisen ◽  
Patrique Fiedler ◽  
Anna Bernhardt ◽  
Ricardo Gonçalves ◽  
Carlos Fonseca

AbstractMonitoring brain activity at home using electroencephalography (EEG) is an increasing trend for both medical and non-medical applications. Gel-based electrodes are not suitable due to the gel application requiring extensive preparation and cleaning support for the patient or user. Dry electrodes can be applied without prior preparation by the patient or user. We investigate and compare two dry electrode headbands for EEG acquisition: a novel hybrid dual-textile headband comprising multipin and multiwave electrodes and a neoprene-based headband comprising hydrogel and spidershaped electrodes. We compare the headbands and electrodes in terms of electrode-skin impedance, comfort, electrode offset potential and EEG signal quality. We did not observe considerable differences in the power spectral density of EEG recordings. However, the hydrogel electrodes showed considerably increased impedances and offset potentials, limiting their compatibility with many EEG amplifiers. The hydrogel and spider-shaped electrodes required increased adduction, resulting in a lower wearing comfort throughout the application time compared to the novel headband comprising multipin and multiwave electrodes.


2021 ◽  
Author(s):  
Alexander J. Towse ◽  
Benjamin C. Fortune ◽  
Chistopher G. Pretty ◽  
Michael P. Hayes

Abstract This paper discusses the development of a tripolar EMG device featuring electrode impedance compensation circuitry. The device also includes circuitry to test the effectiveness of these features at improving EMG signal quality. Due to various factors, the electrode-skin impedance of different electrodes is typically imbalanced. This imbalance increases EMG susceptibility to electrical noise. These issues can be mitigated by applying impedance compensation. This was done for a tripolar configuration specifically to also reduce interference due to crosstalk. The development process and design choices behind the device features are discussed, with particular focus on the impedance compensation circuit. This includes key components used, and the justification behind their selection. Testing found the tripolar electrode configuration had limited effect on crosstalk interference. Fortunately, the impedance compensation circuit could successfully correct for impedance imbalance. This led to a marked reduction in noise due to electrical interference, such as from 50Hz mains hum.


Sensors ◽  
2021 ◽  
Vol 21 (16) ◽  
pp. 5621
Author(s):  
Gozde Goncu-Berk ◽  
Bilge Guvenc Tuna

When e-textile EMG electrodes are integrated into clothing, the fit of the clothing on the body, and therefore its pattern and cut become important factors affecting the EMG signal quality in relation to the seamless contact between the skin and the e-textile electrode. The research so far on these effects was conducted on commercially available clothing or in tubular sleeve forms for arms. There is no study that investigated different clothing pattern and fit conditions and their effect on e-textile EMG electrode performance. This study investigates the effect of clothing pattern and fit in EMG applications using e-textile electrodes integrated onto the sleeves of custom drafted t-shirts in set-in and raglan sleeve pattern variations. E-textile electrode resistance, signal-to-noise ratio (SNRdB), power spectral density and electrode–skin impedance are measured and evaluated in set-in sleeve and raglan sleeve conditions with participants during a standardized arm movement protocol in comparison to the conventional hydrogel Ag/AgCl electrodes. The raglan sleeve pattern, widely used in athletic wear to provide extra ease for the movement of the shoulder joint, showed superior performance and therefore indicated the pattern and cut of a garment could have significant effect on EMG signal quality in designing smart clothing.


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