Development of a quasi-dry electrode for EEG recording

Mota, Armando R.; Duarte, Luciana Tavares; Rodrigues, Diana Cristina; Martins, Ana; Machado, A. V.; Vaz, F.; Fiedler, Patrique; Haueisen, Jens; Nóbrega, J. M.; Fonseca, C.

doi:10.1016/j.sna.2013.06.013

Cited by 85 publications

(84 citation statements)

References 14 publications

(20 reference statements)

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“…One study reports the use of only a very small volume of gel, which is released by pressure on the electrode, but this requires a system, which is able to apply pressure to all the electrodes. [ 10 ] Several studies report the fabrication of microstructures on the surface of the electrodes in order to increase the surface area and decrease the electrode impedance. [11][12][13][14] We recently reported the use of conducting polymers as dry electrodes with enhanced performance.…”

Section: Doi: 101002/adhm201300614mentioning

confidence: 99%

Ionic Liquid Gel‐Assisted Electrodes for Long‐Term Cutaneous Recordings

Leleux

Johnson

Strakosas

et al. 2014

Adv Healthcare Materials

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Section: Doi: 101002/adhm201300614mentioning

confidence: 99%

Ionic Liquid Gel‐Assisted Electrodes for Long‐Term Cutaneous Recordings

Leleux

Johnson

Strakosas

et al. 2014

Adv Healthcare Materials

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“…This arrangement causes skin irritation (erythema) and leads to electrical degradation for periods of use that extend more than a few hours, typically caused by drying of the electrolyte gel (6). Recent technologies replace the gel (7,8) with needles (8,9), contact probes (10,11), capacitive disks (12,13), conductive composites (14,15), or nanowires (16). Such dry electrodes have some promise, but they require multistep preparations, obtrusive wiring interfaces, and/or cumbersome mechanical fixtures.…”

mentioning

confidence: 99%

Soft, curved electrode systems capable of integration on the auricle as a persistent brain–computer interface

Norton

Lee

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

311

280

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Recent advances in electrodes for noninvasive recording of electroencephalograms expand opportunities collecting such data for diagnosis of neurological disorders and brain-computer interfaces. Existing technologies, however, cannot be used effectively in continuous, uninterrupted modes for more than a few days due to irritation and irreversible degradation in the electrical and mechanical properties of the skin interface. Here we introduce a soft, foldable collection of electrodes in open, fractal mesh geometries that can mount directly and chronically on the complex surface topology of the auricle and the mastoid, to provide highfidelity and long-term capture of electroencephalograms in ways that avoid any significant thermal, electrical, or mechanical loading of the skin. Experimental and computational studies establish the fundamental aspects of the bending and stretching mechanics that enable this type of intimate integration on the highly irregular and textured surfaces of the auricle. Cell level tests and thermal imaging studies establish the biocompatibility and wearability of such systems, with examples of high-quality measurements over periods of 2 wk with devices that remain mounted throughout daily activities including vigorous exercise, swimming, sleeping, and bathing. Demonstrations include a text speller with a steadystate visually evoked potential-based brain-computer interface and elicitation of an event-related potential (P300 wave).or more than 80 y, electroencephalography (EEG) has provided an effective noninvasive means to study human brain activity (1). EEG is instrumental in a wide range of clinical and research applications, from diagnosing epilepsy (2) to improving our understanding of language comprehension (3) and the development of brain-computer interfaces (BCI) (4). Conventional EEG recording systems, particularly the physical interface between the sensor (commonly known as an electrode) and the head, have limitations that constrain the more widespread use of EEG monitoring. Electrodes typically consist of rigid metal disks mechanically secured to the head with a mesh cap and chin strap, where electrolyte gels (5) enable efficient electrical coupling by reducing the impedance at the skin interface. This arrangement causes skin irritation (erythema) and leads to electrical degradation for periods of use that extend more than a few hours, typically caused by drying of the electrolyte gel (6). Recent technologies replace the gel (7, 8) with needles (8, 9), contact probes (10, 11), capacitive disks (12, 13), conductive composites (14, 15), or nanowires (16). Such dry electrodes have some promise, but they require multistep preparations, obtrusive wiring interfaces, and/or cumbersome mechanical fixtures. These shortcomings limit the potential for long-term use in diagnosis of neurological disabilities (17, 18) or in persistent BCI (17,19). For example, although microneedle electrodes can record EEG signals for a few hours (20), the interface does not offer the robustness, comfort, or eas...

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“…The impedance of dry non-contact electrodes mainly depend on garment hair, the distance of air gap and the surface area of electrodes. In recent years, some new electrode concepts were proposed to reduce the electrode impedance, such as quasi-dry electrodes [12], a concept between "wet" and "dry" electrodes, hydrate the local scalp area by releasing a small amount of moisturizing solution from the electrode reservoir, and achieve impedance in the order of a few tens of kΩ.…”

Section: Wet/gel Electrodementioning

confidence: 99%

Active Electrodes for Wearable EEG Acquisition: Review and Electronics Design Methodology

Mitra

Hoof

et al. 2017

IEEE Rev. Biomed. Eng.

127

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Abstract-Active Electrodes (AE), i.e. electrodes with built-in readout circuitry, are increasingly being implemented in wearable healthcare and lifestyle applications due to AE's robustness to environmental interference. An AE locally amplifies and buffers µV-level EEG signals before driving any cabling. The low output impedance of an AE mitigates cable motion artifacts thus enabling the use of high-impedance dry electrodes for greater user comfort. However, developing a wearable EEG system, with medical grade signal quality on noise, electrode offset tolerance, common-mode rejection ratio (CMRR), input impedance and power dissipation, remains a challenging task. This paper reviews state-of-the-art bio-amplifier architectures and low-power analog circuits design techniques intended for wearable EEG acquisition, with a special focus on AE system interfaced with dry electrodes. Index Terms-Active electrode, instrumentation amplifier (IA), electroencephalography (EEG), dry electrodes, common-mode rejection ratio (CMRR), brain-computer interface (BCI)I. INTRODUCTION ecent advances in biomedical technologies, integrated circuits (ICs), sensors and data analysis techniques have accelerated the development of wearable technology for Telehealth applications. Today, miniature and low-power medical sensors can be easily integrated into various accessories that continuously sense, process and transfer people's physiological information during their daily life activities. By reducing the need for manual intervention and by lowering the cost, these medical devices are being widely used in personal healthcare and home diagnostics, such as wellness and health monitoring, home rehabilitation, and the early detection of brain disordersElectroencephalography (EEG)

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Development of a quasi-dry electrode for EEG recording

Cited by 85 publications

References 14 publications

Ionic Liquid Gel‐Assisted Electrodes for Long‐Term Cutaneous Recordings

Ionic Liquid Gel‐Assisted Electrodes for Long‐Term Cutaneous Recordings

Soft, curved electrode systems capable of integration on the auricle as a persistent brain–computer interface

Active Electrodes for Wearable EEG Acquisition: Review and Electronics Design Methodology

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