Capacitive Sensing of Electrocardiographic Potential Through Cloth From the Dorsal Surface of the Body in a Supine Position: A Preliminary Study

Ueno, Atsushi; Akabane, Y.; Kato, Tsuyoshi; Hoshino, Hiroshi; Kataoka, Sachiyo; Ishiyama, Yoji

doi:10.1109/tbme.2006.889201

Cited by 155 publications

(73 citation statements)

References 18 publications

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“…Noncontact electrodes have been typically described simply as coupling signals through a small capacitance (10's pF) [11], [12], [27]. In reality, however, there is typically an important resistive element ( ) as well, since the typical insulation (i.e., fabric) will also have a non-neglible resistance [28]. As shown previously, signal coupling through noncontact electrodes can be actually dominated by the resistive part of the source impedance which can cause a large input voltage noise.…”

Section: B Noncontact Capacitive Electrodesmentioning

confidence: 99%

Dry-Contact and Noncontact Biopotential Electrodes: Methodological Review

Jung

Cauwenberghs

2010

IEEE Rev. Biomed. Eng.

859

596

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Abstract-Recent demand and interest in wireless, mobile-based healthcare has driven significant interest towards developing alternative biopotential electrodes for patient physiological monitoring. The conventional wet adhesive Ag/AgCl electrodes used almost universally in clinical applications today provide an excellent signal but are cumbersome and irritating for mobile use. While electrodes that operate without gels, adhesives and even skin contact have been known for many decades, they have yet to achieve any acceptance for medical use. In addition, detailed knowledge and comparisons between different electrodes are not well known in the literature. In this paper, we explore the use of dry/noncontact electrodes for clinical use by first explaining the electrical models for dry, insulated and noncontact electrodes and show the performance limits, along with measured data. The theory and data show that the common practice of minimizing electrode resistance may not always be necessary and actually lead to increased noise depending on coupling capacitance. Theoretical analysis is followed by an extensive review of the latest dry electrode developments in the literature. The paper concludes with highlighting some of the novel systems that dry electrode technology has enabled for cardiac and neural monitoring followed by a discussion of the current challenges and a roadmap going forward.

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Section: B Noncontact Capacitive Electrodesmentioning

confidence: 99%

Dry-Contact and Noncontact Biopotential Electrodes: Methodological Review

Jung

Cauwenberghs

2010

IEEE Rev. Biomed. Eng.

859

596

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“…6, corroborate that the force exerted on the backrest and the variations in electrode capacitance (C e ) are probably related. This variation in electrode capacitance could explain the abnormal ECG waveforms recorded in [8], and the extra peaks in the ECG in [12], both recorded with capacitive electrodes.…”

Section: A Capacitance Variations In Electrodesmentioning

confidence: 94%

“…These filters, however, also attenuate the ECG signal. If the signal does not saturate any stage because of excessive interference, digital filters can yield a clean ECG signal [8]. Furthermore, in long-term measurements, perspiration can reduce microphonics [9], as corroborated in [8], but unavoidable relative movements between the body and electrodes result in large artifacts.…”

Section: B Respiration and Cardiac-related Movements In Capacitive Ementioning

confidence: 98%

“…If the signal does not saturate any stage because of excessive interference, digital filters can yield a clean ECG signal [8]. Furthermore, in long-term measurements, perspiration can reduce microphonics [9], as corroborated in [8], but unavoidable relative movements between the body and electrodes result in large artifacts. If capacitive electrodes are fixed on a foam-covered backrest, relative movements between the body surface and the electrodes should be smaller as the electrodes better adapt to the torso surface.…”

Section: B Respiration and Cardiac-related Movements In Capacitive Ementioning

confidence: 98%

“…An alternative technique is to detect bioelectric signals through the subject's clothes by using electrodes placed on an object that comes into contact with his/her body [6], [7], [8]. A capacitor is formed between the skin and the electrode metal, and the electrically-insulating clothes become the capacitor's dielectric.…”

Section: Introductionmentioning

confidence: 99%

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Microphonics in biopotential measurements with capacitive electrodes

Luna-Lozano¹,

Pallás-Areny²

2010

2010 Annual International Conference of the IEEE Engineering in Medicine and Biology

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Abstract-Biopotential measurements with capacitive electrodes do not need any direct contact between electrode and skin, which saves the time devoted to expose and prepare the contact area when measuring with conductive electrodes. However, mechanical vibrations resulting from physiological functions such as respiration and cardiac contraction can change the capacitance of the electrode and affect the recordings. This transformation of mechanical vibrations into undesired electric signals is termed microphonics. We have evaluated microphonics in capacitive ECG recordings obtained from a dressed subject seated on a common chair with electrodes placed on the front side of the backrest of the chair. Depending on the softness of the backrest, the recordings may be clearly affected by the displacement of the thorax back wall due to the respiration and to the heart's mechanical activity. I. INTRODUCTIONONVENTIONAL surface biopotential measurements require the exposure and preparation of the skin areas where electrodes are to be placed, and/or the use of an electrolyte. Dry-electrodes do not need any electrolyte nor skin preparation but still need the exposure of the body contact areas. Off-body biopotential measurements have been tried [1], [2] that do not need any contact with the body, but the actual origin of the recorded signals is disputed because electrostatic charges and distance variations between the body and the electrodes can result in signals larger than surface biopotentials, hence not attributable to them [3], [4].Strapping electrically insulated metal electrodes to the body implies a mechanical contact that establishes a fixed distance between the body and the metal part of the electrode, thus offering more reliable signals [5]. An alternative technique is to detect bioelectric signals through the subject's clothes by using electrodes placed on an object that comes into contact with his/her body [6], [7], [8]. A capacitor is formed between the skin and the electrode metal, and the electrically-insulating clothes become the capacitor's dielectric. This approach frees the user from servitudes such as battery replacement in portable devices and avoids any cumbersome electrodes or wires. However, distance variations between capacitor plates (the skin and the electrode) can result in artifacts [9]. Those distance variations can result from relatively large voluntary movements but also from physiological movements such as those related to the breathing and heart activity. In this work we analyze the origin, relevance and reduction of those physiologically-induced movement artifacts. II. MICROPHONICS IN MEASUREMENTS WITH CAPACITIVE ELECTRODESMicrophonics is any electrical interference caused by mechanical vibration. When a metal electrode is placed on a seat's backrest and a dressed person comes into mechanical contact with it, thoracic movements due to respiration and heart contractions may change the actual distance between the body and the electrode (see Fig. 1). In each cardiac cycle, atrial and ventricula...

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Foldable Textile Electronic Devices Using All‐Organic Conductive Fibers

et al. 2014

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Scalable conductive multifilament of poly(3,4-ethylenedioxythiophene) doped with poly(4-styrene sulfonate) (PEDOT:PSS) and poly(vinyl alcohol) (PVA) was fabricated by a coagulation of spinning dope solution in cold methanol. The multifilament was composed of uniform circular fibers with an average diameter of 60 AE 5 mm and showed good enough mechanical properties for textile processes while maintaining electronic conductivity. The PEDOT:PSS/PVA blended fibers displayed an actuation response when a voltage was applied in air and the foldable textiles based on the PEDOT:PSS/PVA blended fibers worked as flexible electrodes to detect human heartbeats. The organic conductive fibers can be a platform for lightweight wearable electronics. H. Miura et al./Foldable Textile Electronic Devices Using … ADVANCED ENGINEERING MATERIALS 2014, 16, No. 5

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Capacitive Sensing of Electrocardiographic Potential Through Cloth From the Dorsal Surface of the Body in a Supine Position: A Preliminary Study

Cited by 155 publications

References 18 publications

Dry-Contact and Noncontact Biopotential Electrodes: Methodological Review

Dry-Contact and Noncontact Biopotential Electrodes: Methodological Review

Microphonics in biopotential measurements with capacitive electrodes

Foldable Textile Electronic Devices Using All‐Organic Conductive Fibers

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