Textile electrodes in Electrical Bioimpedance measurements - a comparison with conventional Ag/AgCl electrodes (original) (raw)
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Textile based electrodes for ECG and EMG measurements
2017
This work is financed by FEDER funds through the Competitivity Factors Operational Programme - COMPETE and by national funds through FCT – Foundation for Science and Technology within the scope of the project POCI-01-0145-FEDER-007136.
Characterization of the Electrode-Skin Impedance of Textile Electrodes
Characterization of the Electrode-Skin Impedance of Textile Electrodes, 2014
Wearable systems are expected to contribute for improving traditional biopotential signals monitoring devices due to higher freedom and unobtrusiveness provided to the wearer. Textile electrodes present advantages compared with the conventional Ag/AgCl electrodes for the capturing of biopoten-tials, namely in terms of skin irritation due to the hydrogel and the need of a technician to place the electrodes on the correct positions. Due to the lack of hydrogel, textile electrodes present different electrical contact characteristics. The skin-electrode impedance is an important feature since it affects the captured signal quality. Although a low impedance is desired, a comfortable wearable system should not require the electrodes to be covered by the hydrogel or be moistened. A forearm sleeve provided with textile electrodes was used to study the electrode-skin impedance and the signal-to-noise ratio (SNR) of surface electromyographic (EMG) signals on a long-term use basis. The sleeve can be adjusted for different levels of tightening to control the pressure applied on the electrodes. The obtained results provide valuable information on the pressure that the textile garments of a sleeve or vest should apply on the recording electrodes, in order to assure a good electrical and mechanical contact between the electrodes and the skin and decrease the noise due to motion. It was observed that the electrode-skin impedance measurement alone is not sufficient to establish a relation with the SNR. The extraction of parameters from an electrical equivalent model of the electrode-skin interface allows to determine a relation with the model parameters and the SNR. The evaluation of these parameters during long-term monitoring will allow assessing the quality of biopotential measurements in textile electrodes.
Evaluation of dry textile electrodes for long-term electrocardiographic monitoring
BioMedical Engineering OnLine, 2021
Background Continuous long-term electrocardiography monitoring has been increasingly recognized for early diagnosis and management of different types of cardiovascular diseases. To find an alternative to Ag/AgCl gel electrodes that are improper for this application scenario, many efforts have been undertaken to develop novel flexible dry textile electrodes integrated into the everyday garments. With significant progresses made to address the potential issues (e.g., low signal-to-noise ratio, high skin–electrode impedance, motion artifact, and low durability), the lack of standard evaluation procedure hinders the further development of dry electrodes (mainly the design and optimization). Results A standard testing procedure and framework for skin–electrode impedance measurement is demonstrated for the development of novel dry textile electrodes. Different representative electrode materials have been screen-printed on textile substrates. To verify the performance of dry textile electr...
Frontiers in electronics, 2021
Electronic textile (e-textile) systems applied to biological signal monitoring are of great interest to the healthcare industry, given the potential to provide continuous and long-term monitoring of healthy individuals and patients. Most developments in e-textiles have focused on novel materials and systems without systematic considerations into how the hierarchical structure of fibrous assemblies may influence performance and compatibility of the materials during use. This study examines mechanisms underlying the stability and quality of textile-based electrocardiogram (ECG) electrodes used in a smart bra. Signal quality of the biometric data obtained affects feedback and user experience and may be influenced by characteristics and properties of the material. Under stationary and dynamic conditions, analysis of the raw ECG signal and heart rate, with respect to textile-electrode material properties have been performed. Currently, there is no standardized procedure to compare the ECG signal between electrode materials. In this study, several methods have been applied to compare differences between silverbased textile electrodes and silver/silver-chloride gel electrodes. The comparison methods serve to complement visual observations of the ECG signal acquired, as possible quantitative means to differentiate electrode materials and their performance. From the results obtained, signal quality, and heart rate (HR) detection were found to improve with increased skin contact, and textile structures with lower stretch and surface resistance, especially under dynamic/movement test conditions. It was found that the performance of the textile electrode materials compared exceeded ECG signal quality thresholds previously established for acceptable signal quality, specifically for the kurtosis (K > 5), and Pearson correlation coefficients (r ≥ 0.66) taken from average ECG waveforms calculated.
Textile application in bio-potential recording used for medicinal purposes : an overview
2016
Bio-potential recordings in the form of electrocardiograms (ecg), electroencephalograms (eeg), electrooculograms (eog) and electromyograms (emg) are indispensable and vital tools for tracking person's health [1]. Commercially available portable bio-signal monitoring device available now days, has given the facility to monitor cardiac patients continuously at any place and situation. Thereby it can be used effectively in telemedicine and home-care scenarios for diseases prevention and management, early diagnosis and home rehabilitation. Electrodes in such system serves as signal acquisition apparatus that creates an electrical interface between the body and the measurement system, allowing the electrical charges to flow through the tissue and to sense the endogenous bio-potential signals [2-3]. An electrode during its development stages has undergone through vast changes. Heart bioelectrical phenomenon and study of ecg was traced back in early 1842, when italian physicist calo matteucci [4] found that an electric current accompanies each heart beat. Richard caton, a liverpool physician was the first to use electrodes in 1875 to detect electroencephalogram by placing electrodes on two points of the external surface, one on gray matter and the other on the surface of the skull. Later, ag/agcl body-surface plate electrodes were used for ecg measurement, with electrolyte between the electrode and skin to improve skin-electrode contact. Success of ag/agcl electrodes over other electrodes made from different materials was mainly attributed to good conductivity of silver and weak polarization of ag/agcl, acquiring high fidelity signals [5]. Such superiority of the ag/agcl electrode still remain unbeaten and been widely used in regular ecg measurement nowadays. But, it is not an ideal electrode, for long-term monitoring, due to dehydration of electrolyte or wet gel, affecting the signal quality [6-7]. Even this gel will cause some skin allergies such as skin irritation, dermal inflammation, and other skin problems [8]. Also, wet gel electrodes adhere to the skin, causing the patient discomfort. Researchers have done intensive efforts to overcome these limitations of classical electrode. Options were tried out in the form of dry electrodes and textile electrodes with vivid structures.
Elastic Textile Wristband for Bioimpedance Measurements
Sensors
In this paper, wristband electrodes for hand-to-hand bioimpedance measurements are investigated. The proposed electrodes consist of a stretchable conductive knitted fabric. Different implementations have been developed and compared with Ag/AgCl commercial electrodes. Hand-to-hand measurements at 50 kHz on forty healthy subjects have been carried out and the Passing–Bablok regression method has been exploited to compare the proposed textile electrodes with commercial ones. It is demonstrated that the proposed designs guarantee reliable measurements and easy and comfortable use, thus representing an excellent solution for the development of a wearable bioimpedance measurement system.
A Hybrid Textile Electrode for Electrocardiogram (ECG) Measurement and Motion Tracking
Materials
Wearable sensors have great potential uses in personal health monitoring systems, in which textile-based electrodes are particularly useful because they are comfortable to wear and are skin and environmentally friendly. In this paper, a hybrid textile electrode for electrocardiogram (ECG) measurement and motion tracking was introduced. The hybrid textile electrode consists of two parts: A textile electrode for ECG monitoring, and a motion sensor for patient activity tracking. In designing the textile electrodes, their performance in ECG measurement was investigated. Two main influencing factors on the skin-electrode impedance of the electrodes were found: Textile material properties, and electrode sizes. The optimum textile electrode was silver plated, made of a high stitch density weft knitted conductive fabric and its size was 20 mm × 40 mm. A flexible motion sensor circuit was designed and integrated within the textile electrode. Systematic measurements were performed, and result...
Application of Textile Electrodes in Medical Telemetry
2019
Textile sensors and, in particular, textile electrodes are becoming more widely used in medical practice because of their characteristics: quick response, flexibility in electrode design, low price/cost-effectiveness. The objective of this paper is to discuss questions related to the design, the performance evaluation and the use/ implementations of textile electrodes in the context of long-term ambulatory (telemetric) measurements. The applications of textile electrodes are summarized according to sensor features as well as to different applications for registration of biomedical signals, predominantly related to the heart activity of patients with cardiovascular diseases.
Proceedings of the ICTs for improving Patients Rehabilitation Research Techniques, 2013
This paper discusses the reliability of textile sensors in wearable monitoring application. A methodology for the validation of new textile electrodes for monitoring subjects in daily activities is proposed. The protocol is divided in 2 phases: a laboratory set of tests to verify the "absolute" reliability of the electrodes; a second set of trials is carried out with subject performing activities of daily living while monitored through wearable systems. A two-lead portable electrocardiograph was used during the experimental protocol. ECG Signals and derived parameters were analyzed to assess signal quality and its processing possibility with respect to standard silver-silver chloride electrodes as reference. The method was applied to a case study to demonstrate applicability and results with silver based textile electrodes.