Electrocardiographic Electrodes Research Articles

Hydrogels and Carbon Nanotubes: Composite Electrode Materials for Long-Term Electrocardiography Monitoring.

This paper presents methods for developing high-performance interface electrode materials designed to enhance signal collection efficacy during long-term (over 24 h) electrocardiography (ECG) monitoring. The electrode materials are fabricated by integrating commercial ECG liquid hydrogels with carbon nanotubes (CNTs), which are widely utilized in dry-electrode technologies and extensively discussed in the current scientific literature. The composite materials are either prepared by dispersing CNTs within the commercial liquid hydrogel matrix or by encasing the hydrogels in macroscopic CNT films. Both approaches ensure the optimal wetting of the epidermis via the hydrogels, while the CNTs reduce material impedance and stabilize the drying process. The resulting electrode materials maintain their softness, allowing for micro-conformal skin attachment, and are biocompatible. Empirical testing confirms that the ECG electrodes employing these hybrid hydrogels adhere to relevant standards for durations exceeding 24 h. These innovative hybrid solutions merge the benefits of both wet and dry ECG electrode technologies, potentially facilitating the extended monitoring of ECG signals and thus advancing the diagnosis and treatment of various cardiac conditions.

Optimization of dry laser-induced graphene (LIG) electrodes for electrocardiography (ECG) signals monitoring

This work presents the optimization of the fabrication procedure for laser-induced graphene (LIG) electrodes intended for biopotentials acquisition. The results presented in this study demonstrate a significant improvement with respect to the performance obtained for other LIG-based electrodes previously reported in the literature. In particular, we propose the use of a galvanometric laser instead of a CNC laser to improve the engraving resolution and the LIG synthesis process, thus enhancing the surface area of the interface skin–electrode. For that, we have studied the resistance of the resulting LIG patterns as a function of the laser parameters (engraving power and scan speed) seeking their optimization. After tunning the laser fabrication process, we have fabricated and characterized electrocardiogram (ECG) electrodes with different surface areas using a commercial silver-based electrode as a reference. Thus, circular electrodes with a diameter of 15 mm, 10 mm and 6.5 mm were used to acquire the ECG on different volunteers using a commercial equipment. The signals acquired were processed afterwards with cutting edge processing techniques to perform a statistical analysis in terms of sensitivity, specificity, positive prediction and accuracy for the detection of QRS complexes. The results demonstrate that the proposed electrodes improve the signal acquisition with respect to the previously reported LIG-based electrodes in terms of noise and do present comparable or even better results than commercial electrodes (even with a smaller surface area) with the additional advantage of not requiring the use of an electrolyte gel.

Application of Augmented Reality Technology for Chest ECG Electrode Placement Practice

This study presents an augmented reality application for training chest electrocardiography electrode placement. AR applications featuring augmented object displays and interactions have been developed to facilitate learning and training of electrocardiography (ECG) chest lead placement via smartphones. The AR marker-based technique was used to track the objects. The proposed AR application can project virtual ECG electrode positions onto the mannequin’s chest and provide feedback to trainees. We designed experimental tasks using the pre- and post-tests and practice sessions to verify the efficiency of the proposed AR application. The control group was assigned to learn chest ECG electrode placement using traditional methods, whereas the intervention group was introduced to the proposed AR application for ECG electrode placement. The results indicate that the proposed AR application can encourage learning outcomes, such as chest lead ECG knowledge and skills. Moreover, using AR technology can enhance students’ learning experiences. In the future, we plan to apply the proposed AR technology to improve related courses in medical science education.

Continuous Monitoring of Psychosocial Stress by Non-Invasive Volatilomics.

Stress is becoming increasingly commonplace in modern times, making it important to have accurate and effective detection methods. Currently, detection methods such as self-evaluation and clinical questionnaires are subjective and unsuitable for long-term monitoring. There have been significant studies into biomarkers such as HRV, cortisol, electrocardiography, and blood biomarkers, but the use of multiple electrodes for electrocardiography or blood tests is impractical for real-time stress monitoring. To this end, there is a need for non-invasive sensors to monitor stress in real time. This study looks at the possibility of using breath and skin VOC fingerprinting as stress biomarkers. The Trier social stress test (TSST) was used to induce acute stress and HRV, cortisol, and anxiety levels were measured before, during, and after the test. GC-MS and sensor array were used to collect and measure VOCs. A prediction model found eight different stress-related VOCs with an accuracy of up to 78%, and a molecularly capped gold nanoparticle-based sensor revealed a significant difference in breath VOC fingerprints between the two groups. These stress-related VOCs either changed or returned to baseline after the stress induction, suggesting different metabolic pathways at different times. A correlation analysis revealed an association between VOCs and cortisol levels and a weak correlation with either HRV or anxiety levels, suggesting that VOCs may include complementary information in stress detection. This study shows the potential of VOCs as stress biomarkers, paving the way into developing a real-time, objective, non-invasive stress detection tool for well-being and early detection of stress-related diseases.

A System to Improve Compliance with Electrocardiography Electrode Expiration Tracking.

Electrocardiography (ECG) electrodes require special expiration tracking after the manufacturer's packaging is opened. Compliance with this requirement, however, can be inconsistent. The authors tested the efficacy of a device that provides for expiration tracking of bulk-packaged electrodes to improve compliance. The device tested is a bin with an automated countdown timer that could be used for storing and dispensing open ECG electrodes. Seven operating rooms were inspected three times each before and after implementation of the device. Compliance with expiration dating of open electrodes was recorded for each inspection. Compliance was found in 3 of the 21 (14.3%) baseline inspections. Following implementation of the devices, compliance was found in 20 of 21 (95.2%) inspections. This increase in compliance was statistically significant (p < 0.01). A storage and dispensing device with automated countdown timer significantly improved compliance with expiration dating regulations for bulk-packaged ECG electrodes. It also has the potential to reduce supply cost, packaging waste, and inconvenience compared with individually wrapped electrodes.

Screen-printed fabric electrode for electrocardiogram monitoring on commercial textiles

Due to the low-cost fabrication, printing electronics on flexible substrates shows great potential in robotics, wearable healthcare, and persistent human-machine interfaces. Noninvasive dry-electrodes for electrocardiography (ECG) monitoring are an important technique for detecting early arrhythmias. This article describes a screen printing method for fabricating textile ECG electrodes. The biocompatible carbon ink served as the active electrochemical layer, while the silver paste acted as the conductive path, respectively. The measured results showed that the textile electrode had similar ECG signal monitoring performance compared to commercially available Ag/AgCl electrodes under conditions where the subjects were walking, stationary, and jogging. And the pre-made textile electrodes can be easily connected to the sports bra for monitoring daily exercise ECG. This study demonstrated the feasibility of utilizing textile electrodes for applications in the wearable healthcare industry.

Multifunctional, breathable MXene-PU mesh electronic skin for wearable intelligent 12-lead ECG monitoring system

With the advent of an aging society and increasing concern for cardiovascular health, comfortable long-term electrocardiographic (ECG) monitoring systems in daily life are much in demand. If the system can give real-time feedback on cardiovascular status and offer timely personalized advice like doctors, it will be beneficial to promote cardiovascular health and alleviate the imbalance of medical resources. Herein, we report a multifunctional, conformal, and air-permeable electronic skin (e-skin) based on MXene-Polyurethane mesh (MPM). When used as ECG electrodes, the e-skin shows ultra-low electrode–skin contact impedance (4.68 kΩ at 1 kHz), high signal-to-noise ratio (16.5 dB), and high breathability (2.1838 kg/m2/day), and can be continuously worn for at least 7 days. As a strain sensor, the e-skin exhibits a large measurement range (>40 %) and unique segmental sensitivity (GF = 172.54 in 0 ∼ 18.64 % and 79.38 in 18.64 ∼ 50 %), which is suitable for detecting both subtle and large physiological signals. More significantly, by combining the MPM e-skin with a flexible printed circuit board (FPCB) and a merged convolutional neural network & long-short-term memory (CNN & LSTM) intelligent algorithm, the acquired wearable intelligent e-skin system can realize daily 12-hour 12-lead ECG monitoring with diagnostic accuracy over 99 % for four arrhythmias. These results show that the MPM e-skin has huge potential in multifunctional intelligent healthcare systems. In particular, an intelligent ECG system similar to a “daily doctor” is proposed for daily long-term cardiovascular health monitoring.

Improving public health using contactless ECG electrodes for long-term monitoring of arrhythmia

Cardiovascular disease (CVD) is the leading cause of death and disability worldwide, resulting in 17.3 million deaths annually. Thus, any CVD symptoms should be immediately diagnosed for effective treatments [1]. In this case, Electrocardiography (ECG) is widely considered for monitoring and diagnosing heart symptoms. The traditional wet Ag/AgCl electrodes can acquire high-quality ECG signals. However, they cause skin irritation and require careful skin preparation by a specialist. Therefore, they are not practical for efficient long-term ECG monitoring. To overcome these limitations, contactless capacitive electrodes are introduced as an alternative. But these electrodes suffer various shortfalls in collecting high-quality and clinically acceptable signals. As a coupling capacitor between the body and electrode is formed in these sensors and this capacitor changes due to the subject’s physiological or body movements leading to Motion Artifacts (MAs). In addition, the variable skin potential across the capacitor forms an additive voltage that may distort the ECG signal adversely. This presentation aims to illustrate a comprehensive literature review and methodology used in my study. Regarding the methodology, I intend to simulate the equivalent model of the measurement system and implement it in the real world. Moreover, two issues will be addressed in my research questions. Firstly, I will extract the variable impedance between the sensor and the subject’s skin, which has the highest correlation with MAs according to literature, by injecting a voltage with a known frequency into the circuit. Unlike many previous methods, the ECG signal, and impedance signal will be measured simultaneously. I will address the optimal frequency and impedance signal with maximum correlation with MAs, which are the gaps in previous works. Secondly, in past studies, the effects of skin potential on MAs have not been sufficiently investigated, which is aimed to be analyzed, estimated, and subtracted from the polluted ECG noise signal.

Real time system on chip based wearable cardiac activity monitoring sensor

In this research, a real time low power wearable cardiac activity monitoring device is introduced to display real time electrocardiography (ECG) signal and heart rate (HR). ECG records heart’s electrical activity and heart rate measures the contraction of the heart. The developed device consumes very less power as SoC used in this research has power consumption of 85 μW at 1.1V supply voltage. To measure heart rate and ECG waveform, the pre-gelled ECG electrodes are attached on the RA, LA and LL positon of the human’s body. These pre-gelled ECG electrodes attached to the ECG lead which is further connected to the ECG device. The ECG system is validated and the measured average HR of the subject was 71 to 82 beats per minute (BPM) and ECG graph was also plotted.

Probes of New Types of Electrodes of ECG

Long-term electrocardiography (ECG) monitoring can scrutinize human health, which is very essential for the early detection and treatment of cardiovascular disorders. For present, commercially used silver/silver chloride (Ag/AgCl) electrodes have drawbacks, and these would be more obvious in long-term monitoring. Therefore, people are developing new types of electrodes for ECG from different perspectives. At present, innovations are made: 1) Applying conductive thread into sewing to make textile electrodes for wearable ECG monitoring. 2) New material (Graphite Based Electrode) replacing the conventionally used Ag/AgCl.

Armband Sensors Location Assessment for Left Arm-ECG Bipolar Leads Waveform Components Discovery Tendencies around the MUAC Line.

Sudden cardiac death (SCD) risk can be reduced by early detection of short-lived and transient cardiac arrhythmias using long-term electrocardiographic (ECG) monitoring. Early detection of ventricular arrhythmias can reduce the risk of SCD by allowing appropriate interventions. Long-term continuous ECG monitoring, using a non-invasive armband-based wearable device is an appealing solution for detecting early heart rhythm abnormalities. However, there is a paucity of understanding on the number and best bipolar ECG electrode pairs axial orientation around the left mid-upper arm circumference (MUAC) for such devices. This study addresses the question on the best axial orientation of ECG bipolar electrode pairs around the left MUAC in non-invasive armband-based wearable devices, for the early detection of heart rhythm abnormalities. A total of 18 subjects with almost same BMI values in the WASTCArD arm-ECG database were selected to assess arm-ECG bipolar leads quality using proposed metrics of relative (normalized) signal strength measurement, arm-ECG detection performance of the main ECG waveform event component (QRS) and heart-rate variability (HRV) in six derived bipolar arm ECG-lead sensor pairs around the armband circumference, having regularly spaced axis angles (at 30° steps) orientation. The analysis revealed that the angular range from −30° to +30°of arm-lead sensors pair axis orientation around the arm, including the 0° axis (which is co-planar to chest plane), provided the best orientation on the arm for reasonably good QRS detection; presenting the highest sensitivity (Se) median value of 93.3%, precision PPV median value at 99.6%; HRV RMS correlation (p) of 0.97 and coefficient of determination (R2) of 0.95 with HRV gold standard values measured in the standard Lead-I ECG.

Flexible Hybrid Electronics Nanofiber Electrodes with Excellent Stretchability and Highly Stable Electrical Conductivity for Smart Clothing.

In this paper, a side-by-side, dual-nozzle electrospinning process was used to prepare a flexible hybrid electronics (FHE) material with excellent stretchable properties. A highly stable electrical conductivity was also imparted to the resulting membrane electrodes using silver nanoparticles (AgNPs) and carbon-based nanomaterials of different structures. The AgNP/carbon-based nanomaterials were coated onto bicomponent polymer nanofibers (composed of polyurethane (PU) and polyvinylidene difluoride (PVDF)) on the nanofiber membrane. The FHE nanofiber electrodes were finally integrated into clothing designed to accurately measure human body sensing signals (e.g., electrocardiography (ECG) and electromyography (EMG) signals). To effectively increase the high electrical conductivity, a polymer-type dispersant (polyisobutylene-b-poly(oxyethylene)-b-polyisobutylene, a triblock copolymer) was used to effectively and stably disperse AgNPs with different particle sizes and carbon-based nanomaterials with different geometric dimensions (e.g., zero-dimensional carbon black, one-dimensional carbon nanotubes, and two-dimensional graphene) through non-covalent adsorption. Moreover, the bicomponent PVDF-PU nanofibers were immersed in a mixed dispersant of AgNPs and carbon-based nanomaterials at low concentrations, and thermal post-treatment was conducted to improve the electrical conductivity. The AgNP/graphene oxide (GO) nanofiber electrode exhibited a continuous phase with a stable material microstructure after 5000 repetitions of 50% tension-tension fatigue testing. The waveform pattern obtained from the proposed AgNP/GO nanofiber electrode was compared with those of traditional ECG and EMG electrodes. The nanofiber web electrode treated with organic/inorganic mixed dispersants and verified via tests of its electrical and fatigue properties was found to be suitable for long-term ECG and EMG monitoring, and it has excellent potential in wearable smart sensors.

System for Storage, Dispensing, and Tracking Expiration of Electrocardiography Electrodes.

Electrocardiography electrodes have expiration dates that are foreshortened once the manufacturer's packaging is opened. A system is described for storing and dispensing these perishable electrodes while tracking their new expiration date for safety and regulatory purposes.

Getting Ready for Wound Certification: Promoting Skin Health and Preventing Injuries.

Getting Ready for Wound Certification: Promoting Skin Health and Preventing Injuries.

Novel 3D-printed Electrodes for Implantable Biopotential Monitoring.

A major bottleneck in the manufacturing process of a medical implant capable of biopotential measurements is the design and assembly of a conductive electrode interface. This paper presents the use of a novel 3D-printing process to integrate conductive metal surfaces on a low-temperature co-fired ceramic base to be deployed as electrodes for electrocardiography (ECG) implants for small animals. In order to fit the ECG sensing system within the size of an injectable microchip implant, the electronics along with a pin-type lithium-ion battery are inserted into a cylindrical glass tube with both ends sealed by these 3D printed composite electrode discs using biomedical epoxy. In the scope of this paper, we present a proof-of-concept in vivo experiment for recording ECG from an avian animal model under local anesthesia to verify the electrode performance. Simultaneous recording with a commercial device validated the measurements, demonstrating promising accuracy in heart rate and breathing rate monitoring. This novel technology could open avenues for the mass manufacturing of miniaturized ECG implants.Clinical relevance- A novel manufacturing process and an implantable system are presented for continuous physiological monitoring of animals to be used by veterinarians, animal scientists, and biomedical researchers with potential future applications in human health monitoring.

Self-adhesive, stretchable, and dry silver nanorods embedded polydimethylsiloxane biopotential electrodes for electrocardiography

Biopotential signals are extremely useful in assessing organ function and diagnosing diseases. This study proposes a highly flexible, conductive, antibacterial, and self-adhesive silver nanorods (AgNRs) embedded polydimethylsiloxane (PDMS) dry electrode for long-term electrocardiogram (ECG) monitoring with portable instrumentation. We use a unique glancing angle deposition method to fabricate AgNRs and embedded them in a biocompatible PDMS matrix. These electrodes do not cause skin irritation even after several hours of use and work efficiently without skin preparation. These AgNRs-PDMS electrodes have an electrical resistivity of 10−7 Ω m and a skin contact impedance of 93.9 ± 0.7 kΩ to 6.2 ± 3.7 kΩ for frequencies ranging from 40 Hz to 1 kHz, which is around 18% less than most conventional Ag/AgCl wet electrodes. The fabricated electrodes have a signal-to-noise ratio of 12 dB, comparable to that of a conventional Ag/AgCl electrode. A signal acquisition circuit is designed to detect ECG signals combined with proposed dry electrodes and a wireless monitoring device. Finally, real-time ECG signals are displayed on a mobile phone via an Android application. These AgNRs-PDMS dry electrodes, in combination with the portable wireless device, may be used in future clinical studies that require real-time and long-term ECG monitoring.

MEGnet: Automatic ICA-based artifact removal for MEG using spatiotemporal convolutional neural networks

Magnetoencephalography (MEG) is a functional neuroimaging tool that records the magnetic fields induced by neuronal activity; however, signal from non-neuronal sources can corrupt the data. Eye-blinks, saccades, and cardiac activity are three of the most common sources of non-neuronal artifacts. They can be measured by affixing eye proximal electrodes, as in electrooculography (EOG), and chest electrodes, as in electrocardiography (ECG), however this complicates imaging setup, decreases patient comfort, and can induce further artifacts from movement. This work proposes an EOG- and ECG-free approach to identify eye-blinks, saccades, and cardiac activity signals for automated artifact suppression.The contribution of this work is three-fold. First, using a data driven, multivariate decomposition approach based on Independent Component Analysis (ICA), a highly accurate artifact classifier is constructed as an amalgam of deep 1-D and 2-D Convolutional Neural Networks (CNNs) to automate the identification and removal of ubiquitous whole brain artifacts including eye-blink, saccade, and cardiac artifacts. The specific architecture of this network is optimized through an unbiased, computer-based hyperparameter random search. Second, visualization methods are applied to the learned abstraction to reveal what features the model uses and to bolster user confidence in the model's training and potential for generalization. Finally, the model is trained and tested on both resting-state and task MEG data from 217 subjects, and achieves a new state-of-the-art in artifact detection accuracy of 98.95% including 96.74% sensitivity and 99.34% specificity on the held out test-set. This work automates MEG processing for both clinical and research use, adapts to the acquired acquisition time, and can obviate the need for EOG or ECG electrodes for artifact detection.

Trans-Ocular Brain Impedance Indices Predict Pressure Reactivity Index Changes in a Porcine Model of Hypotension and Cerebral Autoregulation Perturbation.

Cerebrovascular autoregulation (CA) is a protective mechanism that enables the cerebral vasculature to automodulate tone in response to changes in cerebral perfusion pressure to ensure constant levels of cerebral blood flow (CBF) and oxygen delivery. CA can be impaired after neurological injury and contributes to secondary brain injury. In this study, we report novel impedance indices using trans-ocular brain impedance (TOBI) during controlled systemic hemorrhage and hypotension to assess CA in comparison with pressure reactivity index (PRx). Yorkshire swine were instrumented to record intracranial pressure (ICP), mean arterial pressure (MAP), and CBF. TOBI was recorded using electrocardiographic electrodes placed on the closed eyelids. Impedance changes (dz) were recorded in response to introducing an alternating current (0.4mA) through the electrodes. MAP, ICP, and CBF were also measured. Animals were subjected to a controlled hemorrhage to remove 30-40% of each animal's total blood volume over 25-35min. Hemorrhage was titrated to reach an MAP of approximately 35mm Hg and end-tidal carbon dioxide above 28mm Hg. PRx was calculated as a moving Pearson correlation between MAP and ICP. TOBI indices were calculated as the amplitude of the respiratory-induced changes in dz. DZx was calculated as a moving Pearson correlation between dz and MAP. TOBI indices (dz and DZx) were compared with hemodynamic indicators and PRx. dz was shown to be highly correlated with MAP, ICP, cerebral perfusion pressure, and CBF (r = - 0.823, - 0.723, - 0.813, and - 0.726), respectively (p < 0.0001). During hemorrhage, cerebral perfusion pressure and CBF had a mean percent decrease (standard deviation) from baseline of - 54.2% (12.5%) and - 28.3% (14.7%), respectively, whereas dz increased by 277% (268%). Receiver operator characteristics and precision-recall curves demonstrated high predictive performance of DZx when compared with PRx with an area under the curve above 0.82 and 0.89 for receiver operator characteristic and precision-recall curves, respectively, with high sensitivity and positive predictive power. TOBI indices appear to track changes in PRx and hemodynamics that affect CA during hemorrhage-induced hypotension. TOBI may offer a suitable, less invasive surrogate to PRx for monitoring and assessing CA.

3D Printable and Biocompatible Iongels for Body Sensor Applications

AbstractSoft‐ionic materials with biocompatibility and 3D printability are needed to develop next‐generation devices to interface between electronic and biological signals. Herein, thermoreversible and biocompatible ionic liquid gels or iongels, which can be processed by direct ink writing are reported. The iongels are designed by taking advantage of polyvinyl alcohol/phenol interactions to gelify biocompatible cholinium carboxylate ionic liquids. The obtained iongels are stable, soft, and flexible materials (Young modulus between 14 and 70 kPa) with high ionic conductivity (1.8 × 10–2 S cm–1). Interestingly, they presented thermoreversible properties with gel–sol transitions ranging from 85 and 110 °C, which allows the iongel processing via direct ink writing 3D printing by material extrusion at temperatures over its transition. These 3D printable iongels are integrated into a variety of body sensors applications, namely pressure sensors, motion sensors and electrodes for electrophysiological recordings. The iongels are used as pressure sensors with a sensitivity of 0.1 kPa–1, ten times higher than that of others similar materials reported so far; showing its ability to detect human motion. Furthermore, the iongels showed excellent performance in electrodes for electrocardiography (ECG) recording, presenting good stability over time with electrocardiographic waves maintained their typical shape even after weeks.

Wearable Smart Textiles for Long-Term Electrocardiography Monitoring-A Review.

The continuous and long-term measurement and monitoring of physiological signals such as electrocardiography (ECG) are very important for the early detection and treatment of heart disorders at an early stage prior to a serious condition occurring. The increasing demand for the continuous monitoring of the ECG signal needs the rapid development of wearable electronic technology. During wearable ECG monitoring, the electrodes are the main components that affect the signal quality and comfort of the user. This review assesses the application of textile electrodes for ECG monitoring from the fundamentals to the latest developments and prospects for their future fate. The fabrication techniques of textile electrodes and their performance in terms of skin–electrode contact impedance, motion artifacts and signal quality are also reviewed and discussed. Textile electrodes can be fabricated by integrating thin metal fiber during the manufacturing stage of textile products or by coating textiles with conductive materials like metal inks, carbon materials, or conductive polymers. The review also discusses how textile electrodes for ECG function via direct skin contact or via a non-contact capacitive coupling. Finally, the current intensive and promising research towards finding textile-based ECG electrodes with better comfort and signal quality in the fields of textile, material, medical and electrical engineering are presented as a perspective.