Electrocardiographic Electrodes Research Articles

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.

Development of a model of electric impedance in the contact between the skin and a capacitive active electrode when measuring electrocardiogram in combustiology

Long-term ECG (electrocardiogram) measurement in patients with burns is a complicated problem since the overlapping of surface contact electrodes can lead to additional injuries. The possibility of ECG recording in patients with burns using capacitive electrodes was not proved, and there are no models of the electrode contact with a patient’s body while rehabilitation means are used. In this paper, the model of the contact between capacitive electrodes and the skin was modified and the circuit model of the contact: skin – bandages (saline solution) – film – active capacitive electrode, was described. The influence of the parameters of a capacitive electrode on the amplitude-frequency characteristics (AFC) of the contact of an electrode with skin was assessed. It was found that contact capacitance is crucial to obtain a high-quality ECG signal. The parameters of the impedance of bandages, saline solution, a dielectric film were calculated, and their effect on the AFC was studied. Based on the modified model, the AFC contact was modeled taking into consideration all the calculated parameters; it was found that the resulting AFC of the contact corresponds to the frequency range of the ECG signal. Analysis of the calculations proves the possibility of using capacitive electrodes when applying various rehabilitation means. It was found that at a change in the impedance of the saline solution from 0.1 gigaohms to 1 gigaohm, the changes in the AFC of the contact are not crucial for the final quality of the received signal. All calculations were carried out by modeling in the Qucs environment (ngspice SPICE). Simulation results can be used in the development of new types of capacitive electrocardiographic electrodes. The proposed model can be used to study other wound covers, as well as to model physiological processes when putting artificial skin and wound covers

Ictal activation of oxygen-conserving reflexes as a mechanism for sudden death in epilepsy.

To test the hypothesis that death with physiological parallels to human cases of sudden unexpected death in epilepsy (SUDEP) can be induced in seizing rats by ictal activation of oxygen-conserving reflexes (OCRs). Urethane-anesthetized female Long-Evans rats were implanted with electrodes for electrocardiography (ECG), electrocorticography (ECoG), and respiratory thermocouple; venous and arterial cannulas; and a laryngoscope guide and cannula or nasal cannula for activation of the laryngeal chemoreflex (LCR) or mammalian diving reflex (MDR), respectively. Kainic acid injection, either systemic or into the ventral hippocampus, induced prolonged acute seizures. Reflex challenges during seizures caused sudden death in 18 of 20 rats-all MDR rats (10) and all but two LCR rats (8) failed to recover from ictal activation of OCRs and died within minutes of the reflexes. By comparison, 4 of 4 control (ie, nonseizing) rats recovered from 64 induced diving reflexes (16 per rat), and 4 of 4 controls recovered from 64 induced chemoreflexes (16 per rat). Multiple measures were consistent with reports of human SUDEP. Terminal central apnea preceded terminal asystole in all cases. Heart and respiratory rate fluctuations that paralleled those seen in human SUDEP occurred during OCR-induced sudden death, and mean arterial pressure (MAP) was predictive of death, showing a 17 or 15mm Hg drop (MDR and LCR, respectively) in the 20 s window centered on the time of brain death. OCR activation was never fatal in nonseizing rats. These results present a method of inducing sudden death in two seizure models that show pathophysiology consistent with that observed in human cases of SUDEP. This proposed mechanism directly informs previous findings by our group and others in the field; provides a repeatable, inducible animal model for the study of sudden death; and offers a potential explanation for observations made in cases of human SUDEP.

Development of Small-Size Active Electrodes for Electrocardiography and Electroencephalography

Amplifying cascades of active electrodes have been developed using NI Multisim software and assembled on a breadboard. It has been shown that NI Multisim allows developing electrodes with virtual characteristics differing from the characteristics of real electrodes by no more than 3%, which is an acceptable result.

Skin Preparation and Electrode Replacement to Reduce Alarm Fatigue in a Community Hospital Intensive Care Unit.

Nurses in intensive care units are exposed to hundreds of alarms during a shift, and research shows that most alarms are not clinically relevant. Alarm fatigue can occur when a nurse becomes desensitized to alarms. Alarm fatigue can jeopardize patient safety, and adverse alarm events can lead to patients dying. To evaluate how a process intervention affects the number of alarms during an 8-hour shift in an intensive care unit. A total of 62 patients from an intensive care unit were included in the study; 32 of these patients received the intervention, which included washing the patient's chest with soap and water and applying new electrocardiography electrodes at the start of a shift. The number of alarms, clinical diagnoses, and demographic variables were collected for each patient. A Poisson regression model was used to evaluate the impact of the intervention on the overall number of clinical alarms during the shift, with no adjustments to the alarm settings or other interventions. After relevant covariates are controlled for, the results suggest that patients in the intervention group presented significantly fewer alarms than did patients in the control group. Managing clinical alarms is a main issue in terms of both patient safety and staff workload management. The results of this study demonstrate that a relatively simple process-oriented strategy can decrease the number of alarms.

Spectral trimming technique: a new approach for suppressing motion artefacts in stress electrocardiography

Motion artefacts in electrocardiographic (ECG) signal are suppressed mainly by adaptive noise cancellation and wavelet denoising. While the former requires a motion sensor in addition to ECG electrodes, the latter removes some of the desired low-frequency components in the signal. In this paper spectral trimming technique is being introduced for suppressing the motion artefacts in stress electrocardiography. In this method, Fourier spectral coefficients up to 1.221 Hz of noisy signal are trimmed on the basis of template derived from resting ECG signal in the same subject. The proposed spectral trimming technique has yielded the lowest value of mean ± standard deviation for root mean square error (18.92 ± 8.71) and highest value of the signal to noise ratio (6.439 ± 4.266) as compared to other three methods, namely adaptive noise cancellation, wavelet decomposition and adaptive line enhancement with compatible value of correlation coefficient. Subsequently, spectral trimming technique has been implemented in real-time (deferred by 8.2 s) application for stress electrocardiography. Spectral trimming technique thus offers a method of choice for motion artefact suppression in offline as well as deferred online applications. This method takes care of the limitations of conventional methods such as adaptive noise cancellation or wavelet denoising for suppressing motion artefacts in stress electrocardiography.

Electronic‐ECM: A Permeable Microporous Elastomer for an Advanced Bio‐Integrated Continuous Sensing Platform

AbstractTissue interfaced electronics have become promising candidates for transcending beyond conventional diagnostic technology, enabling chronic, quantitative health monitoring possibilities; however, these systems have primarily relied on impenetrable materials that contribute to the mechanical and physical mismatch of bioelectronic interfaces. Inspired by the soft mechanics and physical architecture of the epidermal extracellular matrix, this study presents a 3D microporous, fibrous mesh of polydimethylsiloxane for epidermal electronics. The resulting elastic microfiber mat, exhibits a minimal mechanical footprint with analogous viscoelastic behavior, cytocompatibility, and biofluid‐permeable interface capable of small molecule, gas, and transdermal water diffusion. Electrocardiography electrodes heterogeneously integrate within the synthetic electronic‐extracellular matrix (e‐ECM) membrane and achieve chronic high resolution biopotential monitoring during typically debilitating environments (e.g., vigorous sweating) for conventional bioelectronics. The e‐ECM platform provides a substrate template for open‐mesh electronics, enabling advanced implementations in long‐term quantitative analysis monitoring for wearable and implantable devices.

Awake Volunteer Pain Scores During Neuromuscular Monitoring.

There is a need for easy to use, reliable neuromuscular monitors (NMMs). This multicenter, prospective, unblinded study compared the discomfort associated with neurostimulation in unmedicated healthy volunteers when using the new electromyography (EMG)-based TetraGraph and acceleromyography (AMG)-based TOF-Watch NMMs. The secondary aim was to compare the repeatability of the train-of-four (TOF) ratios (TOFRs) obtained with the 2 devices. The TOF measurements of 135 volunteers from 3 university hospitals were analyzed (age: 38.3 ± 12 years [mean ± standard deviation [SD]]; male/female ratio = 63:72). The left or right ulnar nerve was stimulated at the wrist in TOF mode with 20, 30, 40, and 50 mA stimulating current intensities with both devices in random order. The TOF-Watch used standard electrocardiography (ECG) electrodes (Red Dot; 3M Health Care) for nerve stimulation. The stimulating surface area of 1 ECG electrode is 113 mm. The piezoelectric probe was attached to the thumb, and a hand adapter was used to ensure consistency of AMG measurements. The TetraGraph uses proprietary surface strip electrodes for nerve stimulation and muscle action potential recording, whose stimulating surface area is roughly twice as big as that of standard ECG electrodes (228.5 mm). The volunteers were asked to rate the discomfort associated with neurostimulation on a 0-10 verbal numerical rating scale (VNRS) score anchored with 0 (no pain) and 10 (worst pain ever experienced). A linear mixed-effects model was used to evaluate the difference in VNRS scores between devices. P <.05 was accepted as the level of significance. In the linear mixed-effects model, there were no differences in VNRS scores between devices at any of the stimulating current intensities, P = .38. The median (range) VNRS scores obtained with TOF-Watch and TetraGraph devices were 2 (0-7) vs 2 (0-8) at 20 mA, 3 (1-9) vs 3 (1-9) at 30 mA, 5 (1-10) vs 5 (1-10) at 40 mA, and 5 (1-10) vs 6 (1-10) at 50 mA stimulating current intensities. The mean of the 1469 TOFRs obtained with TetraGraph was 100.43% ± 7.74% (standard error = 0.2%). Due to technical difficulties, the repeatability of the TOFRs could not be determined. Despite the different size and design of the stimulating electrodes, the 2 NMMs caused the same level of discomfort in unmedicated healthy volunteers.

All organic graphene oxide and Poly (3, 4-ethylene dioxythiophene) - Poly (styrene sulfonate) coated knitted textile fabrics for wearable electrocardiography (ECG) monitoring

This research approach has been used to enhance and investigate the electrical performance of graphene-based textiles by using an exhaust dyeing method. We developed a highly flexible and wearable e-textile for smart clothing in general and electrocardiogram (ECG) biomedical applications in particular. One step dyeing and reduction of graphene oxide on the textile substrate was accomplished simultaneously at 90 °C in 2 h. After one bath dyeing and reduction of GO, the knitted fabric was coated with conductive polymer PEDOT: PSS via dip coating as a layer by layer (LBL) technique. The resultant knitted textile electrode showed a reduction in sheet resistance from 2.5 MΩ∼140KΩ with increasing (1∼10) dyeing cycles. The electrical conductivity was further the improved, as sheet resistance was decreased from 180KΩ∼120Ω when coated with PEDOT: PSS as compared to pristine PEDOT: PSS and rGO. The results showed that washing has an adverse effect on electrical conductivity. The textile electrode was stable up to 20∼30 washing and 120∼130 bending cycles. The developed electrodes were used as an ECG electrode, with low impedance and higher contact to human skin. The textile electrode showed the enhanced performance to detect the high-quality electrocardiograms (ECG) signals for heart rate in both wet and dry conditions.

Positioning an ECG electrode to the dorsal side can record higher amplitude of CMAPs during cryoballoon ablation.

PurposePhrenic nerve injury (PNI) is one of the important complications during cryoballoon (CB) ablation. Recording diaphragmatic compound motor action potentials (CMAPs) during CB ablation can predict PNI. CMAP monitoring may be inaccurate when CMAP amplitudes are low. We examined the effect of positioning an electrocardiography (ECG) electrode at the dorsal side.MethodsWe retrospectively analyzed the cases of 197 consecutive patients who underwent CB ablation for pulmonary vein isolation (PVI) (April 2016 to December 2018) at our institution. CMAP amplitudes were monitored using two recording methods just before cryoapplication. (a) Conventional method: right‐arm ECG electrode positioned 5 cm above the xiphoid on the ventral side; left‐arm ECG electrode positioned along the costal margin. (b) Our original method: right‐arm electrode positioned 5 cm above the xiphoid on the dorsal side; left‐arm electrode positioned along the costal margin.ResultsThe CMAP amplitude during right phrenic nerve pacing was significantly higher at the dorsal side than the ventral side (0.80 ± 0.31 mV vs 0.66 ± 0.29 mV, P < .01). Similarly, the CMAP amplitude during left phrenic nerve pacing was significantly higher at the dorsal side than the ventral side (0.92 ± 0.39 mV, 0.73 ± 0.37 mV, P < .01). PNI occurred in six patients (3.0%); three patients experienced transient PNI, another three patients experienced persistent PNI, and none developed permanent PNI.ConclusionsCMAP amplitudes were significantly high at the dorsal side compared to the ventral side. Monitoring phrenic nerve function using an ECG electrode at the dorsal side is a simple and easy procedure.

Synthesis of graphite/Ag/AgCl nanocomposite electrode materials

Nanocomposite electrode materials composed of graphite, Ag and AgCl were prepared by impregnation of graphite with a suspension of silver nanoparticles followed by anodizing in hydrochloric acid to obtain a layer of silver chloride on the surface of the nanoparticles. Silver nanoparticles were synthesized by the reduction of silver salts in benzyl alcohol. It was shown that the mass fraction of 1% Ag in the nanocomposite is optimal for creating a uniform coating of carbon surface with nanoparticles. The preliminary treatment of the graphite surface by the 0.75HNO3-0.25H2SO4 mixture resulted in formation of silver nanoparticles with the smallest size of 5–10 nm and their uniform distribution over the graphite surface. It was found that the nanocomposite electrode materials under study meet general requirements for electrocardiographic electrodes.

Current echocardiography practice in Serbia - a national survey by the Echocardiographic Society of Serbia

Introduction/Objective. The purpose of the Echocardiographic Society of Serbia (ECHOS) national survey was to assess current echocardiography practice in Serbia, the availability of different echocardiographic techniques and self-perceived need for improvement at personal and institutional level. Methods. A survey comprising 20 questions about demographics, numbers and distribution of echocardiographic equipment and techniques, image acquisition and reporting standards as well as future educational preferences was sent to all ECHOS members via email. Results. A total of 106 members (42%) answered the survey. Echocardiographic examinations are most frequently performed by cardiologists and internal medicine specialists. Transesophageal echocardiography (TOE), stress echocardiography (SECHO) and speckle tracking echocardiography (SpTE) are available in approximately 20% of centers, three-dimensional echocardiography in 11%, while contrast echocardiography is practiced in only two centers. Less than a third of respondents always attach electrocardiographic electrodes and archive examinations. Almost all respondents (96%), always evaluate both systolic and diastolic function of the left ventricle (LV), although systolic LV function is frequently assessed (55%) using non-standard methods. The newer echocardiographic machines are more often available at university than non-university centers (87 versus 44%, p &lt; 0.01). SECHO was perceived as the most needed technique at the institutional level, while SpTE and TOE were most often reported personal aspirations of the respondents. Conclusion. Advanced techniques, SECHO and TOE are needed but rarely performed outside the university hospitals in Serbia. In order to achieve a better adherence to standards of practice in echocardiography, the development of national guidelines and personal and laboratory accreditation seem warranted.

How to Connect Conductive Flexible Textile Tracks to Skin Electrocardiography Electrodes and Protect Them Against Washing

Cardiovascular diseases are the leading cause of lethal issues worldwide. The most effective way to combat these diseases is the real-time monitoring of the electrocardiogram (ECG) that reflects the electrical signals generated by the heart cells. So far, the ECG is recorded by using the cutaneous conventional medical electrodes (Ag/AgCl). These electrodes are not adapted for long-term use as they are not fully integrated into underwear and generally can provoke skin irritation, because of the ionic gel that serves to reduce the impedance of the electrode/ skin interface. The first part of this paper concerns the design and realization by embroidery of three different patterns of conductive tracks that could be adopted as connection lines between an electronic module and ECG electrodes. In order to make these conductive tracks washable, two encapsulation methods have been investigated. The reliability of the developed conductive tracks and encapsulation methods has been analyzed. The second part of this study is focused on the development of washable embroidered ECG bands operating without any ionic gel as alternatives to medical electrodes (Ag/AgCl). The acquisition of ECG signals has been carried out on 3 female and 6 male healthy subjects aged between 25 and 55 years. In the last stage of this paper, we explore the ECG signal in static condition, the spectral power density of the ECG signal, the signal-to-noise ratio (SNR) of ECG electrodes before and after 50 washing cycles.

Brainstem activity, apnea, and death during seizures induced by intrahippocampal kainic acid in anaesthetized rats.

To investigate how prolonged seizure activity affects cardiorespiratory function and activity of pre-Bötzinger complex, leading to sudden death. Urethane-anesthetized female Long-Evans rats were implanted with nasal thermocouple; venous and arterial cannulae; and electrodes for electrocardiography (ECG) and hippocampal, cortical, and brainstem recording. Kainic acid injection into the ventral hippocampus induced status epilepticus. Seizures caused hypertension, tachycardia, and tachypnea punctuated by recurrent transient apneas. Salivation increased considerably: in 11 of 12 rats, liquid with alkaline pH consistent with saliva was expelled from the mouth. Most transient apneas were obstructive: nasal airflow ceased, while, in 83%, efforts to breathe persisted as continued rhythmic activity of respiratory pre-Bötzinger neurons, inspiratory electromyography (EMG), and excursions of the chest wall and abdomen. Blood pressure oscillated in time with respiratory efforts. This pattern also occurred in a minority of cases (16%) of incomplete apnea, but not in rare cases (1%) of transient central apneas. During transient obstructive apneas, the frequency of all inspiratory efforts decreased abruptly by ~30%, suggesting a resetting of the central respiratory rhythm generator. Twenty-two of thirty-one rats died, due either to obstructive apnea (12) or central apnea following progressive slowing of respiration (10). Most rats dying of central apnea had experienced several transient obstructive apneas. Negative DC field potential shifts of the brainstem followed the final breath, consistent with previous reports on spreading depolarization in mouse models. Timing suggests that the DC shift is a consequence rather than cause of respiratory collapse. Cardiac activity continued for tens of seconds. Seizure activity in forebrain induces pronounced autonomic activation and disrupts activity in medullary respiratory centers, resulting in death from either obstructive or central apnea. These results directly inform mechanisms of death in status epilepticus, and indirectly provide clues to mechanisms of sudden unexpected death in epilepsy (SUDEP).

Skin sympathetic nerve activity as a biomarker for syncopal episodes during a tilt table test

Autonomic imbalance is the proposed mechanism of syncope during a tilt table test (TTT). We have recently demonstrated that skin sympathetic nerve activity (SKNA) can be noninvasively recorded using electrocardiographic electrodes. The purpose of this study was to test the hypothesis that increased SKNA activation precedes tilt-induced syncope. We studied 50 patients with a history of neurocardiogenic syncope undergoing a TTT. The recorded signals were band-pass filtered at 500-1000 Hz to analyze nerve activity. The average SKNA (aSKNA) value at baseline was 1.38 ± 0.38 μV in patients without syncope and 1.42 ± 0.52 μV in patients with syncope (P = .77). On upright tilt, aSKNA was 1.34 ± 0.40 μV in patients who did not have syncope and 1.39 ± 0.43 μV in patients who had syncope (P = .65). In all 14 patients with syncope, there was a surge of SKNA before an initial increase in heart rate followed by bradycardia, hypotension, and syncope. The peak aSKNA immediately (<1 minute) before syncope was significantly higher than baseline aSKNA (2.63 ± 1.22 vs 1.39 ± 0.43 μV; P = .0005). After syncope, patients were immediately placed in the supine position and aSKNA dropped significantly to 1.26 ± 0.43 μV; (P = .0004). The heart rate variability during the TTT shows a significant increase in parasympathetic tone during syncope (low-frequency/high-frequency ratio: 7.15 vs 2.21; P = .04). Patients with syncope do not have elevated sympathetic tone at baseline or during the TTT except immediately before syncope when there is a transient surge of SKNA followed by sympathetic withdrawal along with parasympathetic surge.

Reliability Challenges in Fabrication of Flexible Hybrid Electronics for Human Performance Monitors: A System-Level Study

Flexible hybrid electronics (FHE) interface rigid electronic components with flexible sensors, circuits, and substrates. This paper reports the reliability improvement of an FHE human performance monitor (HPM), designed to monitor electrocardiography (ECG) signals. The $50.8 {\,\,\mathrm {mm}} \times 50.8 {\,\,\mathrm {mm}}$ HPM is fabricated on Kapton HN polyimide (PI) substrate with flexible gold (Au) ECG electrodes on one side of the substrate and rigid electronic components for signal processing and communication mounted on the other side of the substrate. Our previously reported HPMs demonstrated reliability issues due to: 1) cracking of the copper (Cu) circuitry and 2) thinning and lack of adhesion at the printed Au and plated Cu interface that connected printed sensors to the Cu circuitry. Both failure mechanisms resulted in electrical opens in the circuit, which caused device failure. We explored effects of different design parameters, such as PI substrate thickness (50 versus $125~\mu \text{m}$ ), Cu circuit thickness (2 versus 6 $\mu \text{m}$ ), solder reflow temperature [205 °C for Tin-Lead (Sn-Pb) versus 175 °C for Tin-Bismuth (Sn–Bi) solder], solder pad design, and optimized inkjet printing (printing on bare Cu versus Au-plated Cu) on improving FHE reliability. Test vehicles (TVs) with different combinations of these factors were fabricated and bend-tested to determine the most robust configuration. TVs with 50- $\mu \text{m}$ -thick PI substrate, 6- $\mu \text{m}$ -thick Cu circuit, Sn–Bi solder, redesigned solder pads with rounded corners, and printed Au traces on Au plated Cu pads demonstrated the best reliability results.

Graphene and Poly(3,4-ethylene dioxythiophene):Poly(4-styrenesulfonate) on Nonwoven Fabric as a Room Temperature Metal and Its Application as Dry Electrodes for Electrocardiography.

Highly conductive, metal-like poly(ethylene terephthalate) (PET) nonwoven fabric was prepared by coating poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) containing dimethyl sulfoxide (DMSO) onto PET nonwoven fabric previously coated with graphene/graphite. The sheet resistance of the original nonwoven fabric decreases from >80 MΩ□-1 to 1.1 Ω□-1 after coating with 10.7 wt % graphene and 5.48 wt % PEDOT:PSS with a maximum current at breakdown of 4 A. This sheet resistance is lower than previously reported sheet resistances of fabrics coated with graphene films, PEDOT:PSS films, or PEDOT:PSS coated fabrics from the literature. The effect of temperature on the resistance of graphene/PEDOT:PSS coated fabric has revealed that the resistance decreases with increasing temperature, analogous to semiconductors, with a clear semiconductor-metal transition occurring at 290 K. Finally, a coating of 18 wt % graphene/graphite and 2.5 wt % PEDOT:PSS (Rs = 5.5 Ω□-1) screen printed on the nonwoven fabric was shown to function as an electrode for electrocardiography without any hydrogel and with dry skin conditions. This composite coating finds application in wearable electronics for military and consumer sectors.

Validation of Printed, Skin‐Mounted Multilead Electrode for ECG Measurements

AbstractAn electrocardiography (ECG) monitoring can be used to detect heart‐related abnormalities by recording cardiac activity over a period of time. The conventional 12‐lead ECG measurement system is the standard practice for the evaluation of the heart's electrical activity. However, a recent trend is to develop patch‐type measurement devices for unobtrusive ECG monitoring by reducing device size and number of electrodes on the skin. This development aims to minimize the discomfort for the user from the wearable recording devices. A printed, bandage‐type hybrid system for continuous ECG monitoring to allow as much comfort as possible while maintaining the signal quality required for medical evaluation is proposed. Movement artifacts in recorded ECG signals are a challenge in long‐term monitoring while the patients are engaged in their everyday activities. The movement artifacts from the printed skin‐conformable electrode are compared to commercial exercise stress‐test ECG electrodes during different physical activities and stationary periods. The results show that the signal quality obtained with the multilead patch ECG electrode, manufactured with printing technologies, is comparable to electrodes currently used in healthcare.

PU nanoweb-based textile electrode treated with single-walled carbon nanotube/silver nanowire and its application to ECG monitoring

This paper is a research on textile electrodes fabricated by applying single-walled carbon nanotube (SWCNT) and silver nanowire (AgNW) to polyurethane (PU) nanoweb for monitoring electrocardiography (ECG) signals. In order to impart electrical conductivity, PU nanoweb was treated with SWCNT and AgNW. The PU nanoweb was dipped into 15 g of SWCNT dispersion mixed with 5 g of AgNW dispersion, and it was also treated with heat post-treatment and ethanol pre-treatment for enhanced conductivity. The electrical properties were evaluated by electrical linear resistance and impedance. The tensile properties were measured by Instron. By using the treated specimens, the wearable textile sensors were fabricated and verified to properly act as ECG electrodes via wear-trials compared to the conventional ECG electrode. To compare the ECG signals between Ag/AgCl electrode and textile electrodes, morphology of waveforms was compared and statistical analysis was also conducted. The results of the electrical properties showed that specimens SA1-H, SA1-E, and SA1-HE was much lower than SA1, and especially, SA1-H showed the lowest resistance. It corresponded to the results of impedance that specimen SA1 had the highest and specimen SA1-H had the lowest value. The results of the tensile properties showed that specimen SA1-H had higher tensile strength and elongation at break than the untreated. And, the results of the wear-trials showed that specimen SA1-H had the performance for ECG signals monitoring regardless of rest/stress-states, age, sex, and BMI index of the participants. Thus, it confirmed that the wearable textile sensors fabricated by using the SWCNT/AgNW treated PU nanoweb was suitable for ECG monitoring. Based on the results, it should have approximately 10 Ω cm−1 when applied as the ECG electrode for long-term bio-monitoring smart clothing.