Patch Electrode Research Articles

Development and validation of Motion Artefact Rejection System (MARS) for electrocardiography using novel skin-stretch estimation approach

Electrocardiography (ECG) is widely used in clinical practice, for example to diagnose coronary artery disease or the cause of chest pain during a stress test, while the patient is running on a treadmill. However, artefacts due to subject’s movement are hard to identify and eliminate and can be easily mistaken for symptoms of arrhythmia, leading to misdiagnosis and false alarms. Skin stretch has been identified as a major source of motion artefacts in ECG signals.A Motion Artefact Rejection System (MARS) has been developed, where a polymer patch electrode with Young’s modulus lower than of skin was used to simultaneously measure ECG and skin stretch. Skin-stretch artefacts were induced in 7 subjects across the following age groups: 18–35 years (3 subjects), 36–55 years (2 subjects), and 56 years and above (2 subjects). The motion artefact measured using patch electrodes was used in advanced signals processing algorithms- Principal Component Analysis (PCA) and Independent Component Analysis (ICA).A novel, state-of-the-art technique to identify and eliminate motion artefacts from ECG signals has been developed which is feasible for medical implementations.

A Low-Power High-Data-Transmission Multi-Lead ECG Acquisition Sensor System.

This study presents a low-power multi-lead wearable electrocardiogram (ECG) signal sensor system design that can simultaneously acquire the electrocardiograms from three leads, I, II, and V1. The sensor system includes two parts, an ECG test clothing with five electrode patches and an acquisition device. Compared with the traditional 12-lead wired ECG detection instrument, which limits patient mobility and needs medical staff assistance to acquire the ECG signal, the proposed vest-type ECG acquisition system is very comfortable and easy to use by patients themselves anytime and anywhere, especially for the elderly. The proposed study incorporates three methods to reduce the power consumption of the system by optimizing the micro control unit (MCU) working mode, adjusting the radio frequency (RF) parameters, and compressing the transmitted data. In addition, Huffman lossless coding is used to compress the transmitted data in order to increase the sampling rate of the acquisition system. It makes the whole system operate continuously for a long period of time and acquire abundant ECG information, which is helpful for clinical diagnosis. Finally, a series of tests were performed on the designed wearable ECG device. The results have demonstrated that the multi-lead wearable ECG device can collect, process, and transmit ECG data through Bluetooth technology. The ECG waveforms collected by the device are clear, complete, and can be displayed in real-time on a mobile phone. The sampling rate of the proposed wearable sensor system is 250 Hz per lead, which is dependent on the lossless compression scheme. The device achieves a compression ratio of 2.31. By implementing a low power design on the device, the resulting overall operational current of the device is reduced by 37.6% to 9.87 mA under a supply voltage of 2.1 V. The proposed vest-type multi-lead ECG acquisition device can be easily employed by medical staff for clinical diagnosis and is a suitable wearable device in monitoring and nursing the off-ward patients.

Investigating stimulation parameters for preferential small-fiber activation using exponentially rising electrical currents.

Electrical stimulation is widely used in pain research and profiling, but current technologies lack selectivity toward small sensory fibers. Pin electrodes deliver high current density in upper skin layers, and it has been proposed that slowly rising exponential pulses can elevate large-fiber activation threshold and thereby increase preferential small-fiber activation. Optimal stimulation parameters for the combined pin electrode and exponential pulse stimulation have so far not been established, which is the aim of this study. Perception thresholds were compared between pin and patch electrodes using single 1- to 100-ms exponential and rectangular pulses. Stimulus-response functions were evaluated for both pulse shapes delivered as single pulses and pulse trains of 10 Hz using intensities from 0.1 to 20 times perception threshold. Perception thresholds (mA) decreased when duration was increased for both electrodes with rectangular pulses and the pin electrode with exponential pulses. For the patch electrode, perception thresholds for exponential pulses decreased for durations ≤10 ms but increased for durations ≥15 ms, indicating accommodation of large fibers. Stimulus-response curves for single pulses were similar for the two pulse shapes. For pulse trains, the slope of the curve was higher for rectangular pulses. Maximal large-fiber accommodation to exponential pulses was observed for 100-ms pulses, indicating that 100-ms exponential pulses should be applied for preferential small-fiber activation. Intensity of 10 times perception threshold was sufficient to cause maximal pain ratings. The developed methodology may open new opportunities for using electrical stimulation paradigms for small-fiber stimulation and diagnostics.NEW & NOTEWORTHY Selective activation of small cutaneous nerve fibers is pivotal for investigations of the pain system. The present study demonstrated that patch electrode perception thresholds increase with increased duration of exponential currents from 20 to 100 ms. This is likely caused by large-fiber accommodation, which can be utilized to activate small fibers preferentially through small-diameter pin electrodes. This finding may be utilized in studies of fundamental pain mechanisms and, for example, in small-fiber neuropathy.

Preferential activation of small cutaneous fibers through small pin electrode also depends on the shape of a long duration electrical current

BackgroundElectrical stimulation is widely used in experimental pain research but it lacks selectivity towards small nociceptive fibers. When using standard surface patch electrodes and rectangular pulses, large fibers are activated at a lower threshold than small fibers. Pin electrodes have been designed for overcoming this problem by providing a higher current density in the upper epidermis where the small nociceptive fibers mainly terminate. At perception threshold level, pin electrode stimuli are rather selectively activating small nerve fibers and are perceived as painful, but for high current intensity, which is usually needed to evoke sufficient pain levels, large fibers are likely co-activated. Long duration current has been shown to elevate the threshold of large fibers by the mechanism of accommodation. However, it remains unclear whether the mechanism of accommodation in large fibers can be utilized to activate small fibers even more selectively by combining pin electrode stimulation with a long duration pulse.ResultsIn this study, perception thresholds were determined for a patch- and a pin electrode for different pulse shapes of long duration. The perception threshold ratio between the two different electrodes was calculated to estimate the ability of the pulse shapes to preferentially activate small fibers. The perception threshold ratios were compared between stimulation pulses of 5- and 50 ms durations and shapes of: exponential increase, linear increase, bounded exponential, and rectangular. Qualitative pain perception was evaluated for all pulse shapes delivered at 10 times perception threshold. The results showed a higher perception threshold ratio for long duration 50 ms pulses than for 5 ms pulses. The highest perception threshold ratio was found for the 50 ms, bounded exponential pulse shape. Results furthermore revealed different strength-duration relation between the bounded exponential- and rectangular pulse shapes. Pin electrode stimulation at high intensity was mainly described as “stabbing”, “shooting”, and “sharp”.ConclusionThese results indicate that long duration pulses with a bounded exponential increase preferentially activate the small nociceptive fibers with a pin electrode and concurrently cause elevated threshold of large non-nociceptive fibers with patch electrodes.

Pharmacological enhancement of repolarization reserve in human induced pluripotent stem cells derived cardiomyocytes

BackgroundHuman induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are used for many applications including safety pharmacology. However, a deficiency or complete absence of several K+ currents suggests repolarization reserve is low in hiPSC-CMs. We determined whether a dual Ito and IKr activator can improve repolarization reserve in hiPSC-CMs resulting in a more electrophysiologically mature phenotype. Methods and ResultsHuman iPSC were maintained on growth factor and differentiated into the cardiac phenotype by addition of selective Wnt molecules. Current and voltage clamp recordings in single cells were made using patch electrodes. Extracellular field potentials were made using a microelectrode array on hiPSC monolayers. Action potential recordings from hiPSC-CMs following application of an IKr inhibitor resulted in depolarization of the membrane potential and prolongation of the APD. A flattening of the T-wave was noted on the pseudo-ECG. In contrast, application of the IKr and Ito agonist, NS3623, resulted in hyperpolarization of the membrane, slowing of the spontaneous rate and shortening of the APD. Voltage clamp recording showed a significant increase in IKr; no enhancement of Ito in hiPSC-CMs was noted. AP clamp experiments revealed that IKr plays a role in both phase 3 repolarization and phase 4 depolarization. mRNA analysis revealed that KCNH2 is abundantly expressed in hiPSC-CM, consistent with electrophysiological recordings. ConclusionsAlthough NS3623 is a dual Ito and IKr activator in ventricular myocytes, application of this compound to hiPSC-CMs enhanced only IKr and no effect on Ito was noted. Our results suggest IKr enhancement can improve repolarization reserve in this cell type. The disconnect between a dramatic increase in Ito in adult myocytes versus the lack of effect in hiPSC-CMs suggest that the translation of pharmacological effects in hiPSC-CM to adult myocytes should be viewed with caution.

A miniaturized multi-clamp CMOS amplifier for intracellular neural recording.

Intracellular electrophysiology is a foundational method in neuroscience and uses electrolyte-filled glass electrodes and benchtop amplifiers to measure and control transmembrane voltages and currents. Commercial amplifiers perform such recordings with high signal-to-noise ratios (SNRs) but are often expensive, bulky, and not easily scalable to many channels due to reliance on board-level integration of discrete components. Here, we present a monolithic complementary-metal-oxide-semiconductor (CMOS) multi-clamp amplifier integrated circuit capable of recording both voltages and currents with performance exceeding that of commercial benchtop instrumentation. Miniaturization enables high-bandwidth current mirroring, facilitating the synthesis of large-valued active resistors with lower noise than their passive equivalents. This enables the realization of compensation modules that can account for a wide range of electrode impedances. We validate the amplifier’s operation electrically, in primary neuronal cultures, and in acute slices, using both high-impedance sharp and patch electrodes. This work provides a solution for low-cost, high-performance and scalable multi-clamp amplifiers.

Assessing the modulation of cutaneous sensory fiber excitability using a fast perception threshold tracking technique

Topical application of lidocaine-and-prilocaine (LP) cream attenuates the functionality of small cutaneous nerve fibers. The aim of this human study was to measure the underlying excitability modulation of small cutaneous nerve fibers using a novel and fast perception threshold tracking (PTT) technique. Small sensory fibers were selectively blocked by 120-minute topical application of LP and confirmed by quantitative sensory testing. Excitability changes of small (activated by a specially designed pin electrode) and large (patch electrode) nerve fibers were assessed as the strength-duration relation and threshold electrotonus. The excitability assessed by the strength-duration relation and threshold electrotonus was significantly modulated for the small afferents (P < 0.05, Wilcoxon's test) but not the large afferents. This novel PTT technique was able to assess inhibition of membrane properties of small cutaneous fibers, suggesting the usefulness of the technique as a diagnostic method for assessing impairment of small fibers, as seen in many types of polyneuropathies.

Functional Role of T-tubules on Calcium Transients in Canine Cardiac Myocytes

Background: A loss of t-tubules and alterations in ultrastructure occur in cultured ventricular myocytes. A similar alteration in t-tubules and ultrastructure is well documented under certain pathological conditions such as heart failure. We examined the ultrastructural changes in cultured canine cardiac cells and determined the functional impact these changes have on excitation-contraction coupling and Ca2+ transients. Materials, Methods and Results: Atrial, ventricle, and Purkinje myocytes were isolated by enzymatic dispersion. Atrial and ventricular myocytes were cultured for up to 48 h. Voltage clamp recordings were made with patch electrodes. Ca2+ transient was recorded as a laser scanning confocal microscope in myocytes loaded with Ca2+ fluorescent dyes. Membrane ultrastructure was imaged in myocytes stained with the membrane selective dye, di-8-ANEPP. Freshly isolated ventricular myocytes had a well-developed t-tubule system, while Purkinje cells had no t-tubules; some atrial cells exhibited a primitive t-tubule system. In atrial and Purkinje cells, the Ca2+ transient had a U-shaped profile with the fluorescence highest at the edge of the cell. In contrast, ventricular myocytes showed a homogeneous rise in Ca2+ at the edge and center of cells. Ventricular myocytes cultured for 2 days showed a nearly complete loss of t-tubules. The Ca2+ transients revealed a phenotypic switch from a homogeneous profile to a “U”-shaped profile. Interestingly, atrial cells in culture maintained their primitive t-tubule system. Conclusions: Our results show that atrial and ventricular myocytes respond differently to being placed in culture. Ventricular myocytes, but not atrial myocytes, quickly lose their t-tubules accompanied by a Ca2+ transient profile suggestive of a phenotypic switch in Ca2+ handling. The differential response also suggests that the various cardiac tissue types would respond differently to pathophysiological stresses.

Improvement of Left Ventricular Ejection Fraction by a Novel Electrical Microcurrent Therapy in a Sheep Model of Chronic Heart Failure

Purpose The burden of systolic heart failure (HF) is ever increasing, and the need for novel HF treatment strategies is huge. Direct application of electrical microcurrent to the heart triggers reverse remodeling and reduces myocardial inflammation. The aim of the present study was to test the efficacy of chronic application of microcurrent by a dedicated implantable generator for the first time in a sheep model of chronic heart failure. Methods Twelve sheep were subjected to implantation of the microcurrent system, which consists of (a) an extremely thin patch electrode on the epicardium of the left ventricle (LV), (b) a transvenous counter electrode in the right ventricle and (c) a subcutaneous microcurrent generator connected to both electrodes. Whereas in five sheep the surgical procedure and the electrode design were optimized, in the remaining seven sheep HF was induced by injection of 90 µm microspheres directly into the left coronary artery. Microembolization was repeated until a sustained reduction of LV ejection fraction (LVEF) was achieved, which was defined as a stable mean reduction by 25% as confirmed by echocardiography. Thereafter the device was activated to continuously apply transmyocardial microcurrent to the failing LV. LVEF was repeatedly measured after microcurrent treatment by echocardiography until 12 weeks after start of therapy. Results LVEF strongly decreased after microembolization (baseline, 70.9 ± 5.0%; after embolization, 44.2 ±13.4%, P Conclusion Continuous microcurrent therapy applied over several weeks is associated with a strong improvement of LVEF in a sheep model of chronic systolic HF. As demonstrated earlier, a mitigated inflammatory response to ischemia may be one of the underlying reasons. Future trials are warranted to further test this promising novel therapy, with the intention to induce and sustain intrinsic myocardial recovery and to ultimatively establish a novel treatment strategy for systolic HF.

Functional Impact of Cell Culture on Excitation-Contraction Coupling in Canine Myocytes

Downregulation of ion currents as well as a loss of T-tubules is documented during heart failure. A similar reduction of both has been observed in cultured ventricular myocytes. We further assessed the functional impact of cell-culture on excitation-contraction (EC) coupling in dog ventricular, atrial and Purkinje myocytes. Ventricular, atrial and Purkinje myocytes were isolated and cultured for up to 48 hours. Myocytes were stained with di-8-ANEPPS to visualize ultrastructure and Ca2+ transients (CaTs) were recorded by confocal microscopy. Ion channel currents were assessed via patch electrode voltage clamp. Membrane staining with di-8-ANEPPS indicated dog ventricular myocytes having an extensive T-tubular network; atrial myocytes having a rudimentary T-tubule system at best, and Purkinje myocytes having no T-tubules. Transverse X-t lines scans of electrically stimulated ventricular myocytes showed CaTs rising synchronously across the cell, whereas in Purkinje myocytes the CaT rise showed a U-shaped profile. CaT rise in atrial myocytes typically showed a U-shaped profile, but less pronounced than that in Purkinje myocytes. Ventricular myocytes cultured for 48 hours indicated a dramatic loss of T-tubules and a switch from a synchronous CaT rise to a U-shaped profile. In cultured atrial cells, no loss of T-tubules nor alterations in CaTs was noted. ICa in ventricular myocytes cultured for 48 hours was reduced by 21%. Comparative assessment of culture-induced changes in ion channel currents in atrial myocytes is ongoing. While cultured ventricular myocytes show a loss of T-tubules and phenotypic switch from a homogeneous CaT rise to a ‘U’-shaped profile, atrial myocytes cultured identically show little change in ultrastructure and CaT profile. These results suggest that character and degree of change in EC coupling induced by similar pathological insults markedly depends on cardiac myocyte type.

Design of composite microneedle sensor systems for the measurement of transdermal pH

Abstract Carbon loaded polystyrene microneedle patches have been prepared using silicone micro-moulding techniques and the ability of the needles to serve as viable transdermal sensors has been evaluated. The population of quinone groups at the interface of the embedded carbon nanoparticles was increased through anodisation and their pH dependent redox transitions exploited as the basis of a reagentless pH sensor. The peak position of the quinone oxidation process was found to shift in accordance with Nernstian behaviour and the influence of penetration depth on response has been investigated. The analytical applicability of the microneedle electrode patch was critically evaluated through using tomato skin as model transdermal skin mimic. Despite the increased complexity of the matrix, the microneedle sensor response was found to compare favourably with conventional/commercial pH probes.

From Bernstein's rheotome to Neher-Sakmann's patch electrode. The action potential.

The aim of this review was to provide an overview of the most important stages in the development of cellular electrophysiology. The period covered starts with Bernstein's formulation of the membrane hypothesis and the measurement of the nerve and muscle action potential. Technical innovations make discoveries possible. This was the case with the use of the squid giant axon, allowing the insertion of “large” intracellular electrodes and derivation of transmembrane potentials. Application of the newly developed voltage clamp method for measuring ionic currents, resulted in the formulation of the ionic theory. At the same time transmembrane measurements were made possible in smaller cells by the introduction of the microelectrode. An improvement of this electrode was the next major (r)evolution. The patch electrode made it possible to descend to the molecular level and record single ionic channel activity. The patch technique has been proven to be exceptionally versatile. In its whole‐cell configuration it was the solution to measure voltage clamp currents in small cells. See also: https://doi.org/10.14814/phy2.13860 & https://doi.org/10.14814/phy2.13862

Multisite Intracellular Recordings by MEA.

The enormous advances made over the last 50 years in materials science, microelectronics, and nanoelectronics, together with the acknowledgment that substrate-integrated planar multielectrode arrays (MEA) are limited to recording of extracellular field potentials (FPs) rather than the entire electrophysiological signaling repertoire of the brain, have prompted a number of laboratories to merge the advantages of planar MEA technologies (non-damaging and durable) with those of the classical sharp and patch electrodes for intracellular recordings. Unlike extracellular planar electrode-based MEAs, the new generation of three-dimensional (3D) vertical nanoelectrodes are designed to functionally penetrate the plasma membrane of cultured cells and operate in a similar manner to classical intracellular microelectrodes. Although only approximately 10 years has elapsed since the development of the first vertical 3D nanostructure-based MEAs, this technology has progressed to enable recordings of attenuated intracellular action potentials (APs) and synaptic potentials from individual neurons, cardiomyocytes, and striated myotubes. Furthermore, recently the scaling advantages of nanochip/microchip fabrication technologies enabled simultaneously intracellular recordings of APs from hundreds of cultured cardiomyocytes, thus heralding a new milestone in MEA technology.In this chapter we present the earliest and today's cutting-edge achievements of this "young vertical nano-sensors MEA technology" at the single-cell and network levels, explain the biophysical principles and the various configurations used to form functional nanoelectrode/cell hybrids, and describe the quality and characteristic features of the recorded intracellular APs and subthreshold synaptic potentials by the vertical nanoelectrode-based MEA. Basic cell-biological mechanisms that curtail the length of time intracellular access by the nanoelectrodes are discussed, and approaches to overcome this problem are offered.Recent development of biotechnologies that use induced human pluripotent stem cells taken from healthy subjects and patients, and in vitro drug screening for the development of personalized medicine as well as basic brain research will benefit tremendously from the use of MEAs that record the entire brain electrophysiological signaling repertoire from individual cells within an operational network rather than only extracellular FPs.

Using Light to Endow Stem-Cell-Derived Cardiomyocytes With Virtual IK1 Conductances

Using Light to Endow Stem-Cell-Derived Cardiomyocytes With Virtual IK1 Conductances

Antenna‐based solutions for RF probes in ultra high field magnetic resonance imaging scanners

AbstractVarious approaches to designing unconventional antenna‐based RF probes for obtaining homogeneous 600 MHz B1 magnetic field in 14 T MRI scanners are investigated. Proposed solutions include microstrip patch antennas with engineered multidielectric substrates, acting as surface coils, and systems of vis‐à‐vis placed patch antennas to be used as volume coils with essentially increased Q‐factors compared to those of birdcage coils. Various options of controlling magnetic near fields in antenna systems with flat, cylindrical and cosine‐shaped substrates, as well as with tapered patch electrodes, are demonstrated. Problems of fabricating unconventional microstrip patch antennas for MRI applications are also addressed.

Transcoronary pacing

Transcoronary pacing is auseful therapeutic option for the treatment of unheralded bradycardias in the setting of percutaneous coronary interventions (PCI). In the present study, we investigated the influence of stent implantation and transient myocardial ischemia on the feasibility of transcoronary pacing in aporcine model. 7adult pigs underwent apercutaneous coronary intervention with implantation of acoronary stent under general anaesthesia in an animal catheterization laboratory. Transcoronary pacing was established by using astandard guidewire isolated with an angioplasty balloon positioned in the periphery of the right coronary artery serving as the cathode. As the indifferent anode, askin patch electrode at the back of the animal was used. The reliability of transcoronary pacing was assessed by measurement of threshold and impedance data and the magnitude of the epicardial electrogram at baseline, after implantation of acoronary stent and finally during myocardial ischemia. Effective transcoronary pacing could be demonstrated in all cases with the standard unipolar transcoronary pacing setup yielding alow pacing threshold at baseline of 1.3 ± 0.8 V with an impedance of 283 ± 67 Ω. Implantation of acoronary stent did not influence the pacing threshold (1.0 ± 0.4 V) and impedance (262 ± 63 Ω). Acute myocardial ischemia lead to asignificant but clinically nonrelevant increase of the pacing threshold to 2.0 ± 0.6 V and adrop in pacing impedance (137 ± 39 Ω). Transcoronary pacing in the animal model is not affected by implantation of acoronary stent in the same vessel used for pacing. Despite asignificant increase in pacing threshold, the transcoronary pacing approach is reliable in acute myocardial ischemia during apercutaneous coronary intervention.

Real-Time ECG-Based Detection of Fatigue Driving Using Sample Entropy.

In present work, the heart rate variability (HRV) characteristics, calculated by sample entropy (SampEn), were used to analyze the driving fatigue state at successive driving stages. Combined with the relative power spectrum ratio β/(θ + α), subjective questionnaire, and brain network parameters of electroencephalogram (EEG) signals, the relationships between the different characteristics for driving fatigue were discussed. Thus, it can conclude that the HRV characteristics (RR SampEn and R peaks SampEn), as well as the relative power spectrum ratio β/(θ + α) of the channels (C3, C4, P3, P4), the subjective questionnaire, and the brain network parameters, can effectively detect driving fatigue at various driving stages. In addition, the method for collecting ECG signals from the palm part does not need patch electrodes, is convenient, and will be practical to use in actual driving situations in the future.

ECG Monitoring Garment Using Conductive Carbon Paste for Reduced Motion Artifacts.

The heart is a fundamental organ of the human circulatory system and the continuous measurement of electrocardiogram (ECG) signals is of great importance for pre-detection of heart diseases. Dry electrodes that do not require electrolyte gel have been developed for wearable ECG monitoring applications. However, this kind of electrode often introduces motion artifacts because of the high contact impedance between the electrode and skin. We propose a wearable ECG monitoring garment that employs electrodes made of conductive carbon-based paste. This paste is directly applied to the skin and after drying for 5 min, it forms a patch electrode that is detachable and flexible. The contact impedance between the patch electrode and the skin is very low because the paste covers the skin in a conformal manner. The experimental results show that the contact area of the carbon-based paste on the skin replica is almost 100%. At frequencies under 10 Hz, the contact impedance of the patch electrode is of 70.0 kΩ, much lower than the typical 118.7 kΩ impedance of a Ag/AgCl electrode. We also demonstrate that the ECG signals measured using the custom-designed garment and the patch electrodes are very stable even during actions such as walking and running.

Wearable carbon nanotubes-based polymer electrodes for ambulatory electrocardiographic measurements

A simplified method is presented to fabricate polymer composite electrodes for electrocardiograph (ECG) measurements. The composite electrode was fabricated by loading a high content of carbon nanotubes (CNTs) and silver nanoparticles (Ag NPs) in polydimethylsiloxane (PDMS). The conductive polymer mixture was prepared by ultrasonically stirring and heat-stirring. Polymer electrodes were fabricated by the doctor blade technique. Two-dimensional electrodes were fabricated to evaluate the effect of thickness on signal quality. Three polymer electrodes were combined into the ECG electrode patch. The polymer electrodes were successfully applied in ECG measurements. Continuous measurements for 14days indicated the polymer electrodes are suitable for long-term monitoring. Wearable electrodes were fabricated with a layer of gauze embedded by the CNT/Ag-PDMS mixtures. Conductive wires were sewed in the gauze as connectors for the measurement circuit. Three wearable electrodes were sewed into a vest as a measurement module. The ECG measurement results demonstrated that the wearable electrodes are qualified for such medical devices. The CNT-based polymer electrodes are flexible, washable, and suitable for long-term wear, possessing great promise in practical applications in wearable medical instruments.

Left cervical vagal nerve stimulation reduces skin sympathetic nerve activity in patients with drug resistant epilepsy

We recently reported that skin sympathetic nerve activity (SKNA) can be used to estimate sympathetic tone in humans. In animal models, vagal nerve stimulation (VNS) can damage the stellate ganglion, reduce stellate ganglion nerve activity, and suppress cardiac arrhythmia. Whether VNS can suppress sympathetic tone in humans remains unclear. The purpose of this study was to test the hypothesis that VNS suppresses SKNA in patients with drug-resistant epilepsy. ECG patch electrodes were used to continuously record SKNA in 26 patients with drug-resistant epilepsy who were admitted for video electroencephalographic monitoring. Among them, 6(2men, age 40 ± 11 years) were previously treated with VNS and 20 (7 men, age 37 ± 8 years) were not. The signals from ECG leads I and II were filtered to detect SKNA. VNS had an on-time of 30 seconds and off-time of 158 ± 72 seconds, with output of 1.92 ± 0.42 mA at 24.17 ± 2.01 Hz. Average SKNA during VNS off-time was 1.06 μV (95% confidence interval [CI] 0.93-1.18) in lead I and 1.13 μV (95% CI 0.99-1.27) in lead II, which was significantly lower than 1.38 μV (95% CI 1.01-1.75; P = .036) and 1.38 μV (95% CI 0.98-1.78; P = .035) in the control group, respectively. Heart rate was 65 bpm (95% CI 59-71) in the VNS group, which was significantly lower than 77 bpm (95% CI 71-83) in the control group. Patients with VNS had significantly lower SKNA than those without VNS.