Ring Electrode Research Articles

Current of injury amplitude during left bundle branch area pacing implantation: impact of filter settings, ventricular pacing, and lead type.

Monitoring current of injury (COI) during left bundle branch area pacing (LBBAP) implantation is useful to evaluate lead depth. Technical aspects for recording COI amplitude have not been well studied. Our aims were to evaluate the impact of high-pass filter settings on electrogram recordings during LBBAP implantation. Consecutive patients with successful LBBAP implantation had unipolar recordings of COI at final lead position at different high-pass filter settings (0.01-1 Hz) from the tip electrode during sensing and pacing, and from the ring electrode during sensing. Duration of saturation-induced signal loss was also measured at each filter setting. COI amplitudes were compared between lumenless and stylet-driven leads. A total of 156 patients (96 males, aged 81.4 ± 9.6 years) were included. Higher filter settings led to significantly lower COI amplitudes. In 50 patients with COI amplitude < 10 mV, the magnitude of the drop was on average 1-1.5 mV (and up to 4 mV) between 0.05 and 0.5 Hz, meaning that cut-offs may not be used interchangeably. Saturation-induced signal loss was on average 10 s at 0.05 Hz and only 2 s with 0.5 Hz. When pacing was interrupted, the sensed COI amplitude varied (either higher or lower) by up to 4 mV, implying that it is advisable to periodically interrupt pacing to evaluate the sensed COI when reaching levels of ∼10 mV. Lead type did not impact COI amplitude. High-pass filters have a significant impact on electrogram characteristics at LBBAP implantation, with the 0.5 Hz settings having the most favourable profile.

Tripolar concentric ring electrodes for capturing localised electroencephalography signals during sleep.

By design, tripolar concentric ring electrodes (TCRE) provide more focal brain activity signals than conventional electroencephalography (EEG) electrodes placed further apart. This study compared spectral characteristics and rates of data loss to noisy epochs with TCRE versus conventional EEG signals recorded during sleep. A total of 20 healthy sleepers (12 females; mean [standard deviation] age 27.8 [9.6] years) underwent a 9-h sleep study. Participants were set up for polysomnography recording with TCRE to assess brain activity from 18 sites and conventional electrodes for EEG, eyes, and muscle movement. A fast Fourier transform using multitaper-based estimation was applied in 5-s epochs to scored sleep. Odds ratios with Bonferroni-adjusted 95% confidence intervals were calculated to determine the proportional differences in the number of noisy epochs between electrode types. Relative power was compared in frequency bands throughout sleep. Linear mixed models showed significant main effects of signal type (p < 0.001) and sleep stage (p < 0.001) on relative spectral power in each power band, with lower relative spectral power across all stages in TCRE versus EEG in alpha, beta, sigma, and theta activity, and greater delta power in all stages. Scalp topography plots showed distinct beta activation in the right parietal lobe with TCRE versus EEG. EEG showed higher rates of noisy epochs compared to TCRE (1.3% versus 0.8%, p < 0.001). TCRE signals showed marked differences in brain activity compared to EEG, consistent with more focal measurements and region-specific differences during sleep. TCRE may be useful for evaluating regional differences in brain activity with reduced muscle artefact compared to conventional EEG.

Three-dimensional carbon interdigitated ring array nanofibers for electrochemical detection of dopamine neurotransmitter

Dopamine (DA) neurotransmitter is a prominent component of the central nervous system and its deficiency contributes to several diseases, such as Parkinson’s disease and schizophrenia, which significantly influence the quality of life of affected individuals. This paper introduces a circular interdigitated ring electrode, the three-dimensional carbon interdigitated ring array nanofibers (3D C-IDRA NFs), for the detection of DA using amperometric detection. The study utilized cyclic voltammetry and chronoamperometry to investigate DA. The integration of carbon nanofibers (CNFs) with 3D C-IDRA demonstrated enhanced surface area, increased current peak, and superior performance compared to the standalone 3D C-IDRA electrode, as evidenced by a redox amplification factor of 2.94 and a collection efficiency of 81.1%. The results highlight that integrating CNFs with 3D C-IDRA improves the electrochemical performance in detecting DA neurotransmitter. Thus, this discovery elucidates the advantageous potential of the 3D C-IDRA NF electrode in a wide range of applications.

Method for measuring the setting process of cement-water mixtures by electrical impedance

The setting and hardening of cement paste can be taken as the progressive hydration reaction of cement. This paper reports the findings on setting time of cement paste at early hydration by using a novel method named relative electrical impedance (REI). The novel REI method measures the relative electrical impedance between electrodes (ring shaped) embedded in the cement paste. REI measurements were conducted on cement paste samples with a water-cement ratio of 1:2 over 24 hours. REI measurements were compared with VICAT and heat latent methods for indirect validation. It was found that the proposed REI technique determined the 4 periods of the setting time process (sleeping, hydration, deceleration, and diffusion) and allowed the measurement of the sleeping period in detail. It was concluded that the novel REI method could be used as a new method to measure the setting time of cement paste in early hydration.

Ground Resistance Estimation for a DC Converter Station: Theory versus Experiment

This paper is aimed at proposing a calculation model for the ground resistance of a grounding scheme servicing a high-voltage direct-current converter station. The method is based on the equivalence of current conduction and electric field from the grounding scheme through the surrounding medium. The grounding scheme is composed of three concentric ring electrodes supported by two horizontal conductors and eight vertical rods. The calculated ground resistance is 4.8 Ω against the experimental value of 5 Ω with an error of 4.2%. The calculated ground resistance value agrees reasonably well with that of 4.7 Ω as obtained using CYMGRD software (version 7.0). The calculated surface-potential values over the ground surface agreed reasonably well with those measured experimentally, with an average deviation not exceeding 6.5%. This study is designed to investigate how ground resistance is decreased by the increase in the scheme parameters, including the rods’ diameter and length, as well as the radius of the inner and outer rings. The dependency of the ground resistance on the soil type is also investigated.

Lead performance of stylet-driven leads in left bundle branch area pacing: Results from a large single-center cohort and insights from in vitro bench testing

BackgroundLeft bundle branch area pacing (LBBAP) requires deep septal lead deployment for left-sided conduction stimulation. Advancing leads toward deep septal positions might add mechanical stress on these leads. Concerns about lead performance and reliability remain an unanswered question. ObjectiveThe purpose of this study was to analyze lead performance and integrity of stylet-driven pacing leads (SDLs) for LBBAP. MethodsThis study assessed lead fracture rates of SDL in a large single-center cohort of adult LBBAP patients. Fluoroscopic analysis of lead bending angulations at the septal insertion point and in vitro bench testing of lead preconditioning were performed to simulate clinical use conditions. Lead performance was compared between LBBAP and conventional right ventricular apical pacing (RVp) sites. ResultsThe study included 325 LBBAP patients (66% male; age 71±15 years). During median follow-up of 18 months, 2 patients (0.6%) experienced conductor fracture between tip housing and ring electrode, whereas no such fractures occurred with RVp patients (n = 149; P = .22). X-ray analysis revealed that high lead bending angulations occurred in 1.3% of the patients. Accelerated bench testing of excessive preconditioned leads showcased a higher probability of early conductor fracture compared to standard preconditioned leads. ConclusionThe incidence of early conductor failure in LBBAP seems higher than with conventional RVp sites. The most vulnerable lead part seems to be the interelectrode space between the tip housing and ring electrode. Excessive angulation and preconditioning might contribute to early fatigue fracture.

Tripolar concentric ring electrodes for capturing localised electroencephalography signals during sleep

Tripolar concentric ring electrodes for capturing localised electroencephalography signals during sleep

Structural Optimization of Reactor for the Enhancement of CO2 Electrochemical Reduction Based on Gas–Liquid Mixing Flow Model

The CO2 electrochemical reduction reaction (CO2ERR) is heralded for carbon dioxide and renewable energy utilization. However, complexities in catalyst optimization and reactor structure research hinder its practical application. Herein, rather than traditional catalyst optimization, emphasis is placed on refining the reactor structure to enhance gas–liquid mixing. The goal is to raise the CO2 concentration in the reaction zone and extend its residence refining CO2ERR. Building on prior reactor designs, this work introduces the N‐reactor (the nozzle‐type reactor) with a ring electrode suited for gas–liquid mixing and reaction interplay. Through finite element simulations using the gas–liquid flow model, compared with the S‐reactors (the wide‐straight‐type reactor and the narrow‐straight‐type reactor), the N‐reactor's ring electrode shows a 12.99% CO2 concentration rise in the electrode zone and a 67.11% surge at the cathode exit. As a consequence, the total concentration of the product methanol is increased by 6.37%, with a maximum concentration increase of 26.96% and a concentration increase of 49.08% at the cathode outlet. These results validate the feasibility of optimizing the reaction from the perspective of gas–liquid mixing flow and provide novel methods and ideas for further optimization of CO2ERR, contributing to the practical application of the technology.

Effects of structural variation in electrospray systems on spray characteristics.

Electrospraying is a method of atomizing fluids using a high voltage potential difference. Since the atomization of electrostatic atomization does not directly charge the nozzle but only uses the potential difference, various equipment structures are possible. In the case of this study, 12 different equipment structures of nozzle, ring electrode, and substrate were configured, and data on atomization characteristics of electrospray, such as spray modes applied voltage, coating area, coating current, spray velocity, and factors used in industrial processes, were verified. Data are provided for the generation process using uniform and continuous electrospray.

Influence of dark adaptation on the perceptual threshold of electrically evoked phosphenes

Aims/Purpose: Phosphenes are light phenomena in the eye that have been studied since the 18th century. They can be evoked mechanically or by electrostimulation, for example. The perception of phosphenes and their threshold, the limit of phosphene perception, has been the subject of numerous studies. In this work, the dynamics of the threshold shift of electrically evoked phosphenes during dark adaptation is recorded. Statistically it was tested whether the phosphene thresholds differ before and after dark adaptation.Methods: A study was conducted on 16 healthy subjects (7 w, 9 m, 28.5 ± 6.8 yr). Each subject sat approximately 30 cm in front of a black cloth‐covered semi‐circular screen placed on a table. On the table was a signal generator (33250A, Agilent Technologies Inc, Santa Clara, CA, USA) with a rotary control for the subject's own setting of the current intensity for the current stimulation (sinusoidal, 20 Hz) using a transcranial electrical stimulator (DC‐Stimulator PLUS, neuroConn GmbH, Ilmenau, Germany). The electrodes were a ring electrode at one eye and a rectangular electrode at the back of the head. After the subject had been instructed, and the electrodes had been attached, the subject had to set the phosphene threshold in room light conditions (125 cd/sqm) 10 times in succession (baseline B1, bright adapted). Lightproof glasses were then worn. For 40 min, each subject adjusted the threshold at intervals of 2 min. After 40 min, 10 more threshold values were recorded (baseline B2, dark adapted). Means were calculated for each subject for both baselines B1 and B2 and tested for discrimination using the Wilcoxon signed‐rank test.Results: All subjects were able to successfully complete the test. The global thresholds before and after dark adaptation were 132.3 ± 13.8 μA and 329.5 ± 38.0 μA respectively. The difference between the conditions B1 and B2 is significant (p = 0.0002). All measurement curves of the threshold progression show an increasing behaviour with a pronounced plateau after approximately 15 min.Conclusions: We successfully performed a study on the generation of phosphenes during current stimulation. The dynamics of the threshold progression from light to dark adaptation could be recorded. A significant threshold shift is shown for all subjects.

Predictive Modelling and Optimization of Double Ring Electrode Based Cold Plasma Using Artificial Neural Network

Predictive Modelling and Optimization of Double Ring Electrode Based Cold Plasma Using Artificial Neural Network

Experimental Investigation of Electrospraying Properties Based on Ring Electrode Modification.

Electrospraying uses a high-voltage potential difference to create fine droplets. This study conducts a comparative analysis of the spray pattern and droplet properties using ring electrode parameters. The spray pattern and droplet characteristics are analyzed based on the experimental parameters of the ring electrode. The results show that the cone-jet mode forms quickly for the ring electrode. In addition, as the ring diameter decreases, the ring voltage increases and an increase in the distance between the ring and the nozzle in the bottom direction decreases the Sauter mean diameter and its standard deviation. The optimal conditions for the formation of fine and uniform droplets include a ring diameter of 15 mm, a ring voltage of 7 kV, and a nozzle-to-ring distance of (+) 20 mm.

A novel electrode for reducing tissue thermal damage in radiofrequency-induced intestinal anastomosis

Purpose This study aimed to design a novel electrode for reducing tissue thermal damage in radiofrequency-induced intestinal anastomosis. Material and methods We developed and compared two electrodes (Ring electrode, and Plum electrode with reduced section of the middle fusion area by nearly 80% arising from novel structural design) by performing ex-vivo experiments and finite element analysis. Results In contrast to the Ring electrode group, slightly higher mean strength is acquired with the tensile force and burst pressure results increasing from 9.7 ± 1.47 N, 84.0 ± 5.99 mmHg to 11.1 ± 1.71 N, 89.4 ± 6.60 mmHg, respectively, as well as a significant reduction in tissue thermal damage for the Plum electrode group, with compression pressure of 20 kPa, RF energy of 120 W and welding duration of 8 s applied to the target regions to achieve anastomosis. Besides, the novel structural design of the Plum electrode can counteract the tension generated by intestinal peristalsis and enhance the biomechanical strength of the anastomotic area. The histological observation showed that the fusion area of the two-layer intestinal tissue is tightly connected with decreased thickness. Conclusion The novel electrode (Plum electrode) could reduce tissue thermal damage in radiofrequency-induced intestinal anastomosis.

Investigating the Effect of Alkali Metal Cations on Kolbe Electrolysis

Carboxylic acids, a major fraction of pyrolysis oil can be transformed electrochemically in alkanes and alcohols by Kolbe and Hofer Moest reaction. The selectivity of electrochemical decarboxylation depends on various factors, i.e. electrode material and reaction conditions (supporting electrolyte, pH and current densities) which are well explained in the literature1–3. Alkali metal cations (Li+, Na+, K+, Cs+) are widely considered inert,4 nevertheless in recent studies, a significant influence on different electrochemical reactions such as methanol5,6, ethanol7, and formic acid8 oxidation is reported. It is assumed that oxygenated species present on the electrode surface form (strong/weak) non-covalent interaction with the alkali metal cations.In this work, we studied the electrochemical oxidation of acetic acid (Kolbe electrolysis) and explored the influence of monovalent alkali metal cations (Li+, Na+, K+ and Cs+). It is observed that the product distribution and overall electrochemical activity are influenced by the presence of cations with K+ being most suitable for Kolbe electrolysis (order of activity Li+<Na+<K+~Cs+). The trend was observed irrespectively of the electrolyte conditions throughout the entire pH range at low current densities (25 mA/cm2), i.e. at pH 3 where OER is dominating, pH 5 where OER transitioned to Kolbe electrolysis and pH 9 where Hofer Moest reaction occurs. With increasing current densities (>50 mA/cm2), the influence of cations on electrooxidation diminishes showing the limitations of the effect of non-covalent interactions.To confirm the surface coverage and transition of OER to Kolbe reaction with increasing potential, we probed reaction selectivity in the inflection zone potential regime by means of RRDE. The analysis confirmed that the OER is suppressed completely in the presence of K+ cations after reaching potentials of ~2.5VRHE (inflection zone), while for Li+, OER still proceeds as confirmed by the ORR reaction at the ring electrode. Because surface coverage reflects the high activity of Kolbe electrolysis, we confirmed that the smaller cations interfere more strongly with the electrode surface adsorbed oxygenates due to strong non-covalent interaction and thus affecting the reaction. References F. J. Holzhäuser, J. B. Mensah, and R. Palkovits, Green Chem., 22, 286–301 (2020).C. Stang and F. Harnisch, ChemSusChem, 9, 50–60 (2016).T. Ashraf, A. P. Rodriguez, B. Mei, and G. Mul, Faraday Discuss. (2023)H. J. Schäfer, in Comprehensive Organic Synthesis, B. M. Trost and I. Fleming, Editors, p. 633–658, Pergamon, Oxford (1991)K. Silambarasan, J. Joseph, and S. Mayavan, Applied Surface Science, 489, 149–153 (2019).D. Strmcnik et al., Nature Chem, 1, 466–472 (2009).C. Han et al., ACS Appl. Mater. Interfaces, 14, 5318–5327 (2022).B. A. F. Previdello, E. G. Machado, and H. Varela, RSC Advances, 4, 15271–15275 (2014). Figure 1

Electrochemical Stimulation of Monopolar Electrodes

Changes in the electrostatic potential within an aqueous acidic solution induced by the passage of current between the Au disk of a stationary Au|Au ring disk electrode and a distant counter electrode, Idisk made it possible to stimulate the reduction of selenite to elemental selenium at the concentric Au ring electrode polarized at Eringo just positive to its otherwise expected onset. This effect was ascribed to variations in the surface overpotential, and, thus, in the rates of selenite reduction along the ring, we define, hereafter, as a monopolar electrode. The stimulation efficiency could be accurately determined from a coulometric analysis of the peak for Se oxidation observed by subsequently scanning the ring linearly toward positive potentials to yield selenite. Shown in the figure below is a series of linear scan \\voltammograms, LSV, recorded at a scan rate of 50 mV/s for the ring polarized at Eringo in the range 0.39 - 0.45 V (see legend) following Nstim = 40 between Edisk = 0.75 and 1.00 V, where the black curve corresponds to the LSV recorded without any prior stimulation under otherwise identical conditions. As clearly indicated the stripping charge associated with the oxidation of elemental Se increases as the potential at which the ring is polarized is decreased. Excellent quantitative agreement was obtained between the current flowing through the ring, Iring , and Eringo as a fucntion of Idisk and theoretical simulations employing COMSOL using parameters extracted from independent measurements performed under otherwise identical experimental conditions. This novel tactic is expected to open new prospects for gaining insight into surfacediffusion and other interfacial dynamics phenomena.AcknowledgementsThis work was supported by the US NSF Award 1808592Literature Cited1) Han, Q.; Georgescu, N. S.; Gibbons, J.; Scherson, D. Electrochim. Acta 2019, 325, 134957 Figure 1

Diameter Measurement of Jet-Grouting Column Using Geo-Electrical Probe: Construction and Field Testing

Uncertainty about the geometry of jet grouting columns is a serious challenge to the efficiency of jet grouting technology. If this challenge can be met, jet grouting can become an efficient method of soil improvement. One proposed approach is measurement based on changes in the electrical resistivity between the column and surrounding soil. This approach is non-destructive, easy to use, fast and accurate. This paper reviews jet-grouting methods using the experimental research approach and reports on the design and construction of a probe equipped with ring electrodes that is suitable for measurement of the column diameter. The approach is based on the geoelectric method and Wenner theory. The probe was field tested on jet-grouting columns in a project in Bandar-e Gaz. The probe results were validated by visually observing the dimensions of the excavated column. The results showed that the probe performed well. The device measured a 90-cm column as being from 81 to 88 cm with an error of about 10%. The method of measuring the difference in electrical resistance was shown to be an accurate approach to solving the problem of uncertainty in the geometry of jet-grouting columns.

Looking for optimal concentric ring electrodes: influence of design aspects on their performance

Concentric ring electrodes (CREs) allow improved spatial resolution, reduced crosstalk and interference, and increased bandwidth in the sensing of bioelectrical activity. A wide variety of designs have been used, but their selection is rarely well-founded. The aim of this work is to assess the implications of aspects of CRE design such as the distance between poles, their width and their maximum diameter on aspects such as the signal amplitude (and, therefore, quality), Laplacian estimation error and spatial selectivity (SS). For this purpose, a finite dimensional model of the CRE was used, and its response to the activity of an electric dipole of variable depth was simulated via finite element method modeling. Our results show that increasing the electrode size increases the error to a greater extent than the signal amplitude increases. Pole widths should be as small as possible. The middle ring of the tripolar CRE should be as far away as possible from the central disc. Tripolar CREs typically outperform bipolar CREs of the same outer diameter, significantly reducing the Laplacian estimation error and improving the SS at the cost of a small decrease in signal amplitude. Our results also show that the design of current commercial versions of CREs can be optimized. Furthermore, we propose a methodology that facilitates the selection of an adequate CRE configuration based on the specifications for CRE performance and practical aspects, such as the depth of activity sources to be recorded from and/or the maximum size of electrodes to be used. The monitoring and analysis of bioelectrical signals in a wide range of applications can benefit from the enhanced electrode design and methodology proposed in this work.

Salt transport dynamics across the sediment-underground brine interface driven by tidal hydrology and benthic crab burrowing in muddy tidal flats

Muddy coasts with burrows are widespread globally and most contain brine in underground aquifers. Salt evaporated on a tidal flat surface is an important source of shallow underground brine (phreatic brine and brine in the top layer). However, the salt accumulation/release process in shallow underground brine during tidal cycles remains unclear. To analyze the abovementioned process, sediment permeability and pore-water parameters are measured, and electrical resistivity tomography and ring electrode resistivity probe monitoring are conducted in a tidal flat on the south bank of Laizhou Bay, China, where underground brine occurs and biological activities are pronounced. The results show that evaporated salt on the surface of tidal flats and offshore high-salinity underground brine are the two salt sources of shallow underground brine in tidal flats. Dense burrows and large tidal ranges can accelerate the rate of salt cycling, and promoting the exchange of surface and deep salt through the top layer. During the flooding tide, shallow underground brine is primarily replenished by evaporated salt on the beach surface. In areas with dense burrows, some evaporated salt on the beach surface can pass through the top layer to recharge the phreatic brine. During the ebbing tide, the salt in layers U and B is released into seawater and phreatic brine, respectively. When seawater recedes from the beach surface, a trace amount of phreatic brine and salt in the top layer is released to the beach surface via an upward flow field. Layers U and B are the main areas of salt accumulation and release. The proportion of salt accumulation/release in layer M is the lowest; however, layer M is the most susceptible to salt accumulation and features the highest pore-water salinity among the top layers.

High-Yield Synthesis of Colloidal Carbon Rings and Their Applications in Self-Standing Electrodes of Li-O2 Batteries.

The use of carbon materials in porous electrodes has impressive advantages. However, precisely tailoring the multilevel pore structure of carbon electrodes remains an unsolved challenge. Here, we report a highly efficient site-selective growth strategy to synthesize colloidal carbon rings by templating patchy droplets. Carbon rings are used for the direct fabrication of self-standing porous electrodes with hierarchical pores for lithium-oxygen batteries (LOBs). In situ atomic force microscopy reveals that during discharge the discharge products densely nucleate and grow on carbon rings, demonstrating that such rings are a very potential electrode material in LOBs. The hollow carbon ring electrode (HCRE) possesses micrometer-scale channels formed by random packing of rings and nanochannels consisting of ring-shaped hollow cavities connected by nanosized pores in the wall. Both channels contribute to ion transportation and gas diffusion, but the storage of the discharge products mainly lies in micrometer-scale channels, leading to a high discharge capacity of LOBs (20 658 mAh/g). Our work paves a new way to construct hierarchically porous electrodes for application in electrocatalysis and electrochemical energy storage.

Cathodal HD-tDCS and attention: A study on patients with intractable left lateral frontal lobe epilepsy

ObjectiveDefects in the attentional network in patients with epilepsy are influenced by factors such as the location of epileptic foci. Examining the impact of cathodal high-definition transcranial direct current stimulation (HD-tDCS) on attention components could provide insights into potential attention-related side effects of tDCS. This study aimed to investigate the effect of cathodal HD-tDCS on interictal epileptiform discharges (IEDs), auditory/visual (A/V) attention components, and reaction time (RT) in patients with intractable focal left lateral frontal lobe epilepsy (LFLE). MethodsTo control for variations in individual epilepsy syndrome, 12 adult participants diagnosed with drug-resistant left LFLE with focal cortical IEDs on C3 underwent repeated measurements at pretest, posttest, and follow-up steps. 4 × 1 ring electrodes (cathode on C3 and four anodes on F3, P3, T3, and Cz) delivered 2 mA DC for 20 min per session for 10 consecutive days. The integrated visual and auditory continuous performance test (IVA+) assessed the A/V attention components and RT. One-way repeated-measure ANOVA was used. ResultsThe findings suggest a significant effect in reducing IEDs. The IVA+ results showed a significant improvement in auditory divided attention and visual selective and focused attention (p < 0.05). In the follow-up, these changes demonstrated lasting efficacy. A/V speed scales increased (p < 0.05), showing a significant decrease in reaction time. ConclusionsCathodal HD-tDCS significantly reduced IEDs and improved the components of auditory divided attention, visual focused attention, and visual selective attention, with a reduction in patient reaction time. A significant lasting, side-effect-free positive effect was observed for up to one month after the intervention.