Electrode Tip Research Articles

Sensing of nitrate/nitrite ions in aqueous medium using poly(m-aminophenol)/silver core–shell hybrid modified graphite electrode

A very facile methodology was developed for reliable sensing of nitrate/nitrite ions in the aqueous medium using poly(m-aminophenol)/silver core–shell hybrid coated graphite electrode. The hybrid consisting of a uniform silver nanoparticle core coated with a polymer shell, was synthesized by the thermal reduction of poly(meta-aminophenol) complex with silver mono-positive ions. This core–shell hybrid was fabricated on the tip of the graphite electrode by the drop-casting method and was used as a working electrode in a two electrode setup to study the sensing performance of nitrate/nitrite ions in aqueous medium. The sensitivity and limit of detection (LOD) of the sensor were determined as ∼ 190 mA mM-1cm−2 and ∼ 0.02 mM, respectively for the nitrate/nitrite anions. Very good selective response of poly(m-aminophenol)/silver core–shell hybrid towards nitrate/nitrite ions were also confirmed over the other common tested anions/cations. The mechanism of selective sensing of nitrate/nitrite by the core–shell hybrid has been explained on the basis of selective dipole interaction as well as hydrogen bonding interaction. A reliable result was verified with an accuracy of ∼ 99 ± 4 % for nitrate/nitrite ions in real water samples.

Effectiveness and cost-effectiveness of radiofrequency denervation versus placebo for chronic and moderate to severe low back pain: study protocol for the RADICAL randomised controlled trial

IntroductionLow back pain (LBP) is the leading global cause of disability. Patients with moderate to severe LBP who respond positively to a diagnostic medial nerve branch block can be offered...

Clinical outcomes of conjunctivochalasis treatment with a new ophthalmic radiofrequency device

PurposeTo investigate the safety and efficacy of a new micro-controlled radiofrequency device for treatment of conjunctivochalasis (Cch).MethodsData of 127 patients (230 eyes) who underwent ophthalmic radiofrequency treatment for Cch from January 2020 to June 2023 were analyzed retrospectively. Cch coagulation was performed with a radiofrequency electrode tip (OcuRF®, Ilooda, Korea) and a high-frequency radio-wave electric unit (0.6 ~ 0.8 watts, 2 MHz, Acutron™, Ilooda, Korea). Pre- and postoperative Cch grading, slit-lamp photography, tear film break-up time (TBUT), and bulbar conjunctival hyperemia using Keratograph 5 M (Oculus, Wetzlar, Germany) were evaluated. Cch grade 0 or 1 after surgery was regarded as ‘success’. Complications, recurrence, and additional treatment rates were analyzed.ResultsIn 227 (98.7%) eyes, the radiofrequency treatment led to marked improvement of Cch, with 224 (97.4%) eyes achieving grade 0 or 1 at 2 months postoperatively. Eight eyes (3.5%) received additional treatment. TBUT improved from 3.17 ± 0.82 s to 5.28 ± 1.10 s after surgery (P < 0.001). The total bulbar conjunctival hyperemia value showed an improvement from 1.7 ± 0.6 to 1.4 ± 0.6 postoperatively (P < 0.05). No serious complications were observed.ConclusionThe novel ophthalmic radiofrequency device led to a marked improvement of Cch with no serious adverse events during the entire follow-up period. Our results suggest that the radiofrequency device presents a safe and efficacious treatment option for Cch.

Analysis of the influence of electrode rotation on the desulfurization behavior during electroslag remelting process

A transient multi-physics coupling mathematical model is developed to investigate the influence of electrode rotation on desulfurization in the electroslag remelting (ESR) process. This model incorporates a thermodynamic and kinetic model to calculate the sulfur transfer rate from steel to slag, while simultaneously including the magnetohydrodynamic flow, heat transfer, and species transport. The volume of fluid (VOF) approach is employed to track the slag-steel interface. Experimental validation is conducted to ensure the reliability of the model. Sulfur in steel is primarily removed at the slag-electrode interface and the slag-droplet interface, but the slag-metal pool interface contributes very little to desulfurization. The electrode rotation disperses the molten droplets and enhances the heat convection, resulting in a reduction of the total amount of Joule heat and the temperature within the mold. At the electrode tip, rotating the electrode achieves a higher removal of sulfur, more than 10 % compared to the static electrode. The final removal ratios of sulfur are 78.79 %, 82.01 %, 84.90 %, and 80.81 % with the electrode rotating at 0, 20, 40, and 60 rpm, respectively. The optimal desulfurization is achieved at the rotating speed of 40 rpm, due to the refined droplets, the faster renewal rate of the slag-steel interface, the elevated temperature of the interface, and the longer residence time for droplets passing through the slag layer.

General Method for Fitting Kinetics from the SECM Images of Reactive Sites on Flat Surfaces.

Scanning electrochemical microscopy (SECM) is a technique for imaging electrochemical reactions at a surface. The interaction between electrochemical reactions occurring at the sample and scanning electrode tip is quite complicated and requires computer modeling to obtain quantitative information from SECM images. Often, existing computer models must be modified, or a new model must be created from scratch to fit kinetic parameters for different reactive features. This work presents a method that can simulate the SECM image of a reactive feature of any shape on a flat surface which is coupled to a computer program which effectuates the automated fitting of kinetic information from these images. This fitting program is evaluated along with several methods for estimating the shapes of reactive features from their SECM images. Estimates of the reactive feature shape from SECM images were not sufficiently accurate and produced median relative errors for the surface rate constant that were >50%. Fortunately, more precise techniques for imaging the reactive features such as optical microscopy can supply sufficiently accurate shapes for the fitting procedure to produce accurate results. Fits of simulated SECM images using the actual shape from the simulation produced median relative errors for the surface rate constant that were <10% for the smallest reactive features tested. This method was applied to the SECM images of aluminum alloy AA7075 which revealed diffusion-limited kinetics for ferrocene methanol reduction over inclusions in the surface of the alloy.

Thermoablative Treatment of Papillary Microcarcinomas of Thyroid.

Recently, locoregional treatment with ultrasound-guided radiofrequency has been proposed as a new, effective, and safe procedure for low-risk papillary thyroid microcarcinoma (PTC < 1 cm), not eligible or recruitable for surgery. Until now, the gold standard has been the surgery and then the active surveillance. The aim of the study is to present our experience of ultrasound-guidedthermoablation, a procedure performed before demolitive surgery and post-active surveillance. It is a non-invasive treatment that does not require general anesthesia, with a low risk of complications, hypothyroidism, and hypoparathyroidism. All nodules described on ultrasound showed a volumetric increase (follow-up from 12 to 36 months). The cytological examination in all cases showed TIR 4b and TIR 5 papillary microcarcinoma. All the patients were offered the possibility of radiofrequency thermoablation; they were all informed and gave their consent. 18G active tip electrode needles 7 or 10 mm (Amica Gen HS) were used with the moving shot method under local anesthesia in a day hospital setting. No severe complications were reported. Contrast-Enhanced Ultrasonography (CEUS) with SonoVue (CEUS Sonovue) was performed post-procedure and then at 1, 3, 6, and 12 months, which documented complete revascularization and progressive volumetric reduction of the treated area. Our experience has confirmed that radiofrequency ablation can effectively eliminate small papillary thyroid carcinomas with fewer complications. In our opinion, it is a valid alternative for the treatment of low-risk and indolent papillary thyroid microcarcinomas, even in the absence of surgical contraindications.

Use of a Suction-Monopolar Stimulator for Continuous Neurophysiology Monitoring During Endonasal Resection of a Cavernous Sinus Schwannoma: 2-Dimensional Operative Video.

Cavernous sinus schwannomas are exceptionally rare tumors.1,2 Although these tumors commonly originate from the trigeminal nerve, instances involving the oculomotor, abducens, trochlear nerves, and the carotid plexus have also been documented.2-7 In this operative video, we showcase a 44-year-old man with a medical history of acromegaly and schwannomatosis who presented with retro orbital pain and a growing cystic lesion in the left cavernous sinus. Genetic testing ruled out neurofibromatosis types 1 and 2. An endonasal resection was recommended considering the left side and extradural location of the lesion.8 The tumor was excised through an endonasal transpterygoid approach using 2 suctions, one of which was equipped with an electrode tip for continuous monitoring of extraocular nerves during the resection process. Imaging postoperatively demonstrated near-total resection. Institutional review board approval was not required; the patient agreed to undergo the procedure and to have his operative video published.

Plasma pressure profiles in a sheared-flow-stabilized Z-pinch

We report the plasma pressure reached inside the central plasma column of a sheared-flow-stabilized Z-pinch using Thomson scattering measurements. Building on previously reported experimental results and the analysis methods established for the high temperature and moderate density plasmas generated on the FuZE device, we show evidence of a central plasma region with higher electron temperature and density, which is consistent with a pinch behavior. Elevated electron temperatures up to 2.25 ± 0.8 keV and densities up to (4.9±0.2)×1017 cm−3 are observed to temporally coincide with the fusion neutron production from the plasma. Reconstructed plasma pressure profiles highlight the presence of a several millimeter-wide column with elevated pressure whose location varies shot-to-shot. The plasma pressure rises as neutron production from the deuterium plasma increases, reaching a peak value of 2.6 kBar. This peak value is consistent with a radially force-balanced pinch equilibrium model based on the measured ∼320 kA pinch current. Complete datasets were obtained at two axial locations, 10 and 20 cm axial position from the tip of the central electrode, which corroborate the estimated neutron source axial lengths.

Clinical Applications for Spread of Excitation Functions Obtained Via Electrically Evoked Compound Action Potentials (eCAP).

To assess the clinical utility of spread of excitation (SOE) functions obtained via electrically evoked compound action potentials (eCAP) to 1) identify electrode array tip fold-over, 2) predict electrode placement factors confirmed via postoperative computed tomography (CT) imaging, and 3) predict postoperative speech recognition through the first year post-activation in a large clinical sample. Retrospective case review. Cochlear implant (CI) program at a tertiary medical center. Two hundred seventy-two ears (238 patients) with Cochlear Ltd. CIs (mean age = 46 yr, range = 9 mo-93 yr, 50% female) implanted between August 2014 and December 2022 were included. eCAP SOE widths (mm) (probe electrodes 5, 11, and 17), incidence of electrode tip fold-over, CT imaging data (electrode-to-modiolus distance, angular insertion depth, scalar location), and speech recognition outcomes (consonant-nucleus-consonant [CNC], AzBio quiet, and +5 dB SNR) through the first year after CI activation. 1) eCAP SOE demonstrated a sensitivity of 85.7% for identifying tip fold-over instances that were confirmed by CT imaging. In the current dataset, the tip fold-over incidence rate was 3.1% (7 patients), with all instances involving a precurved electrode array. 2) There was a significant positive relationship between eCAP SOE and mean electrode-to-modiolus distance for precurved arrays, and a significant positive relationship between eCAP SOE and angular insertion depth for straight arrays. No relationships between eCAP SOE and scalar location or cochlea diameter were found in this sample. 3) There were no significant relationships between eCAP SOE and speech recognition outcomes for any measure or time point, except for a weak negative correlation between average eCAP SOE widths and CNC word scores at 6 months post-activation for precurved arrays. In the absence of intraoperative CT or fluoroscopic imaging, eCAP SOE is a reasonable alternative method for identifying electrode array tip fold-over and should be routinely measured intraoperatively, especially for precurved electrode arrays with a sheath.

Enhancing fine particle removal by electrostatic precipitation from flue gas with a high PM concentration: Effect of various electrode configurations

Particle pollution has hazardous effects on air quality and human health, especially fine particle. However, the highly efficient removal of fine particles is an unsolved problem in electrostatic precipitators (ESPs). In this study, a transparent ESP was designed to investigate the effect of fine particles on the corona discharge performance and the role of ionic wind in particle migration. And five types of typical discharge electrodes were applied. The results showed that the presence of fine particles could weaken the corona current produced by electrode discharge. Among these electrodes, the spike electrode can reduce the adverse effect of the particle space charge. The maximum ionic wind velocity around the electrode tips and within the near-plate region could reached 5.67 m/s and 5.00 m/s under an applied voltage of 30 kV, respectively. Combining the effects of corona discharge and ionic wind, the collection efficiencies of fine particles decreased in the following order: spike electrode (medium needle) > spike electrode (longest needle) > arista electrode > spike electrode (shortest needle) > sawtooth electrode. In general, spike electrode discharge has better performance for particle charging and particle collection efficiency and is suitable for fine particle removal in ESPs. In addition, electrode configuration/arrangement optimization methods were proposed to enhance fine particle removal in ESPs.

Investigating mechanisms of debris removal in ultrasonic vibration-assisted EDM drilling

In traditional electrical discharge machining (EDM) of micro-holes, the debris removal becomes increasingly challenging as hole depth increases, significantly affecting the machining of difficult-to-machine materials. To address this issue,we first developed a micro-hole gap flow field model for a novel longitudinal–torsional ultrasonic vibration (LTV) electrode EDM drilling method. We analyzed the effects of three types of electrodes — rotation electrodes, longitudinal ultrasonic vibration (LUV) electrodes, and LTV electrodes — on the flow velocity in the micro-hole interstitial flow field. Next, we simulated the motion of fluid and debris in the interstitial flow field of micro-holes, theoretically verifying the advantage of electrode ultrasonic vibration in enhancing debris removal efficiency. Additionally, we observed the electrode tip morphology, the elemental composition on the electrode surface, and the morphology of the micro-hole inlet/outlet and inner wall to further elucidate the debris removal mechanism and confirm the superior drilling performance of the ultrasonic vibration electrodes. At an optimal ultrasonic amplitude (AL=4μm), the LUV electrode demonstrated improved consistency in the micro-hole inlet/outlet and achieved a micro-hole taper of 0.014°. The material removal rate (MRR) using the LTV electrode reached 5.14 × 105μm3/s, nearly 1.5 times higher rotation electrode. This method successfully produced a positively tapered hole suitable for injector nozzles.

Classification of Partial Discharge Sources in Ultra-High Frequency Using Signal Conditioning Circuit Phase-Resolved Partial Discharges and Machine Learning

This work presents a methodology for the generation and classification of phase-resolved partial discharge (PRPD) patterns based on the use of a printed UHF monopole antenna and signal conditioning circuit to reduce hardware requirements. For this purpose, the envelope detection technique was applied. In addition, test objects such as a hydrogenerator bar, dielectric discs with internal cavities in an oil cell, a potential transformer and tip–tip electrodes immersed in oil were used to generate partial discharge (PD) signals. To detect and classify partial discharges, the standard IEC 60270 (2000) method was used as a reference. After the acquisition of conditioned UHF signals, a digital signal filtering threshold technique was used, and peaks of partial discharge envelope pulses were extracted. Feature selection techniques were used to classify the discharges and choose the best features to train machine learning algorithms, such as multilayer perceptron, support vector machine and decision tree algorithms. Accuracies greater than 84% were met, revealing the classification potential of the methodology proposed in this work.

Accuracy of Boltless Frame-Based Stereo-Electroencephalography Electrode Implantation.

Boltless implantation of stereo-electroencephalography electrode is a useful alternative especially when anchor bolt is not available such as in country with limited resources or is less appropriate such as placement in patients with thin skull or at the occiput area, despite some drawbacks including potential dislodgement. While the accuracy of implantation using anchor bolt is well-studied, data on boltless implantation remain scarce. This study aimed to reveal the accuracy, permissible error for actual placement of electrodes within the grey matter, and delayed electrode dislodgement in boltless implantation. A total of 120 electrodes were implanted in 15 patients using a Leksell Stereotactic G Frame with each electrode fixed on the scalp using sutures. Target point error was defined as the Euclidean distance between the planned target and the electrode tip on immediate postimplantation computed tomography. Similarly, delayed dislodgement was defined as the Euclidean distance between the electrode tips on immediate postimplantation computed tomography and delayed MRI. The factors affecting accuracy were evaluated using multiple linear regression. The permissible error was defined as the largest target point error that allows the maximum number of planned gray matter electrode contacts to be actually placed within the gray matter as intended. The median (IQR) target point error was 2.6 (1.7-3.5) mm, and the permissible error was 3.2 mm. The delayed dislodgement, with a median (IQR) of 2.2 (1.4-3.3) mm, was dependent on temporal muscle penetration (P = 5.0 × 10-4), scalp thickness (P < 5.1 × 10-3), and insertion angle (P = 3.4 × 10-3). Boltless implantation of stereo-electroencephalography electrode offers an accuracy comparable to those using anchor bolt. During the planning of boltless implantation, target points should be placed within 3.2 mm from the gray-white matter junction and a possible delayed dislodgement of 2.2 mm should be considered.

Electrode structural effects on the mechanism of high-voltage pulse rock breaking

In the oil drilling process, drilling costs account for more than 50% of total E&P costs. High-voltage electric pulse rock breaking is an economical and effective rock-breaking method that has received widespread attention. At present, there is not much research on the influence of the shape of the electrode tip on high-voltage pulse rock breaking. This paper establishes a system of equations that control the electric breakdown field based on the changes in the electric field inside the rock. Then, using this model, we conducted simulation and laboratory experiments to understand how rocks break under different conditions, such as load voltages, electrode spacing, and electrode tip shapes. The results show that the volume of broken rock is directly related to the loading voltage. The best loading voltage range is between 200 and 220 kV. Increasing the spacing between electrodes helps break more rock, but if the electrode spacing is too large, it's hard to make a hole in the rock, and the rock won't break. An electrode spacing of around 35 mm is the best. The shape of different electrode tips directly affects the high-voltage pulse breaking effect. Hemispherical electrode tips are less favorable for rock breaking, while oval electrode tips are the best. The laboratory experiments and simulations give the same conclusions and verify the applicability and correctness of our model. This study aims to help design high-voltage electric pulse devices.

Spark-Discharge-Activated 3D-Printed Electrochemical Sensors.

3D printing technology is a tremendously powerful technology to fabricate electrochemical sensing devices. However, current conductive filaments are not aimed at electrochemical applications and therefore require intense activation protocols to unleash a suitable electrochemical performance. Current activation methods based on (electro)chemical activation (using strong alkaline solutions and organic solvents and/or electrochemical treatments) or combined approaches are time-consuming and require hazardous chemicals and dedicated operator intervention. Here, pioneering spark-discharge-activated 3D-printed electrodes were developed and characterized, and it was demonstrated that their electrochemical performance was greatly improved by the effective removal of the thermoplastic support polylactic acid (PLA) as well as the formation of sponge-like and low-dimensional carbon nanostructures. This reagent-free approach consists of a direct, fast, and automatized spark discharge between the 3D-electrode and the respective graphite pencil electrode tip using a high-voltage power supply. Activated electrodes were challenged toward the simultaneous voltammetric determination of dopamine (DP) and serotonin (5-HT) in cell culture media. Spark discharge has been demonstrated as a promising approach for conductive filament activation as it is a fast, green (0.94 GREEnness Metric Approach), and automatized procedure that can be integrated into the 3D printing pipeline.

Calculation of the (I-V) Characteristics of Corona Discharge in an Asymmetrical Model from Active Electrodes to Passive Electrodes

This research discusses the comparison of the formulation of the current-voltage (I-V) characteristics of symmetric and asymmetric direct current CCP equipment in the case of corona discharges in the air. The electrode configuration model taken for the symmetric CCP case is the coaxial cylinder and for the asymmetric CCP case is the plane-serrated knife. Both types of electrodes use a modified capacitance concept in the (I-V) characteristic calculations. This concept originates from a geometric approach solution (electrode sizes), where there is a corona electric current multiplier factor (corona current multiplication factor compared to conventional electric current) as well as the nature of the corona discharge which will collect at the sharp tip of the active electrode.

Efficient Fabrication of Bioinspired Flexible Pressure Sensors via Electrohydrodynamic Jet Printing Method.

Bioinspired microdevices have made significant strides in various applications including human motion and health detection. However, facile and highly efficient fabrication approach of flexible pressure sensors remains a great challenge. Herein, inspired by the gecko's foot structure, a flexible pressure sensor with microdomes structure is fabricated by tip-assisted on-demand electrohydrodynamic jet (EHD-jet) printing method. Ascribed to the interlocking electrodes with microdome structure, 3Ddeformation rates are substantially enlarged. When the microdromes structure is under pressure, the resistivity of carbon nanotubes film coated on the surface of microdomes structure will change remarkably. By using the combined effect of assisted tip and ring focusing electrode, the influence and constraints on microstructure fabrication caused by substrate material and morphology are minimized. The desired uniform structures can be adjusted rapidly by changing the printing parameters and liquid properties. High length-height ratio (0.64) of microdomes enhances sensitivity, with minimum detection limit is 2Pa and response time is 40ms. Finally, the bionic flexible sensor indicated excellent performance in capable of detecting pressure, sound vibrations and human motion. This work presents a new method for high-efficiency fabrication micro-nano patterns for flexible sensors inspired, which could be used in wearable tech and health monitoring.

Detection of electrode misalignment and its effect on joint quality in resistance spot welding: a low-cost computer vision-based approach

Electrode misalignment in resistance spot welding can be caused by poor fitting or deformation of electrode with continuous usage. This leads to asymmetric weld nugget formation, porosity and expulsion. This paper presents a novel low-cost real-time inspection system for angular misalignment using an image processing approach. The proposed solution can effectively segment the electrode tips even from the image captured at noisy industrial background such as automotive assembly line, by using a regional convolutional neural network based object identification method. The trained model has a mean average precision and recall of 99.01% and 96.6%, respectively. A series of image processing tools and mathematical operations were used to identify the edge line contours of electrode tips accurately from the detection mask, and determine the angular misalignment with a maximum deviation of less than 0.06°. Experimental results showed that the weld nuggets exhibited porosity, shrinkage voids, and cracks when performed under angular misalignment conditions.

Influence of tissue-electrode distance on unipolar and bipolar voltage for large-tip, ring-, and mini-electrodes

Abstract Background The characteristics of intracardiac unipolar and bipolar voltage electrograms (EGM) acquired by electrophysiological catheters depend on the electrical source and on the electrode design and configuration. Purpose The aim of the study was to assess the impact of the electrode configuration and their distance from the myocardial tissue (electric source) on the unipolar and bipolar intracardiac electrograms recorded with a multi-electrode focal ablation catheter. Methods We retrospectively analyzed left atrial 3D electroanantomical maps (EAMs) of 25 patients performed in sinus rhythm using the IntellaNav Mifi OI catheter (Boston Scientific, USA) with a 4.5 mm tip-electrode, three mini-electrodes and three 2 mm ring electrodes. The unipolar and bipolar EGMs were characterized based on the peak-to-peak amplitude (amp), the signal duration (width), the maximal slope, and the relative high power spectrum (HF_rel) as ratio of the power spectrum of frequencies above and below 50Hz. Distances of the electrode from the tissue were calculated from the electroanatomic reconstruction. Except for the HF_rel with absolute values are reported, all characteristics are normalized using the tip-electrode for unipolar or tip-to-ring electrode values for bipolar measures. EGMs with bipolar voltage amplitude of &amp;gt;0.5 mV were included to focus on healthy tissue. Results We analyzed the EGMs of 5183 catheter positions with horizontal to perpendicular orientation. From horizontal catheter orientation with a similar distance from the tissue for all electrodes, the unipolar EGM of the ring electrodes showed an increased amplitude (140%), slope (150%) and HF_rel (16% vs 11%) compared to the tip- and mini-electrodes. For bipolar EGM, however, the tip- ring pair showed the largest amplitude, width, and slope. The HF_rel was larger for the ring electrode pairs compared to the tip-ring electrode (58% to 39%). The median amplitude (amp), slope, and HF_rel for the ring electrodes showed a strong power-law decay function with distance, whereas the width increases linearly with distance from the surface (Figure, blue dotted lines). The intersection (red circle) of the steep linear decline at close distance to the tissue (reflecting a strong influence on the EGM) with the flat line at larger distances (dash-dotted lines) was considered as nearfield boundary. A HF_rel cutoff of &amp;gt;10% for unipolar (Figure, red arrow) and &amp;gt;30% for bipolar EGMs might be used to identify this boundary. Conclusion We confirmed a higher amplitude for small ring-electrodes compared to larger tip electrodes in unipolar amplitude but not for bipolar electrograms. Furthermore, a strong decay of the amplitude, slope and HF_rel with distance could be observed. The decay functions are suggestive for a nearfield boundary distance below 4mm from the tissue. Further studies are warranted to confirm this observation.Summary of characteristics over distance

Spectral computed tomography (SCT) after cardiovascular electronic devices implantation: No more blinding lights

Accurate localization of intraventricular electrode tips in patients with Cardiac Implantable Electronic Devices (CIEDs) remains a challenge, necessitating advanced imaging techniques. Traditional methodologies, such as Chest X-ray (CXR) and echocardiography, may prove insufficient in precisely determining electrode positions. ECG-gated contrast enhanced coronary