Electrode Impedance Research Articles

Cochlear health in a cohort of cochlear implant users carrying the p.Pro51Ser variant in the COCH gene (DFNA9): A cross-sectional study evaluating the changes in the electrically evoked compound action potential (eCAP).

The present study focuses on DFNA9, an autosomal dominant disorder caused by pathogenic variants in the COCH gene. These mutations induce the formation of aggregates that are toxic to the fibrocytes in the extracellular matrix, ultimately leading to degeneration of spiral ganglion neurons (SGNs), which are crucial for transmitting auditory signals from the cochlea to the brain. An important tool for evaluating the function of the SGNs, which are the target cells of a cochlear implant (CI), is the electrically evoked compound action potential (eCAP). Therefore, the main objective is to evaluate the eCAP to describe the function of the SGNs and study cochlear health in CI patients with DFNA9. For this reason, we included 15 carriers of the p.Pro51Ser variant in the COCH gene who received a MED-EL CI (DFNA9 group) and 15 matched control CI subjects without DFNA9 to compare the impedances and subsequently the threshold, amplitude and slope of the eCAP amplitude growth function (AGF). These parameters were evaluated from intraoperative autoART recordings (MED-EL) during CI surgery. Matching of the two groups was based on sex, age at implantation, duration of deafness, and type of implant. The first results, regarding the difference in impedance between DFNA9 and non-DFNA9 patients, show a significant interaction between time and group in the middle and basal electrodes, indicating that electrode impedances were similar in the early phase after implantation between the two groups, but increased significantly more for the DFNA9 group up to one year after implantation. Secondly, the results show that the success rate (present or absent) to record eCAP responses is lower in the DNFA9 group: eCAPs were detectable in 75.5 % of the intraoperative measurements (145/192) in comparison to 96.9 % (186/192) in the group without DFNA9. ECAP absence in the DFNA9 group was observed across the whole electrode array, but more pronounced in the basal region (channels 11 and 12). Additionally, comparing the parameters of the AGF, the maximum eCAP amplitude was consistently smaller and the AGF slope consistently shallower for the DFNA9 group compared to the control group throughout the entirety of the electrode array. Finally, the eCAP thresholds in patients with DFNA9 were higher compared to those in the control patients for all cochlear locations. To our knowledge, this is the first study to investigate the eCAP measurements in patients with DFNA9. As proven in the literature, eCAP measures correlate well with the health and survival of SGC. This means that the results of our study predominantly suggest that DFNA9 leads to an even stronger reduction in excitability and neuronal health than seen in other causes of deafness.

Investigation of feasibility of early fitting after cochlear implantation and comparison with classical fitting method.

Investigation of feasibility of early fitting after cochlear implantation and comparison with classical fitting method.

The Effect of a CNT/MnO2 Nanoparticle Composite–Based Multi-Shell Typed Electrode for a Fiber Supercapacitor (FSC)

Fiber supercapacitors have attracted significant interest as potential textile energy storage devices due to their remarkable flexibility and rapid charge/discharge capabilities. This study describes the fabrication of a composite fiber supercapacitor (FSC) electrode through a multi-shell architecture, featuring layers of carbon nanotube (CNT) conductive shells and MnO₂ nanoparticle active shells. The number of layers was adjusted to assess their impact on FSC energy storage performance. Increasing the number of shells reduced electrode resistance and enhanced pseudocapacitive characteristics. Compared to the MnS@1 electrode, the MnS@5 electrode exhibited a high areal capacitance of 301.2 mF/cm², a 411% increase, but showed a higher charge transfer resistance (RCT) of 701.6 Ω. This is attributed to reduced ion diffusion and charge transfer ability resulting from the thicker multi-shell configuration. These results indicate that fine-tuning the quantity of shells is crucial for achieving an optimal balance between energy storage efficiency and stability.

Welding Mechanisms in Silver Nanowires under Femtosecond Laser Irradiation for Reduced Sheet Resistance Electrode Fabrication

Welding Mechanisms in Silver Nanowires under Femtosecond Laser Irradiation for Reduced Sheet Resistance Electrode Fabrication

Challenges and Solutions for Fuel Cell stacks in Transportation

Abstract Due to the advantages of environmental friendliness and high energy density, fuel cells have broad application prospects in many fields, such as automobiles, ships, aerospace, etc. However, commercial applications of fuel cells also face challenges of durability and reliability, especially in shock and vibration environments. Here, the electrochemical and mechanical behaviours of fuel cells under vibration environments are described, and the effects of vibration and shock conditions on the electrochemical, mechanical, water and gas transport, and durability performance of fuel cells are systematically reviewed, involving the variation laws of assembly torque, sealing, relative slippage between cells, water and gas transport, electrical resistance, and membrane electrodes. In addition, the methods that can mitigate the effects of vibration on fuel cells in existing studies are summarised. Finally, discussions and perspectives on the research methods of fuel cell performance under vibration are presented. It is hoped that the review can provide a systematic comprehension and direction for vibration protection of fuel cells.

Sericin Electrodes with Self-Adhesive Properties for Biosignaling.

The combination of green manufacturing approaches and bioinspired materials is growingly emerging in different scenarios, in particular in medicine, where widespread medical devices (MDs) as commercial electrodes for electrophysiology strongly increase the accumulation of solid waste after use. Electrocardiogram (ECG) electrodes exploit electrolytic gels to allow the high-quality recording of heart signals. Beyond their nonrecyclability/nonrecoverability, gel drying also affects the signal quality upon prolonged monitoring of biopotentials. Moreover, gel composition often causes skin reactions. This study aims to address the above limitation by presenting a composite based on the combination of silk sericin (SS) as a structural material, poly(vinyl alcohol) (PVA) as a robustness enhancer, and CaCl2 as a plasticizer. SS/PVA/CaCl2 formulations, optimized in terms of weight content (wt %) of single constituents, result in a biocompatible, biodegradable "green" material (free from potentially irritating cross-linking agents) that is, above all, self-adhesive on skin. The best formulation, i.e., SS(4 wt %)/PVA(4 wt %)/CaCl2(20 wt %), in terms of long-lasting skin adhesion (favored by calcium-ion coordination in the presence of environmental/skin humidity) and time-stability of electrode impedance, is used to assemble ECG electrodes showing quality trace recording over longer time scales (up to 6 h) than commercial electrodes. ECG recording is performed using customized electronics coupled to an app for data visualization.

Numerical Study for the Detection of Fault using Electrical Resistivity Tomography

Abstract Electrical Resistivity Tomography (ERT) is a well-known standard geophysics technique for identification of geological phenomena such as faulting. The resolving power of this method is constrained by electrode spacing, device used, electrode configuration, resistivity contrast, and so on. On faulting, fault types are assumed to influence greater than the other parameter. In this research, we carried out a simulation study to detect the resolving power of ERT system using available software in public domain. Three different electrode configurations were used, namely Wenner, Schlumberger, and Dipole-dipole. We varied electrode spacing and resistivity contrast and fault types to yield optimal result. The results of this research are the most optimal model for identifying fault zones was a model that used a Dipole-dipole array with an electrode spacing of 1 m. The smaller the electrode spacing and the greater the number of cells in modelling, it produces a higher resolution modelling cross-section, so that the inversion results are more accurate to the models.

Distribution of relaxation times analysis of rotating disk electrode impedance spectra

Distribution of relaxation times analysis of rotating disk electrode impedance spectra

Evaluation of Safety and Effectiveness of the LISTENT LCI-20PI Cochlear Implant in Post-Lingually Deafened Individuals.

Background: Cochlear implantation is safe and effective in restoring hearing and speech recognition abilities for individuals with severe to profound sensorineural hearing loss. This prospective multicenter clinical trial was conducted to evaluate the safety and effectiveness of a novel cochlear implant (CI) system, the LISTENT LCI-20PI device, in post-lingually deafened individuals. Methods: The LCI-20PI CI system was implanted in 70 individuals 6-68 (27.7 ± 14.0) years old. The safety and effectiveness of the devices were evaluated during a 1-year follow-up. Results: Electrically evoked compound action potential were successfully measured in 98.6% (69/70) of subjects. Electrode impedance was within normal limits of 0.7-20 kOhm in 99.8% of cases. All subjective T/C levels were successfully measured on the selected 12 electrodes of the LCI-20PI recipients at device activation and 1 month, 3 months, 6 months, and 12 months post-activation. The mean open-set monosyllabic-word recognition score (MRS), disyllabic-word recognition score (DRS), and sentence recognition score (SRS) were 28.9 ± 21.0%, 30.3 ± 25.8%, and 36.3 ± 36.3% at 6 months post-activation, and 57.1 ± 21.1%, 69.1 ± 24.4%, and 89.7 ± 21.5% at 12 months post-activation, respectively. Sex, side of the ear implanted, residual hearing, duration of deafness, etiology of deafness, and surgeon did not influence postoperative speech recognition performance. Conclusion: The novel LCI-20PI CI device is safe and effective in post-lingually deafened recipients.

Graphene nanoplatelet-coated electrodes with cellulose binders for 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl-based aqueous posolyte

This study investigates the development of cellulose-bonded graphene nanoplatelet-coated electrodes for organic flow batteries (OFBs) utilizing 4-Hydroxy-2,2,6,6-Tetramethylpiperidine 1-oxyl (TEMPOL) as the active material. Graphite felt electrodes were coated via an optimized dip-coating process, varying the number of dips (1, 5 and 10). Cyclic voltammetry (CV) showed a 150% increase in oxidation peak current and a 250% increase in reduction peak current for the 10-dipped electrodes compared to pristine ones. Electrochemical impedance spectroscopy (EIS) revealed a 35% reduction in charge transfer resistance (Rp) for the 5-dipped electrodes, indicating enhanced ion transfer efficiency. Surface characterization analyses, including SEM, XRD and Raman spectroscopy, confirmed uniform graphene coatings and structural integrity, while contact angle measurements demonstrated a transition from hydrophobic (157°) to hydrophilic (0°) surfaces, improving wettability and electrolyte interaction. These findings establish cellulose as a sustainable, cost-effective binder, with potential scalability for large-scale energy storage applications.

Long‐Term Neural Recording Performance of PEDOT/CNT/Dexamethasone‐Coated Electrode Array Implanted in Visual Cortex of Rats

Implantable neural electrode arrays can be inserted in the brain to provide single‐cell electrophysiology recording for neuroscience research and brain–machine interface applications. However, maintaining signal quality over time is complicated by inflammatory tissue responses and degradation of electrode materials. Organic electrode coatings offer a solution by enhancing recording and stimulation capabilities, including reduced impedance, increased charge injection capacity, and the ability to incorporate and release anti‐inflammatory drugs. Herein, acid‐functionalized multiwalled carbon nanotubes (CNTs) loaded with dexamethasone (Dex) are incorporated into poly(3,4‐ethylendioxythiophene) (PEDOT) as electrode coatings. The electrochemical stability and recording performance of the PEDOT/CNT/Dex coating over an extended period of ≈18 months are investigated. Cyclic voltammetry (CV) stimulation is used to release Dex in half of the recording sites during the first 11 days of implantation to reduce the acute inflammation. The PEDOT/CNT/Dex‐coated floating microelectrode arrays demonstrate stable in vivo electrode impedance and successful detection of visually evoked neural activity from the rat visual cortex even at chronic time points. Additionally, the CV‐stimulated sites exhibit higher single‐unit (SU) recording yield, amplitudes, and signal‐to‐noise ratio compared to unstimulated sites. These results highlight the potential of anti‐inflammatory treatments to improve the quality and longevity of chronic neural recordings.

Innovative Method for Reliable Measurement of PEM Water Electrolyzer Component Resistances.

Understanding the sheet resistance of porous electrodes is essential for improving the performance of polymer electrolyte membrane (PEM) water electrolyzers and related technologies. Despite its importance, existing methods often fail to provide reliable and comprehensive data, especially for porous materials with complex morphologies and non-uniform thicknesses. This study introduces a robust and straightforward method for determining the sheet resistance of porous electrodes using a novel probe concept based on industrial printed circuit board (PCB) technology. This probe measures resistance across ten distances, ranging from 250 µm to 2500µm, enabling local mapping of resistance. The study focuses on the sheet resistance of key components in PEM water electrolyzers, including the gas diffusion layer (GDL), porous transport layer (PTL), and catalyst layers deposited on a membrane. Additionally, an image-processing-based method is presented to obtain the thickness distribution of the studied catalyst layers, facilitating a detailed analysis of the electrical in-plane resistivity with thickness variations. Overall, this methodology has the potential to expedite material integration and bridge the gap between electrode engineering and single-cell testing, thereby advancing the development of PEM water electrolyzers.

Distribution and role of peripheral arterial chemoreceptors in cardio-respiratory control of the South American rattlesnake (Crotalus durissus).

Peripheral arterial chemoreceptors monitor the levels of arterial blood gases and adjust ventilation and perfusion to meet metabolic demands. These chemoreceptors are present in all vertebrates studied to date but have not been described fully in reptiles other than turtles. The goals of this study were to (1) identify functional chemosensory areas in the South American rattlesnake (Crotalus durissus), (2) determine the neurochemical content of putative chemosensory cells in these areas and (3) determine the role each area plays in ventilatory and cardiovascular control. To this end, rattlesnakes were instrumented with transonic flow probes, arterial catheters and subcutaneous impedance electrodes to measure shunt fraction, heart rate, blood pressure and ventilation. The catheters were placed at three putative chemosensory sites, the bases of the aortic arch and pulmonary artery, and the carotid bifurcation, for site-specific activation with sodium cyanide (NaCN). These same sites were subsequently examined using immunohistochemical markers for acetylcholine, tyrosine hydroxylase (the rate-limiting enzyme in catecholamine synthesis) and serotonin to identify putative oxygen-sensing cells. All three sites were chemosensory and stimulating each led to cardiovascular (shunt fraction and heart rate) and respiratory adjustments although not in an identical fashion. All three chemosensory areas contained cells positive for serotonin; however, cells positive for vesicular acetylcholine transporter (VAChT) were found only in the aorta and pulmonary artery. We found no labelling for tyrosine hydroxylase at any site.

Effect of Carbon Nanotubes Conductors on Electrolyte Wettability and Electrochemical Performance of Lithium-Ion Battery Electrodes.

Electrolyte wettability significantly effects the electrochemical performance of lithium-ion batteries (LIBs). In this study, buoyancy testing is employed to accurately measure the force-time curve of electrolyte penetration into the electrodes and thereby calculate the wettability rate. Electrochemical performance is comprehensively evaluated through CR2025 coin half-cell testing, four-point probe analysis, and C-rate cycling experiments. The effects of conductive agent content, morphology, and size on wettability, conductivity and electrochemical performance are investigated. The results show that carbon nanotube (CNT) conductive agent have strong effect on electrolyte wettability, conductivity, and electrochemical performance. Specifically, electrodes with 3 % CNT content show a 48.9 % increase in wettability, a 95.7 % reduction in electrode resistance, and a 10 % increase in cycle life compared to 1 % CNT. The results show that wettability and conductivity have an equally important effect on electrochemical properties. Larger CNT sizes improve wettability but increase electrode resistance, negatively impacting LIB performance. CNT conductive agents facilitate electrolyte movement along the nanotubes, reducing tortuosity and enhancing wettability. Optical observation of the wetting process on the surface and cross-section of the pure conductive agent electrode strongly supports this conclusion. These results provide valuable insight into optimizing LIB performance by manipulating CNT properties and incorporating them as conductive agents.

Conducting Polymer Microelectrode Arrays for Simultaneous Electrophysiology and Advanced Brain Imaging

AbstractIn neuroscience research and clinical practice, electrophysiology is used to record and stimulate specific parts of the brain with high temporal resolution. This capability can be augmented by magnetic resonance imaging (MRI), which provides anatomical and functional information about the brain with large spatial coverage. However, metallic electrodes, commonly used in electrophysiology, are fundamentally incompatible with MRI due to heating concerns and imaging artefacts. Here, it is demonstrated that flexible micro‐electrocorticography (µECoG) arrays, with electrodes made of poly(3,4‐ethylenedioxythiophene) doped with polystyrene sulfonate (PEDOT:PSS), are compatible with ultra‐high magnetic field MRI up to 9.4 T. A scalable fabrication process is adopted that results in very repeatable electrochemical properties across devices. The volumetric capacitance of PEDOT:PSS leads to low electrode impedance and enables high‐resolution neural recordings of single‐unit activity from the cortical surface of rodents. Furthermore, the µECoG array creates minimal distortion in T2‐weighted anatomical brain MRI. Multimodal brain monitoring is demonstrated by performing simultaneous blood oxygen level‐dependent functional MRI (BOLD fMRI) in parallel with electrical stimulation from the µECoG array. The results show that the PEDOT:PSS µECoG arrays enable the combination of high‐resolution electrophysiology and advanced brain imaging in vivo.

Electrochemical Switching of Laser-Induced Graphene/Polymer Composites for Tunable Electronics.

Laser reduction of graphene oxide (GO) is a promising approach for achieving flexible, robust, and electrically conductive graphene/polymer composites. Resulting composite materials show significant technological potential for energy storage, sensing, and bioelectronics. However, in the case of insulating polymers, the properties of electrodes show severely limited performance. To overcome these challenges, we report on a post-processing redox treatment that allows the tuning of the electrochemical properties of laser-induced rGO/polymer composite electrodes. We show that the polymer substrate plays a crucial role in the electrochemical modulation of the composites' properties, such as the electrode impedance, charge transfer resistance, and areal capacitance. The mechanism behind the reversible control of electrochemical properties of the rGO/polymer composites is the cleavage of polymer chains in the vicinity of rGO flakes during redox cycling, which exposes rGO active sites to interact with the electrolyte. Sequential redox cycling improves composite performance, allowing the development of devices such as electrolyte-gated transistors, which are widely used in chemical sensing applications. Our strategy enables the engineering of the electrochemical properties of rGO/polymer composites by post-treatment with dynamic switching, opening up new possibilities for flexible electronics and electrochemical applications having tunable properties.

Electrodeposited Nitrate-Intercalated NiFeCe-Based (Oxy)hydroxide Heterostructure as a Competent Electrocatalyst for Overall Water Splitting.

Electrochemical water splitting is a promising method for the generation of "green hydrogen", a renewable and sustainable energy source. However, the complex, multistep synthesis processes, often involving hazardous or expensive chemicals, limit its broader adoption. Herein, a nitrate (NO3-) anion-intercalated nickel-iron-cerium mixed-metal (oxy)hydroxide heterostructure electrocatalyst is fabricated on nickel foam (NiFeCeOxHy@NF) via a simple electrodeposition method followed by cyclic voltammetry activation to enhance its surface properties. The NiFeCeOxHy@NF electrocatalyst exhibited a low overpotential of 72 and 186 mV at 10 mA cm-2 for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively, in 1.0 M KOH. In a two-electrode system, the NiFeCeOxHy@NF obtained a low voltage of 1.47 V at 10 mA cm-2 in 1.0 M KOH with robust stability. Results revealed that the notable activity of the NiFeCeOxHy@NF catalyst is primarily due to (i) hierarchical nanosheet morphology, which provides a large surface area and abundant active sites; (ii) NO3- anion intercalation enhances electrode stability and eliminates the need for binders while simultaneously promoting a strong catalyst-substrate adhesion, resulting in decreased electrode resistance and accelerated reaction kinetics; and (iii) the unique superhydrophilic surface properties facilitate electrolyte penetration through capillary action and minimize gas bubble formation by reducing interfacial tension.

A multi-scale circuit model bridges molecular modeling and experimental measurements of conductive metal-organic framework supercapacitors.

A multi-scale model is crucial for combining experiments and simulations to reveal the energy storage mechanism. As novel electrode materials, conductive metal-organic frameworks (c-MOFs) provide an ideal platform for understanding the energy storage process in supercapacitors. However, the prevailing circuit models lack consideration of the distinctive transmission path of c-MOFs, which hinders accurate descriptions of c-MOF supercapacitors. By proposing a concept for representing the c-MOF electrode as a crystal-matrix electrode according to the crystallinity, we developed a universal multi-scale circuit model considering crystal shape and porosity to describe the impedance and capacitance of c-MOF electrodes. For supercapacitors with c-MOF electrodes and ionic liquid electrolytes, results predicted from the new multi-scale circuit model, based on microscale parameters obtained from molecular dynamics simulations, demonstrate quantitative agreement with experimental data for electrodes with different crystallinities.

Stretchable impedance electrode array with high durability for monitoring of cells under mechanical and chemical stimulations.

Electrochemical impedance spectroscopy (EIS) serves as a non-invasive technique for assessing cell status, while mechanical stretching plays a pivotal role in stimulating cells to emulate their natural environment. Integrating these two domains enables the concurrent application of mechanical stimulation and EIS in a stretchable cell culture system. However, challenges arise from the difficulty in creating a durable and stable stretchable impedance electrode array. To overcome this limitation, we have developed a cell culture system integrated with a stretchable impedance electrode array (SIEA). This design enabled impedance monitoring during cell proliferation under mechanical stimulation over a long period of time due to the high mechanical durability and electrochemical stability of the SIEA. Our evaluation also involved testing the cytotoxicity of doxorubicin on H9C2 cells directly on the SIEA. The results underscore the significant potential of our SIEA device as an effective tool for monitoring cells subjected to mechanical stimulation and as a platform for drug toxicity testing.

Prussian Blue and Polyvinylpyrrolidone‐Embedded Hollow Fiber Gradient Polysulfone Membrane for Uric Acid Biosensor Application

ABSTRACTTraditional biosensors have drawbacks such as temperature sensitivity and cross‐reactivity. An innovative UA biosensor was developed. It combined Prussian Blue, carbon nanotubes, PVP with uricase oxidase in a polysulfone hollow fiber gradient membrane, forming a multilayer 3D structure. The optimal pH and temperature for the biosensor were determined to be 8.0 and 37°C, respectively. Electrochemical impedance spectroscopy (EIS) showed that the nanoparticles significantly reduced the working electrode's impedance, enhancing electron transfer. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to study the electrochemical behavior of UA oxidation. A distinct oxidation peak for UA was observed at 0.7 V. The sensor exhibited a sensitivity of 0.33 × 10−6 A/mM, a linear working range from 1.2 to 12 mM, and a detection limit of 0.424 mM. The porous structure of the membrane and the nanoparticles' synergistic effect contributed to high sensor stability. After continuous use for a week, the sensor maintained approximately 90% of its initial performance. This research demonstrates the effectiveness of our method in developing highly sensitive and stable biosensors for UA detection, providing a promising solution for accurate and reliable uric acid level monitoring.