Capacitive Technique Research Articles

Blue Energy Extraction Performance by Polyelectrolyte-Coated Porous Electrodes: Effects of Opposing Polyelectrolyte Interaction in Micropores.

In the capacitive mixing technique, the electrode used to extract blue energy is typically composed of a carbon-based porous electrode material. Polyelectrolyte (PE) surface coating on porous electrodes serves as an intermediate soft layer, which can significantly enhance the energy extraction performance (EEP). Herein, the blue energy extraction performance by using PE-coated electrodes is studied by a statistical thermodynamic theory, with the exploration of the interplay effects between opposing polyelectrolyte interactions and pore size. Because of the interaction between opposing PE coatings, the response of electrostatic properties in the pore to surface potential variations is enhanced during charging/discharging processes, leading to a better EEP. Both the surface charge accumulation and surface potential rise in the charging process can be raised as the results of PE coating. For the cases studied, the extraction efficiency can be promoted up to 45% compared with the cases of bare electrodes. For narrow pores, the PE promotion effects are suppressed by strong pore confinement. The optimal PE coating condition is determined by the competitive results between pore size (H) and polyelectrolyte chain length (N), with that Ĥ ≡ H/(2Nσ) being mostly in [0.1, 0.5], where σ is the PE segment diameter.

Non-destructive assessment of the internal defects of FRED® pear by a low radio-frequency capacitive technique

Postharvest pear fruit internal browning damages were assessed non-destructively using a capacitive instrumental chain in the super low (SLF) – low (LF) radiofrequency region combined with Image analysis. A rapid, inexpensive, and non-destructive instrumental chain was set up: an LCR meter interfaced with a PC receives and transmits signals through a parallel plate capacitor in the frequency range from 100 Hz to 10 kHz. The capacitance data were used to classify the FRED® pear fruit into two classes, “with defects” and “healthy”, using the unsupervised fuzzy C-means clustering analysis. The main results show good classification rates: 91 % of the samples are correctly classified as damaged. Further samples should be implemented to understand how the model performs with samples from different ripening stages. Despite this, the technique appears promising for non-destructive internal quality assessment in pear fruit.

A Brief Review of Hemp Fiber Length Measurement Techniques

Accurate fiber length measurement is essential for the processing and quality management of textile products. This article reviews the current methods used to measure fiber length, including manual, photoelectric, capacitive, and optical techniques. Existing sample preparation processes for natural fiber characterization have been primarily developed for cotton and wool fibers. However, hemp fibers present unique challenges due to their greater length variability, high strength, and low elongation, making some traditional sample preparation methods less effective. Image processing offers a promising approach for scalable and precise measurement of hemp fiber length. Nevertheless, current image processing techniques are limited by the inability to effectively handle overlapping fibers, which increases both the time and cost of testing. Continued research into developing more advanced segmentation algorithms could lead to more widely adopted commercial methods for fiber measurement.

Novel Fe doped NiO-based electrode material for photoactivated catalyst and supercapacitor application

Pure NiO and Fe-doped NiO NPs were prepared using coprecipitation synthesis for potential usage in supercapacitors and photocatalytic degradation of MB dye. The synthesized materials such as NiO, Fe1%NiO, Fe3%NiO, Fe5%NiO, and Fe7%NiO are efficient photocatalysts. Different characterization techniques like XRD, SEM, EDX, PL, and UVVis spectroscopy were used to examine synthesized nanomaterial. In order to improve the photocatalytic activity, the optical properties of prepared nanoparticles were enhanced by adding Fe into NiO. The optimal sample Fe5%NiO with bandgap 3.21 eV led to the degradation of 95 % of MB dye during the time interval of 120 min. The optimal catalyst's high ratio of surface-to-volume provides many active sites to degrade the pollutant. Cyclic test and reusability were also performed to check the stability of the optimum catalyst. To study the capacitive properties CV, GCD, and EIS techniques were utilized. The greatest specific capacitance of the 5 % Fe-doped NiO is equivalent to 1200 F/g, suggesting a significant increase above other reported materials based on NiO. These nanostructures showed good charging-discharging retention. The high capacitance of these nanostructures has shown that they have potential use in supercapacitors. This study will be helpful for manufacturing innovation.

RETRACTED: Theoretical development and validation of asphalt concrete density measurement using non-contact interdigital coplanar capacitive sensor

Asphalt concrete (AC) density serves as a critical criterion for quality control and quality assurance in asphalt pavement construction. Current non-destructive testing (NDT) approaches have shown potential for AC density measurement, but they present disadvantages such as inefficiency and unstable accuracy. This paper developed a novel NDT approach for AC density measurement based on non-contact interdigital coplanar capacitive sensor (ICCS). The feasibility of this approach was evaluated through both numerical and experimental validations. Firstly, the theoretical model of non-contact ICCS for AC density measurement was established based on conformal mapping technique, partial capacitance technique, and dielectric mixing model. Secondly, numerical simulations were performed to validate the developed theoretical model under two scenarios. Thirdly, laboratory experiments were conducted to measure capacitance data and predict density for three common types of ACs. Finally, the error of non-contact ICCS was discussed and compared with that of other NDT instruments. The results indicated that the developed theoretical model could establish the relationship between AC density and capacitance value, which provided the basis for AC density measurement using non-contact ICCS. It was also observed that the capacitance data obtained by the proposed model closely matched those computed by numerical simulations. The maximum errors between theoretical and numerical data were 4.10% and 1.08% for two cases respectively, which proved the feasibility of the theoretical model. Furthermore, experimental results indicated that the capacitance value of AC specimens increased by about 1 pF as the rolling time increases due to a decrease in the volume of air in AC, which reaffirms the validity of AC density measurement using non-contact ICCS. Additionally, the non-contact ICCS demonstrated excellent accuracy with a maximum error of 6.69%, which is comparable to the current mainstream NDT approaches. And it has the advantages of lower cost, simpler data processing and higher efficiency. The findings of this paper offer a new and reliable method and tool for non-destructive and large-scale AC density measurement.

Tailoring iron MOF/carbon nanotube composites as flow electrodes for high-performance capacitive deionization

Capacitive deionization techniques are of interest in water treatment technology due to their low cost, excellent efficiency, and environmental friendliness. Currently, metal–organic frameworks are highly impactful candidates for use as electrode materials in electrochemistry. It provides a large pore volume, good chemical stability, and a high specific surface area. Tuning metal–organic frameworks with carbon materials will have a good impact on electrode materials with increasing performance. This study shows a facile and effective strategy for arranging flow capacitive desalination technology for salt removal. The conducting network of Fe-MOF/CNTs provides rapid electron transport and offers a high diffusion length of ions. This material exhibited excellent desalination performance, with a high salt adsorption of 80.575 mg/g at 1.6 V at an initial NaCl concentration of 1000 mg/L. Overall, the facile method and fabrication strategy greatly advances water treatment applications.

Advancements in and Research on Coplanar Capacitive Sensing Techniques for Non-Destructive Testing and Evaluation: A State-of-the-Art Review.

In contrast to conventional non-destructive testing (NDT) and non-destructive evaluation (NDE) methodologies, including radiography, ultrasound, and eddy current analysis, coplanar capacitive sensing technique emerges as a novel and promising avenue within the field. This paper endeavors to elucidate the efficacy of coplanar capacitive sensing, also referred to as capacitive imaging (CI), within the realm of NDT. Leveraging extant scholarly discourse, this review offers a comprehensive and methodical examination of the coplanar capacitive technique, encompassing its fundamental principles, factors influencing sensor efficacy, and diverse applications for defect identification across various NDT domains. Furthermore, this review deliberates on extant challenges and anticipates future trajectories for the technique. The manifold advantages inherent to coplanar capacitive sensing vis-à-vis traditional NDT methodologies not only afford its versatility in application but also underscore its potential for pioneering advancements in forthcoming applications.

A Comprehensive Review on Control Technique and Socio-Economic Analysis for Sustainable Dynamic Wireless Charging Applications

Dynamic wireless power transfer (DWPT) has garnered significant attention as a promising technology for electric vehicle (EV) charging, eliminating the need for physical connections between EVs and charging stations. However, the improvement in power transfer efficiency is a major challenge among the research community. Different techniques are investigated in the literature to maximize power transfer efficiency. The investigations include the power electronic circuit, magnetic coupler design, compensating capacitance and control technique. Also, the investigations are carried out based on the type of wireless charging system, which is either a static or dynamic scenario. There are a good number of review articles available on the power electronic circuit and compensator design aspects of WPT. However, studies on the controller design and tracking maximum efficiency are some of the important areas that need to be reviewed. This paper provides a comprehensive review of bibliometric analysis on the DWPT technology, design procedure, and control technique to increase the power transfer and socio-economic acceptance analysis. The manuscript also provides information on the challenges and future direction of research in the field of DWPT technology.

A Low-Power High-Sensitivity Photocurrent Sensory Circuit with Capacitive Feedback Transimpedance for Photoplethysmography Sensing.

This study presents an integrated analog front-end (AFE) tailored for photoplethysmography (PPG) sensing. The AFE module introduces a novel transimpedance amplifier (TIA) that incorporates capacitive feedback techniques alongside common drain feedback (CDF) TIA. The unique TIA topology achieves both high gain and high sensitivity while maintaining low power consumption. The resultant PPG sensor module demonstrates impressive specifications, including an input noise current of 4.81 pA/sqrt Hz, a transimpedance gain of 18.43 MΩ, and a power consumption of 68 µW. Furthermore, the sensory system integrates an LED driver featuring automatic light control (ALC), which dynamically adjusts the LED power based on the strength of the received signal. Employing 0.35 µm CMOS technology, the AFE implementation occupies a compact footprint of 1.98 mm × 2.475 mm.

Non-Destructive Measurement on Kwini Mango Fruit using Capacitive Sensing Technique at 250kHz to 2MHz for Ripeness Determination

This study aims to evaluate the characteristics and quality of Kwini mango fruit using non-destructive capacitive sensing methods. Unlike other fruits, identifying ripe Kwini mangoes can be challenging due to their green appearance and unfamiliar characteristics to consumers. Despite the growing interest in non-destructive fruit quality assessment techniques, there has not been significant prior exploration of capacitive sensing in the context of Kwini mangoes. Therefore, in this experiment, a parallel plate was used to measure the capacitance of Kwini mango fruit at frequencies ranging from 250 kHz to 2 MHz. Results showed that the moisture content and pH level decreased within 15 days of investigation. This technique was able to predict Kwini maturity with significant precision by applying the capacitance formula. Because of its high R2 value and sensitivity in linear regression, 500kHz was determined to be the most efficient operating frequency for Kwini mango fruits among the frequencies evaluated. In this experiment, the relationship between capacitance and Brix also yielded encouraging findings. The study also includes the development of a GUI application for determining the sweetness and maturity of Kwini mangoes. Overall, this research demonstrates the potential of capacitive sensing technology as a non-destructive approach to measuring Kwini mango fruit ripeness.

Quantifying squeeze film damping in four-leaf clover-coupled micro-resonators: A comprehensive study under variable vacuum degrees

The squeeze film effect has a significant impact on the performance of micro-resonators when utilizing the electrostatic excitation and capacitive detection technique, due to the narrow air gaps present. It becomes the most critical damping effect that needs to be addressed. However, when micro-resonators are encapsulated in vacuum or rarefied air, squeeze film damping analysis can become considerably complex due to high-quality factors. In this study, we systematically investigate the squeeze film damping of a widely-used four-leaf clover-coupled micro-resonator under different vacuum degrees. The characteristic frequencies of micro-resonators are determined by applying the principle of mode superposition. Subsequently, the energy transfer theory is utilized to derive the theoretical formula for the quality factor caused by squeeze film damping, for varying levels of vacuum. Finite element analysis is then conducted to simulate the characteristic behavior and squeeze film damping of the resonator, confirming the accuracy of the proposed theory. In the experiment, a novel four-leaf silicon micro-resonator is fabricated using bulk anisotropic wet etching and other micromachining technologies. An experimental platform is established to study the squeeze film damping of the micro-resonator under various vacuum degrees, where the micro-resonator is excited electrostatically and detected capacitively. The frequency response and quality factor of the resonator under different vacuum degrees are measured using a house-made modal test circuit board. The experimental results demonstrate excellent agreement with the theoretical and simulated results, indicating that the proposed method can be a reliable and precise guide for understanding the squeeze film damping effect in advance, once the primary model of a micro-resonator has been designed.

Multiphase LLC DC-Link Converter with Current Equalization Based on CM Voltage-Controlled Capacitor

In this study, a current-equalization technology utilizing a variable-capacitance technique for a multiphase inductor–inductor–capacitor (LLC) converter is studied. Accordingly, the proposed method involves adjusting the resonant capacitance of the LLC resonant converter to balance the currents between phases. This is achieved primarily by biasing ferroelectric multilayer ceramic capacitors (MLCCs) through a step-down circuit and a common-mode bias structure. These ferroelectric MLCCs serve as the resonant elements, allowing for variable capacitance by leveraging capacitance sensitivity to their trans voltages. This approach provides additional control flexibility to the resonant circuit. Furthermore, since each phase operates independently, the circuit can be scaled to accommodate any number of phases. Moreover, all switches in the circuit have zero-voltage switching (ZVS) turn-on, minimizing switching losses. This study initially analyzes and evaluates the proposed common-mode bias variable capacitance technique and the corresponding operational principles. Subsequently, a two-phase LLC experimental circuit based on a field-programmable gate array (FPGA) digital controller is utilized to assess current equalization and efficiency. That is to say, this experimentation aims to validate the effectiveness of the current-equalization variable-capacitance technique in an LLC resonant converter.

The analytical model of time-harmonic electric field and impedance spectrum in the multilayered interdigital electrode structure

Accurately determining the time-harmonic electric field and impedance spectrum in the multilayered interdigital electrode (IDE) transducers with lossy dielectrics is essential for the design of the structure, the property estimation of the dielectric, and performance optimization. This paper presents an analytical model of the electric field and impedance within a multilayered interdigitated electrode (IDE) when subjected to alternating excitation through the method of separation of variables (MSV). The equivalent circuit of IDE is established, where the impedance is the parallel of capacitive coupling and resistive coupling between electrodes. The general solutions for the electric field and impedance involving arbitrary numbers and complex permittivities of the dielectric layers are analytically derived. However, due to the approximation of boundary conditions, these physical quantities cannot be accurately obtained by the conventional analytical method using conformal mapping technique (CMT) and partial capacitance technique (PCT). The proposed model exhibits proficiency in generating precise electric field images and impedance values that closely correspond with simulated data, even when accounting for the frequency-dependent characteristics of permittivity and conductivity in lossy dielectrics. Moreover, the approaches to improve the sensitivity of a traditional three-layered IDE-based sensor are demonstrated. For a three-layered IDE-based capacitive sensor, improving the sensitivity can be accomplished through the incorporation of a ground plane at the substrate's bottom and increasing the metallization rate. Conversely, it is recommended to reduce the metallization rate, increase substrate thickness, and remove the ground plane in order to enhance the sensitivity of the IDE-based impedance sensor. The experimental results demonstrate that the proposed model generates outstanding impedance spectra (involving capacitance spectra and resistance spectra) results for various metallization ratios and top layers. This exemplifies the model's potential for predicting, designing, and enhancing a complex multilayered IDE-based transducer to achieve precise and sensitive detection.

Optimization of activated carbon electrodes for desalination using capacitive deionization technique: strategies toward capacitive deionization cell refreshment

Optimization of activated carbon electrodes for desalination using capacitive deionization technique: strategies toward capacitive deionization cell refreshment

Data and measurement mechanism integrated imaging method for electrical capacitance tomography

This study presents a new imaging paradigm for overcoming the challenges limiting the improvement of the imaging quality in the electrical capacitance technique. The new imaging model enables the integration of measurement physics, sparsity-induced prior and physics-informed multi-fidelity learning prior (PIMFLP), as well as the synergy between data-driven and measurement physics modeling paradigms. The transformed L1 norm is used to model the PIMFLP, and the maximum correntropy criterion is used as a data misfit term to restrict the adverse impact of noises or outliers. The PIMFLP is learned from data and characterizes the structural details of imaging targets. The half-quadratic optimization method is developed to overcome computational challenges in solving the novel imaging model. A new physics-informed multi-fidelity learning method is developed to predict PIMFLP by synergizing deep convolutional neural network with measurement physics, and a new bilevel optimization model solved by a new nested algorithm that merges the genetic algorithm and the split Bregman method is proposed for training. Comparisons with other popular reconstruction algorithms confirm that the new imaging method leads to the improved reconstruction accuracy and noise immunity, and opens up new possibilities for unlocking the potential of the measurement technology.

The capacitance/conductance and surface state intensity characteristics of the Al/(CMAT)/p-Si structures

To determine the Al/(CMAT)/p-Si structure’s admittance analysis, capacitance/conductance versus frequency (C/G-V-f) data was obtained in the 3 kHz-3 MHz and −2/4 V ranges at room temperature. The powder form of CeMgAl11O19: Tb (CMAT) was thermally evaporated onto the front of p-Si wafer at 10−6 Torr as interfacial layer. From the Nicollian and Brews method, voltage-dependent spectra of Rs were derived for various frequencies. The parallel conductance and low-high frequency capacitance (CLF-CHF) techniques, respectively, were used to determine the voltage and frequency dependent spectra of Nss and their lifetime (τ). Surface states (Nss), which are identified by admittance measurements, emerge at the M/S interlayer because of high capacitance and conductance values at low frequencies. This can also be explained by the Nss’s ability to track ac signals well at lower frequencies. The normalized parallel conductance versus frequency (Gp/ω-f) plot under various biases shows a peak because of Nss existence. x-ray diffractometer (XRD) was used for structural investigation and the average crystal size (D) of the nanocrystals (CMAT) was found to be less than 0.34 nm by using the Debye-Scherer’s equation.

Equivalent circuit model of the traveling wave electrode for lithium niobate thin film Mach-Zehnder modulators.

We propose an equivalent circuit model of the traveling wave electrode for lithium niobate thin film (TFLN) Mach-Zehnder modulators, in which the distributed capacitance and conformal mapping techniques are applied to calculate the microwave refractive index, microwave loss, and characteristic impedance. Their accuracies are verified by comparing with the results of the finite element method, and the relative errors are less than 3.282%, 1.776%, and 5.334%, respectively. The influence of the electrode's structural parameters on the modulation performances is analyzed, and a 3dB modulation bandwidth around 84GHz with an 8-mm-long traveling wave electrode is obtained.

Characterization of a segmented printed circuit board (PCB) as a standard for absorbed dose to water from alpha-emitting radionuclides.

Our previous work introduced and evaluated a standard for surface absorbed dose rate per unit radioactivity to water from unsealed alpha-emitting radionuclides used in targeted radionuclide therapy (TRT). An overall uncertainty over 4.0% at k=1 was reported for the absorbed dose to air measurements, which was partially attributed to the rotational alignment uncertainty in the geometrical setup. A printed circuit board (PCB) with a segmented guard was constructed to align the extrapolation chamber (EC) and the source plates using a differential capacitance technique. The PCB EC aimed to enhance the repeatability of the ionization current measurements. The PCB EC was evaluated using a thin film 210Po source. The measured absorbed dose to air cavity was compared with the Monte Carlo (MC) calculations. Using the extrapolation method, the surface absorbed dose rate to water was calculated. The PCB EC was constructed with a 4.50mm diameter collector surrounded by four sectors and a guard electrode. The sectors were isolated for rotational alignment and later connected to the guard for ionization current measurements. A bridge circuit measured differential capacitance between opposing sectors, and a hexapod motion stage rotated the source substrate to minimize the differential capacitance. The EC was evaluated using a 210Po source with a 3.20mm diameter and 1.253 Ci radioactivity. MC simulations were performed to calculate the , , and correction factors. Ionization current measurements were performed for air gaps in the 0.3-0.525mm range and surface absorbed dose rate to water was calculated. Rotational offsets of up to 3.0° were found and the current repeatability was found to increase with the absorbed dose to air uncertainty calculated to be ∼2.0%. Using the capacitance method, the effective EC diameter was measured to be 4.53mm. The recombination, polarity, and electrometer corrections were reported to be within 1.00% across all measurement trials. The MC-calculated correction factors were calculated to be much larger than the recombination and polarity correction factors. The average , , and corrections were calculated to be 1.063, 0.9402, and 2.136, respectively. The MC-calculated absorbed dose to air was found to overestimate the absorbed dose by over 4.00% when compared with the measured absorbed dose to air. The surface absorbed dose rate to water was calculated to be Gy/s/Bq with an overall uncertainty of 4.07%. The constructed PCB EC was deemed suitable as an absorbed dose standard. A repeatable rotational alignment was achieved using the differential capacitance technique. The metal electrodes on the PCB made a difference of<1.00% on the backscatter correction when compared to the EC comprised of polystyrene-equivalent collector. A 20% difference in the surface absorbed dose rate to water was found between the two ECs, which is attributed to the cavity diameter differences leading to different magnitudes of dose fall-off along the lateral direction.

Ca2+-activated K+ channels modulate membrane potential in the human parathyroid cell: Possible role in exocytosis

The relationships between parathyroid hormone (PTH) secretion and parathyroid cell membrane potential, including the identities and roles of K+ channels that regulate and/or modulate membrane potential are not well defined. Here we have used Western blot/immunohistochemistry as well as patch-clamp and perifusion techniques to identify and localize specific K+ channels in parathyroid cells and to investigate their roles in the control of membrane potential and PTH secretion. We also re-investigated the relationship between membrane potential and exocytosis. We showed that in single human parathyroid cells K+ current is dependent on at least two types of Ca2+-activated K+ channels: a small-conductance Ca2+-activated K+ channel (KSK) and a large-conductance voltage and Ca2+-activated K+ channel (KBK). These channels were sensitive to specific peptide blocking toxins including apamin, charybdotoxin, and iberiotoxin. These channels confer sensitivity of the membrane potential in single cells to high extracellular K+, TEA, and peptide toxins. Blocking of KBK potently inhibited K+ channel current, and KBK was shown to be expressed in the plasma membrane of parathyroid cells. In addition, when using the capacitance technique as an indicator of exocytosis, clamping the parathyroid cell at −60 mV prevented exocytosis, whereas holding the membrane potential at 0 mV facilitated it. Taken together, the results show that human parathyroid cells have functional KBK and KSK channels but the data presented herein suggest that KBK/KSK channels likely contribute to the maintenance of the membrane potential, and that membrane potential, per se, modulates exocytosis independently of [Ca2+]i.

Optimal Location and Size of Solar photovoltaic Generator to Improve the Stability of Iraqi National Super Grid Power System

The Iraqi National Super Grid Power System is facing significant challenges in terms of stability and reliability, leading to power outages and disruptions. One potential solution to this problem is the integration of solar photovoltaic generator (SPVG) into the grid system. This article explores the optimal location and size of solar PV generators in order to improve the stability and reliability of the Iraqi National Super Grid Power System (INSGPS). The simulation results showed that the bus (20) is the optimal location for connecting the solar PV generator, and also through the simulation a 1000 MW is the optimal capacity (optimal size) of the SPVG determined using the capacitance technique, that gives the least losses in the power system network, which led to an improvement in the voltage margin and an increase in the load factor, which enhanced the stability of the system. The program software, which was utilized in this work were done by MATLAB (R2020a) package based on power system network load flow analysis tool-box (PSAT - version 2.1.11) using Newton-Raphson (N-R) algorithm.