Impedance Method Research Articles

Highly sensitive determination of acyclovir using Ti3C2-CS-MWCNTs-COOH/GCE composite as a sensing platform

Acyclovir (Acyclovir, ACV) is an antiviral drug which, despite its favorable safety profile, can have systemic adverse effects, following improper use. This study prepared a clay-like two-dimensional transition metal carbide Ti3C2 by etching Ti3AlC2 with LiF and HCl. Carboxylated multi walled carbon nanotubes (Carboxylated multi-walled carbon nanotubes, MWCNTs-COOH) were combined with Ti3C2 using chitosan (Chitosan, CS) as solvent and ultrasonic treatment. The nanocomposite was then modified onto the surface of a glassy carbon electrode (Glassy carbon electrode, GCE) to develop an electrochemical sensor for the detection of ACV. The Ti3C2-CS-MWCNTs-COOH/GCE nanocomposite was characterized by X-ray diffractometry (X-ray diffractometry, XRD), scanning electron microscope (Scanning electron microscope，SEM), and cyclic voltammetry (Cyclic voltammetry，CV), as well as the electrochemical impedance method (Electrochemical impedance，EIS). The successful preparation of Ti3C2-CS-MWCNTs-COOH, and the good electrochemical performance of the electrode were verified. Linear scanning voltammetry (Linear scan voltammetry，LSV) was used to quantify the ACV. The linear range of the method is wider than other works (0.05 ∼ 20.0 and 20.0 ∼ 500.0 μM), with a low detection limit (0.088 μM). The sensor achieves sensitive detection of ACV and can be used for the analysis of ACV in pharmaceutical and urine dosage forms, with recoveries of 95.5∼97.6% and 95.6∼97.5%, respectively. For the first time, this sensor utilizes clay-like Ti3C2 with a larger specific surface area in combination with MWCNTs-COOH for ACV detection, which exhibits excellent immunity to interference, repeatability, reproducibility, and stability. This method provides a rapid and sensitive method for the determination of ACV, and lays foundations for developing miniaturized field rapid test detectors.

Improving signal isolation in hybrid RF duplexer utilizing a band-pass filter

This study deals with a passive RF duplexer integrated with a two-notch band. To design the model, a band-pass filter is considered. Using micro-strip technology, the RF duplexer substation is simulated. It is a rectangular in parallel coupling with frequency bands of 1 and 5 GHz while existing three ports. Moreover, to enhance the impedance coefficient and decrease the admittance, the method of complementary paired resonators is taken into account. Furthermore, scattering parameters were used by the step impedance method to make an integrated monolayer substrate from signal branching in duplex mode. Thus, the band-pass filter making the frequency cut-off bands allows designing GSM-4G radars. The low cut-off microwave band is included in these bands at the 77 MHz central frequency and the second cut-off band for GSM-4G radars at the 437 MHz central frequency. The duplexer has the total dimensions of 14 mm × 99 mm and the presented RF duplexer is simulated in CST.

Force-position collaborative optimization of rope-driven snake manipulator for capturing non-cooperative space targets

With the rapid development of space activities, non-cooperative space targets increase swiftly, such as failed satellites and upper stages, threating normal spacecrafts seriously. As there are some problems in the capture process, such as excessive collision and fast tumbling of targets, manipulator with redundant Degrees of Freedom (DOFs) can be used to improve the compliance and therefore solve these problems. The Rope-Driven Snake Manipulator (RDSM) is a combination of hyper-redundant DOFs and better compliance, and therefore it is suitable for capturing mission. In this paper, a snake manipulator mechanism is designed, and the complete kinematic model and system dynamic model considering RDSM, target and contact is established. Then, to obtain the configuration of joint with hyper-redundant DOFs, an improved motion dexterity index is proposed as the joint motion optimization target. Besides, the force-position collaborative optimization index is designed to adjust active stiffness, and the impedance control method based on the modified index is used to capture the space target. Finally, the proposed force-position collaborative optimization method is verified by virtual prototype co-simulation. The results demonstrate that based on the proposed method, the collision force is reduced by about 25% compared to normal impedance control, showing higher safety.

Experimental Study on the Boundary Reflection Effect of Stress Wave Propagation Based on the Newly Developed Test Apparatus

There is a ubiquitous boundary reflection effect of stress wave propagation in the indoor experimental studies. It is critical to improve the validity of waveform data by optimizing boundary materials to absorb reflection waves. In the present study, a calculation method for the optimal wave impedance of boundary materials was proposed based on the transmission and reflection principle of one-dimensional stress waves at the interface of different media. By using the calculation method, the optimal wave impedance value of the boundary material was obtained. A one-dimensional stress wave propagation test apparatus was developed for exploring the improvement effect of absorbing materials on the boundary reflection effect. One-dimensional stress wave propagation experimental studies in the complete red sandstone samples were carried out by setting various boundary absorbing materials such as pine pad, rubber pad, and steel pad. The results indicated that the experimental test results were consistent with the theoretical calculation results. In the stress wave propagation tests, the optimal wave impedance value of the boundary material was 1.12 × 106 kg/m2·s. When the pine pads were used as boundary absorbing materials, the suppression effect of boundary reflection effects is relatively the best. The present study provides references for analyzing the characteristics and mechanism of stress wave propagation and attenuation.

On damage location techniques and future prospects for industrial applications utilizing the electromechanical impedance method: a systematic review

On damage location techniques and future prospects for industrial applications utilizing the electromechanical impedance method: a systematic review

Three modes of electrochemical impedance spectroscopy measurements performed on vanadium redox flow battery

This article presents an innovative approach to monitor working redox flow batteries using dynamic electrochemical impedance spectroscopy, diverging from the commonly sequential impedance methods carried out under potentiostatic or galvanostatic conditions close to the open circle voltage. The authors introduce a fresh variation of dynamic impedance measurement that leverages an amplitude-modulated multi-frequency alternating current perturbation signal. This technique leads to a reduction in measurement time, making it possible to monitor impedance in real-time under typical operational conditions. Consequently, it effectively addresses the limitations stemming from the absence of stationary conditions during impedance measurements. There is no doubt that measurement techniques enabling the study of processes during the operational life of a battery provide the most valuable insights into the properties of these systems. The potential of this proposed approach is exemplified through the examination of a full vanadium redox flow battery as a case study. Classical impedance measurements were also conducted under potentiostatic and galvanostatic conditions with sequential frequency signal change, which requires stopping the battery operation, resulting in electrode potential changes of over 200 mV compared to the working system. Spectra for all modes of measurements were compared. In the case of dynamic measurements, such significant differences in spectra during charging and discharging are not observed, which is characteristic of classical measurements. The authors deliberately and consciously refrain from analyzing the results by fitting equivalent circuits.

The Power of Lichens: New Eco‐Friendly Corrosion Inhibitors from Nature

AbstractThis research explores an environmentally friendly alternative: lichens, which produce natural compounds with antioxidant effects. This study focuses on the inhibition of corrosion by lichens, which has not been previously explored for this purpose. The anti‐corrosion potential of methanol extracts of Parmotrema hypoleucinum, Roccella phycopsis, and Xanthoria parietina was examined. The electrochemical impedance and weight loss methods were used to examine the corrosion inhibition process of mild steel XC48 in 1 M HCl by three lichen extracts.

Spacer effects on the performance of MoTe2/MoSe2 and MoTe2/WSe2 heterostructure double gate MOSFET

In this work, the spacer effects (both low and high-k) on the dc and noise characteristics of heterostructure molybdenum ditelluride (MoTe2/MoSe2 and MoTe2/WSe2) double gate (DG) MOSFET is analyzed. To study the device characteristics, a hybrid methodology that uses both QuantumWise ATK and Sentaurus TCAD tool is used. The performance metrics of the device such as on-current (Ion), Ion/Ioff ratio, subthreshold swing (SS), threshold voltage are obtained. The noise performance of the device is also studied (with/without spacer) using impedance field method. Noise parameters such as noise power spectral density (SID) and noise figure (function of both frequency and bias) has also been simulated and noise components such as G-R noise, flicker noise and white noise are obtained. The simulation results shows that the introduction of spacer material enhances the dc performance of the device and influences its noise characteristics.

Utilizing Waste Cotton/Pigeon Pea Stalk Fibers Composites for Enhanced Sound Absorption and Insulation in Automotive Interiors

ABSTRACT This study investigates the synthesis and characterization of composite materials, pigeon pea stem, and cotton fibers blended in different ratios such as 100/0, 70/30, 60/40, 50/50, 30/70, and 0/100. These composite materials were produced using a compression molding technique. According to ASTM standards, the acoustics, thermal conductivity, and physical characteristics of the composite samples were tested to assess their qualities. The impedance tube method detailed in ASTM E1050 was used to determine the sound absorption coefficients (SAC) for acoustics. The SAC values were measured at six frequencies such as 125, 250, 500, 1000, 2000, and 4000 Hz. The results showed that composite samples made from waste cotton and pigeon pea demonstrated sound absorption values of greater than 80%. Superior sound insulation and absorption, moisture absorption, fiber properties have also been demonstrated by waste composites. Especially, the waste cotton/pea stalk waste fiber composites achieved over 75% sound absorption, while the waste 28% composites performed well in terms of sound absorption, moisture absorption, and fiber properties. Even in humid conditions, the composite samples constructed from used cotton and pigeon pea stalks demonstrated good moisture resistance without reducing their insulating qualities. Soundproofing barriers are composite layers of foam or pigeon pea/cotton.

ENERGY TECHNOLOGY OF DAIRY PRODUCTS QUALITY ASSESSMENT USING IMPEDANCEMETRY

The article examines the peculiarities of milk quality research using the impedance method. Impedance is a complex parameter that characterises the interaction of the electric current with milk. The authors have developed a methodology based on the specified method to assess the quality of dairy products and have created a hardware and software complex that makes it possible to analyse the quality of dairy products. The research, conducted using the developed hardware and software complex, revealed several regularities characterising different types of milk. These regularities demonstrate the relationship between the impedance signal and the milk fat index. Analysis of the obtained data allowed us to identify differences in impedance between samples with varying fat content and origin from different manufacturers. The developed experimental setup prototype enabled the following research stages: checking the change in voltage during the passage of an alternating electric current through milk. This work used the AFS Sensor DAQ data acquisition system, designed for sensor control projects and which runs with NI LabVIEW software, for data output. The authors tested the installation while investigating the impedance of dairy products with different fat content and from multiple manufacturers. During the experiment, we measured the impedance and capacitance of the samples, and the obtained data became available on a PC for further analysis. The aim was to study the electrical properties of dairy products and their dependence on the composition and manufacturer. The obtained results represent valuable information for dairy product production and quality control. It is possible to use them to optimise production processes, ensure stable product quality, and improve consumer characteristics of dairy products. The obtained data contribute to a deeper understanding of the relationship between the impedance signal and the composition of dairy products, which can lead to the development of new methods of analysis and evaluation of the quality of food products. In addition, these studies have implications for food science and nutrition. Keywords: dairy products, milk quality, impedancemetry, electrical measurements, hardware and software complex.

Geometric optimisation of a multiple coiled-up resonator for broadband and octave band acoustic absorption

This study presents a comprehensive approach to designing sound absorption metamaterials, aiming to achieve broadband absorption capabilities while maintaining a compact thickness, starting from an exceptionally low frequency of 100 Hz. By employing a parallel arrangement of resonators with varying lengths, the proposed approach exploits the envelopes of absorption frequencies to realize broad-spectrum sound absorption.An analytical model is utilized in the geometric optimization phase, accounting for inlet losses and thermo-viscous losses near the walls. The absorption for multiple ducts coupled in parallel is derived using the series and parallel impedance method. A geometric parameterization procedure is implemented to maximize normal incidence acoustic absorption, leading to design optimization for both broadband and octave-band absorbers. Design maps are established to assess acoustic performance and physical space requirements, facilitating informed decision-making in metamaterial design.Prototype fabrication and experimental validation involve 3D printing of optimized geometries using polylactic acid, followed by testing within impedance tubes according to ISO 10534–2 standards. The results demonstrate the effectiveness of the proposed method in achieving broadband sound absorption across specified frequency ranges.

Development of Anti-TNT@Cu-BTC MOF thin film using drop caste method for trinitrotoluene (TNT) sensing

Antibody functionalised Cu-BTC MOF thin film was prepared using drop-casting method on indium tin oxide (ITO) coated glass substrate for trinitrotoluene (TNT) sensing under certain experimental conditions. Initially, APTES functionalization on ITO substrate using EDC-NHS chemistry was carried out, after which biofunctionalization of Anti-TNT on Cu-BTC MOF (1,3,5-tricarboxylic acid as an organic linker and copper ions as metal) thin film was carried out. Each step of sensor fabrication was characterised by the X-ray diffraction, microscopic and spectroscopic techniques. The interaction of one layer with another is confirmed with the help of FTIR and EDX. ITO substrate modification increases resistance at each stage from 1.29 to 3.3 KΩ. This modified substrate used as a working electrode during the sensing experiment. Afterward, response cum detection of 2,4,6-trinitrotoluene (TNT) in the 0.1 ppm to 0.6 ppm range has been noted by impedance method using three electrode systems of an electrochemical workstation. Host-guest interaction cum mechanism between TNT antibody functionalised APTES@Cu-BTC and TNT analyte has been observed which origins change in their resistance/impedance. The variation in resistance is directly proportional to the concentrations, exhibiting a strong linear relationship with 0.9702 value for R2. We find out that the presence of TNT antibody increases the specificity of TNT sensing and minimizes cross-reactivity with unknown/other interfering compounds. The concentration–response graph shows a 0.04 ppm limit of detection at room temperature.

Synthetic control with target sticking for on-orbit capturing using a dual-arm space robot

On-orbit capturing is a crucial step in the application of dual-arm space robots, aiming to accurately grasp a moving target and avoid damage to the arms terminal parts (i.e. the end effectors) due to contact force saturation. This paper presents a synthetic control method with target sticking for on-orbit capturing using a dual-arm space robot system from the approaching phase to pre-grasping phase. In the approaching phase, an online trajectory planning method based on visual servoing is proposed to obtain the desired trajectories for end effectors in work space. Then the joint torques are designed by the inverse kinematics and inverse dynamics to track the desired trajectories. Different from most of the current research, a new sticking phase is proposed after the approaching phase and before the pre-grasping phase. In the sticking phase, a force and motion control method is designed to maintain a close relative distance between end effectors and the target, which can avoid saturation of contact forces and avoid damage to the end effectors. In what follows, an impedance control method is proposed in the pre-grasping phase to absorb the impact energy and grasp the target accurately. The synthetic control strategy integrates the controllers of all the phases mentioned above. Automatic switching among the phases is realized by using logic judgment according to the system real states, which is more consistent with the real capturing environment. Finally, numerical simulation results demonstrate the effectiveness of the proposed synthetic control scheme. The results can be applied to the trajectory planning and control of on-orbit capturing, avoiding contact force saturation and ensuring the safety of the system.

Performance Evaluation of Cardiac Signal Recording Framework (CARDIF)-A Quantitative Assessment for Long Term Monitoring Applications

Background: Personal health monitoring with wearable electronics has gained momentum in the recent years due to its usage in flexible textile-based sensors/electrodes for recording of physiological vital parameters. Such system provides scope for long term ambulatory ECG measurement and motion tracking applications. The selection /design of textile sensors play a vital role as it has to overcome skin irritations, improve the skin-electrode impedance required for conductivity. The composition of textile materials, shape and size of the textile electrodes contributes significantly towards the conductivity. Objective: To assess the proposed Cardif system for its suitability to introduce in the clinical routine Method: The proposed textile electrodes were designed using knit jersey conductive material. The skin –contact impedance of the proposed textile material, was measured using two electrode impedance method and measurement was done for different age groups by varying the frequency. Results: The measurement results showed that the impedance was decreasing with increasing frequency and was found to be below 1.5Mohm/cm2 in the frequency range of 20Hz to 1KHz for three different age groups. The performance of the CARDIF was assessed using heart rate, RR interval, SNR as well as qualitative assessment through visual inspection and were compared with gel based disposable Ag/AgCl electrodes. Qualitative and quantitative analysis was performed and the various results confirm the proposed textile electrodes for continuous patient monitoring applications.

Small Disturbance Stability Analysis of Onshore Wind Power All-DC Power Generation System Based on Impedance Method

The Onshore Wind Power All-DC Generation System (OWDCG) is designed to integrate with renewable energy sources by modifying the grid structure. This adaptation supports the grid infrastructure and addresses the challenges of large-scale wind power AC collection and harmonic resonance during transmission. Crucially, small disturbance stability parameters are essential for ensuring the system’s stable operation. Unlike conventional power systems, the OWDCG exhibits strong coupling between subsystems, accentuating the small disturbance stability issue due to the dynamic nature of its converter control system. The impedance method facilitates the decomposition of such systems into subsystems, offering insights into the destabilization mechanism through the lens of negative impedance contribution. This approach is conducive to conducting small disturbance stabilization analyses. To tackle this issue, the initial step involves deriving the input and output equivalent impedance models of the subsystem, considering the topological structure, control features, and operational dynamics of the OWDCG. Subsequently, the impact of circuit and control parameters on the system’s impedance characteristics and small-disturbance stability is examined through Bode diagrams and Nyquist curves. This analysis identifies critical parameters for small-disturbance stability, guiding the stable operation and parameter optimization of the OWDCG. The analysis highlights that the main control strategies for stability are the Modular Multilevel Converter (MMC) DC voltage control and the inner-loop current control gain. Validation of the theoretical findings is achieved through simulation results using PSCAD/EMTDC.

Relationship between indicators of physical development and indicators of anaerobic productivity of the body of women 25-35 years old

Purpose. To establish the relationship between body mass, body composition with indicators of anaerobic productivity of women aged 25-35.
 Materials and methods. 392 women aged 25-35 years participated in the study. The power of anaerobic alactate productivity was determined by the 10-second Wingate test. The power of anaerobic lactate productivity was determined by the 30-second Wingate test. The capacity of anaerobic lactate productivity was determined by the e maximum amount of external mechanical work per 1 minute. Body fat percentage, body muscle percentage, and visceral fat content were determined by the bioelectrical impedance method.
 The results. It was found that the correlation of body mass, body mass index and percentage of the muscle component of women aged 25-35 with performance in anaerobic tests is characterized as direct. The degree of correlation of indicators of physical development with absolute indicators of anaerobic productivity is higher than with relative indicators. Performance in anaerobic tests is most strongly correlated with body mass and body mass index. The degree of correlation of body mass, body mass index with tests characterizing the power of anaerobic alactate and lactate productivity of the body corresponds to "high". A "high" degree of correlation of the capacity of anaerobic lactate productivity of the body was established only with body mass.
 Conclusions. Among indicators of physical development, body mass and body mass index have the greatest influence on the anaerobic capabilities of the body of women aged 25-35, who do not play sports. Higher values of body mass and body mass index are predictive of higher level of anaerobic productivity. The high degree of correlation with body mass and body mass index is due to the specifics of the cycle ergometeric tests. Running anaerobic tests will not give a direct correlation of a high degree, because they are related to the movement of body weight along the distance. The percentage content of fat and muscle components, the level of visceral fat cannot be predictors of the level of anaerobic productivity of the body in women who do not do sports.

Analysis of Factors Affecting Sub-Synchronous Oscillation in Doubly-Fed Wind Power Grid-Connected System Based on Impedance Sensitivity and Research on Suppression Strategy

Aiming at the matter of sub-synchronous oscillation (SSO) of the doubly-fed induction generator (DFIG) series compensation capacitors grid connection, a SSO suppression strategy based on adding damping controllers in rotor-side converter (RSC) is put forwarded. Considering the control parameters of power and current control loops of RSC, the equivalent impedance model of DFIG series compensation grid connection (SCGC) is established, and then combined with the equivalent RLC resonant circuit of the system, the mechanism and factors of SSO are analyzed by impedance method. Calculating the impedance sensitivity of the system impedance to parameters by sensitivity analysis method, so as to identify the leading factor affecting the SSO characteristics of wind power system. Combined with the stability criterion of system impedance characteristics, the parameters are adjusted to meliorate system stability. Based on the leading factor affecting the SSO and the mechanism of the SSO, the damping controllers are added in the RSC to supply positive damping for the system to eliminate the negative damping brought by the RSC and rotor resistance, thus suppressing the SSO of the system. The validity of the put forwarded suppression strategy is proved through PSCAD/EMTDC simulation.

Performance of seedlings and yield of soybean genotypes under soil compaction

AbstractThe identification of soybean genotypes tolerant to soil compaction makes it possible to reduce productivity loss under stress conditions. Added to this, the prior selection of these genotypes will result in greater assertiveness in the positioning of cultivars in the field. Thus, the objective was to evaluate the susceptibility of soybean genotypes to compaction in greenhouse and field conditions; verify which characteristics of seedlings under high resistance to root penetration are correlated with crop production in compacted soil; and to validate the substrate mechanical impedance method for evaluating the susceptibility of plant genotypes to soil compaction. Seeds of 20 genotypes were sown in a substrate mechanical impedance system under controlled conditions. The characteristics evaluated were total root length, total root surface area, mean root diameter, total root volume, taproot length, shoot length, root dry matter and seedling shoot dry matter. In the field experiment, half of the planting area was compacted, constituting two treatments, soil with and without compaction. The percentage of seedling emergence, initial plant height, stem diameter, number of nodes, internode length, number of lateral branches, shoot dry matter, final plant height, absolute and relative growth rate, number of pods, weight of 100 seeds and grain yield. In addition, the number of days between soybean sowing until plant flowering and grain harvest was recorded according to genotype and soil compaction level. In a controlled environment, genotypes tolerant to soil compaction show greater plasticity of root characteristics and smaller alterations in the shoot of seedlings. In the field, these genotypes show smaller reductions in growth rate, height, number of pods and grain yield. The shoot dry matter and the root dry matter of soybean seedlings in a mechanical impedance system present a positive and negative correlation, respectively, with soybean yield in compacted soil, indicating that the genetically determined susceptibility to soil compaction stress was similar throughout ontogenesis. The substrate mechanical impedance system used to evaluate the performance of soybean seedlings under stress, facilitates the decision‐making in breeding programs focused on identifying genotypes expressing soil compaction tolerance.

Wide Response Range Photoelectrochemical UV Detector Based on Anodized TiO2-Nanotubes@Ti@quartz Structure.

Conventional sandwich structure photoelectrochemical UV detectors cannot detect UV light below 300 nm due to UV filtering problems. In this work, we propose to place the electron collector inside the active material, thus avoiding the effect of electrodes on light absorption. We obtained a TiO2-nanotubes@Ti@quartz photoanode structure by precise treatment of a commercial Ti mesh by anodic oxidation. The structure can absorb any light in the near-UV band and has superior stability to other metal electrodes. The final encapsulated photoelectrochemical UV detectors exhibit good switching characteristics with a response time below 100 ms. The mechanism of the oxidation conditions on the photovoltaic performance of the device was investigated by the electrochemical impedance method, and we obtained the optimal synthesis conditions. Response tests under continuous spectroscopy confirm that the response range of the device is extended from 300-400 nm to 240-400 nm. This idea of a built-in collector is an effective way to extend the response range of a photoelectrochemical detector.

The Interaction between Anesthetic Isoflurane and Model-Biomembrane Monolayer Using Simultaneous Quartz Crystal Microbalance (QCM) and Quartz Crystal Impedance (QCI) Methods.

The interaction between anesthetic Isoflurane (Iso) and model-biomembrane on the water surface has been investigated using quartz crystal microbalance (QCM) and quartz crystal impedance (QCI) methods. The model-biomembranes used were dipalmitoyl phosphatidyl choline (DPPC), DPPC-palmitic acid (PA) mixture (DPPC:PA = 8:2), DPPC-Alamethicin (Al) mixture (DPPC:Al = 39:1), and DPPC-β-Lactoglobulin (βLG) mixture (DPPC:βLG = 139:1) monolayers, respectively. The quartz crystal oscillator (QCO) was attached horizontally to each monolayer, and QCM and QCI measurements were performed simultaneously. It was found that Iso hydrate physisorbed on each monolayer/water interface from QCM and changed those interfacial viscosities from QCI. With an increase in Iso concentration, pure DPPC, DPPC-PA mixed, and DPPC-Al mixed monolayers showed a two-step process of Iso hydrate on both physisorption and viscosity, whereas it was a one-step for the DPPC-βLG mixed monolayer. The viscosity change in the DPPC-βLG mixed monolayer with the physisorption of Iso hydrate was much larger than that of other monolayers, in spite of the one-step process. From these results, the action mechanism of anesthetics and their relevance to the expression of anesthesia were discussed, based on the "release of interfacial hydrated water" hypothesis on the membrane/water interface.