Electrical Impedance Analysis Research Articles

A novel method for diagnosing rolling bearing surface damage by electric impedance analysis

This paper presents a novel condition monitoring method for rolling bearings, based on measuring the electric bearing impedance. The method can diagnose the presence of damage by frequency-domain analysis, and its extension along the raceway by time-domain analysis. The latter enables the assessment of the severity and the progression of bearing damage. A fatigue test shows that the occurrence of pittings in the bearing raceways causes characteristic peaks in the impedance signal, and that the duration of the peaks increases during damage progression. A second test series with artificial damage shows that the duration of the peaks depends on the bearing load and the length of the damage along the raceway and confirms the explanation hypothesis.

Optimization of an electrical impedance flow cytometry system and analysis of submicron particles and bacteria

Electrical impedance flow cytometry (EIFC) based on microfluidic chips has be en applied to particle and bacterial cell analysis, but detection of submicron particles is limited by the sensitivity of the existing microfluidic systems. Our objective was to increase the sensitivity of a coplanar electrode EIFC system and fulfill the increasing demand of analyzing submicron-organisms such as bacteria, apoptotic bodies, extracellular vesicles, exosomes and viruses. To this end, we optimized a series of parameters, including the width of the electrodes (We) of the microfluidic chip, the width (Wc) and height (Hc) of the channel’s sensing zone, and the buffer conductivity. The results indicated that 10 µm and 5 µm are the optimal We and Wc values, respectively, for microparticle detection. Based on these results, we developed an EIFC chip to test the detection of ⌀ 3.0 µm microspheres and yeast cells suspended in buffers of different conductivity. The optimal conductivities for microsphere and yeast cell detection were approximately 1.6 S/m and 6.4 S/m, respectively. Moreover, submicrospheres of ⌀ 0.2–0.6 µm and bacterial cells of species such as Serratia marcescens (with a cell size of 0.5 × (0.5–1.0) µm) were detected using the optimized EIFC system with a wide channel (Wc = 5 µm). In conclusion, our results demonstrate that the optimized EIFC system can be used to detect almost all types of bacteria in a high-throughput approach, allowing an effective and accurate enumeration of bacteria or other submicron-organisms in liquid samples in the future.

Investigation of impedance and leakage feature in BFO-BTO perovskite system

The present investigation focused on the analysis of structural, electrical impedance, and leakage features of the standard multifunctional-multiferroic perovskite BiFeO3-BaTiO3. We incorporated the standard Rietveld XRD refinement method for the study of the structure and other related parameters. The refinement result illustrates the tetragonal phase with space group P4mm is the most preferable structure for BiFeO3-BaTiO3 at room temperature. The SEM image reveals the polycrystalline nature of BiFeO3-BaTiO3. The electrical impedance feature of BiFeO3-BaTiO3 is investigated through the Nyquist plot over the temperature range (200 °C–325 °C) and frequency range (0.1–5000 kHz). The role of grain and grain boundary on the electrical impedance was found quite prominent within the specified temperature and frequency range. The temperature-dependent I-V characteristic feature of BiFeO3-BaTiO3 illustrates the semiconducting nature.

Influência de um aditivo compensador de retração à base de óxido de cálcio supercalcinado nas propriedades de um concreto autoadensável

ABSTRACT The demand for self-compacting concrete grows continuously due to investments in new infrastructure, upgrades, or replacement of old infrastructure. This type of concrete can mold itself into the spaces intended for it on its own and fill them without the need for any vibration or external compaction. It must achieve three main properties: fluidity, passing ability, and resistance to segregation. Monitoring these properties, the quality, and the increase in the performance of concrete structures is essential to keep up with this growth. In this work, we explore the effect of adding a commercial over calcined calcium oxide-based compound, as a shrinkage-compensating admixture, on the properties of fresh and hardened concrete, particularly on the shrinkage and curing of self-compacting concrete specimens (SCC). Also, an experimental protocol is proposed for the electrical impedance analysis of concrete samples. Fluidity, compression, shrinkage, elastic modulus, and impedance spectroscopy tests were performed, in addition to scanning electron microscopy images. The additive slightly modifies the concrete properties in the fresh state. In hardened concrete, the compressive strength and modulus of elasticity increase, in addition to a reduction in shrinkage with 2.8% of the additive.

Electrical impedance analysis of NaCl and CaCl2 solutions based on equivalent electric circuit

In this paper, we report the behaviour of electrical impedance of sodium chloride (NaCl) and Calcium chloride (CaCl2) with the concentration of 1.25 to 100 mM/L in frequencies ranging from 10 mHz to 1 MHz. The complex electrical impedance (real and imaginary parts) is obtained using the electrical impedance spectroscopy (EIS) technique. The experimental data had been fitted with three models of equivalent electrical circuit (EEC), model-a is Randles circuit, model-b consist of R solution (Rs) in series with constant phase element (CPE) and model-c consist of Randles circuit in series with CPE. Best fit data is obtained from model-c with goodness of fit less than 0.005. The CPE in this circuit associated with the electric double-layer. As expected from the experimental and fitting spectra, even for a low concentration for both salts, an inverse relationship was observed between impedance and salt concentration. The number of ions contains in CaCl2, which are more than NaCl is estimated to be the cause that CaCl2 impedance is lower than NaCl. The total impedance influenced by the CPE component increased significantly at frequencies about 100 Hz, indicating that the equivalent electric circuit used can estimate the effect of double-layer on the measurement.

Higher order modal dynamics of the flexural ultrasonic transducer

The flexural ultrasonic transducer (FUT) consists of a piezoelectric ceramic bonded to an edge-clamped elastic plate, for both generation and detection of ultrasound waves. It is typically employed for proximity measurement, such as in automotive parking systems, and for flow measurement in gases and liquids. Conventional industrial applications have generally incorporated FUTs with resonance frequencies up to around 50 kHz. However, there have been recent advances in the understanding of the FUT, both in terms of fabrication and operation, enabling the potential for measurement in a wider range of applications, including those of elevated pressure, temperature, and requiring multiple operating frequencies. Ultrasound measurement with FUTs at frequencies greater than 50 kHz is desirable in a range of applications, including gas and water metering in petrochemical plants, district heating, and power industries. The major restricting limitation of designing transducers to operate at these higher frequencies has been a relatively poor understanding of these transducers work, including optimisation of design and performance, and the few reports into how different modes of a FUT can be utilised for practical and reliable measurement. In this study, the higher order modal dynamics of the FUT are investigated through measurement of high frequency ultrasound waves in air, for different fundamental operating modes. A combination of experimental techniques is applied, comprising electrical impedance analysis and laser Doppler vibrometry. The experimental research is supported by analytical solutions to reveal complex higher order modal dynamics of the FUT. This investigation represents further development in widening the industrial application potential of the FUT.

Pericyte Contractile Responses to Endothelin-1 and Aβ Peptides: Assessment by Electrical Impedance Assay

Pericytes are vascular mural cells that contract and relax in response to vasoactive stimuli to regulate neurovascular coupling and cerebral blood flow. Pericytes are damaged and degenerate in Alzheimer’s disease (AD). We previously showed that the level of the regulatory vasoconstrictor, endothelin-1 (EDN1), is elevated in AD cerebral cortex and upregulated by amyloid-beta (Aβ). We have used electrical impedance analysis to monitor the contractile and proliferative response of cultured human fetal and adult brain-derived pericytes to EDN1 in real-time. EDN1 caused transient, dose-dependent contraction of fetal and adult brain pericytes that was mediated by EDN1 type A receptors and increased the subsequent proliferation of fetal but not adult cells. The contractile responses to EDN1 were weaker in the adult pericytes. The EDN1-mediated contractile response of fetal pericytes was unchanged after exposure to Aβ1–40 or Aβ1–42 (0.1–10 μM) for 1 h but both contraction and subsequent relaxation were significantly impaired upon exposure to Aβ for 24 h. These data suggest that chronic exposure to Aβ interferes with EDN1-mediated pericyte contractility, potentially contributing to neurovascular uncoupling and reduced cerebral blood flow in AD.

Structural, electrical, dielectric properties and complex impedance analysis of Pr0.6Sr0.4Mn1−xAxO3 perovskites (A = Cr and Ti)

Structural, electrical, dielectric properties and complex impedance analysis of Pr0.6Sr0.4Mn1−xAxO3 perovskites (A = Cr and Ti)

Dielectric relaxation, electrical conductivity measurements, electric modulus and impedance analysis of WO3 nanostructures

The electrical conductivity and dielectric properties of WO3 nanostructures were measured by impedance spectroscopy using 50 Hz–5 MHz frequency in steps of 100 Hz and 303–383 K temperature. The dielectric behavior is analyzed using real and imaginary parts of dielectric constant (ε′), dielectric loss (ε″), loss factor (tan δ), electric modulus (M′ and M″) and impedance (Z′ and Z″) and complex impedance analysis. The electrical conductivity remained originate towards a function of frequency and temperature. The frequency exponent ‘s′ is found to decrease from 0.89 to 0.35 with an increase of temperature which infers the correlated barrier hopping mechanism (CBH) that exists in WO3 nanostructures. The Cole-Cole plot explains the complex impedance for different temperatures.

Gradient-based impedance synthesis for breast and lung cancer cell screening deploying planar and nano-structured electrodes.

World Health Organization articulated 9.8 million casualties globally in 2018 due to cancer. Cancer, as the world's second most fatal disease, can be recuperated well if diagnosed at an early stage. In this work, a gradient-based impedance synthesis of normal and cancerous cells of breast and lungs, is demonstrated numerically for early-stage cancer detection. Low-voltage single-cell level examination is employed for indomitable diagnosis. MCF-7 and MCF-10A are utilized as breast cancer and breastnormal cells, respectively; likewise, SK-MES and NL-20 are utilized as lung cancer and lung normal cell. Pre-examination numerical setup validity ensured with multiple test regimes. Micro-scaled planar and nano-structured electrodes are employed individually to witness the effect of the electrode's structure during electrical impedance examination of cancer and non-cancer cell. Frequency range, at which differential impedance effect is found detectable, for breast and lung cancer cell pairs is determined to be 107Hz and 108Hz, respectively. By surpassing the conventional impedance spectroscopy with tedious data fitting formalities, the gradient synthesis technique for cancer detection is introduced. The gradient synthesis for cancer detection is found independent of electrode shape effect. Gradient for breast cancer cell is found to be 2 times greater than the normal breast cell while for lung cancer cell it is found to be 1.5 times greater than the normal lung cell. Our results suggest that as the frequency of applied electrical stimulus increases, impedance of cancerous cell falls at the rate almost double than its counterpart normal cell. This work provides a theoretical basis for further experimental exploration of gradient-based impedance synthesis in cancer therapy and serves as a design tool for performance optimization. Figure 1 (a) Represents electrical Impedance analysis of breast normal cell MCF-10A and breast cancer cell MCF-7 using micro-scaled planar and nano-structured electrodes. (b) Gradient impedance synthesis performed, for breast normal cell (MCF-10A) and breast cancer cell (MCF-7) likewise for lungs normal cell (NL-20) and lungs cancer cell (SK-MES), which assures clear differential effect for cancer screening. Surpassing the conventional and tedious data fitting impedance spectroscopies, a novel gradient-based impedance spectroscopy for early cancer detection is introduced. It clearly detects cancer without any data fitting formalities to find parameter of identification. Planar and nano structure electrodes are used to witness the impact of electrode shape on cell impedance. Breast normal MCF-10A and cancer cell MCF-7 as well as lungs normal NL-20 and cancer cell SK-MES are examined to reflect the efficacy of our work. Single cell level examination is performed for authenticated results.

Effect of Aerobic Training on Body Composition among Sedentary Women of Manipur

Physical fitness was an important aspect for leading a complete life. Women, in general, have lesser involvement on a physical fitness regime. To maintain the youthfulness of body, regular physical activity and exercise was a key ingredient. This study aims to assess the effect of aerobic training on body composition among sedentary women of Manipur. The study made random inclusion of subjects who volunteer to participate in the training programme from Lairikyengbam Leikai, Imphal East District Manipur. Totally 30 subjects of age 46.5±4.9 years who volunteer to participate in the training were selected and minimize as control group and experimental group with N=15 each. Medical examination was conducted prior to training under registered practitioner. The training intensity was determining by using Karvonen formula. The training was given for 8 weeks regularly for 3 days alternately to determine the changes brought by training on body fat and fat free mass. The measurement was done before training as baseline score and after completion of 8 weeks as final score using Bio Electrical Impedance Analysis (BIA) method, TANITA TBF300. The paired t test was used to analyze the data at a 0.05 level of significance for pre-and post-difference comparisons, followed by an independent t test to compare the mean difference between groups using SPSS software20. It shows statistically significant decrease in body fat (P<0.05) while fat free mass shows statistically not significant (P>0.05). It also shows that fat mass has a significant difference between the experimental and control groups while fat free mass shows no significant difference between groups. The result indicates that aerobic training can be an effective program for body fat reduction and positively alter one's body composition.

Evaluation of heating uniformity and quality attributes during vacuum microwave thawing of frozen apples

This study investigated the effects of air, microwave (MW), and vacuum microwave (VMW) thawing treatments on the physical properties of frozen apples, including weight loss, electrical impedance characteristics for assessment of cellular structure, surface color, and mechanical properties, as well as the heating uniformity in MW and VMW thawing. The results showed that VMW inhibits the localized overheating of the sample during thawing compared to MW thawing. VMW thawing increased the breaking strain of the sample tissues compared to the other samples. The breaking stress and maximum stress, which are indices of the hardness of the tissue, were significantly reduced after freezing–thawing in each thawing method; the phenomenon was thought to be caused by the damage to the cell structure, which was confirmed by the electrical impedance analysis. The level of browning was significantly lower in MW and VMW thawing than in air thawing at 20 °C because they required a relatively short thawing time. This study showed that one of the specific effects of VMW thawing is that it can thaw the sample in a short time by inhibiting excessive heating and localized heating, indicating its potential for application as a high-quality and efficient thawing technology for various foods.

Application of Electroimpedance Spirometry for Clinical Assessment of Respiratory Function Indices

A practical method of studying the dynamics of respiratory function associated with the registration of the electrical impedance of conductive biological fluids exhaled by the patient is described. In the model measuring cell, the physical causes and relationships in the conductivity of the air flow, saturated with an electrolytic fluid aerosol created by an ultrasonic nebulizer have been investigated experimentally. The design of a new electrical impedance spirometer in the form of a mouthpiece with electrical sensors, filled with a porous medium impregnated with electrolyte, through which the patient breathes, is developed and tested. To register fluctuations in the magnitude of the impedance modulus, an original hardware and software complex is used, made on the basis of a high-speed analog-to-digital converter. Based on electrical impedance analysis data, the methods are proposed for quantitative assessment of the basic spirometric medical indicators characterizing the state and functioning of the patient’s breathing apparatus, such as respiration rate, entry and expiration rate, exhaled air volume, amount and concentration of exhaled lung fluid.

The Effectiveness of Adding Pharmacotherapy to Dietary Counseling for Veterans in a Veterans Health Administration Move! Weight Management Program

Background: Over 78% of veterans are overweight or obese. MOVE! is the VA’s national evidence-based self-management program. This program focuses on health and wellness through healthy eating, physical activity, and behavior change (1). We evaluated the effects of adding pharmacotherapy to dietitian coaching in a real-world MOVE! Program in the VA Nebraska-Western Iowa Health Care System.Methods: A systematic retrospective and prospective chart review were completed of 66 patients who completed a minimum of 6 months of medication at our Weight Loss Medicine clinic from June 2017 to February 2020. Body composition was measured using SECA Bio Electrical Impedance Analyzer. Descriptive statistics were used to analyze weight changes, fat mass (FM), and fat-free mass (FFM) changes at 6 and 12 months after starting weight loss medications.Results: The percentage of patients with a 5% decrease in weight from baseline after at least 6 months with pharmacotherapy was 47% and a 10% decrease was 36% after 12 months. In 6 months, a decrease of a minimum of 5% was seen with GLP-1 (semaglutide or liraglutide) 55 % (29/53), orlistat 11% (1/9), and bupropion-topiramate 25 % (1/4). An average of 3.4% FM decrease and a 3.47% FFM increase was seen from baseline to 6 months and 4.8% FM decrease and 4.7% FFM increase was seen from baseline to 12 months. Conclusion: A clinically significant decrease in weight was seen at 6 and 12 months after starting weight loss medication in addition to monthly MOVE! Dietitian visits. A significant decrease was seen in FM and an increase in FFM. Veteran’s receiving a GLP-1 had a greater amount of weight loss compared with Orlistat and bupropion-topiramate. Weight loss medication is recommended as an adjunct to dietitian counseling for optimizing weight loss.References1 Kinsinger LS, Jones KR, Kahwati L et al. Design and dissemination of the MOVE! Weight‐Management Program for Veterans. Prev Chronic Dis 2009; 6: A98

Room temperature electrical impedance analysis of LaFe1-x MgxO3 (x = 0.01 and 0.05) ceramics

The effect of Mg-small doped on the structural and electrical properties of LaFe1-x MgxO3 ceramic materials was studied. A series of LaFe1-xMgxO3 (x= 0.01 and 0.05) perovskite material was synthesized via sol-gel method following by sintering process. Structural properties were investigated by using X-Ray diffraction (XRD). Rietveld refinement analysis have been done using Fullprof software. All of the samples are single-phase with orthorhombic crystal structure and Pnma space group. Lattice parameter slightly increases as the Mg-doping concentration increase. The impedance spectroscopy of the sample was characterized by using the RLC-Meter at a frequency range of 100 Hz - 1 MHz at room temperature. The electrical parameters such as impedance, dielectric constant, tan loss, and conductivity was analyzed using impedance spectroscopy method. The value of the dielectric constant (∊) decreases with increasing frequency and remains constant at higher frequencies. The dielectric loss shows a decrease in the dielectric constant with increasing Mg doping.

Beneficial modification of the electrical properties of ecofriendly ferroelectric ceramic Na0.5Bi0.5TiO3 by substitution of low concentration of Ho+3

Advantage of small amount (0.5 mol%) of holmium ion (Ho+3) substitution in the sodium bismuth titanate (NBT) on its electrical properties had been highlighted. Na0.5Bi0.5TiO3and Na0.5Bi0.495Ho0.005TiO3(NBT-Ho) had been synthesized by using solid state technique. In the dielectric properties, depolarization temperature (Td) and temperature at maximum dielectric constant (Tm) were increased to ˜180 °C and ˜ 355 °C, respectively in compared to Td˜165 °C and Tm˜ 325 °C of pure NBT. In addition, improved insulating nature was found in holmium substituted ceramic, which was confirmed by room temperature leakage current density versus electric field (J-E) measurement and temperature dependent impedance analysis. It showed five times lesser leakage current density at ˜45 kV/cm over its parent ceramic NBT. Leakage current density of holmium substituted NBT in the function of electric field (J versus E graph) displayed that electrical conduction follows the ohmic behavior up to ˜ 7.5 kV/cm electric field, and thereafter, up to ˜ 20.1 kV/cm, space-charge limited conduction mechanisms (SCLC) became to dominate. Moreover, enhanced electromechanical coupling coefficient (kp˜18.67%) in the NBT-Ho in comparison to pure NBT (kp˜18.17%) was obtained.

Digital electrical impedance analysis for single bacterium sensing and antimicrobial susceptibility testing

Single-molecule and single-cell analysis techniques have opened new opportunities for characterizing and analyzing heterogeneity within biological samples. These detection methods are often referred to as digital assays because the biological sample is partitioned into many small compartments and each compartment contains a discrete number of targets (e.g. cells). Using digital assays, researchers can precisely detect and quantify individual targets, and this capability has made digital techniques the basis for many modern bioanalytical tools (including digital PCR, single cell RNA sequencing, and digital ELISA). However, digital assays are dominated by optical analysis systems that typically utilize microscopy to analyze partitioned samples. The utility of digital assays may be dramatically enhanced by implementing cost-efficient and portable electrical detection capabilities. Herein, we describe a digital electrical impedance sensing platform that enables direct multiplexed measurement of single cell bacterial cells. We outline our solutions to the challenge of multiplexing impedance sensing across many culture compartments and demonstrate the potential for rapidly differentiating antimicrobial resistant versus susceptible strains of bacteria.

Effect of substitution of La3+ on structural and electrical properties of Sr(Fe0.5Nb0.5)O3 ceramic

In this work, we have mainly reported the effect of lanthanum substitution on structural, dielectric, impedance and transport properties of strontium iron niobate (i.e., Sr1-xLax(Fe0.5Nb0.5)1-x/4O3 (x = 0, 0.05, 0.1, 0.15, 0.2)). The materials were synthesized using standard ceramic technology. The preliminary structural analysis was done by using the room temperature X-ray diffraction data. The samples of higher concentrations (x = 0.15 and x = 0.20) show the development of an additional phase (i.e., LaNbO4 and Sr3La4O9). Studies of frequency and temperature dependence of dielectric parameters exhibit an anomaly and relaxor behavior in the compounds. The electrical impedance and modulus analysis of frequency and temperature-dependent data show the contributions of grains and grain boundaries in the resistive and capacitive properties of the compounds. The study of transport properties of AC conductivity has provided the conduction and relaxation mechanism. The substitution of La3+ has significantly changed the dielectric constant, tangent loss, and transport properties of the material.

Atomic layer deposited Mo2N thin films using Mo(CO)6 and NH3 plasma as a Cu diffusion barrier

Thin films of molybdenum nitride (Mo2N) are prepared using sequential exposure of molybdenum hexacarbonyl [Mo(CO)6] and NH3 plasma in a plasma-enhanced atomic layer deposition (PEALD) reactor. Several process parameters such as the deposition temperature, plasma power, and post-annealing conditions are systematically investigated to achieve the best quality films. The superior growth kinetics is evident with a significantly higher growth per cycle (GPC) value with lower incubation period for this PEALD process (~1.1 Å, ~36 cycles) when compared to thermal ALD (~0.3 Å, ~63 cycles), both carried out at 200 °C. The growth rate of the Mo2N film reveals a significant jump above 215 °C, indicating a severe decomposition of Mo(CO)6, however, polycrystalline γ-Mo2N films with face-centered-cubic structure are evident within the deposition temperature range of 200–230 °C. The sharp decrease in the resistivity of the as-grown Mo2N films is observed with increasing deposition temperature, film thickness, and plasma power. The resistivity could be further lowered by a post-annealing process and the lowest resistivity of ~395 μΩ cm is achieved for the thin film deposited with 300 watt plasma power and annealed at 700 °C. Finally, the Cu-diffusion barrier capability of an extremely thin film (~7 nm) of as-deposited Mo2N is evaluated in Cu/PEALD-Mo2N/Si structure. The X-ray diffractometry analysis confirms that such a thin layer can successfully prevent the diffusion of Cu up to 500 °C and significant Cu3Si formation was observed only at 600 °C and above. The gradual failure of the diffusion barrier upon annealing is further investigated using electrical impedance (EI) analyses in two different modes. In-plane EI measurements directly indicate the change in the Cu layer at the top, and the formation of Cu3Si can be inferred from the through-plane mode. A comparison with PEALD and thermal-ALD-grown MoNx from EI analyses further reflects the superiority of plasma-enhanced process towards fabricating diffusion barrier layer.

Characterizing temperature dependent complex electrical impedance analysis of LaFe1−xZnxO3(x= 0.03, 0.05, and 0.07) ceramics

LaFe[Formula: see text][Formula: see text]O3([Formula: see text] = 0.03, 0.05, and 0.07) ceramics were prepared in two steps: preparation of the powder form by a sol–gel method followed by sintering-annealing treatments to form the bulk-phase. X-ray diffraction analysis revealed that all ceramics were crystallized in the orthorhombic perovskite structure with Pbnm symmetry. Grain size distribution and morphological characteristics were investigated by scanning electron microscopy. Specific surface area was analyzed through BET–BJH methods. Electrical impedance analysis was investigated as a function of frequency at various temperatures. It was found that the electrical behavior is dominated by grain boundary contribution, i.e., electrical conductivity. The frequency dependence of the complex conductivity was analyzed through Joncher’s power law and the dominance of translational motion with a sudden hopping mechanism in the electrical conduction mechanism increased with increasing Zn content. Activation energy decreased with increasing Zn content.