Electrical Impedance Method Research Articles

High-resolution concentration measurement in water/n-butanol binary system by means of high-frequency electrical impedance method

Chemical composition measurement technologies for binary systems are needed in many industrial and research applications for monitoring fluid composition in pipes and sample analysis. Except for spectroscopy technology, composition measurement is retrieved by monitoring fluid properties as refractive index, density, electrical conductivity or fluid sound velocity. Demanding applications are those where optical access to the fluid is not easy or available, very local or/and fast measurements are required, and where space limitations dictate the use of sub-millimeter non-intrusive sensors. Combination of all the above constraints in one application makes it extremely difficult to cope with. The latter is the motivation for the present work where a novel diagnostic method, based on I-VED (In-Vivo Embolic Detector) patented technology used in humans for the diagnosis of Coronary Artery Disease and Decompression Sickness, is implemented to determine the concentration of a binary mixture using high frequency impedance measurements. At first, the technology allows tuning over a range of excitation frequencies to identify a proper signal where the fluid attains chiefly an ohmic behavior. Then it retrieves chemical composition of the binary system through calibration curves with respect to resistance and temperature. Adaptation of the I-VED as concentration sensor has been driven by the necessity to integrate such a diagnostic in setups where available solutions in literature cannot be applied. Further to satisfying the aforementioned constraints, I-VED offers also other advantages compared to existing technologies as it provides high-scale resolution, it is not sensitive to electromagnetic interference (EMI) and it retrieves an integrated signal of the liquid between the electrodes, so localization of the measuring volume can be controlled. The proposed method has been tested in aqueous solutions of alcohol and its dependence on temperature and alcohol concentration has been investigated at an existing experimental setup named SELENE (SELf-rewetting fluid for ENErgy management), developed for heat transfer research applications.

Sphingosine-1-phosphate in anti-neutrophil cytoplasmic antibody-associated vasculitis: coagulation-related clinical indicators and complications.

Background: Sphingosine-1-phosphate (S1P) plays a significant role in anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV).Methods: We collected the plasma samples from 40 patients with AAV and 10 healthy volunteers. The plasma levels of S1P were tested by enzyme-linked immunosorbent assay (ELISA). The levels of serum creatinine (Scr) were tested by rate method, and then the estimated glomerular filtration rate (eGFR) of the patients was calculated from the Scr, age, and gender. Prothrombin time (PT), partial thromboplastin time (APTT), thrombin time (TT), fibrinogen (FIB), fibrinogen reduction product (FDP), D-dimer and C-reactive protein (CRP) were tested by turbidimetric inhibition immunoassays. Platelets (PLTs) were tested by fluorescently labeled electrical impedance method.Results: The plasma levels of S1P were significantly higher in AAV patients than in healthy volunteers. Correlation analysis showed that plasma levels of S1P were negatively correlated with glomerular filtration (P=0.022, r = −0.306), and positively correlated with circulating levels of Birmingham vasculitis activity score (BVAS), PLT and D-dimer, (P=0.004, r = 0.443; P<0.001, r = 0.654; P=0.006, r = 0.427). The 40 patients with AAV were classified into three groups: the thromboembolism group (with complications of cerebral infarction and myocardial infarction, n=6), cerebral ischemia group (n=4), and cerebral hemorrhage group (n=2). The plasma levels of S1P were highest in the thromboembolism group and lowest in the cerebral hemorrhage group (P=0.003).Conclusions: Plasma levels of S1P were associated with circulating levels of D-dimer, PLT and BVAS in the patients with AAV. Hence, plasma S1P level can be used as a biomarker to predict coagulation-related complications in AAV.

Practical Cross-Section Imaging of External Tendons to Reveal Grout Deficiencies Relative to Strand Pattern

External post-tensioned tendons in concrete segmental bridges have had strand corrosion failures due to grouting deficiencies such as voids or bleed water. Nondestructive assessment of the grout condition is thus often needed, preferably by a cross-section imaging method. Here, a magnetic sensing approach to image the position of the steel strand bundle is combined with an electric impedance method to evaluate the condition of the grout space. Both are embodied in a device that images the tendon’s cross section. The magnetic sensor travels around the circumference of the tendon and measures the force of attraction to the steel strands from which an image of the strand pattern inside the tendon is created. Simultaneously, a traveling plate rotates around the tendon, and variations of the electric impedance between the plate and strands identify grout deficiencies. The impedance and strand position data create a complete color-coded image of the tendon cross-section flagging grout deficiencies. The approach was validated by experiments with tendon specimens with known deficiencies and under field conditions. The method is rapid, economical, easy to replicate, with a small and safe device not requiring specialized operator training.

Electrical impedance and image analysis methods in detecting and measuring Scots pine heartwood from a log end during tree harvesting

Scots pine (Pinus sylvestris L.) heartwood is naturally durable wood material which has not been fully utilized in the wood industry. Currently, there are no practical measurement methods for detecting and measuring heartwood in a tree harvesting. The objective of this study was to evaluate the applicability of an electrical impedance spectroscopy and an image analysis of a log end face for pine heartwood measurements from the harvesting perspective. Both methods were tested with a fresh wood material which was collected during the harvesting operations. The results indicate that both methods have potential to measure the heartwood from processed stems with an average heartwood diameter error being less than two centimeters for each method. However, the image analysis of the log end face is only appropriate when visible contrast between the heartwood and a sapwood exists. Our findings indicate that the studied heartwood detection methods show great potential in measuring the heartwood of the stem in the harvesting phase which would ideally benefit later links in wood value chains.

Accurate estimation of fat amount by electrical impedance method under muscle stretch conditions

Accurate estimation of fat amount by electrical impedance method under muscle stretch conditions

Lubrication Condition Monitoring of Practical Ball Bearings by Electrical Impedance Method

Lubrication Condition Monitoring of Practical Ball Bearings by Electrical Impedance Method

Simple electrode configurations for probing deep organs using Electrical Bio-Impedance techniques

Tetrapolar Impedance Method (TPIM) and Focused Impedance Method (FIM) are two simple modalities of electrical bio-impedance measurement that could be employed to give useful physiological and diagnostic information of the human body. FIM is based on TPIM but uses a combination of two sets of TPIM, producing a focusing effect, which is useful to localize specific target organs. Most non-invasive electrical bio-impedance measurements based on TPIM and FIM use electrodes on one side of the body, outside the skin surface, which gives a shallow depth sensitivity. The sensitivity decreases with depth so that deep organs like lungs, heart, liver, stomach and bladder are not fully assessed through such measurements. Based on a long experience of studying electrical impedance methods, several qualitative ideas are presented in this article for probing deep organs using a few modified TPIM and FIM configurations. The suggestions are based on visualisations of both equipotentials and a popular sensitivity equation for transfer impedance, but not based on any quantitative analysis. Simulation and phantom studies based on these ideas may produce some practically useful electrode configurations for real life bio-impedance measurements.&#x0D; Bangladesh Journal of Medical Physics Vol.11 No.1 2018 P 1-15

Durability of glass fibre-reinforced polymer (GFRP) bars embedded in concrete under various environments. I: Experiments and analysis

This paper presents the tensile strength of glass fibre-reinforced polymer (GFRP) reinforcing bars embedded in concrete that is exposed to tap water, saline solutions and ambient humidity under accelerated conditions. These conditions were used to simulate the effect of river water, seawater or atmospheric moisture on the GFRP bars. In addition, the electrical impedance method was employed to evaluate the water content at different depths of a concrete cover under a variety of ambient humidity conditions. The effects of seawater, water-to-cement ratio (W/C) of the concrete cover, environmental humidity and cover depth were studied. The results revealed that the GFRP bars embedded in concrete exhibited a substantial strength loss when exposed to tap water or high ambient humidity. The degradation of concrete-wrapped GFRP bars immersed in saline solution could be different. This discrepancy is due to the variation of the degradation mechanism after exposure to chloride ions and is related to the cover depth. The depth of the concrete cover also had an evident influence on the durability results of GFRP bars subjected to various humid environments. Furthermore, reducing the W/C of the concrete cover had negative effects on the GFRP reinforcing bars.

Spatially resolved electrical impedance methods for cell and particle characterization.

Electrical impedance is an established technique used for cell and particle characterization. The temporal and spectral resolution of electrical impedance have been used to resolve basic cell characteristics like size and type, as well as to determine cell viability and activity. Such electrical impedance measurements are typically performed across the entire sample volume and can only provide an overall indication concerning the properties and state of that sample. For the study of heterogeneous structures such as cell layers, biological tissue, or polydisperse particle mixtures, an overall measured impedance value can only provide limited information and can lead to data misinterpretation. For the investigation of localized sample properties in complex heterogeneous structures/mixtures, the addition of spatial resolution to impedance measurements is necessary. Several spatially resolved impedance measurement techniques have been developed and applied to cell and particle research, including electrical impedance tomography, scanning electrochemical microscopy, and microelectrode arrays. This review provides an overview of spatially resolved impedance measurement methods and assesses their applicability for cell and particle characterization.

English

The economic importance of Papaya for fruit producers reinforces the idea of alternative (non-invasive and low cost) strategies to measure fruit ripening. In this work, it has been evaluated the kinetics of ripening degree of Papaya based on alternative and non-invasive electrical impedance method that is compared with conventional techniques (mechanical assays, determination of total soluble solids and titratable acidity). It was observed that a single point measurement of real part of impedance (1 MHz) returned relevant information concerning the kinetics of Papaya ripening. These results were in agreement with the firmness of fruit (mechanical assays) and the corresponding variation in total soluble solids, providing advantages for identification of ripening degree and depreciation of Papayas. Keywords: electrical impedance, Papaya, ripening degree, bulky resistance &nbsp

In Vitro Antiatherothrombotic Effects of Extracts from Berberis Vulgaris L., Teucrium Polium L., and Orthosiphon Stamineus Benth.

Coronary artery disease is the leading cause of mortality and morbidity worldwide. The pathogenesis is mainly due to atherosclerosis, plaque rupture, and platelet thrombus formation. The main risk factors for coronary artery disease include obesity, hypercholesterolemia, smoking, diabetes, and high blood pressure. As a part of disease management, treatment options using anticoagulant and antiplatelet drugs can be applied with addition to lipid-lowering medication. However, medicinal plants comprising antiatherothrombotic effects can be used as options to combat the disease rather than drug therapies with lesser adverse effects. Therefore, the haematological effect of Berberis vulgaris L., Teucrium polium L., and Orthosiphon stamineus Benth extracts was studied using in vitro model to prevent and to treat coronary atherothrombotic disease. The aqueous, methanol, and polysaccharide extracts of B. vulgaris, T. polium, and O. stamineus, respectively, were studied for their anticoagulant and antiplatelet effect on human whole blood. Extracts were subjected to the prothrombin time (PT) and activated partial thromboplastin time (APTT) test for anticoagulant activity. The antiplatelet activity was investigated using an electrical impedance method. B. vulgaris aqueous extract (BVAE), B. vulgaris polysaccharide extract (BVPE), T. polium aqueous extract (TPAE), and T. polium polysaccharide extract (TPPE) significantly prolonged the coagulation time in a concentration-dependent manner (p<0.05). The administration of BVAE demonstrated the most effective antiplatelet activity against platelet aggregation caused by arachidonic acid (AA) and collagen. These antiplatelet activities may correspond to the presence of higher total phenolic compound, which thus inhibit the platelet aggregation activity. In conclusion, these findings provide strong evidence on the antiatherothrombotic effect of BVAE and TPAE.

New electrical impedance methods for the in situ measurement of the complex permittivity of anisotropic skeletal muscle using multipolar needles

This paper provides a rigorous analysis on the measurement of the permittivity of two-dimensional anisotropic biological tissues such as skeletal muscle using the four-electrode impedance technique. The state-of-the-art technique requires individual electrodes placed at the same depth in contact with the anisotropic material, e.g. using monopolar needles. In this case, the minimum of measurements in different directions needed to estimate the complex permittivity and its anisotropy direction is 3, which translates into 12 monopolar needle insertions (i.e. 3 directions × 4 electrodes in each direction). Here, we extend our previous work and equip the reader with 8 new methods for multipolar needles, where 2 or more electrodes are spaced along the needle’s shaft in contact with the tissue at different depths. Using multipolar needles, the new methods presented reduce the number of needle insertions by a factor of 2 with respect to the available methods. We illustrate the methods with numerical simulations and new experiments on ex vivo ovine skeletal muscle (n = 3). Multi-frequency longitudinal and transverse permittivity data from 30 kHz to 1 MHz is made publicly available in the supplementary material. The methods presented here for multipolar needles bring closer the application of needle electrical impedance to patients with neuromuscular diseases.

Effect of dexmedetomidine combined with erector spinae plane block on inflammatory responses and cellular immune function after thoracic interbody fusion

Objective To evaluate the effect of dexmedetomidine combined with erector spinae plane block on inflammatory responses and cellular immune function after thoracic interbody fusion in patients. Methods Ninety American Society of Anesthesiologists physical status Ⅰ or Ⅱ patients of both sexes, aged 18-60 yr, with body mass index of 19-25 kg/m2, scheduled for elective thoracic interbody fusion with the vertebral segments involved in the operation <6, were divided into 3 groups(n=30 each)using a random number table method: general anesthesia group(group G), dexmedetomidine group(group D)and dexmedetomidine plus erector spinae plane block group(group DE). In group D and group DE, dexmedetomidine was intravenously infused over 10 min at a loading dose of 0.5 μg/kg starting from 30 min before anesthesia induction, followed by continuous infusion of 0.5 μg·kg-1·h-1 until 15 min before the end of operation. In group DE, bilateral erector spinae blocks were performed under ultrasound guidance at 20 min before anesthesia induction, and 0.25% ropivacaine 30 ml was injected into each side. Patients received patient-controlled analgesia(PCA)after operation. The consumption of propofol was recorded. The patients were followed up for 48 h after operation, and the pressing times of PCA and consumption of sufentanil were recorded. The emergence time, extubation time and volume of blood loss were also recorded. Blood samples were collected from the radial artery immediately before induction(T1), at 30 min of operation(T2), and at 1 h and 1, 3 and 5 days after operation(T3-6)for determination of plasma CD42+ , HLA-DR+ and CD14+ concentrations, white blood cell(WBC)count(by electrical impedance method)and plasma C-reactive protein(CRP)concentrations(by latex-enhanced scattering turbidimetry assay). CD42+ /CD14+ and HLA-DR+ /CD14+ ratios were calculated. Results Compared with group G, the pressing times of PCA and consumption of sufentanil were significantly decreased, CD42+ /CD14+ ratio was decreased, and HLA-DR+ /CD14+ ratio was increased at T3-6 in group D, and the emergence time, extubation time, pressing times of PCA and consumption of sufentanil and propofol were significantly decreased, CD42+ /CD14+ ratio was decreased, HLA-DR+ /CD14+ ratio was increased at T3-6, and the plasma CRP concentrations and WBC count were decreased at T2-6 in group DE (P<0.05). Compared with group D, the emergence time, extubation time, pressing times of PCA and consumption of sufentanil and propofol were significantly decreased, CD42+ /CD14+ ratio was decreased at T5, HLA-DR+ /CD14+ ratio was increased at T3, 4, and the plasma CRP concentrations and WBC count were decreased at T3-6 in group DE (P<0.05). Conclusion Dexmedetomidine combined with erector spinae plane block can reduce inflammatory responses and improve cellular immune function after thoracic interbody fusion in patients. Key words: Dexmedetomidine; Nerve block; Inflammation; Immunity, cellular

Application to Cell Sensing by Electrical Impedance Method Focused on Ion Diffusion around Cell

Application to Cell Sensing by Electrical Impedance Method Focused on Ion Diffusion around Cell

Flow regime identification and classification based on void fraction and differential pressure of vertical two-phase flow in rectangular channel

Better understanding of two-phase flow in narrow rectangular channels is important because it is considerably different from that in round tubes. Two-phase flow in narrow rectangular channels is invariably employed in most of the research reactors that use plate-type nuclear fuels around the world, high-heat-flux compact heat exchangers, and high-performance micro-electronics. In this study, an objective attempt was made to identify and classify various flow regimes in co-current air–water two-phase flow for vertical upward and downward direction flow inside a narrow rectangular channel. The void fraction and differential pressure data of the flow were measured. Flow regimes were identified based on visual observation, mean void fraction, and differential pressure data. A high-speed camera was used to capture images, and the void fraction was measured and analyzed by the electrical impedance method. In addition, digital image analysis was conducted, and differential pressures were measured using differential pressure transducers. Four flow patterns were identified for the vertical upward flow, and seven flow patterns were identified for the vertical downward flow in a narrow rectangular channel.

Unconstrained Cardiac Output Measurement System Based on Thoracic Electrical Impedance Method

An unconstrained cardiac output detection system based on thoracic electrical impedance method and embedded technology is developed in this study. PWM function of PIC embedded MCU, PIC18F4520, and filter circuit are used to generate a constant current sinusoidal signal with a frequency of 50 kHz and a current RMS of 2 mArms, which is applied as an exciting signal to the exciting electrodes located on the positions behind ears and on right lower abdomen. The thoracic electrical impedance is measured by the detecting electrodes pasted along the medial line on the front of the thorax, and is used to calculate cardiac output. A comparative experiment with the thoracic impedance method and the dye dilution method is carried out and the results are investigated. The experimental results show that the two methods have good consistency.

Fertiliser characterisation using optical and electrical impedance methods

This paper addresses the problem of fertiliser characterisation using optical and electrical impedance methods. Comparative analysis was performed to estimate the methods effectiveness for quantitative and qualitative characterisation of water diluted fertiliser. Characterisation using optical method within the deep ultraviolet range indicates the variability of features that was not observed when using the impedance method. The combination of both methods showed potential for more accurate qualitative analysis than each method alone. Finally, both methods showed good sensitivity to fertiliser concentration variation that was possible to fit with a linear function for optical spectroscopy (R2=0.95) and an exponential function for the impedance method (R2=0.99).

Electrical Impedance Methods in Neuromuscular Assessment: An Overview.

Electrical impedance methods have been used as evaluation tools in biological and medical science for well over 100 years. However, only recently have these techniques been applied specifically to the evaluation of conditions affecting nerve and muscle. This specific application, termed electrical impedance myography (EIM), is finding wide application as it can provide a quantitative index of muscle condition that can assist with diagnosis, track disease progression, and assess the beneficial impact of therapy. Using noninvasive surface methods, EIM has been studied in a number of conditions ranging from amyotrophic lateral sclerosis to muscular dystrophy to disuse atrophy. Data support that the technique is sensitive to disease status and can offer the possibility of performing clinical trials with fewer subjects than would otherwise be possible. Recent advances in the field include improved approaches for using EIM as a "virtual biopsy" and the development of combined needle impedance-electromyography technology.

Flow patterns of vertically upward and downward air-water two-phase flow in a narrow rectangular channel

Considering the importance of two-phase flows in narrow rectangular channels and their use in various applications, the hydrodynamics of a co-current air-water two-phase flow in a vertical narrow rectangular channel has been studied. Experiments have been carried out and flow regime maps for vertical upward and vertical downward flows have been plotted based on measured data sets. Flow regimes were identified and classified based on visual observation and void fraction data. Flow visualization was performed using a high speed camera, while a void fraction analysis was done using the electrical impedance method and a digital image analysis. Four different flow patterns were identified for the vertical upward flow and seven flow patterns were identified for the vertical downward flow. The flow regime map for the vertical upward flow was compared with previous studies and also with the flow regime map obtained for the vertical downward flow in this study.

Indirect Measurement of Changes in Hardness of Enzyme-treated Beef in Retort Pouch Using an Electrical Impedance Method

Indirect Measurement of Changes in Hardness of Enzyme-treated Beef in Retort Pouch Using an Electrical Impedance Method