Electrical Impedance Parameters Research Articles

Rapid safety assessment of reconstituted infant formula using electrical impedance analysis

A rapid method to assess freshness is crucial for the safe handling of reconstituted infant formula (RIF) and prevention of food-borne illnesses in infants. This study explored the use of electrical impedance measurement (EIM) at a constant frequency for real-time freshness evaluation of RIF. Initial electrical impedance of 89.16 ± 0.47 Ω decreased to 74.29 ± 0.23 Ω within 48 h at room temperature (20 °C) storage. Under temperature abuse conditions (30 °C), the electrical impedance rapidly dropped from 75.48 ± 0.52 Ω to 60.15 ± 4.76 Ω within 18 h, indicating more rapid spoilage. Notable changes in the electrical impedance were observed during temperature abuse. Empirical model analysis revealed a strong positive correlation between electrical impedance and conventional freshness parameters such as pH, protein, and microbial growth. This study demonstrates the potential of EIM for the rapid detection of freshness changes in RIF, offering valuable insights into the prevention of food-borne illnesses in infants.

Layered mechanical and electrical properties of porcine articular cartilage.

The complex structure and composition of articular cartilage make its performance show depth-dependent characteristics, but its related parameters are not complete at present. In this study, porcine articular cartilage was divided into three zones along the thickness direction, and the cartilage tissue in each zone was tested for electrical impedance, compression relaxation, and permeability to obtain their mechanical and electrical impedance parameters. The results showed that there were significant differences in mechanical and electrical properties of cartilage tissue in different zones in which resistivity, elastic modulus, relaxation time, and final relaxation rate increased gradually from superficial zone to deep zone along the direction of cartilage thickness while the permeability decreased gradually. Bioimpedance analysis can capture the phenomenon of very slight histological changes, which is expected to provide information for predicting cartilage degeneration, but the electrical impedance parameters of cartilage are still very lacking. These data are expected to provide reference for the treatment of clinical osteoarthritis and the research of cartilage repair materials.

Ask the plants directly: Understanding plant needs using electrical impedance measurements

• Presenting a measuring system designed to analyse multiple plants at the same time. • Relating environmental parameters and in vivo plant stem electrical impedance. • Presenting results regarding the relation between stem impedance and soil moisture. • Paving the way in reducing cost and complexity of plant monitoring system. • Introducing a new way to check plant health status towards personalized agriculture. Food security is a major problem nowadays. Ensuring enough food for the entire human population is becoming harder due to climate change and world population growth. Smart agriculture is a promising solution: integrating sensors and data analysis in agriculture is leading to a reduction of food production waste and an increase in production yield. However, currently environmental monitoring is not sufficient since different plants may have disparate reactions even if their environmental conditions are similar. This paper shows a novel way of understanding plant status based on direct measurement of in vivo stem electrical impedance. This was achieved with a system designed by the authors and validated by showing relations (correlation and Granger’s causality) between stem electrical impedance and environment parameters. Validation was accomplished by monitoring and analyzing multiple plants at the same time. Statistical analysis showed a correlation of up to 95% between impedance and soil moisture, and that soil moisture variations caused variation in the impedance of the plants.

Development of a portable impedance meter for diagnostics of biological objects plant origin

The article proposes a technical solution for a multi-frequency meter of electrical impedance parameters based on a precision impedance converter AD5933 from analog devices. The technical solution can be used in the development of portable devices for the diagnosis of biological objects.

A Novel GUI-Based Image Reconstruction Algorithm of EIT Imaging Technique

Electrical impedance tomography (EIT) is a non-invasive technique that is used to estimate the electrical properties of a medical or non-medical object through the boundary data of the object. It used to achieve functional imaging of different objects by measuring electrical conductivity and impedance parameters. In this paper, a novel image reconstruction algorithm is presented, which is based on graphical user interface (GUI) developed on MATLAB software platform. EIT imaging algorithm consists of a forward problem and an inverse problem. The forward problem is formulated with the conductance matrix, and a non-iterative inverse method is used to estimate the conductivity distribution. Image display and data analysis are implemented and controlled directly in the GUI. The numerical simulations and phantom experiments have been carried out to evaluate the performance of the proposed algorithm and other previous research data through quantitative parameters. The obtained result shows satisfactory and comparable results to other EIT imaging algorithm.

Autumn cold acclimation of shoots does not explain the northern distribution limit of three southern exotic tree species in Finland

Frost hardiness (FH) is one of the key traits that limits the distribution of tree species in the north. Different species and ecotypes respond differently to the drivers of frost hardening and may therefore have different survival capacities, especially in their northern distribution range. Several southern tree species such as pedunculate oak (Quercus robur L.), Norway maple (Acer platanoides L.), and mountain elm (Ulmus glabra Hudson) have their natural northern distribution limit in Southern Finland. Here, we examined whether insufficient frost hardening in the autumn limits the northwards distribution of these three species. To that end, we monitored phenological events and frost hardening in the autumn in these exotic species in Central Finland, further north from the natural distribution range of the three exotic species, and for the sake of comparison, in the native silver birch (Betula pendula Roth.). In all species, a timely growth cessation was observed. The water content of the stem decreased, and its dry mass content increased rapidly in August before the onset of frost hardening, after which no major changes were observed in these two traits. In the early phase of hardening, there were differences in leaf colouring between the four species. The values of the electrical impedance parameters of the stem changed during frost hardening, with a clear turning point after the first night frosts at the end of September. Depending on the species and hardening phase, the high temperature exotherm (HTE) of the stem was observed between -3 °C and -10 °C, but HTE did not indicate differences between the species in frost hardening. In all four species, frost hardening started at the beginning of September and proceeded first at equal rates, but the hardening was more rapid later in birch than in the other species. The damaging temperature range assessed by the controlled freezing tests became wider with increasing FH. The occurrence rate of the low temperature exotherm (LTE) varied between the species, and the LTE was observed at around -35 °C in the last sampling at the beginning of December (no LTE was observed in birch). We conclude that the hardening of all four species took place in a timely manner so that in each, the frost hardiness was sufficient to survive the autumn frosts at the experimental site in Central Finland. Further studies are needed to examine whether the exotic three species also tolerate temporarily occurring extreme winter conditions such as temperatures below -35 °C, and the high short-term temperature variations in winter and especially in spring.

Technology of Two-dimensional Bioimpedance Analysis of the Human Body Composition.

The BIA primary result sheets as a rule contain one-dimensional graphical scales with a selected area of normal values. In 1994, Piccoli et al. proposed BIVA, an alternative form of BIA data presentation, where two bioimpedance parameters are considered simultaneously as tolerance ellipses: resistance and reactance normalized to height.The purpose of this study is to develop an approach to data analysis in body composition bioimpedance research in two-dimensional representations.The data of 1.124.668 patients aged 5 to 85 years who underwent a bioimpedance study in Russian Health Centers from 2009 to 2015 were used. Statistical programming in the R Studio environment was carried out to estimate two-dimensional distribution densities of pairs of body composition parameters for each year of life.The non-Gaussian distribution is found in most parameters of bioimpedance analysis of body composition for most ages (Lilliefors test, p-value << 0.0001). The slices of the actual two-dimensional distribution pairs of body composition parameters had an irregular shape. The authors of the article propose using the actually observed distribution for populations where numerous bioimpedance studies have already been carried out. Such technology can be called two-dimensional bioimpedance analysis of human body composition (2DBIA). The 2DBIA approach is clearer for practitioners and their patients due to the use of body composition parameters in addition to electrical impedance parameters.

Recognition of healthy and cancerous breast cells: Sensing the differences by dielectric spectroscopy.

The response of human cells to applied electrical signals depends on the cellular health status, because it is influenced by the composition and structure of the main cellular components. Therefore, electrical impedance-based techniques can be considered as sensitive tools to investigate healthy or disease state at cellular level. The goal of this study is to show that different types of in vitro cellular lines, related to different health status, can be differentiated using impedance spectra analysis. Three different types of human breast cell line, corresponding to healthy, cancerous, and metastatic adenocarcinoma cells, were measured by means of electrical impedance spectroscopy. By modeling the investigated cells with proper resistive and capacitive circuital elements, the magnitude of the cell electrical components and spectra of real and imaginary part of dielectric permittivity were obtained. The latter were subsequently examined with a commonly adopted mathematical model, in order to estimate the values of specific dielectric parameters for the three different cellular lines. The relative variation of cellular capacitance with respect to that of the culture medium, estimated at 100Hz, has a larger value for the two types of cancerous cells with respect to the noncancerous type. Furthermore, the ratio between the real and imaginary part of the dielectric permittivity function has larger values for metastatic cells with respect to the normal and nonmetastatic ones. Therefore, the mentioned relative capacitance allows to discriminate between normal and cancerous cells, whereas the results obtained for the dielectric function can discriminate between metastatic and nonmetastatic cells. This study can be considered as an exploratory investigation of evaluating in vitro the health status of humans cells using selected electrical impedance parameters as potential markers. The obtained results highlight that a standard cultureware system, provided with interdigitated electrodes and appropriate impedance parameters, that is, cellular capacitance and the ratio between the imaginary and real part of cellular dielectric function, can be used to discriminate between healthy and cancerous breast cell lines, as well as different malignancy degrees.

Impedance-Based Monitoring of Mesenchymal Stromal Cell Three-Dimensional Proliferation Using Aerosol Jet Printed Sensors: A Tissue Engineering Application.

One of the main hurdles to improving scaffolds for regenerative medicine is the development of non-invasive methods to monitor cell proliferation within three-dimensional environments. Recently, an electrical impedance-based approach has been identified as promising for three-dimensional proliferation assays. A low-cost impedance-based solution, easily integrable with multi-well plates, is here presented. Sensors were developed using biocompatible carbon-based ink on foldable polyimide substrates by means of a novel aerosol jet printing technique. The setup was tested to monitor the proliferation of human mesenchymal stromal cells into previously validated gelatin-chitosan hybrid hydrogel scaffolds. Reliability of the methodology was assessed comparing variations of the electrical impedance parameters with the outcomes of enzymatic proliferation assay. Results obtained showed a magnitude increase and a phase angle decrease at 4 kHz (maximum of 2.5 kΩ and −9 degrees) and an exponential increase of the modeled resistance and capacitance components due to the cell proliferation (maximum of 1.5 kΩ and 200 nF). A statistically significant relationship with enzymatic assay outcomes could be detected for both phase angle and electric model parameters. Overall, these findings support the potentiality of this non-invasive approach for continuous monitoring of scaffold-based cultures, being also promising in the perspective of optimizing the scaffold-culture system.

Electrical resonance/antiresonance characterization of NDT transducer and possible optimization of impulse excitation signals width and their types

This work presents an experimental method for obtaining the best excitation pulse type and width for optimal driving of an industrial non-destructive testing (NDT) ultrasound transducer by using its electrical impedance parameters as input. Within the optimization method, a classic low-voltage frequency sweeping signal and two different types of high-voltage impulse excitation signals (unipolar and bipolar), with different pulse widths, are used for the electromechanical characterization of the transducer. The optimization of the excitation signal is verified by measuring the voltage, current and electrical power of the excitation and received signals obtained by ultrasound pulse reflection from two cracks (2 mm and 3 mm) in a stainless-steel block. Additionally, the influence of the output electrical impedance of the power amplifier on the optimal transfer of electrical power from the amplifier to the loading (the NDT transducer on the block) and vice versa is also discussed in this work. The optimum working point for the ultrasound NDT transducer, regarding the impulse excitation type and its pulse width, is a bipolar impulse excitation with the width and amplitude calculated from maximum values of the measured voltage, electric current and power generated in the transducer receive mode by the reflected ultrasound signals.

Maturity assessment of tomato fruit based on electrical impedance spectroscopy

Ripening is important to tomato quality, taste and nutrition. In this study, the maturity of plant-fruit was on-line investigated based on electrical impedance spectroscopy (EIS). The electrodes with sensing unit for contact force between samples and electrodes were designed. After fruits turn into green-white, impedance measurements were conducted on the fruit samples at various ripening stages in the range of 1 Hz to 1 MHz. The optimal frequencies (100 Hz, 1 kHz and 1 MHz) for maturity assessment were selected and five electrical impedance parameters at three sensitive frequencies were determined. The equivalent circuit model with CPE was developed and the model performance was evaluated. The soluble solid content and pH of fruit were determined and analyzed to explain the variations in EIS parameters sufficiently. Results showed that the impedance, phase angle, resistance, reactance and capacitance increased with the progression of maturity. The selected impedance parameters could be used to classify tomato samples into immature class or mature class with the accuracy of 88.3%. Impedance analysis for different samples from the same branch demonstrated that the ripening stage of all other samples could be predicted and assessed by the impedance spectroscopy from one sample. Keywords: tomato fruit, maturity, discriminate analysis, electrical impedance spectroscopy DOI: 10.25165/j.ijabe.20191204.4664 Citation: Li J Y, Xu Y, Zhu W J, Wei X H, Sun H W. Maturity assessment of tomato fruit based on electrical impedance spectroscopy. Int J Agric & Biol Eng, 2019; 12(4): 154–161.

Dynamics of Bioimpedance Parameters on Three Frequencies During Ultrafiltration

Background/Aim. At present, methods based on the analysis of non-invasively measured parameters of electrical bioimpedance for the diagnosis of the patient's biohydrality are of interest. The purpose of this article is to investigate the dynamics of electrical impedance parameters (module, phase angle, active and reactive components) of the human body during ultrafiltration of programmed hemodialysis at three frequencies of 20 kHz, 100 kHz, 500 kHz. Equipment and Methods. For the research was used the hemodialysis system Fresenius Medical Care 5008C. This system provided the implementation of the ultrafiltration procedure profile. Also was used the hardware and software complex of monitoring bioimpedasometry TOR-M-1, adapted for hemodialysis procedure and conditions. Using these equipment the dependences of the modulus Z, the phase angle $ \varphi $, active R and the reactive X impedance components corrected to the body length of the patient H, the region of distribution of the bioimpedance vector relative to the tolerance ellipses and the dynamics of these parameters, depending on the volume of the ultrafiltrate and the profile of the ultrafiltration procedure were studied. Dynamics of bioimpedance parameters. It was found that during the ultrafiltration has a characteristic complex nonlinear behavior of the impedance parameters for each individual patient. The intensity of this nonlinearity increases with increasing frequency. It is expressively observed at higher frequencies of 100 kHz and 500 kHz. Interpretation of Impedance Dynamics with Tolerance Ellipses. The non-stationary oscillatory character of the parameter dynamics testifies to the complexity of the individual transient processes of redistribution of volumes of human water sectors in the process of hemodialysis and associated with changes in the ratio of intracellular, extracellular fluids and blood, the structural composition of the liquid. This causes fast flowing changes in active conductivity in the intercellular environment and reactive conductivity due to the action of polarization processes on the dielectric structures of biological tissues. Discussion and Conclusion. Measurements and cumulative analysis of the parameters of electrical impedance directly in the process of hemodialysis allows to objectively monitor the progress of the patient's functional state in real time with an assessment of the presence or absence of a `dry weight 'level, evaluate the nature of the processes of redistribution of intracellular and extracellular sectors of the body and blood, and the differences in the course of the process of ultrafiltration of patients. This can be the basis, if necessary, for promptly adjusting the ultrafiltration process. Widening of the impedance measurement bandwidth enhances the diagnostic capabilities of such monitoring and the timely correction of the ultrafiltration procedure.

Impedance Spectroscopy of Aqueous Solution Samples of Different Glucose Concentrations for the Exploration of Non-Invasive-Continuous-Blood-Glucose-Monitoring

Continuous blood-glucose-monitoring provides maximal information about the fluctuations of blood-glucose levels throughout the day and thus plays a vital role in controlling the blood-glucose level in diabetes. The conventional methods of testing blood-glucose level are invasive, painful and are unsuitable for continuous monitoring. Thus, the battle for developing bloodless and painless blood-glucose monitors has begun from past three decades. Electrical bio-impedance spectroscopy has been suggested as one of the potential technique for the development of such monitors. The present work is aimed at impedance spectroscopy to demonstrate the variation in electrical bio-impedance properties of blood with the change in glucose concentration. Glucose-dependent electrical impedance parameters of aqueous solution samples, of increasing glucose concentration have been determined to accomplish the same. The glucose-dependent capacitance and conductance illustrates the direct variations in impedance parameters with respect to change in glucose concentration. Measurement automation program is developed to ease the measurement procedure, to support continuous measurement, and to compute short-term repeatability of measurement results. The experimental results of the present work will be used to implement electrical bio-impedance spectroscopy technique in the development of non-invasive-continuous-blood-glucose monitoring system.

Dynamics of frequency dependences of parameters of electric impedance of a person during dry fasting

Introduction The article considers the possibility of further development of the method of analysis of the parameters of electrical impedance to determine the current functional state of a person in various conditions of his life, in particular during the dry fasting. The aim of the study was the dispersion properties investigation of the amplitude and phase parameters of human body impedance in the extended frequency band during the weekly one and half day dry fasting. Methods. Measurement of electrical impedance parameters was performed weekly during half a year on one person before, during and after a day and a half fasting . Broadband three-frequency measurement technique is used. The possibility of analyzing the dispersion characteristics of a human body using the Cole hologram is considered. Results and discussion. It is established that in the process of dry fasting there is a change of all parameters of impedance. The most pronounced changes in the parameters of electrical impedance are observed by the definition of the module and the active component at a frequency of 100 kHz, the phase at frequencies 20 and 500 kHz, the reactive component at a frequency of 20 kHz. Conclusion. Changes in the dispersion properties of the human body impedance are noticeable in all parameters especially in phase and reactive resistance. According to the research results an interpretation of changes in the functional state of a person during fasting was made.

Capacitive and resistive characteristics of gallium modified lead zirconate titanate

Gallium (Ga) modified lead zirconate titanate (PbZrTiO3) ceramics with Zr/Ti = 52/48 (i.e., near the morphotropic phase boundary) [i.e., Pb0.94 Ga0.06 (Zr0.48Ti0.52)0.985O3 = PGaZT-6] was fabricated by a mixed-oxide route at high temperatures. Based on determination of basic crystal data using X-ray pattern, single-phase orthorhombic phase of the prepared material obtained. Analysis of the field emission electron scanning microscopy images of the pellet (compacted) sample shows the homogeneous and densely packed grain distribution of varying shapes and size. The dielectric parameters of PGaZT-6 indicate the diffuse phase transition with non-relaxer characteristics of the material. The variation of these dielectric parameters with temperature and frequency of PGaZT-6 follows Jonscher’s universal power law. Thermal (50–500 °C) and electric field (1–1000 kHz) effect on electrical impedance parameters of PGaZT-6 (near MPB) have been analyzed using impedance spectroscopy (IS) technique. Structure-properties of the material has been correlated using this complex technique.

Electrical impedance spectroscopy: A tool to investigate the responses of one halophyte to different growth and stress conditions

In order to evaluate the reliability and the practical use of the electrical impedance spectroscopy method applied in the area of salt resistance, electrical impedance spectra were compared in the leaves of halophyte plants cultivated under different growth conditions (biotope versus controlled conditions, hydroponic versus sand system cultures) and different salt stress conditions. The kinetic of impedance parameters was also monitored under short term salinity. The spectra of electrical impedance of leaves under biotope and laboratory conditions showed difference in the electrical response of Cakile maritima in the biotope and laboratory conditions. The response of electrical impedance parameters to salinity was also different in the hydroponic system when compared to the soil one, indicating more stressful conditions in solution culture. The amplitude of the curves of impedance spectrometry decreased when plants were stressed comparatively to their controls, with the highest electrical resistance in the presence of 50 and 100mM while the lowest value was at 400mM NaCl. The electrical resistance increased at an early stage after the application of salt stress reaching maximal value 180min later, before it rapidly declined thereafter. The observed peak can translate a signal, that the plant could have received, which triggers a cascade of metabolic reactions allowing the plant to regain its hydro-ionic balance. In conclusion, electrical impedance spectroscopy can be used to quickly compare different growth conditions as well as different salinity treatments. This method can also separate between the osmotic and the ionic phases of the response to salt stress.

Variations in electrical impedance and phase angle among seedlings of Pinus densata and parental species in Pinus tabuliformis habitat environment

Electrical impedance (EI) and phase angle (PHI) parameters in AC impedance spectroscopy are important electrical parameters in the study of medical pathology. However, little is known about their application in variation and genetic relationship studies of forest trees. In order to test whether impedance parameters could be used in genetic relationship analysis among conifer species, EI and PHI were measured in a seedling experiment test composed of Pinus tabuliformis, Pinus yunnanensis, and Pinus densata in a habitat of Pinus tabuliformis. The results showed that variations in both EI and PHI among species were significant in different electric frequencies, and the EI and PHI values measured in the two populations of P. densata were between the two parental species, P. yunnanensis and P. tabuliformis. These results show that these two impedance parameters could reflect the genetic relationship among pine species. This was the first time using the two AC impedance spectroscopy parameters to test the genetic relationship analysis between tree species, and would be a hopeful novel reference methodology for future studies in evolution and genetic variation of tree species.

Design of Bulk Acoustic Wave Filters for Beidou Receiver

Based on the thin-film bulk acoustic resonator (FBAR) technology, a new narrow-band bulk acoustic wave (BAW) filter for Beidou B1 band receiver is designed. The aluminum nitride thin film is used as a piezoelectric layer. The Mason model of air-gap TFBAR (AGR) resonators is established in advanced design system to investigate the relationship between electrical impedance and physical parameters. The simulation results illustrate the effect of the area of parallel unit and the number of resonators on the performance of the BAW filters. By changing the series-parallel unit series and area ratio, the pass band of the BAW filter can reach 1556–1566 MHz, and the out-of-band rejection and the insertion loss can reach 47.5 dB and 3.0 dB, respectively.

Dielectric and electrical properties of gadolinium-modified lead-zirconate-titanate system

The gadolinium (Gd) modified lead zirconate titanate (PbZr,TiO3) ceramics with Zr/Ti=48/52 (i.e., near morphotropic phase boundary (MPB)) in a general chemical formula Pb1−xGdx (Zr0.48Ti0.52)1−x/4 O3 (PGZT; x=0, 0.07, 0.10 and 0.12) have been synthesized using a high-temperature solid-state reaction method. Preliminary structural analysis using X-ray powder diffraction (XRD) shows the formation of a single-phase tetragonal structure of the compounds. Detailed studies of dielectric parameters of PGZT exhibit the diffuse phase transition but non-relaxor characteristics in the material for the higher concentration of gadolinium. The ac conductivity spectra of PGZT are found to obey Jonscher’s universal power law. The electrical impedance parameters of PGZT (near MPB) were obtained in a wide range of temperature (25–500°C) and frequency (1–1000kHz) using complex impedance spectroscopy (CIS) technique. Detailed analysis of these parameters shows that bulk (grain) and grain boundary resistance have significant effect on the total impedance of the materials. Temperature dependence of hysteresis characteristics of PGZT confirms that the phase transition parameter of the material is strongly affected by the substitution of Gd at the Pb-sites.

Motion discrimination of throwing a baseball using forearm electrical impedance

The extroversion or hyperextension of elbow joint cause disorders of elbow joint in throwing a baseball. A method, which is easy handling and to measure motion objectively, can be useful for evaluation of throwing motion. We investigated a possibility of motion discrimination of throwing a baseball using electrical impedance method. The parameters of frequency characteristics (Cole-Cole arc) of forearm electrical impedance were measured during four types of throwing a baseball. Multiple discriminant analysis was used and the independent variables were change ratios of 11 parameters of forearm electrical impedance. As results of 120 data with four types of throwing motion in three subjects, hitting ratio was very high and 95.8%. We can expect to discriminate throwing a baseball using multiple discriminant analysis of impedance parameters.