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This paper compares the analytical approach and optimization algorithm for designing a two-bilinear-section-based two-port transfer function hinged on a numerical sweep with the intention of implementing fractional-order (FO) systems in many sensing areas. The study compares analytical and algorithm-based design approaches and tests their effectiveness in designing a two-port system that accommodates phase shifts within the 10° to 80° range and with various phase ripple limits. The impact of phase changes on usable bandwidth (yield maximization) is also explored. The proposed algorithm represents the most optimal approach and calculates zeros/poles frequencies to precisely keep the required mean phase value and phase ripple value for the defined center frequency. Experimental results are provided, utilizing two bilinear sections featuring the current feedback amplifier. Moreover, the implementation of the novel two-port Cole model as an application example of the proposed design is presented and evaluated. The approaches presented are useful in sensing, modeling, and instrumentation.

This work aims to describe the dielectric behaviors of four main tissues in the human forearm using mathematical modelling, including fat, muscle, blood and bone. Multi-frequency bioimpedance analysis (MF-BIA) was initially performed using the finite element method (FEM) with a 3D forearm model to estimate impedance spectra from 10 kHz to 1 MHz, followed by a pilot study involving two healthy subjects to characterize the response of actual forearm tissues from 1 kHz to 349 kHz. Both the simulation and experimental results were fitted to a single-dispersion Cole model (SDCM) and a multi-dispersion Cole model (MDCM) to determine the Cole parameters for each tissue. Cole-type responses of both simulated and actual human forearms were observed. A paired t-test based on the root mean squared error (RMSE) values indicated that both Cole models performed comparably in fitting both simulated and measured bioimpedance data. However, MDCM exhibited higher accuracy, with a correlation coefficient (R2) of 0.99 and 0.89, RMSE of 0.22 Ω and 0.56 Ω , mean difference (mean ± standard deviation) of 0.00 ± 0.23 Ω and −0.28 ± 0.23 Ω , and mean absolute error (MAE) of 0.0007 Ω and 0.2789 Ω for the real part and imaginary part of impedance, respectively. Determining the electrical response of multi-tissues can be helpful in developing physiological monitoring of an organ or a section of the human body through MF-BIA and hemodynamic monitoring by filtering out the impedance contributions from the surrounding tissues to blood-flow-induced impedance variations. [ABSTRACT FROM AUTHOR]

This work aims to describe the dielectric behaviors of four main tissues in the human forearm using mathematical modelling, including fat, muscle, blood and bone. Multi-frequency bioimpedance analysis (MF-BIA) was initially performed using the finite element method (FEM) with a 3D forearm model to estimate impedance spectra from 10 kHz to 1 MHz, followed by a pilot study involving two healthy subjects to characterize the response of actual forearm tissues from 1 kHz to 349 kHz. Both the simulation and experimental results were fitted to a single-dispersion Cole model (SDCM) and a multi-dispersion Cole model (MDCM) to determine the Cole parameters for each tissue. Cole-type responses of both simulated and actual human forearms were observed. A paired t-test based on the root mean squared error (RMSE) values indicated that both Cole models performed comparably in fitting both simulated and measured bioimpedance data. However, MDCM exhibited higher accuracy, with a correlation coefficient (R2) of 0.99 and 0.89, RMSE of 0.22 Ω and 0.56 Ω, mean difference (mean ± standard deviation) of 0.00 ± 0.23 Ω and −0.28 ± 0.23 Ω, and mean absolute error (MAE) of 0.0007 Ω and 0.2789 Ω for the real part and imaginary part of impedance, respectively. Determining the electrical response of multi-tissues can be helpful in developing physiological monitoring of an organ or a section of the human body through MF-BIA and hemodynamic monitoring by filtering out the impedance contributions from the surrounding tissues to blood-flow-induced impedance variations.

Electrical impedance spectroscopy (EIS) has been used as an adjunct to colposcopy for cervical cancer diagnosis for many years, Currently, the template match method is employed for EIS measurements analysis, where the measured EIS spectra are compared with the templates generated from three-dimensional finite element (FE) models of cancerous and non-cancerous cervical tissue, and the matches between the measured EIS spectra and the templates are then used to derive a score that indicates the association strength of the measured EIS to the High-Grade Cervical Intraepithelial Neoplasia (HG CIN). These FE models can be viewed as the computational versions of the associated physical tissue models. In this paper, the problem is revisited with an objective to develop a new method for EIS data analysis that might reveal the relationship between the change in the tissue structure due to disease and the change in the measured spectrum. This could provide us with important information to understand the histopathological mechanism that underpins the EIS-based HG CIN diagnostic decision making and the prognostic value of EIS for cervical cancer diagnosis. A further objective is to develop an alternative EIS data processing method for HG CIN detection that does not rely on physical models of tissues so as to facilitate extending the EIS technique to new medical diagnostic applications where the template spectra are not available.

Electrical impedance spectroscopy is a well-established tool for monitoring changes in the electrical properties of tissue. Most tissue and organ types have been investigated in various studies. As for the small intestine, there are several published studies conducted on pig and rat models. This study investigates the changes in passive electrical properties of the complete wall of the human intestine non-invasively during ischemia. We aim to use the passive electrical properties to assess intestinal viability. The bioimpedance measurements were performed using a two-electrode set-up with a Solartron 1260 Impedance/gain-phase analyser. The small intestinal samples were resected from patients who underwent pancreaticoduodenectomy. Impedance measurements were conducted following resection by placing the electrodes on the surface of the intestine. A voltage was applied across the intestinal sample and the measured electrical impedance was obtained in the ZPlot software. Impedance data were further fitted into a Cole model to obtain the Cole parameters. The Py value was calculated from the extracted Cole parameters and used to assess the cell membrane integrity, thus evaluate the intestinal viability. Eight small intestinal segments from different patients were used in this study and impedance measurements were performed once an hour for a ten-hour period. One hour after resection, the impedance decreased, then increased the next two hours, before decreasing until the end of the experiment. For all the intestinal segments, the Py values first increased and reached a plateau which lasted for 1 - 2 hours, before it decreased irreversibly. The time interval where Py value reached the maximum is consistent with reported viable/non-viable limits from histological analysis.

A non-invasive method of measuring bioimpedance is presented to study the effect of moisturizing cream on human skin. A novel two-electrode system is developed to get electrical access at the area of interest on human skin. Controlled experiments are conducted for a duration of 47 days. Bioimpedance is measured by LCR meter in the frequency range of 1 Hz to 5 kHz. The measured impedance is then fitted with the Cole model and the relevant Cole parameters are extracted. Analysis of variance is performed on the Cole parameters to gain statistical relevance. It is found that one of the Cole parameters, namely the relaxation-time changes significantly due to the treatment of the skin with a moisturizing cream at more than 95% confidence level. The relaxation-time increases sharply during the treatment period and drops sharply in the post-treatment period. The effectiveness of the two types of cream is studied. The gender distinguishability during the application of a moisturizing cream is also studied. A very generic bioimpedance measurement method to assess the physiological condition of local skin is demonstrated here and the method has potential application in human skin related diseases and treatments.

It is difficult to apply bioimpedance technique to discriminate plant tissues due to the large variability of Cole parameters. A novel electronic method for characterizing tissue of fruit or vegetable with discrimination capability is presented. A specially designed electrode-pair is used to measure the bioimpedance and Cole parameters are extracted. The relaxation time which is a fundamental property of a given tissue is then estimated and analysis of variance is performed to gain statistical relevance. Bioimpedance is measured for apple and potato tissues in the frequency range of 1 Hz to 1 MHz and rigorous data analyses are performed. With 99% confidence, it is shown than the relaxation time is independent of position of measurement and is specific for a given fruit or vegetable. Further, the tissues of different species of a given fruit (or vegetable) is shown to be discriminated statistically at the confidence level of 98%. An excellent correlation is shown between the bioimpedance parameters and the parameters of cellular structure. Experimental data shows that our technique can be generalized to distinguish unhealthy or treated fruits (or vegetables) and therefore bearing immense applicability in the characterization of plant tissue.

A differentiator-based set up is proposed as an alternative solution to measure bio-impedance. The method is modifying the differentiator circuit, replacing the capacitor with the Cole-impedance model representing the biological (fruit) sample. The proposed differentiator gain response (with the embedded fruit) is experimentally recorded. The experimental data's post-processing is performed using meta-heuristic optimization techniques to extract the Cole-impedance model unknown parameters by solving a group of nonlinear equations. Three meta-heuristic optimization algorithms are used: the moth-flame, the flower pollination and the cuckoo search optimizations. The impedance generated with the extracted parameters is compared with the impedance measured by the Biologic spectroscopy SP150 for the samples of four types of fruits (Apple, Kiwi, Eggplants and Tomato). Experimental results are in the frequency range of 100 Hz–100 kHz for apples, kiwis and tomatoes, while the frequency range for eggplant tissues is 100 Hz–90 kHz. [ABSTRACT FROM AUTHOR]

This paper reports on the variations in the parameters of the single dispersion Cole bio-impedance model of Daucus Carota Sativus (carrots) under heating and freezing conditions. Experiments are conducted on six samples with recorded live bio-impedance spectra versus temperature. The Cole model parameters are extracted from the measured data using the Flower Pollination Algorithm (FPA) optimization technique and their variations are correlated with well-known bio-chemical and bio-mechanical variations. This represents a non-invasive method for characterizing and measuring the degree of change in biological cellular morphology and composition.

The objective of this work is to develop a technique for filtering parasitic effects from the impedance spectra (IS) measured in biological material phantoms. IS data are contaminated with unexpected capacitive and inductive effects from cable, input/output amplifiers capacitances, electrode polarization, temperature and contact pressure when collecting data. It is proposed a model which contains an RLC-network in series with the Cole model (RSC), then called RLC-Cole. It was built four circuits composed by resistors, capacitors and inductors. An impedance analyzer (HF2IS) was used to perform the measurements in the frequency range of 1 to 3000 kHz. Data were fitted into the model and comparisons to the nominal values were made. In order to validate the proposed model, a gelatin phantom and a chicken breast muscle impedance spectra were also collected and analyzed. After filtering, Cole fitting was performed. Results showed a maximum root-mean-square error of 1% for the circuits, 2.63% for the gelatin phantom, whereas 2.01% for the chicken breast. The RLC-Cole model could significantly remove parasitic effects out of a tissue impedance spectrum measured by a 4-point electrode probe. This may be highly important in EIS systems whose objective is to discriminate a normal tissue from a cancerous one.

Objective . Bioimpedance spectroscopy (BIS) is a popular technique for the assessment of body composition in children and adults but has not found extensive use in babies and infants. This due primarily to technical difficulties of measurement in these groups. Although improvements in data modelling have, in part, mitigated this issue, the problem continues to yield unacceptably high rates of poor quality data. This study investigated an alternative data modelling procedure obviating issues associated with BIS measurements in babies and infants. Approach. BIS data are conventionally analysed according to the Cole model describing the impedance response of body tissues to an appliedACcurrent. This approach is susceptible to errors due to capacitive leakage errors of measurement at high frequency. The alternative is to model BIS data based on the resistance-frequency spectrum rather than the reactance-resistance Cole model thereby avoiding capacitive error impacts upon reactance measurements. Main results. The resistance-frequency approach allowed analysis of 100% of data files obtained from BIS measurements in 72 babies compared to 87% successful analyses with the Cole model. Resistance-frequency modelling error (percentage standard error of the estimate) was half that of the Cole method. Estimated resistances at zero and infinite frequency were used to predict body composition. Resistance-based prediction of fat-free mass (FFM) exhibited a 30% improvement in the two-standard deviation limits of agreement with reference FFM measured by air displacement plethysmography when compared to Cole model-based predictions. Significance. This study has demonstrated improvement in the analysis of BIS data based on the resistance frequency response rather than conventional Cole modelling. This approach is recommended for use where BIS data are compromised by high frequency capacitive leakage errors such as those obtained in babies and infants., (Creative Commons Attribution license.)

An electrical Impedance based tool is designed and developed to aid physicians performing clinical exams focusing on cancer detection. Current research envisions improvement in sensor-based measurement technology to differentiate malignant and benign lesions in human subjects. The tool differentiates malignant anomalies from nonmalignant anomalies using Electrical Impedance Spectroscopy (EIS). This method exploits cancerous tissue behavior by using EIS technique to aid early detection of cancerous tissue.

It is difficult to apply bioimpedance technique to discriminate plant tissues due to the large variability of Cole parameters. A novel electronic method for characterizing tissue of fruit or vegetable with discrimination capability is presented. A specially designed electrode-pair is used to measure the bioimpedance and Cole parameters are extracted. The relaxation time which is a fundamental property of a given tissue is then estimated and analysis of variance is performed to gain statistical relevance. Bioimpedance is measured for apple and potato tissues in the frequency range of 1 Hz to 1 MHz and rigorous data analyses are performed. With 99% confidence, it is shown than the relaxation time is independent of position of measurement and is specific for a given fruit or vegetable. Further, the tissues of different species of a given fruit (or vegetable) is shown to be discriminated statistically at the confidence level of 98%. An excellent correlation is shown between the bioimpedance parameters and the parameters of cellular structure. Experimental data shows that our technique can be generalized to distinguish unhealthy or treated fruits (or vegetables) and therefore bearing immense applicability in the characterization of plant tissue. [ABSTRACT FROM AUTHOR]

Heart failure is a chronic disease marked by frequent hospitalizations due to pulmonary fluid congestion. Monitoring the thoracic fluid status may favor the detection of fluid congestion in an early stage and enable targeted preventive measures. Bioelectrical impedance spectroscopy (BIS) has been used in combination with the Cole model for monitoring body composition including fluid status. The model parameters reflect intracellular and extracellular fluid volume as well as cell sizes, types and interactions. Transthoracic BIS may be a suitable approach to monitoring variations in thoracic fluid content.

Exposures to pulsed electric fields (PEFs) are known to affect cell membranes and consequently also cell–cell interactions as well as associated characteristics. Bioimpedance analysis offers direct and non-invasive insights into structural and functional changes of cell membranes and extracellular matrices through a rigorous evaluation of electrical parameters. Accordingly, the multi-frequency impedance of confluent monolayers of rat liver epithelial WB-F344 cells was monitored in situ before and after exposure to nanosecond PEFs. The results were fitted by two Cole models in series to obtain the Cole parameters for the monolayer. For an interpretation of the results, dielectric parameters were correlated with changes of the TJ-protein zonula occludens (ZO-1) and the paracellular permeability of the monolayer. Cole parameters, in general, change as a function of pulse number and time. The findings demonstrate that impedance analysis is an effective method to monitor changes in cell–cell contacts and paracellular permeability and relate them to exposure parameters. [ABSTRACT FROM AUTHOR]

Abstract Phantoms, or physical simulants of biological specimens are useful for research and development due to the unavailability of real tissues. One such example is human blood, which is a precious resource in healthcare and is not normally available for research purposes, unless it is no longer fit for human use. This work focusses on the considerations for developing a human forearm phantom specifically to exhibit the dielectric properties of fat, muscle and blood tissue domains, for bioimpedance analysis. The behavior for the tissue simulants were identified based on the conductivity and permittivity values within the β dispersion frequency range (1 kHz–2 MHz). A mixture of 80% propylene glycol and 20% 4 M saline solution was found to replicate the properties of blood within acceptable tolerances in the β dispersion frequency range. A 5% agar with 0.05% saline mixture was found to mimic the properties of fat, whereas the muscle properties were mimicked through a suspension of agar, gelatine, saline and propylene glycol. This was followed by construction of the forearm phantom with three geometries to simulate the three arterial diameter instances due to blood flow. The measurements were performed using the Quadra® Impedance Spectroscopy device within 1 kHz–349 kHz which were fitted to a Cole model to estimate the entire frequency spectrum within 1 kHz–2 MHz and compared with a previously performed simulation study. This methodology can provide a very economical, reproducible and robust means for investigating the dielectric response of tissues across several research and training platforms, and more importantly bioimpedance applications. Highlights • Electrical response of tissues is the basis of bioimpedance applications. • Dielectric phantoms provide better alternatives to real tissues. • Fat, muscle and blood tissues within a human forearm were considered. • A mixture of saline and propylene glycol mimicked the dielectric response of blood. • Gelatine and agar suspensions were found to mimic muscle and fat tissues. [ABSTRACT FROM AUTHOR]

Many practical systems, such as thermal system, economic system and electric power system, can be more accurately described by the fractional-order system rather than integer-order system. Therefore, it is an important topic to study the fractional-order system and estimate its parameters. The problem of parameter estimation is essentially a multi-dimensional parameter optimization problem. In this paper, according to the average value of position information, an improved Tent mapping and a piecewise mutation probability, a modified particle swarm optimization (MPSO) algorithm is presented to solve the parameter estimation problem. The performance of MPSO is tested with eight benchmark functions, which proves the effectiveness of the algorithm. Based on the double-dispersion Cole model, the proposed MPSO algorithm is used to estimate the parameters for the generated simulated datasets. Experimental results show that the MPSO algorithm for parameters identification of the Cole model is an effective and promising method with high accuracy and good robustness. [ABSTRACT FROM AUTHOR]

Copyright of Technical Electrodynamics / Tekhnichna Elektrodynamika is the property of National Academy of Sciences of Ukraine, Institute of Electrodynamics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Heart failure (HF) affects at least 26 million people worldwide and is considered a global pandemic. Almost 1 out of 4 hospitalised patients are rehospitalised for HF within the 30-day post-discharge period. This can be avoided if changes to the hemodynamics of the HF patient's body are early detected. Bioimpedance Spectroscopy (BIS) is a method that allows the measurement and analysis of multi-frequency body complex impedance and can be used to detect changes to the HF patient's hemodynamics. This paper presents the calibration and validation process of a low-cost portable BIS system, as well as, the study of the best Cole parameter estimation methods. The BIS system was calibrated using a three reference circuit method and a Resistance-Capacitance-Inductance (RCL) meter as calibration system. After calibration, BIS impedance measurements of validation circuits presented an average phase error of 0.76 degrees and an average magnitude relative error of 0.6 % when compared with standard values. Regarding Cole parameters estimation, using the Impedance model and the Non-Linear Least Squares method for curve fitting, the relative errors were below 4 % when compared with the expected values. [ABSTRACT FROM AUTHOR]

Electrical impedance measurement data and fractional calculus have been utilized for modeling bioimpedance properties of human skin. We introduced and proposed revisited Cole model using modified distributed order operator based on the Caputo-Weyl fractional derivatives. Our proposed model presents essentially modified single-dispersion Cole model, since it introduces a new parameters k and σ in single-dispersion Cole impedance equation. These parameters characterize the width of interval around fractional index α and they are important for more accurate describing bioimpedance properties of human skin. The impedance spectrum was measured in a finite frequency range up to 100 kHz. Our proposed modified Cole model fits much better to experimental curve in a given frequency range compared to existing Cole models. The fitting is done using the Levenberg-Marquardt nonlinear least squares.

Objective: Proposing a good electrode-electrolyte interface (EEI) model and properly identifying relevant parameters may help designing safer and more optimized auditory nerve fiber stimulation and recording in cochlear implants (CI). However, in the literature EEI model parameter values exhibit large variability. We aim to explain some root causes of this variability using the Cole model and its simpler form, the Basic RC model., Approach: We use temporal and spectral methods and fit the models to stimulation pulse voltage response (SPVR) and electrochemical impedance spectroscopy (EIS) data., Main Results: Temporal fittings show that there are multiple sets of model parameters that provide a good fit to the SPVR data. Therefore, small methodological differences in literature may result in different model fits. While these models share similar characteristics at high frequencies >500 Hz, the SPVR fitting is blind to low frequencies, thus it cannot correctly estimate the Faradaic resistor. Similarly, the polarization capacitor and its fractional order are not estimated robustly (capacitor variations in the nano- to micro-farad range) due to limited observation of mid-range frequencies. EIS provides a good model fit down to ~3Hz, and thus robust estimation for the polarization capacitor. At lower frequencies charge mechanisms may modify the EEI, requiring multi-compartment Cole model fitting to EIS to improve the estimation of Faradaic characteristics. Our EIS data measurements down to 0.05Hz show that a two-compartment Cole model is sufficient to explain the data., Significance: Our study describes the scope and limitation of SPVR and EIS fitting methods, by which literature variability is explained among CI EEI models. The estimation of mid-to-low-frequency characteristics of the CI EEI is not in the scope of the SPVR method. EIS provides a better fit; however, its results should not be extrapolated to unobserved frequencies where new charge transfer mechanisms may emerge at the EEI., (Creative Commons Attribution license.)

Clarifying changes in gastrointestinal tissue compressed by surgical stapler is a crucial prerequisite for stapler design optimization. For this study, a stapler was modified, and multifrequency bioimpedance of a porcine small intestine tissue compressed by the stapler was measured. The Cole model was fitted to the bioimpedance, and changes in tissue were analyzed using model parameters: G , extracellular fluid conductance; Δ G, intracellular fluid conductance; C , equivalent capacitance of cell membrane. The changes could be divided into two stages: first, all parameters decreased sharply with slopes more than 15.70 ± 2.67, 4.25 ± 1.23 μS/s and 72.68 ± 6.99 pF/s respectively; and subsequently, with an increase in compression strength, G decreased with slopes less than 2.54 ± 0.40 μS/s, Δ G decreased slightly with slope of 0.26 ± 0.04 μS/s after fluctuating mildly, and C remained nearly invariant after initially increasing with slope of −2.94 ± 0.64 pF/s. In conclusion, when the stapler is closed, a portion of tissue is squeezed out of the measurement space, causing all parameters' sharp decrease. Subsequently, the stapler continues compressing the tissue, leading to extracellular fluid expulsion. The changes in intracellular fluid are related to the compression strength and may be explained by cell restoration. This study could provide a basis for stapler design optimization. [ABSTRACT FROM AUTHOR]

ObjectivesThe purpose of our study was to estimate skin structure and conductivity distribution in a cross section of local tissue using non-invasive measurement of impedance data. The present study was designed to evaluate the efficiency of skin depth information through computer simulations. The multilayer tissue model was composed of epidermis, dermis tissues, and subcutaneous.MethodsIn this study, electrical characteristics of skin models were used for conductivity of 0.13 S/m, 0.26 S/m, 0.52 S/m, permittivity of 94,000 F/m, and a frequency of 200 Hz. The effect of the new method was assessed by computer simulations using three-electrode methods. A non-invasive electrical impedance method has been developed for analysis using computer simulation and a skin electrical model with low frequency range. Using the three-electrode method differences through the potentials between measurement electrodes and reference electrodes can be easily detected. The Cole electrical impedance model, which is better suited for skin was used in this study.ResultsIn this study, experiments using three-electrode methods were described by computer simulation based on a simple model. This electrical impedance model was fitted and developed in comparison with our model for measurement of skin impedance.ConclusionsThe proposed electrical model for skin is suitable for use in interpretation of changes in impedance characterization of the skin. Using the computer simulation method, information on skin impedance depth can be more accurately developed and predicted.

Stem-Boring Pest (SBP) cause the most prevalent problem that harms the health of trees. Traditional SBP prevention uses manual survey of wormholes and is a time-consuming process. This paper proposes a novel Trunk Wormhole Detection (TWD) method based on Bio-Impedance Spectroscopy (BIS) measurements. A horizontal and a vertical trunk wormhole phantoms are prepared, and comparative BIS measurements under the situations without and with holes are performed using a precision impedance analyzers WK6500B. Remarkable differences both on impedance amplitudes and phases have been found before and after the holes formed in the phantoms. The Cole model parameter analysis finds that the Cole parameter R8 decreases by 43.82% in the horizontal phantom, and decreases by 63.13% in the vertical phantoms, which suggests that R8 may be an efficient indicator to detect trunk wormholes. [ABSTRACT FROM AUTHOR]

BACKGROUND Acquisition of electrical impedance spectroscopy ( EIS) measurements enables one to obtain information about the features of cell cultures, which can be applied for real-time and on-line monitoring purposes. RESULTS Impedance measurements were carried out in three different cell specimens with different sizes and shapes ( Vero cells, hybridoma and Escherichia coli) at different stages of cell culture, as well as during a controlled detachment process of an adherent animal cell line. The relaxation spectra obtained were fitted to a Cole impedance model and the corresponding parameters analyzed. The use of a four-electrodes measurement system decreased the dependency on the electrode interface's impedance, and thus resulted in a system more sensitive to the cell features. The EIS monitoring of different cultures expansion showed the expected inverse proportional relationship between the central relaxation frequency and the cell cross-sectional area. The morphological changes of fibroblast cells during the detachment processes were also studied. Interestingly, EIS displayed the proportional relationship between the α parameter of the Cole impedance model and the cell shape dispersion from spherical morphology (considering spherical shape ideality). CONCLUSION The results obtained reveal the potential for developing a real-time monitoring tool for cell morphology features such as cell size and shape, which are involved in many cellular processes like cell expansion, differentiation, cell attachment or cell death. © 2015 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Fitting the measured bioimpedance spectroscopy (BIS) data to the Cole model and then extracting the Cole parameters is a common practice in BIS applications. The extracted Cole parameters then can be analysed as descriptors of tissue electrical properties. To have a better evaluation of physiological or pathological properties of biological tissue, accurate extraction of Cole parameters is of great importance. This paper proposes an improved Cole parameter extraction based on bacterial foraging optimization (BFO) algorithm. We employed simulated datasets to test the performance of the BFO fitting method regarding parameter extraction accuracy and noise sensitivity, and we compared the results with those of a least squares (LS) fitting method. The BFO method showed better robustness to the noise and higher accuracy in terms of extracted parameters. In addition, we applied our method to experimental data where bioimpedance measurements were obtained from forearm in three different positions of the arm. The goal of the experiment was to explore how robust Cole parameters are in classifying position of the arm for different people, and measured at different times. The extracted Cole parameters obtained by LS and BFO methods were applied to different classifiers. Two other evolutionary algorithms, GA and PSO were also used for comparison purpose. We showed that when the classifiers are fed with the extracted feature sets by BFO fitting method, higher accuracy is obtained both when applying on training data and test data. [ABSTRACT FROM AUTHOR]

Affordable and portable indirect impedance measurement techniques with minimum hardware and post-processing requirements are necessary for various applications, and in particular for bioimpedance measurements. In this paper, a new method to extract the single-dispersion Cole bioimpedance model parameters is presented using a simple circuit consisting of a operational amplifier and a set of resistors. We examine the theory behind this magnitude-only method and demonstrate its application for the extraction of impedance data from a number of different fruit samples. Three means to compute the single-dispersion Cole model parameters are given and discussed under different measurement scenarios, and compared with experimental results. [ABSTRACT FROM AUTHOR]

In this study, electrical impedance spectroscopy measurements are performed during electroporation of monolayers of differentiated myotubes. The time resolution of the system (1 spectrum/ms) enable 860 full spectra (21 frequencies from 5 kHz to 1.3 MHz) to be acquired during the time gap between consecutive pulses (interpulse) of a classical electroporation treatment (8 pulses, 100 μs, 1 Hz). Additionally, the characteristics of the custom microelectrode assembly used allow the experiments to be performed directly in situ in standard 24 multi-well plates. The impedance response dynamics are studied for three different electric field intensities (400, 800 and 1200 V/cm). The multifrequency information, analysed with the Cole model, reveals a short-term impedance recovery after each pulse in accordance with the fast resealing of the cell membrane, and a long-term impedance decay over the complete treatment in accordance with an accumulated effect pulse after pulse. The analysis shows differences between the lowest electric field condition and the other two, suggesting that different mechanisms that may be related with the reversibility of the process are activated. As a result of the multifrequency information, the system is able to measure simultaneously the conductivity variations due to ion diffusion during electroporation. Finally, in order to reinforce the physical interpretation of the results, a complementary electrical equivalent model is used. [ABSTRACT FROM AUTHOR]

Highlights: [•] Presents indirect measurement of single and double dispersion Cole impedance parameters from step response. [•] Simple test circuit presented. [•] Reduces the hardware requirements by removing need for sinusoidal signal generation and measurement of phase and magnitude. [•] Impact of noise on extracted parameter accuracy studied. [•] Experimentally validated from the step response using apples as the Cole impedances. [Copyright &y& Elsevier]

In bioelectrical impedance spectroscopy (BIS), it is assumed that the current path is only extracellular at the lowest frequencies and that it is both extra- and intracellular at the highest frequencies. We tested validity of BIS assumptions in bodybuilders who have an increased intracellular volume due to hypertrophy of muscle fibres. The study was observational cross-sectional in a study group of thirty professional bodybuilders compared with thirty control subjects. Resistance (R) and reactance (Xc) vector components fitting the Cole's arc with BIS (SFB3 analyser) were compared with components at 50??kHz frequency. The average Cole's arc in bodybuilders was significantly smaller and shifted to the left in the R???Xc plane (both R and Xc values were smaller at any individual frequency). The ratio of Xc at 5??kHz and Xc at the characteristic frequency was 70??% in bodybuilders and 64??% in control subjects, indicating a huge intracellular flow of the electric current at low frequencies in both groups (expected ratio close to 0 if the current path was extracellular). As a consequence of a common path, the correlation coefficient between R values at 50??kHz and at other frequencies (from 0 to infinity) was 0??94 to 1??00. The correlation between total body water estimated with BIS or with R at 50??kHz was 0??98. Hence, there was equivalence between information provided by the vector components R and Xc at 50??kHz and that provided by 496 correlated vectors that were measured with BIS. [ABSTRACT FROM PUBLISHER]

This research realizes fractional-order devices or constant phase element (CPE) using continued fraction expansion (CFE) and rational function approximation methods. An RC ladder network prototype was realized using CFE based on the Cauer network principle. The RC ladder network and signal flow graph (SFG) were employed to realize the proposed CPE. Voltage gain circuits and voltage-mode integrators were realized by using operational transconductance amplifiers (OTA) and grounded capacitors. The proposed CPE was subsequently synthesized using voltage gain circuits and voltage-mode integrators based on SFG. The proposed CPE could function as fractional-order capacitor and fractional-order inductor. Besides, the CPE could be constructed in arbitrary fractional-orders. The impedance and operation frequency are independently tunable by manipulating OTA bias current. To validate, the proposed fractional-order device was applied to six types of electrical Cole models of skull tissues, and simulation results were compared with the approximation function and theory. The electrical characteristics of the Cole models based on the proposed CPE are comparable to the theoretical characteristics of the Cole model. [ABSTRACT FROM AUTHOR]