rss_2.0Journal of Electrical Bioimpedance FeedSciendo RSS Feed for Journal of Electrical Bioimpedance of Electrical Bioimpedance 's Cover impedance characterization of porcine tissue using machine learning<abstract> <title style='display:none'>Abstract</title> <p>The incorporation of sensors onto the stapling platform has been investigated to overcome the disconnect in our understanding of tissue handling by surgical staplers. The goal of this study was to explore the feasibility of <italic>in vivo</italic> porcine tissue differentiation using bioimpedance data and machine learning methods. <italic>In vivo</italic> electrical impedance measurements were obtained in 7 young domestic pigs, using a logarithmic sweep of 50 points over a frequency range of 100 Hz to 1 MHz. Tissues studied included lung, liver, small bowel, colon, and stomach, which was further segmented into fundus, body, and antrum. The data was then parsed through MATLAB's classification learner to identify the best algorithm for tissue type differentiation. The most effective classification scheme was found to be cubic support vector machines with 86.96% accuracy. When fundus, body and antrum were aggregated together as stomach, the accuracy improved to 88.03%. The combination of stomach, small bowel, and colon together as GI tract improved accuracy to 99.79% using fine k nearest neighbors. The results suggest that bioimpedance data can be effectively used to differentiate tissue types <italic>in vivo</italic>. This study is one of the first that combines <italic>in vivo</italic> bioimpedance tissue data across multiple tissue types with machine learning methods.</p> </abstract>ARTICLE2021-07-02T00:00:00.000+00:00Electrical impedance to easily discover undeclared freeze-thaw cycles in slaughtered bovine meat<abstract> <title style='display:none'>Abstract</title> <p>A portable electrical impedance spectroscopy device was developed to monitor the bioimpedance resistive component of bovine meat by injecting a sinusoidal current of 1 mA at 65 kHz. Both right and left longissimus dorsi muscles were trimmed from 4 slaughtered cows. The left muscle portions were frozen to −18 °C for 7 days while the right ones were meantime maintained at 5 °C. Mean value of impedance per length (Ω/cm) of frozen and thawed left samples was 31% lower than that of right non-frozen one (P = 0.0001). It was concluded that the device is reliable for monitoring the maturation of beef meat in situ with the possibility of revealing undeclared freeze-thaw cycles.</p> </abstract>ARTICLE2021-03-30T00:00:00.000+00:00Impedance-based real-time monitoring of neural stem cell differentiation<abstract> <title style='display:none'>Abstract</title> <p>We present here the first impedance-based characterization of the differentiation process of two human mesencephalic fetal neural stem lines. The two dopaminergic neural stem cell lines used in this study, Lund human mesencephalic (LUHMES) and human ventral mesencephalic (hVM1 Bcl-X<sub>L</sub>), have been developed for the study of Parkinsonian pathogenesis and its treatment using cell replacement therapy. We show that if only relying on impedance magnitude analysis, which is by far the most usual approach in, e.g., cytotoxicity evaluation and drug screening applications, one may not be able to distinguish whether the neural stem cells in a population are proliferating or differentiating. However, the presented results highlight that equivalent circuit analysis can provide detailed information on cellular behavior, e.g. simultaneous changes in cell morphology, cell-cell contacts, and cell adhesion during formation of neural projections, which are the fundamental behavioral differences between proliferating and differentiating neural stem cells. Moreover, our work also demonstrates the sensitivity of impedance-based monitoring with capability to provide information on changes in cellular behavior in relation to proliferation and differentiation. For both of the studied cell lines, in already two days (one day after induction of differentiation) equivalent circuit analysis was able to show distinction between proliferation and differentiation conditions, which is significantly earlier than by microscopic imaging. This study demonstrates the potential of impedance-based monitoring as a technique of choice in the study of stem cell behavior, laying the foundation for screening assays to characterize stem cell lines and testing the efficacy epigenetic control.</p></abstract>ARTICLE2021-10-06T00:00:00.000+00:00Electrical bioimpedance: from the past to the future<abstract> <title style='display:none'>Abstract</title> <p>This year, 2021, marks the “coming of age” for JoEB with its indexing in PubMed Central. It is also a century since some of the earliest studies on tissue impedance. This editorial briefly reviews the time-line of research in the field to mark this occasion.</p> </abstract>ARTICLE2021-03-30T00:00:00.000+00:00Electrical Impedance tomography – recent applications and developments<abstract> <title style='display:none'>Abstract</title> <p>Electrical impedance tomography (EIT) is a low-cost noninvasive imaging method. The main purpose of this paper is to highlight the main aspects of the EIT method and to review the recent advances and developments. The advances in instrumentation and in the different image reconstruction methods and systems are demonstrated in this review. The main applications of the EIT are presented and a special attention made to the papers published during the last years (from 2015 until 2020). The advantages and limitations of EIT are also presented. In conclusion, EIT is a promising imaging approach with a strong potential that has a large margin of progression before reaching the maturity phase.</p></abstract>ARTICLE2021-10-06T00:00:00.000+00:00Segmental volume and circulatory changes that occur in humans and Rhesus monkeys during 4 hour, −6 degree head down tilt<abstract> <title style='display:none'>Abstract</title> <p>Nonhuman primates are often used to investigate physiologic processes that occur in man during aerospace/cardiovascular orthostatic research. Few studies have compared nonhuman primates and man under identical test conditions to assess the degree of similarity between the two species. Impedance plethysmography was used to measure calf, thigh, pelvic, thoracic, upper arm, and lower arm volume changes in eight rhesus (Macacca Mulatta) monkeys and twelve human subjects during four hour exposures to −6 degree head down tilt (HDT).</p> </abstract>ARTICLE2021-04-17T00:00:00.000+00:00Technology of two-dimensional bioimpedance analysis of the human body composition<abstract> <title style='display:none'>Abstract</title> <p>The BIA primary result sheets as a rule contain one-dimensional graphical scales with a selected area of normal values. In 1994, Piccoli <italic>et al</italic>. 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.</p> <p>The purpose of this study is to develop an approach to data analysis in body composition bioimpedance research in two-dimensional representations.</p> <p>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.</p> <p>The non-Gaussian distribution is found in most parameters of bioimpedance analysis of body composition for most ages (Lilliefors test, p-value &lt;&lt; 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.</p> </abstract>ARTICLE2021-07-02T00:00:00.000+00:00Bioimpedance to assess the body composition of high-performance karate athletes: applications, advantages and perspectives<abstract> <title style='display:none'>Abstract</title> <p>Karate, a millennial martial art, was recently inserted among traditional Olympic combat sports for the Olympic Games in Japan. The aim of the present study is to determine, through bioimpedance analysis, the body composition of high-performance athletes participating in the São Paulo Olympic Karate Project. Participants were 22 athletes of both sexes, average age of 23.6 (6.0) years old, body mass of 66.6 (13.5) kg and fat percentage of 16.6 (5.5)%. Bioimpedance test indicated significant differences between sexes related to sexual dysmorphia, which had an impact on bioelectrical variables. Through comparative evaluation between male and female athletes, this study contributes to body composition analysis, indicating that, in the future, related bioimpedance tests should be used beyond their classical application, including phase angle, muscle function and other attributes.</p></abstract>ARTICLE2021-11-20T00:00:00.000+00:00Comparison of electrical impedance tomography and ultrasonography for determination of solid and cystic lesion resembling breast tumor embedded in chicken phantom<abstract> <title style='display:none'>Abstract</title> <p>Ultrasonography (US) and Electrical Impedance Tomography (EIT) can be used to detect breast cancer. Ultrasonography is based on non-ionizing radiations without adverse biological effects. A set of electrodes was placed around the torso and a small alternating current (AC) was injected via two of the electrodes into the object. This study aimed to acquire preliminary data to evaluate the EIT method for differentiation of artificial solid and cystic tumors in comparison to standard US.</p> <p>This study used a phantom made from chicken meat. In order to obtain the image of the solid tumor, an olive with carrot insertion was done, and the cystic tumor was created by filling a small balloon with water. GE Logic C5 ultrasound was performed with a 12 MHz linear transducer. For EIT measurement, 16 ECG electrodes and 32 ECG electrodes were placed. Data processing was done using the Graz consensus Reconstruction algorithm for EIT (GREIT) and Newton's One Step Error Reconstructor (NOSER) methods.</p> <p>The artificial solid tumor produced an ultrasound image of an oval, inhomogeneous lesions. The GREIT method with 16 electrodes of artificial solid tumor did not show a match between the reconstructed image and the original object containing 2 anomalies, but a match was found with 32 electrodes. In the NOSER method, both 16 and 32 electrodes showed a match. Ultrasound of the artificial cystic tumor showed an oval, circumscribed, anechoic with posterior enhancement. Both the GREIT and NOSER methods using the artificial cystic tumor showed a match between the reconstructed image and the original object containing two anomalies.</p> <p>EIT has a lower imaging resolution in comparison to ultrasonography, but is progressively maturing as a tool for monitoring and imaging. The solid and cystic anomalies on the phantoms were visualized by the GREIT and NOSER methods except for the solid anomaly with the GREIT 16 electrodes.</p></abstract>ARTICLE2021-11-20T00:00:00.000+00:00Design of a drop-in EBI sensor probe for abnormal tissue detection in minimally invasive surgery<abstract> <title style='display:none'>Abstract</title> <p>It is a common challenge for the surgeon to detect pathological tissues and determine the resection margin during a minimally invasive surgery. In this study, we present a drop-in sensor probe based on the electrical bioimpedance spectroscopic technology, which can be grasped by a laparoscopic forceps and controlled by the surgeon to inspect suspicious tissue area conveniently. The probe is designed with an optimized electrode and a suitable shape specifically for Minimally Invasive Surgery (MIS). Subsequently, a series of <italic>ex vivo</italic> experiments are carried out with porcine liver tissue for feasibility validation. During the experiments, impedance measured at frequencies from 1 kHz to 2 MHz are collected on both normal tissues and water soaked tissue. In addition, classifiers based on discriminant analysis are developed. The result of the experiment indicate that the sensor probe can be used to measure the impedance of the tissue easily and the developed tissue classifier achieved accuracy of 80% and 100% respectively.</p> </abstract>ARTICLE2020-12-31T00:00:00.000+00:00Multichannel cell detection in microcompartments by means of true parallel measurements using the Solartron S-1260<abstract> <title style='display:none'>Abstract</title> <p>Designing proper frontend electronics is critical in the development of highly sophisticated electrode systems. Multielectrode arrays for measuring electrical signals or impedance require multichannel readout systems. Even more challenging is the differential or ratiometric configuration with simultaneous assessment of measurement and reference channels. In this work, an eight-channel frontend was developed for contacting a 2×8 electrode array (8 measurement and 8 reference electrodes) with a large common electrode to the impedance gain-phase analyzer Solartron 1260 (S-1260). Using the three independent and truly parallel monitor channels of the S-1260, impedance of trapped cells and reference material was measured at the same time, thereby considerably increasing the performance of the device. The frontend electronics buffers the generator output and applies a potentiostatic signal to the common electrode of the chip. The applied voltage is monitored using the current monitor of the S-1260 via voltage/current conversion. The frontend monitors the current through the electrodes and converts it to a voltage fed into the voltage monitors of the S-1260. For assessment of the 8 electrode pairs featured by the chip, a relay-based multiplexer was implemented. Extensive characterization and calibration of the frontend were carried out in a frequency range between 100 Hz and 1 MHz. Investigating the influence of the multiplexer and the frontend electronics, direct measurement with and without frontend was compared. Although differences were evident, they have been negligible below one per cent. The significance of measurement using the complex S-1260-frontend-electrode was tested using Kohlrausch's law. The impedance of an electrolytic dilution series was measured and compared to the theoretical values. The coincidence of measured values and theoretical prediction serves as an indicator for electrode sensitivity to cell behavior. Monitoring of cell behavior on the microelectrode surface will be shown as an example.</p> </abstract>ARTICLE2020-07-24T00:00:00.000+00:00Segmental volume changes that occur in nonhuman primates during short term head up (HUT) and head down (HDT) tilt<abstract> <title style='display:none'>Abstract</title> <p>Nonhuman primates are often used in biomedical research and to investigate physiologic processes that occur in man. Impedance plethysmography was used to measure calf, thigh, pelvic, abdominal, and thoracic volume changes in ten Rhesus and eight squirrel monkeys during five-minute exposures to HUT and HDT at angles of 5, 10, and 20 degrees. Calf, rump and tail measurements were made in three squirrel monkeys at 10 and 20 degrees of HUT and HDT. Fluid volume changes in all segments of the Rhesus monkeys were found to change during HUT an HDT in direct relation to the angle of tilt used. However, the volume changes that occurred in the squirrel monkeys were found to be quite different. Their calf, thigh, and pelvic segments <underline>lost</underline> volume during <underline>both</underline> HUT and HDT while their abdominal and thoracic segments responded similarly to those of the Rhesus monkeys. These results and those of the calf/tail measurements of the squirrel monkeys suggest that they may utilize their tails as a compensatory reservoir during postural changes and therefore, may not be an appropriate animal model for man under some orthostatic test conditions.</p> </abstract>ARTICLE2020-03-18T00:00:00.000+00:00Biosensor of inflammation biomarkers based on electrical bioimpedance analysis on immobilized DNA without chemical modification<abstract> <title style='display:none'>Abstract</title> <p>The development of biosensors to identify molecular markers or specific genes is fundamental for the implementation of new techniques that allow the detection of specific Deoxyribonucleic acid (DNA) sequences in a fast, economic and simple way. Different detection techniques have been proposed in the development of biosensors. Electrical Bioimpedance Spectroscopy (EBiS) has been used for diagnosis and monitoring of human pathologies, and is recognized as a safe, fast, reusable, easy and inexpensive technique. This study proves the development of a complementary DNA (cDNA) biosensor based on measurements of EBiS and DNA's immobilization with no chemical modifications. The evaluation of its potential utility in the detection of the gene expression of three inflammation characteristic biomarkers (NLRP3, IL-1β and Caspase 1) is presented. The obtained results demonstrate that EBiS can be used to identify different gene expression patterns, measurements that were validated by Quantitative Polymerase Chain Reaction (qPCR). These results indicate the technical feasibility for a biosensor of specific genes through bioimpedance measurements on the immobilization of cDNA.</p> </abstract>ARTICLE2020-06-25T00:00:00.000+00:00Monitoring electric impedance during freezing and thawing of saline and de-ionized water<abstract> <title style='display:none'>Abstract</title> <p>Physiological saline (0.9% NaCl) and deionized water were frozen in a laboratory chest freezer and impedance was monitored throughout freezing and thawing. The resistive and reactive components of electrical impedance were measured for these samples during freezing and thawing (heating) within a temperature range between 20 °C and −48 °C. The impedance of saline solution and de-ionized water increases sharply at the freezing point, similar to what is known for, e.g., complex tissues, including meat. Yet, only the saline solution impedance shows another sharp increment at a temperature between −30 and −20 °C. Changes of the electric properties after solidification suggest that the latter is linked to transformations of the ice lattice structure. We conclude that the electrical properties might serve as sensitive indicators of these phase changes.</p> </abstract>ARTICLE2020-12-31T00:00:00.000+00:00Time domain characterization of the Cole-Cole dielectric model<abstract> <title style='display:none'>Abstract</title> <p>The Cole-Cole model for a dielectric is a generalization of the Debye relaxation model. The most familiar form is in the frequency domain and this manifests itself in a frequency dependent impedance. Dielectrics may also be characterized in the time domain by means of the current and charge responses to a voltage step, called response and relaxation functions respectively. For the Debye model they are both exponentials while in the Cole-Cole model they are expressed by a generalization of the exponential, the Mittag-Leffler function. Its asymptotes are just as interesting and correspond to the Curie-von Schweidler current response which is known from real-life capacitors and the Kohlrausch stretched exponential charge response.</p> </abstract>ARTICLE2020-12-31T00:00:00.000+00:00 and conductivity models of the left heart ventricle<abstract> <title style='display:none'>Abstract</title> <p>Ventricular Assist Devices (VADs) are used to treat patients with cardiogenic shock. As the heart is unable to supply the organs with sufficient oxygenated blood and nutrients, a VAD maintains the circulation to keep the patient alive. The observation of the patient's hemodynamics is crucial for an individual treatment; therefore, sensors to measure quantifiable hemodynmaic parameters are desirable.</p> <p>In addition to pressure measurement, the volume of the left ventricle and the progress of muscle recovery seem to be promising parameters. Ongoing research aims to estimate ventricular volume and changes in electrical properties of cardiac muscle tissue by applying bioimpedance measurement. In the case where ventricular insufficiency is treated by a catheter-based VAD, this very catheter could be used to conduct bioimpedance measurement inside the assisted heart. However, the simultaneous measurement of bioimpedance and VAD support has not yet been realized, although this would allow the determination of various loading conditions of the ventricle. For this purpose, it is necessary to develop models to validate and quantify bioimpedance measurement during VAD support.</p> <p>In this study, we present an <italic>in silico</italic> and an <italic>in vitro</italic> conductivity model of a left ventricle to study the application of bioimpedance measurement in the context of VAD therapy. The <italic>in vitro</italic> model is developed from casting two anatomical silicone phantoms: One phantom of pure silicone, and one phantom enriched with carbon, to obtain a conductive behavior close to the properties of heart muscle tissue. Additionally, a measurement device to record the impedance inside the ventricle is presented. Equivalent to the <italic>in vitro</italic> model, the <italic>in silico</italic> model was designed. This finite element model offers changes in material properties for myocardium and the blood cavity.</p> <p>The measurements in the <italic>in vitro</italic> models show a strong correlation with the results of the simulation of the <italic>in silico</italic> model. The measurements and the simulation demonstrate a decrease in impedance, when conductive muscle properties are applied and higher impedances correspond to smaller ventricle cross sections.</p> <p>The <italic>in silico</italic> and <italic>in vitro</italic> models are used to further investigate the application of bioimpedance measurement inside the left heart ventricle during VAD support. We are confident that the models presented will allow for future evaluation of hemodynamic monitoring during VAD therapy at an early stage of research and development.</p> </abstract>ARTICLE2020-08-26T00:00:00.000+00:00Finite element simulation of the impedance response of a vascular segment as a function of changes in electrode configuration<abstract> <title style='display:none'>Abstract</title> <p>Monitoring a biological tissue as a three dimensional (3D) model is of high importance. Both the measurement technique and the measuring electrode play substantial roles in providing accurate 3D measurements. Bioimpedance spectroscopy has proven to be a noninvasive method providing the possibility of monitoring a 3D construct in a real time manner. On the other hand, advances in electrode fabrication has made it possible to use flexible electrodes with different configurations, which makes 3D measurements possible. However, designing an experimental measurement set-up for monitoring a 3D construct can be costly and time consuming and would require many tissue models. Finite element modeling methods provide a simple alternative for studying the performance of the electrode and the measurement set-up before starting with the experimental measurements. Therefore, in this study we employed the COMSOL Multiphysics finite element modeling method for simulating the effects of changing the electrode configuration on the impedance spectroscopy measurements of a venous segment. For this purpose, the simulations were performed for models with different electrode configurations. The simulation results provided us with the possibility of finding the optimal electrode configuration including the geometry, number and dimensions of the electrodes, which can be later employed in the experimental measurement set-up.</p> </abstract>ARTICLE2020-12-31T00:00:00.000+00:00Introducing the hybrid “K-means, RLS” learning for the RBF network in obstructive apnea disease detection using Dual-tree complex wavelet transform based features<abstract> <title style='display:none'>Abstract</title> <p>Apnea is one of the deadliest diseases that can be prevented and cured if it is detected in time. In this paper, we propose a precise method for early detection of the obstructive sleep apnea (OSA) disease using the latest feature selection and extraction methods. The feature selection in this paper is based on the Dual tree complex wavelet (DT-CWT) coefficients of the ECG signals of several patients. The feature extraction from these coefficients is done using frequency and time techniques. The Feature selection is done using the spectral regression discriminant analysis (SRDA) algorithm and the classification is performed using the hybrid RBF network. A hybrid RBF neural network is introduced in this paper for detecting apnea that is much less computationally demanding than the previously presented SVM networks. Our findings showed a 3 percent improvement in the detection and at least a 30 percent reduction in the computational complexity in comparison with methods that have been presented recently.</p> </abstract>ARTICLE2020-03-18T00:00:00.000+00:00Electrode positioning to investigate the changes of the thoracic bioimpedance caused by aortic dissection – a simulation study<abstract> <title style='display:none'>Abstract</title> <p>Impedance cardiography (ICG) is a non-invasive method to evaluate several cardiodynamic parameters by measuring the cardiac-synchronous changes in the dynamic transthoracic electrical impedance. ICG allows us to identify and quantify conductivity changes inside the thorax by measuring the impedance on the thorax during a cardiac cycle. Pathologic changes in the aorta, like aortic dissection, will alter the aortic shape as well as the blood flow and consequently, the impedance cardiogram. This fact distorts the evaluated cardiodynamic parameters, but it could lead to the possibility to identify aortic pathology. A 3D numerical simulation model is used to compute the impedance changes on the thorax surface in case of the type B aortic dissection. A sensitivity analysis is applied using this simulation model to investigate the suitability of different electrode configurations considering several patient-specific cases. Results show that the remarkable pathological changes in the aorta caused by aortic dissection alters the impedance cardiogram significantly.</p> </abstract>ARTICLE2020-06-25T00:00:00.000+00:00Design of Howland current sources using differential evolution optimization<abstract> <title style='display:none'>Abstract</title> <p>Howland circuits have been widely used in Electrical Bioimpedance Spectroscopy applications as reliable current sources. This paper presents an algorithm based on Differential Evolution for the automated design of Enhanced Howland Sources according to arbitrary design constraints while respecting the Howland ratio condition. Results showed that the algorithm can obtain solutions to commonly sought objectives, such as maximizing the output impedance at a given frequency, making it a versatile method to be employed in the design of sources with specific requirements. The mathematical modeling of the source output impedance and transconductance, considering a non-ideal operational amplifier, was validated against SPICE simulations, with results matching up to 10 MHz.</p> </abstract>ARTICLE2020-12-31T00:00:00.000+00:00en-us-1