BIOELECTRICAL IMPEDANCE VECTOR ANALYSIS IDENTIFIES SARCOPENIA IN NURSING HOME RESIDENTS
Loss of muscle mass and water shifts between body compartments are contributing factors to frailty in the elderly. The body composition changes are especially pronounced in institutionalized elderly. We investigated the ability of single-frequency bioelectrical impedance analysis (BIA) to identify b...
Bioelectrical impedance analysis for bovine milk: Preliminary results
Bertemes-Filho, P.; Valicheski, R.; Pereira, R. M.; Paterno, A. S.
2010-04-01
This work reports the investigation and analysis of bovine milk quality by using biological impedance measurements using electrical impedance spectroscopy (EIS). The samples were distinguished by a first chemical analysis using Fourier transform midinfrared spectroscopy (FTIR) and flow citometry. A set of milk samples (100ml each) obtained from 17 different cows in lactation with and without mastitis were analyzed with the proposed technique using EIS. The samples were adulterated by adding distilled water and hydrogen peroxide in a controlled manner. FTIR spectroscopy and flow cytometry were performed, and impedance measurements were made in a frequency range from 500Hz up to 1MHz with an implemented EIS system. The system's phase shift was compensated by measuring saline solutions. It was possible to show that the results obtained with the Bioelectrical Impedance Analysis (BIA) technique may detect changes in the milk caused by mastitis and the presence of water and hydrogen peroxide in the bovine milk.
Bioelectrical impedance analysis of bovine milk fat
Veiga, E. A.; Bertemes-Filho, P.
2012-12-01
Three samples of 250ml at home temperature of 20°C were obtained from whole, low fat and fat free bovine UHT milk. They were analysed by measuring both impedance spectra and dc conductivity in order to establish the relationship between samples related to fat content. An impedance measuring system was developed, which is based on digital oscilloscope, a current source and a FPGA. Data was measured by the oscilloscope in the frequency 1 kHz to 100 kHz. It was showed that there is approximately 7.9% difference in the conductivity between whole and low fat milk whereas 15.9% between low fat and free fat one. The change of fatness in the milk can be significantly sensed by both impedance spectra measurements and dc conductivity. This result might be useful for detecting fat content of milk in a very simple way and also may help the development of sensors for measuring milk quality, as for example the detection of mastitis.
Bioelectrical impedance analysis of bovine milk fat
Three samples of 250ml at home temperature of 20°C were obtained from whole, low fat and fat free bovine UHT milk. They were analysed by measuring both impedance spectra and dc conductivity in order to establish the relationship between samples related to fat content. An impedance measuring system was developed, which is based on digital oscilloscope, a current source and a FPGA. Data was measured by the oscilloscope in the frequency 1 kHz to 100 kHz. It was showed that there is approximately 7.9% difference in the conductivity between whole and low fat milk whereas 15.9% between low fat and free fat one. The change of fatness in the milk can be significantly sensed by both impedance spectra measurements and dc conductivity. This result might be useful for detecting fat content of milk in a very simple way and also may help the development of sensors for measuring milk quality, as for example the detection of mastitis.
Bioelectrical Impedance Vector Analysis and Muscular Fitness in Healthy Men
Fernando Rodríguez-Rodríguez
2016-07-01
Full Text Available Muscle strength can define the general muscular fitness (MF measurable through hand-grip strength (HG, which is a factor that relates to the health of people of different ages. In this study we evaluated the muscle strength together with a bioimpedance electric analysis in 223 healthy Colombian adult subjects. The bioelectrical impedance vector analysis (BIVA was conducted to determine the resistance (R, reactance (Xc and phase angle (PhA. We classified the subjects into three groups (for tertiles, obtaining lower values of R and Xc in subjects with lower HG, plus a high correlation between PhA and HG. An increase in the level of PhA is associated with a high level of MF in a sample of healthy Latin American adult men. The BIVA’s parameters and PhA are a potentially effective preventive measure to be integrated into routine screening in the clinical setting.
Bioelectrical Impedance Vector Analysis and Muscular Fitness in Healthy Men.
Rodríguez-Rodríguez, Fernando; Cristi-Montero, Carlos; González-Ruíz, Katherine; Correa-Bautista, Jorge Enrique; Ramírez-Vélez, Robinson
2016-01-01
Muscle strength can define the general muscular fitness (MF) measurable through hand-grip strength (HG), which is a factor that relates to the health of people of different ages. In this study we evaluated the muscle strength together with a bioimpedance electric analysis in 223 healthy Colombian adult subjects. The bioelectrical impedance vector analysis (BIVA) was conducted to determine the resistance (R), reactance (Xc) and phase angle (PhA). We classified the subjects into three groups (for tertiles), obtaining lower values of R and Xc in subjects with lower HG, plus a high correlation between PhA and HG. An increase in the level of PhA is associated with a high level of MF in a sample of healthy Latin American adult men. The BIVA's parameters and PhA are a potentially effective preventive measure to be integrated into routine screening in the clinical setting. PMID:27384579
Selma Civar Yavuz
2011-02-01
Full Text Available Objectives: The purpose of this investigation was to determine the effect of maximal exercise on percent body fat (%BF using bioelectrical impedance analysis in highly active male athletes at university. Design: The subjects of the study consisted of fifty-two (52 males with mean age of 21.68±1.66 years old, height of 164.46±5.21cm and weight of 57.69±6.61kg. All of the subjects joined the study voluntarily and were students in Akdeniz University School of Physical Education and Sport. Methods: All participants made two visits to the laboratory on separate days. On the first visit, anthropometric measurements were collected, orientation with the respiratory metabolic mouthpiece and treadmill was provided. During the second visit subjects exercised on a treadmill at different workloads in order to familiarize them to the treadmill. Percent body fat was assessed using a leg-to-leg bioelectrical impedance analyzer (BIA; Tanita Model TBF-300A. BIA measures of %BF were obtained immediately before and within five minutes following the exercise test. Results: Differences were found between pre and post exercise bioelectrical impedance values. There is significant difference respectively in weight, BMI, Body fat Percent, impedance (p<0.001 and fat mass, fat free mass, total body water values (p<0.05. Conclusions: Maximal exercise can effect the bioelectrical impedance analysis measurement.
Smartphone-Based Bioelectrical Impedance Analysis Devices for Daily Obesity Management
Ahyoung Choi; Justin Younghyun Kim; Seongwook Jo; Jae Hwan Jee; Heymsfield, Steven B.; Bhagat, Yusuf A.; Insoo Kim; Jaegeol Cho
2015-01-01
Current bioelectric impedance analysis (BIA) systems are often large, cumbersome devices which require strict electrode placement on the user, thus inhibiting mobile capabilities. In this work, we developed a handheld BIA device that measures impedance from multiple frequencies (5 kHz~200 kHz) with four contact electrodes and evaluated the BIA device against standard body composition analysis systems: a dual-energy X-ray absorptiometry (DXA) system (GE Lunar Prodigy, GE Healthcare, Buckingha...
Bioelectrical impedance analysis as a laboratory activity: At the interface of physics and the body
Mylott, Elliot; Kutschera, Ellynne; Widenhorn, Ralf
2014-05-01
We present a novel laboratory activity on RC circuits aimed at introductory physics students in life-science majors. The activity teaches principles of RC circuits by connecting ac-circuit concepts to bioelectrical impedance analysis (BIA) using a custom-designed educational BIA device. The activity shows how a BIA device works and how current, voltage, and impedance measurements relate to bioelectrical characteristics of the human body. From this, useful observations can be made including body water, fat-free mass, and body fat percentage. The laboratory is engaging to pre-health and life-science students, as well as engineering students who are given the opportunity to observe electrical components and construction of a commonly used biomedical device. Electrical concepts investigated include alternating current, electrical potential, resistance, capacitance, impedance, frequency, phase shift, device design, and the use of such topics in biomedical analysis.
Lamb, Maxine J. E.; Byrne, Christopher D.; Wilson, James F; Wild, Sarah H.
2014-01-01
OBJECTIVE: To investigate whether bioelectrical impedance analysis could be used to identify overweight individuals at increased cardiometabolic risk, defined as the presence of metabolic syndrome and/or diabetes.DESIGN AND METHODS: Cross-sectional study of a Scottish population including 1210 women and 788 men. The diagnostic performance of thresholds of percentage body fat measured by bioelectrical impedance analysis to identify people at increased cardiometabolic risk was assessed using re...
Validity of Bioelectrical Impedance Analysis to Estimation Fat-Free Mass in the Army Cadets
Langer, Raquel D.; Borges, Juliano H.; Pascoa, Mauro A.; Cirolini, Vagner X.; Gil Guerra-Júnior; Ezequiel M. Gonçalves
2016-01-01
Background: Bioelectrical Impedance Analysis (BIA) is a fast, practical, non-invasive, and frequently used method for fat-free mass (FFM) estimation. The aims of this study were to validate predictive equations of BIA to FFM estimation in Army cadets and to develop and validate a specific BIA equation for this population. Methods: A total of 396 males, Brazilian Army cadets, aged 17–24 years were included. The study used eight published predictive BIA equations, a specific equation in FFM est...
Feasibility of bioelectrical impedance analysis in children with a severe generalized cerebral palsy
Veugelers, Rebekka; Penning, Corine; van Gulik, Laura; Tibboel, Dick; Evenhuis, Heleen
2006-01-01
textabstractObjective: The need is strong for an accurate and easy-to-perform test to evaluate the nutritional state of children who have a severe generalized cerebral palsy, defined as a severe motor handicap and an intellectual disability. For that purpose, we determined the feasibility of bioelectrical impedance analysis (BIA) in these children and evaluated their nutritional state. Methods: BIA recordings were done in 35 children who had a severe generalized cerebral palsy using a single-...
Bioelectrical impedance analysis for the prediction of hot carcass weight in buffalo calf
Leopoldo Iannuzzi
2010-01-01
Full Text Available Twenty young buffalo male calves were fed ad libitum with a total mix ration and with vitamin-mineral integration for 14 months. Seven days before slaughter, the animals were weighed and bioelectrical impedance measurements were collected in live animals. Physical and chemical characteristics were assessed on the Longissimus dorsi muscle after slaughter. Correlations and regression equations were calculated to determine the possible use of bioelectrical impedance for evaluating hot carcass weight. Bioelectrical impedance analysis at different frequencies, simple correlation and analysis of regression were examined for all the data collected, supporting the possibility of hot carcass weight prediction with equation at multifrequency. The results show that, probably due to the variability in animal live weight, the distribution of the colour parameters was not normally distributed. Moreover, using different frequencies of resistance and reactance, hot carcass weight in buffalo may be predicted with the following equation: Y=98.47–8.84(Rs100KHz+4.41(Rs1000 KHz-116.27(Xc5 KHz+51.04(Xc50 KHz+20.30(Xc100 KHz-33.92(Xc500 KHz+9.01(Xc1000 KHz±ε (Adjusted R Square value of .907 and SE of 5.728 However, further studies are required to improve the technique also in buffalo, after standardization of the method.
Sproule, Douglas M; Montes, Jacqueline; Dunaway, Sally L; Montgomery, Megan; Battista, Vanessa; Shen, Wei; Punyanitya, Mark; De Vivo, Darryl C; Kaufmann, Petra
2010-11-01
Accurate, noninvasive measures of body composition are needed for management of patients with spinal muscular atrophy. Fat mass index (fat mass/height(2) in kg/m(2)) was measured in 16 subjects with spinal muscular atrophy using 5 bioelectrical impedance analysis equations and compared with a reference method, dual-energy x-ray absorptiometry. The machine default equation, validated by Cordain, was the primary analysis. Fat mass index calculated by impedance measures differed by between -2.5 kg/m(2) and 1.7 kg/m(2) from the reference mean (8.3 ± 5.0 kg/m(2)). The Cordain equation provided the smallest difference (-0.4 ± 2.0 kg/m(2)), with correlation coefficient of 0.92. The Cordain equation showed high sensitivity (85.7%) and specificity (100%) for prediction of ''at risk for overweight'' (fat mass index > 85th percentile for age and gender). Although insufficiently accurate for use as a research tool, bioelectrical impedance can have application as a well-tolerated, noninvasive, easily used screening tool for excess adiposity in patients with spinal muscular atrophy. PMID:20388937
Selma Civar Yavuz
2011-01-01
Objectives: The purpose of this investigation was to determine the effect of maximal exercise on percent body fat (%BF) using bioelectrical impedance analysis in highly active male athletes at university. Design: The subjects of the study consisted of fifty-two (52) males with mean age of 21.68±1.66 years old, height of 164.46±5.21cm and weight of 57.69±6.61kg. All of the subjects joined the study voluntarily and were students in Akdeniz University School of Physical Educ...
The use of bioelectrical impedance analysis for body composition in epidemiological studies
Böhm, A; Heitmann, B L
2013-01-01
BACKGROUND/OBJECTIVES: Bioelectrical impedance analysis (BIA) is a relatively simple, inexpensive and non-invasive technique to measure body composition and is therefore suitable in field studies and larger surveys. SUBJECTS/METHODS: We performed an overview of BIA-derived body fat percentages (BF......%) from 55 published studies of healthy populations aged 6-80 years. In addition, the relationship between body mass index (BMI) and body composition is documented in the context of BIA as a good alternative to closely differentiate which composition of the body better relates to the risk of...
İhsan Çetin
2015-12-01
Full Text Available Objective: In this study, it was aimed to evaluate segmental body composition of children diagnosed with obesity using bioelectrical impedance analysis method in terms of different gender. Methods: 48 children, aged between 6-15 years, 21 of whom were boys while 27 were girls, diagnosed with obesity in Erciyes University Medical Faculty Department of Pediatric Endocrinology Outpatient Clinic were included in our study from April to June in 2011. Those over 95 percentile were defined as obese group. Tanita BC-418 device was used to analyze the body composition. Results: As a result of bioelectrical impedance analysis, lean body mass and body muscle mass were found to be statistically significantly higher in obese girls compared with obese boys. However, lean mass of the left arm, left leg muscle mass and basal metabolic rate were found to be statistically significantly lower in obese girls compared with obese boys. Conclusion: Consequently, it may be suggest that segmental analysis, where gender differences are taken into account, can provide proper exercise pattern and healthy way of weight loss in children for prevention of obesity and associated diseases including obesity and type 2 diabetics and cardiovascular diseases.
Smartphone-Based Bioelectrical Impedance Analysis Devices for Daily Obesity Management.
Choi, Ahyoung; Kim, Justin Younghyun; Jo, Seongwook; Jee, Jae Hwan; Heymsfield, Steven B; Bhagat, Yusuf A; Kim, Insoo; Cho, Jaegeol
2015-01-01
Current bioelectric impedance analysis (BIA) systems are often large, cumbersome devices which require strict electrode placement on the user, thus inhibiting mobile capabilities. In this work, we developed a handheld BIA device that measures impedance from multiple frequencies (5 kHz~200 kHz) with four contact electrodes and evaluated the BIA device against standard body composition analysis systems: a dual-energy X-ray absorptiometry (DXA) system (GE Lunar Prodigy, GE Healthcare, Buckinghamshire, UK) and a whole-body BIA system (InBody S10, InBody, Co. Ltd, Seoul, Korea). In the study, 568 healthy participants, varying widely in body mass index, age, and gender, were recruited at two research centers: the Samsung Medical Center (SMC) in South Korea and the Pennington Biomedical Research Center (PBRC) in the United States. From the measured impedance data, we analyzed individual body fat and skeletal muscle mass by applying linear regression analysis against target reference data. Results indicated strong correlations of impedance measurements between the prototype pathways and corresponding InBody S10 electrical pathways (R = 0.93, p 0.728 (paired t-test), DXA mean body fat 29.45 ± 10.77 kg, estimated body fat 29.52 ± 12.53 kg). Thus, this portable BIA system shows a promising ability to estimate an individual's body composition that is comparable to large stationary BIA systems. PMID:26364636
Fukuda, David H; Stout, Jeffrey R; Moon, Jordan R; Smith-Ryan, Abbie E; Kendall, Kristina L; Hoffman, Jay R
2016-02-01
Raw bioelectrical impedance analysis (BIA) data [resistance (R); reactance (Xc)] through bioelectrical impedance vector analysis (BIVA) and phase angle (PhA) have been used to evaluate cellular function and hydration status. The purpose of this investigation was to examine the effects of resistance training (RT) on classic and specific BIVA in elderly women. Twenty women (mean ± SD; age: 71.9 ± 6.9 years; BMI: 24.5 ± 3.0 kg m(-2)) completed a 6-month RT program. Whole-body, single-frequency BIA, body geometry, and leg strength (5RM) measures were completed at baseline (t0), 3 months (t3), and 6 months (t6). The mean impedance vector displacements were compared using Hotelling's T(2) test to evaluate changes in R and Xc relative to height (R/ht; Xc/ht) or body volume (Rsp; Xcsp) estimated from the arms, legs, and trunk. 5RM, PhA, and BIVA variables were compared using ANOVA. PhA improved at t6 (p < 0.01), while 5RM improved at t3 and t6 (p < 0.01). Using classic BIVA, 6 months (T(2) = 31.6; p < 0.01), but not 3 months of RT (T(2) = 4.5; p = 0.20), resulted in significant vector migration. Using specific BIVA, 6 months (T(2) = 24.4; p < 0.01), but not 3 months of RT (T(2) = 5.5; p = 0.10), also resulted in significant vector migration. 5RM was correlated to both PhA (r = 0.48-56) and Xcsp (r = 0.45-53) at all time points. Vector displacements were likely the result of improved cellular integrity (Xcsp) and cellular health (PhA). PMID:26657810
Kapica, Dominik; Warchulińska, Joanna; Jakubiak, Monika; Teter, Mariusz; Mlak, Radosław; Hałabiś, Magdalena; Wójcik, Waldemar; Małecka-Massalska, Teresa
2015-09-01
Introduction: Bioelectrical impedance analysis (BIA) is a useful tool to asses human body composition and nutrition status; multi-frequency BIA has a higher accuracy than single-frequency BIA. In our study a difference of impedance values (Z) at 5, 100 and 200 kHz and Z200/Z5 index between professional athletes and control group were determined. Methods: In this research 105 people were tested, divided into control group (72 people: 35 males and 37 females) and professional athletes (33 people: 16 males and 17 females). Impedance was measured at three frequency values - 5, 100 and 200 kHz; with received values the Z200/Z5 index was calculated. Results: In most compared subgroups impedance values showed significantly lower values in athletes than in control group (5 kHz - males: p=0.136, females: p=0.001, 100 kHz - males: p=0.039, females: pnutrition status and general health condition of athletes than in control group.
Company, Joe; Ball, Stephen
2010-01-01
The primary purpose of this study was to investigate the accuracy of the DF50 (ImpediMed Ltd, Eight Mile Plains, Queensland, Australia) bioelectrical impedance analysis device using dual-energy x-ray absorptiometry as the criterion in two groups: endurance athletes and power athletes. The secondary purpose was to develop accurate body fat…
Camina Martín, M A; de Mateo Silleras, B; Redondo del Río, M P
2014-11-01
In clinical practice, geriatric nutritional assessment usually includes nutritional screening, a simple anthropometric assessment, measurement of various biochemical parameters, such as serum albumin, and sometimes (not always) body composition analysis (BCA). However, there is a high prevalence of undiagnosed malnutrition in patients with dementia. Several factors contribute to this situation; probably, the most notable is the methodology used to assess body composition (BC). In this regard, for BCA, techniques are needed that are noninvasive, affordable, safe, simple and that require the minimum possible collaboration by the elderly patient. Consequently, body mass index (BMI) and waist circumference (WC) are widely used as indicators of overall and central adiposity, respectively; however, there is no consensus on the cutoffs for the elderly, and changes in BC (especially muscle-mass depletion) are masked by normal values of BMI and WC. Bioimpedance analysis is a simple, cost-effective and precise method for BCA, provided that cross-validated equations are used. Its main disadvantage is that it is highly sensitive to changes in body water (overhydration or dehydration), leading to substantial errors in BC estimates. However, using Bioelectrical Impedance Vector Analysis errors are minimized, as there is no need for the subject to be normally hydrated and it does not require the use of predictive models. PMID:25117995
Kushner, R.F.; Kunigk, A.; Alspaugh, M.; Andronis, P.T.; Leitch, C.A.; Schoeller, D.A. (Univ. of Chicago, IL (USA))
1990-08-01
The bioelectrical-impedance-analysis (BIA) method accurately measures body composition in weight-stable subjects. This study validates the use of BIA to measure change in body composition. Twelve obese females underwent weight loss at a mean rate of 1.16 kg/wk. Body composition was measured by deuterium oxide dilution (D2O), BIA, and skinfold anthropometry (SFA) at baseline and at 5% decrements in weight. Highly significant correlations were obtained between D2O and BIA (r = 0.971) and between D2O and SFA (r = 0.932). Overall, BIA predicted change in fat-free mass with greater accuracy (to 0.4 kg) and precision (+/- 1.28 kg) than did anthropometry (to 0.8 kg and +/- 2.58 kg, respectively). We conclude that BIA is a useful clinical method for measuring change in body composition.
The bioelectrical-impedance-analysis (BIA) method accurately measures body composition in weight-stable subjects. This study validates the use of BIA to measure change in body composition. Twelve obese females underwent weight loss at a mean rate of 1.16 kg/wk. Body composition was measured by deuterium oxide dilution (D2O), BIA, and skinfold anthropometry (SFA) at baseline and at 5% decrements in weight. Highly significant correlations were obtained between D2O and BIA (r = 0.971) and between D2O and SFA (r = 0.932). Overall, BIA predicted change in fat-free mass with greater accuracy (to 0.4 kg) and precision (+/- 1.28 kg) than did anthropometry (to 0.8 kg and +/- 2.58 kg, respectively). We conclude that BIA is a useful clinical method for measuring change in body composition
Bioelectrical Impedance Assessment of Wound Healing
Lukaski, Henry C.; Moore, Micheal
2012-01-01
Objective assessment of wound healing is fundamental to evaluate therapeutic and nutritional interventions and to identify complications. Despite availability of many techniques to monitor wounds, there is a need for a safe, practical, accurate, and effective method. A new method is localized bioelectrical impedance analysis (BIA) that noninvasively provides information describing cellular changes that occur during healing and signal complications to wound healing. This article describes the ...
Smartphone-Based Bioelectrical Impedance Analysis Devices for Daily Obesity Management
Ahyoung Choi
2015-09-01
Full Text Available Current bioelectric impedance analysis (BIA systems are often large, cumbersome devices which require strict electrode placement on the user, thus inhibiting mobile capabilities. In this work, we developed a handheld BIA device that measures impedance from multiple frequencies (5 kHz~200 kHz with four contact electrodes and evaluated the BIA device against standard body composition analysis systems: a dual-energy X-ray absorptiometry (DXA system (GE Lunar Prodigy, GE Healthcare, Buckinghamshire, UK and a whole-body BIA system (InBody S10, InBody, Co. Ltd, Seoul, Korea. In the study, 568 healthy participants, varying widely in body mass index, age, and gender, were recruited at two research centers: the Samsung Medical Center (SMC in South Korea and the Pennington Biomedical Research Center (PBRC in the United States. From the measured impedance data, we analyzed individual body fat and skeletal muscle mass by applying linear regression analysis against target reference data. Results indicated strong correlations of impedance measurements between the prototype pathways and corresponding InBody S10 electrical pathways (R = 0.93, p < 0.0001. Additionally, body fat estimates from DXA did not yield significant differences (p > 0.728 (paired t-test, DXA mean body fat 29.45 ± 10.77 kg, estimated body fat 29.52 ± 12.53 kg. Thus, this portable BIA system shows a promising ability to estimate an individual’s body composition that is comparable to large stationary BIA systems.
Maxine J E Lamb
Full Text Available OBJECTIVE: To investigate whether bioelectrical impedance analysis could be used to identify overweight individuals at increased cardiometabolic risk, defined as the presence of metabolic syndrome and/or diabetes. DESIGN AND METHODS: Cross-sectional study of a Scottish population including 1210 women and 788 men. The diagnostic performance of thresholds of percentage body fat measured by bioelectrical impedance analysis to identify people at increased cardiometabolic risk was assessed using receiver-operating characteristic curves. Odds ratios for increased cardiometabolic risk in body mass index categories associated with values above compared to below sex-specific percentage body fat thresholds with optimal diagnostic performance were calculated using multivariable logistic regression analyses. The validity of bioelectrical impedance analysis to measure percentage body fat in this population was tested by examining agreement between bioelectrical impedance analysis and dual-energy X-ray absorptiometry in a subgroup of individuals. RESULTS: Participants were aged 16-91 years and the optimal bioelectrical impedance analysis cut-points for percentage body fat for identifying people at increased cardiometabolic risk were 25.9% for men and 37.1% for women. Stratifying by these percentage body fat cut-points, the prevalence of increased cardiometabolic risk was 48% and 38% above the threshold and 24% and 19% below these thresholds for men and women, respectively. By comparison, stratifying by percentage body fat category had little impact on identifying increased cardiometabolic risk in normal weight and obese individuals. Fully adjusted odds ratios of being at increased cardiometabolic risk among overweight people with percentage body fat ≥ 25.9/37.1% compared with percentage body fat <25.9/37.1% as a reference were 1.93 (95% confidence interval: 1.20-3.10 for men and 1.79 (1.10-2.92 for women. CONCLUSION: Percentage body fat measured using
A Emami Naini
2012-01-01
Conclusion: The study showed that there is significant difference between the two methods. However, there was 98% direct correlation between them. It is concluded that bioelectrical impedance analysis could be a better alternative for accurate evaluation of dry weight in PD patients because it is a fast and cheap method and does not depend on examiner′s capability. Further studies based on the results of this method are recommended to consider this method as the gold standard.
Saladino, Charles F
2014-01-01
Reviews Treating restrictive eating disorder patients is metabolically and psychologically complex. Determining body composition is an important diagnostic and treatment option for these patients, because it ascertains whether the acquisition of body mass during refeeding is metabolically appropriate - ideally an approximate 20/80% - 25/75% fat/lean body mass ratio. The purpose of this paper is to evaluate the efficacy of Bioelectrical Impedance Analysis (BIA) during the treatment period of p...
Luke, Amy; Bovet, Pascal; Forrester, Terrence E.; Lambert, Estelle V; Plange-Rhule, Jacob; Dugas, Lara R.; Durazo-Arvizu, Ramon A; Kroff, Jacolene; Richie, Whitney N.; Schoeller, Dale A
2013-01-01
Background/Objectives Bio-electrical impedance analysis (BIA) is used in population and clinical studies as a technique for estimating body composition. Because of significant underrepresentation in existing literature, we sought to develop and validate predictive equation(s) for BIA for studies in populations of African origin. Subjects/Methods Among five cohorts of the Modeling the Epidemiologic Transition Study (METS), height, weight, waist circumference and body composition, using isotope...
Marini E; Buffa R; Saragat B; Coin A; Toffanello ED; Berton L; Manzato E; Sergi G
2012-01-01
Elisabetta Marini,1 Roberto Buffa,1 Bruno Saragat,1 Alessandra Coin,2 Elena Debora Toffanello,2 Linda Berton,2 Enzo Manzato,2 Giuseppe Sergi21Department of Environmental and Life Sciences, University of Cagliari, Italy; 2Department of Medicine-DIMED, Geriatrics Section, University of Padua, ItalyPurpose: The aim of this paper is to investigate whether bioelectrical impedance vector analysis (BIVA) can be a suitable technique for the assessment of sarcopenia. We also investigate the potential ...
Validity of Bioelectrical Impedance Analysis to Estimation Fat-Free Mass in the Army Cadets
Raquel D. Langer
2016-03-01
Full Text Available Background: Bioelectrical Impedance Analysis (BIA is a fast, practical, non-invasive, and frequently used method for fat-free mass (FFM estimation. The aims of this study were to validate predictive equations of BIA to FFM estimation in Army cadets and to develop and validate a specific BIA equation for this population. Methods: A total of 396 males, Brazilian Army cadets, aged 17–24 years were included. The study used eight published predictive BIA equations, a specific equation in FFM estimation, and dual-energy X-ray absorptiometry (DXA as a reference method. Student’s t-test (for paired sample, linear regression analysis, and Bland–Altman method were used to test the validity of the BIA equations. Results: Predictive BIA equations showed significant differences in FFM compared to DXA (p < 0.05 and large limits of agreement by Bland–Altman. Predictive BIA equations explained 68% to 88% of FFM variance. Specific BIA equations showed no significant differences in FFM, compared to DXA values. Conclusion: Published BIA predictive equations showed poor accuracy in this sample. The specific BIA equations, developed in this study, demonstrated validity for this sample, although should be used with caution in samples with a large range of FFM.
V-dotO2max prediction from multi-frequency bioelectrical impedance analysis
Bioelectrical impedance analysis (BIA) has been shown to be highly related to skeletal muscle mass and blood volume, both of which are important determinants of maximal oxygen uptake (V-dotO2max). The aim of the present study was therefore to investigate the ability of whole-body and segmental multi-frequency BIA to improve current nonexercise V-dotO2max prediction models. Data for V-dotO2max (mL min−1), anthropometry, self-reported physical activity (PA-R) and BIA were collected in 115 men and women. Multiple linear regression analysis (MLR) was used to develop the most parsimonious prediction model. Segmental BIA was not superior to whole-body measurements. Correlation coefficients between V-dotO2max and resistance indices were significantly higher at 500 kHz compared to 50 kHz (p 2max (r = 0.89). After adjusting for age, gender and PA-R, MLR revealed that the inclusion of intracellular resistance index was slightly, but significantly (p 2max (−1). In short, whole-body BIA marginally improves the accuracy of nonexercise V-dotO2max prediction models and its advantage is most pronounced in individuals with particularly low V-dotO2max
Validity of Bioelectrical Impedance Analysis to Estimation Fat-Free Mass in the Army Cadets
Langer, Raquel D.; Borges, Juliano H.; Pascoa, Mauro A.; Cirolini, Vagner X.; Guerra-Júnior, Gil; Gonçalves, Ezequiel M.
2016-01-01
Background: Bioelectrical Impedance Analysis (BIA) is a fast, practical, non-invasive, and frequently used method for fat-free mass (FFM) estimation. The aims of this study were to validate predictive equations of BIA to FFM estimation in Army cadets and to develop and validate a specific BIA equation for this population. Methods: A total of 396 males, Brazilian Army cadets, aged 17–24 years were included. The study used eight published predictive BIA equations, a specific equation in FFM estimation, and dual-energy X-ray absorptiometry (DXA) as a reference method. Student’s t-test (for paired sample), linear regression analysis, and Bland–Altman method were used to test the validity of the BIA equations. Results: Predictive BIA equations showed significant differences in FFM compared to DXA (p < 0.05) and large limits of agreement by Bland–Altman. Predictive BIA equations explained 68% to 88% of FFM variance. Specific BIA equations showed no significant differences in FFM, compared to DXA values. Conclusion: Published BIA predictive equations showed poor accuracy in this sample. The specific BIA equations, developed in this study, demonstrated validity for this sample, although should be used with caution in samples with a large range of FFM. PMID:26978397
Estimation of fat-free mass in Asian neonates using bioelectrical impedance analysis.
Tint, Mya-Thway; Ward, Leigh C; Soh, Shu E; Aris, Izzuddin M; Chinnadurai, Amutha; Saw, Seang Mei; Gluckman, Peter D; Godfrey, Keith M; Chong, Yap-Seng; Kramer, Michael S; Yap, Fabian; Lingwood, Barbara; Lee, Yung Seng
2016-03-28
The aims of this study were to develop and validate a prediction equation of fat-free mass (FFM) based on bioelectrical impedance analysis (BIA) and anthropometry using air-displacement plethysmography (ADP) as a reference in Asian neonates and to test the applicability of the prediction equations in an independent Western cohort. A total of 173 neonates at birth and 140 at two weeks of age were included. Multiple linear regression analysis was performed to develop the prediction equations in a two-third randomly selected subset and validated on the remaining one-third subset at each time point and in an independent Queensland cohort. FFM measured by ADP was the dependent variable, and anthropometric measures, sex and impedance quotient (L2/R50) were independent variables in the model. Accuracy of prediction equations was assessed using intra-class correlation and Bland-Altman analyses. L2/R50 was the significant predictor of FFM at week two but not at birth. Compared with the model using weight, sex and length, including L2/R50 slightly improved the prediction with a bias of 0·01 kg with 2 sd limits of agreement (LOA) (0·18, -0·20). Prediction explained 88·9 % of variation but not beyond that of anthropometry. Applying these equations to the Queensland cohort provided similar performance at the appropriate age. However, when the Queensland equations were applied to our cohort, the bias increased slightly but with similar LOA. BIA appears to have limited use in predicting FFM in the first few weeks of life compared with simple anthropometry in Asian populations. There is a need for population- and age-appropriate FFM prediction equations. PMID:26856420
Márcia Marília Gomes Dantas
2015-09-01
Full Text Available Background: The prevalence of abnormal nutritional status has increased in children and adolescents. Nutritional assessment is important for monitoring the health and nutritional status. Bioelectrical impedance vector analysis (BIVA combines changes in tissue hydration and structure and body composition that can be assessed. Objectives: The objective of this study was to use BIVA to evaluate nutritional status in 60 prepubertal children, aged between 8 and 9 years, supplemented with zinc, to detect possible changes in body composition. Design: We performed a randomized, controlled, triple-blind study. The children were divided into the control group (CG; sorbitol 10%, n=29 or the experimental group (EG; 10 mg Zn/day, n=31, and the duration of the experiment was 3 months. Anthropometric assessments were performed for all of the children. Results: The body mass index-for-age increased after oral zinc supplementation in the EG (p=0.005. BIVA indicated that the CG demonstrated a tendency for dehydration and decreased soft tissue and the EG demonstrated a tendency for increased soft tissue, primarily the fat-free mass. After analyses of BIVA ellipses, we observed that this method could detect improvements in body composition in healthy children supplemented with zinc. Conclusions: These results suggest that BIVA could be an auxiliary method for studying a small population undergoing zinc intervention.
Teresa Malecka-Massalska
2012-01-01
Full Text Available Background and Objectives. The study was conducted to evaluate soft tissue hydration and mass through pattern analysis of vector plots as height, normalized resistance, and reactance measurements by bioelectric impedance vector analysis in Taiwanese and Polish college students. Methods. Whole-body measurements were made with ImpediMed bioimpedance analysis SFB7 BioImp v1.55 (Pinkenba Qld 4008, Australia in 16 Taiwanese and Polish men and 16 Taiwanese and Polish women. Results. Mean vectors of Taiwanese men and women groups versus the Polish men and women groups were characterized by almost the same normalized resistance component with reactance component (separate 95% confidence limits, <0.05 indicating that there were no differences of soft tissue hydration and mass. Interpretation and Conclusion. The evaluation of soft tissue hydration and mass through pattern analysis of vector plots as height, normalized resistance, and reactance measurements by bioelectric impedance vector analysis in Taiwanese and Polish college students did not differ between these two diverse ethnic groups. Further observational research investigating these properties in larger groups would be welcomed to elucidate and/or confirm these findings.
Marini E
2012-12-01
Full Text Available Elisabetta Marini,1 Roberto Buffa,1 Bruno Saragat,1 Alessandra Coin,2 Elena Debora Toffanello,2 Linda Berton,2 Enzo Manzato,2 Giuseppe Sergi21Department of Environmental and Life Sciences, University of Cagliari, Italy; 2Department of Medicine-DIMED, Geriatrics Section, University of Padua, ItalyPurpose: The aim of this paper is to investigate whether bioelectrical impedance vector analysis (BIVA can be a suitable technique for the assessment of sarcopenia. We also investigate the potential use of specific BIVA as an indicator of sarcopenic obesity.Subjects and methods: The sample comprised 207 free-living elderly individuals of both sexes, aged 65 to 93 years. Anthropometric and bioelectrical measurements were taken according to standard criteria. The “classic” and “specific” BIVA procedures, which respectively correct bioelectrical values for body height and body geometry, were used. Dual energy X-ray absorptiometry (DXA was used as the reference method for identifying sarcopenic and obese sarcopenic individuals. Bioelectrical and DXA values were compared using Student’s t-test and Hotelling’s T2 test, as well as Pearson’s correlation coefficient.Results: According to classic BIVA, sarcopenic individuals of both sexes showed higher values of resistance/height (R/H; p < 0.01 and impedance/height (Z/H; p < 0.01, and a lower phase angle (p < 0.01. Similarly, specific BIVA showed significant differences between sarcopenic and nonsarcopenic individuals (men: T2 = 15.7, p < 0.01; women: T2 = 10.7, p < 0.01, with the sarcopenic groups showing a lower specific reactance and phase angle. Phase angle was positively correlated with the skeletal muscle mass index (men: r = 0.52, p < 0.01; women: r = 0.31, p < 0.01. Specific BIVA also recognized bioelectrical differences between sarcopenic and sarcopenic obese men (T2 = 13.4, p < 0.01, mainly due to the higher values of specific R in sarcopenic obese individuals.Conclusion: BIVA detected
Larissa Rodrigues Neto Angéloco
2012-06-01
Full Text Available OBJECTIVE: The aim of the present study was to determine the impedance of Wistar rats treated with high-fat and high-sucrose diets and correlate their biochemical and anthropometric parameters with chemical analysis of the carcass. METHODS: Twenty-four male Wistar rats were fed a standard (AIN-93, high-fat (50% fat or high-sucrose (59% of sucrose diet for 4 weeks. Abdominal and thoracic circumference and body length were measured. Bioelectrical impedance analysis was used to determine resistance and reactance. Final body composition was determined by chemical analysis. RESULTS: Higher fat intake led to a high percentage of liver fat and cholesterol and low total body water in the High-Fat group, but these changes in the biochemical profile were not reflected by the anthropometric measurements or bioelectrical impedance analysis variables. Anthropometric and bioelectrical impedance analysis changes were not observed in the High-Sucrose group. However, a positive association was found between body fat and three anthropometric variables: body mass index, Lee index and abdominal circumference. CONCLUSION: Bioelectrical impedance analysis did not prove to be sensitive for detecting changes in body composition, but body mass index, Lee index and abdominal circumference can be used for estimating the body composition of rats.
Andreacci, Joseph L.; Dixon, Curt B.; Rompolski, Krista; VanGorden, Kelly M.
2008-01-01
Bioelectrical impedance analysis (BIA) is a fast, easy to administer, and relatively inexpensive method of evaluating body composition. Due to the ease of operation, interest in using BIA to estimate percentage of body fat (%BF) has grown, especially in settings where body composition assessments are often performed without the benefit of…
Yamada Y
2013-04-01
Full Text Available Yosuke Yamada,1,2 Yoshihisa Masuo,3 Eitaro Nakamura,4 Shingo Oda5 1Laboratory of Sports and Health Science, Kyoto Prefectural University of Medicine, Kyoto, Japan; 2Japan Society for the Promotion of Science, Tokyo, Japan; 3Waseda University Research Institute for Elderly Health, Saitama, Japan; 4Department of Sport Science, Kyoto Iken College of Medicine and Health, Kyoto, Japan; 5Faculty of Health and Well-being, Kansai University, Osaka, Japan Abstract: The aim of this study was to evaluate and quantify differences in muscle distribution in athletes of various ball sports using segmental bioelectrical impedance analysis (SBIA. Participants were 115 male collegiate athletes from four ball sports (baseball, soccer, tennis, and lacrosse. Percent body fat (%BF and lean body mass were measured, and SBIA was used to measure segmental muscle volume (MV in bilateral upper arms, forearms, thighs, and lower legs. We calculated the MV ratios of dominant to nondominant, proximal to distal, and upper to lower limbs. The measurements consisted of a total of 31 variables. Cluster and factor analyses were applied to identify redundant variables. The muscle distribution was significantly different among groups, but the %BF was not. The classification procedures of the discriminant analysis could correctly distinguish 84.3% of the athletes. These results suggest that collegiate ball game athletes have adapted their physique to their sport movements very well, and the SBIA, which is an affordable, noninvasive, easy-to-operate, and fast alternative method in the field, can distinguish ball game athletes according to their specific muscle distribution within a 5-minute measurement. The SBIA could be a useful, affordable, and fast tool for identifying talents for specific sports. Keywords: discriminant analysis, cluster and factor analysis, segmental bioelectrical impedance analysis, baseball, lacrosse
Rae, L S; Vankan, D M; Rand, J S; Flickinger, E A; Ward, L C
2016-06-01
Thirty-five healthy, neutered, mixed breed dogs were used to determine the ability of multifrequency bioelectrical impedance analysis (MFBIA) to predict accurately fat-free mass (FFM) in dogs using dual energy X-ray absorptiometry (DXA)-measured FFM as reference. A second aim was to compare MFBIA predictions with morphometric predictions. MFBIA-based predictors provided an accurate measure of FFM, within 1.5% when compared to DXA-derived FFM, in normal weight dogs. FFM estimates were most highly correlated with DXA-measured FFM when the prediction equation included resistance quotient, bodyweight, and body condition score. At the population level, the inclusion of impedance as a predictor variable did not add substantially to the predictive power achieved with morphometric variables alone; in individual dogs, impedance predictors were more valuable than morphometric predictors. These results indicate that, following further validation, MFBIA could provide a useful tool in clinical practice to objectively measure FFM in canine patients and help improve compliance with prevention and treatment programs for obesity in dogs. PMID:27256027
Bioelectric impedance phase angle in breast carcinoma
Ruchi Tyagi
2014-01-01
Full Text Available Context: Worldwide breast cancer is the most frequently diagnosed life threatening cancer and the leading cause of death in women. Bioelectric impedance analysis (BIA affords an emerging opportunity to assess prognosis because of its ability to non invasively assess cell and plasma membrane structure and function by means of phase angle. Aims: To compare the phase angle between patients of breast cancer and their matched control with the help of BIA. Settings and Design: After taking clearance from ethical committee, a total of 34 female cases of histologically proven infiltrating ductal breast carcinoma were included from the surgery IPD, department of surgery. Equal numbers of the matched controls were recruited from the friends and relatives of cases. Materials and Methods: Bio Electrical Impedance Analyzer (BIA BODY STAT QUAD SCAN 4000 was used to measure resistance (R and reactance (Xc by recording a voltage drop in applied current. Phase angle is the ratio of reactance to resistance and is a measure of cell vitality. Statistical analysis used: Unpaired "t" test was applied. Results: In control group, the phase angle showed a mean of 5.479 whereas in test group, it showed a mean value of 4.726. The P value showed a significant difference (P < 0.0001. The smaller the phase angle values were higher was the tumor, nodes, metastases (TNM staging. The phase angles differed significantly from the healthy age matched control values. Conclusions: This study demonstrated that phase angle is a strong predictor of severity of breast cancer and differed significantly between the two groups.
Wang, Jing
2015-01-01
Electrical bioimpedance measurement is widely used today for monitoring body condition. The applications include and go beyond, body composition assessment, nutritional status evaluation, and cancer detection. The modalities for interpreting the impedance information have also developed quickly over the recent decades from single frequency bioimpedance analysis to spectrum and to images. Bioimpedance is measured by computing the relationship between voltage and current. In a current based bio...
Samoni, Sara; Vigo, Valentina; Reséndiz, Luis Ignacio Bonilla; Villa, Gianluca; De Rosa, Silvia; Nalesso, Federico; Ferrari, Fiorenza; Meola, Mario; Brendolan, Alessandra; Malacarne, Paolo; Forfori, Francesco; Bonato, Raffaele; Donadio, Carlo; Ronco, Claudio
2016-01-01
Background Studies have demonstrated a positive correlation between fluid overload (FO) and adverse outcomes in critically ill patients. The present study aims at defining the impact of hyperhydration on the Intensive Care Unit (ICU) mortality risk, comparing Bioelectrical Impedance Vector Analysis (BIVA) assessment with cumulative fluid balance (CFB) recording. Methods We performed a prospective, dual-centre, clinician-blinded, observational study of consecutive patients admitted to ICU with...
Hofsteenge, Geesje H.; Chinapaw, Mai JM; Weijs, Peter JM
2015-01-01
Background In clinical practice, patient friendly methods to assess body composition in obese adolescents are needed. Therefore, the bioelectrical impedance analysis (BIA) related fat-free mass (FFM) prediction equations (FFM-BIA) were evaluated in obese adolescents (age 11–18 years) compared to FFM measured by dual-energy x-ray absorptiometry (FFM-DXA) and a new population specific FFM-BIA equation is developed. Methods After an overnight fast, the subjects attended the outpatient clinic. Af...
Comparison of body fat in Brazilian adult females by bioelectrical impedance analysis
Body-fat is essential for human body, provided that its amount is at healthy levels. If in-excess body-fat is deleterious, its lack is otherwise also harmful. Estimated percent body-fat performed with commercially available devices measuring bioimpedance have many advantages, such as easy measurement and low cost. However, these measurements are based on standard models and equations that are not disclosed by manufacturers, and this leads to questioning the validity of these estimates for Brazilian females. The aim of this study was to compare electrical tetrapolar and octapolar impedance results obtained with commercially available equipment: Maltron BF-906 and OMRON 510-W. Data analysis involved descriptive and inferential statistics. Devices used in this study to estimate body fat quantity have not shown any significant differences in results; this is a major issue when selecting equipment based on three factors: study focus, available financial resources, and target population. Results obtained from the two devices have not shown any significant differences, which lead to the conclusion that either device may be reliably used.
Comparison of body fat in Brazilian adult females by bioelectrical impedance analysis
Altamir, Vaz; Frère, Slaets Annie France; Ramírez Leonardo, López
2012-12-01
Body-fat is essential for human body, provided that its amount is at healthy levels. If in-excess body-fat is deleterious, its lack is otherwise also harmful. Estimated percent body-fat performed with commercially available devices measuring bioimpedance have many advantages, such as easy measurement and low cost. However, these measurements are based on standard models and equations that are not disclosed by manufacturers, and this leads to questioning the validity of these estimates for Brazilian females. The aim of this study was to compare electrical tetrapolar and octapolar impedance results obtained with commercially available equipment: Maltron BF-906 and OMRON 510-W. Data analysis involved descriptive and inferential statistics. Devices used in this study to estimate body fat quantity have not shown any significant differences in results; this is a major issue when selecting equipment based on three factors: study focus, available financial resources, and target population. Results obtained from the two devices have not shown any significant differences, which lead to the conclusion that either device may be reliably used.
Chen, Kuen-Tsann; Chen, Yu-Yawn; Wang, Chia-Wei; Chuang, Chih-Lin; Chiang, Li-Ming; Lai, Chung-Liang; Lu, Hsueh-Kuan; Dwyer, Gregory B.; Chao, Shu-Ping; Shih, Ming-Kuei; Hsieh, Kuen-Chang
2016-01-01
Bioelectrical impedance analysis (BIA) is a common method for assessing body composition in research and clinical trials. BIA is convenient but when compared with other reference methods, the results have been inconclusive. The level of obesity degree in subjects is considered to be an important factor affecting the accuracy of the measurements. A total of 711 participants were recruited in Taiwan and were sub-grouped by gender and levels of adiposity. Regression analysis and Bland-Altman analysis were used to evaluate the agreement of the measured body fat percentage (BF%) between BIA and DXA. The BF% measured by the DXA and BIA methods (Tanita BC-418) were expressed as BF%DXA and BF%BIA8, respectively. A one-way ANOVA was used to test the differences in BF% measurements by gender and levels of adiposity. The estimated BF%BIA8 and BF%DXA in the all subjects, male and female groups were all highly correlated (r = 0.934, 0.901, 0.916, all P< 0.001). The average estimated BF%BIA8 (22.54 ± 9.48%) was significantly lower than the average BF%DXA (26.26 ± 11.18%). The BF%BIA8 was overestimated in the male subgroup (BF%DXA< 15%), compared to BF%DXA by 0.45%, respectively. In the other subgroups, the BF%BIA8 values were all underestimated. Standing BIA estimating body fat percentage in Chinese participants have a high correlation, but underestimated on normal and high obesity degree in both male and female subjects. PMID:27467065
Yerlikaya, Emrah; Karageçili, Hasan; Aydin, Ruken Zeynep
2016-04-01
Obesity is a key risk for the development of hyperglycemia, hypertension, hyperlipidemia, insulin resistance and is totally referred to as the metabolic disorders. Diabetes mellitus, a metabolic disorder, is related with hyperglycemia, altered metabolism of lipids, carbohydrates and proteins. The minimum defining characteristic feature to identify diabetes mellitus is chronic and substantiated elevation of circulating glucose concentration. In this study, it is aimed to determine the body composition analyze of obese and (obese+diabetes) patients.We studied the datas taken from three independent groups with the body composition analyzer instrument. The body composition analyzer calculates body parameters, such as body fat ratio, body fat mass, fat free mass, estimated muscle mass, and base metabolic rate on the basis of data obtained by Dual Energy X-ray Absorptiometry using Bioelectrical Impedance Analysis. All patients and healthy subjects applied to Siirt University Medico and their datas were taken. The Statistical Package for Social Sciences version 21 was used for descriptive data analysis. When we compared and analyzed three groups datas, we found statistically significant difference between obese, (obese+diabetes) and control groups values. Anova test and tukey test are used to analyze the difference between groups and to do multiple comparisons. T test is also used to analyze the difference between genders. We observed the statistically significant difference in age and mineral amount pcontrol group were analyzed, there were significant difference between most parameters. In terms of education level among the illiterate and university graduates; fat mass kg, fat percentage, internal lubrication, body mass index, water percentage, protein mass percentage, mineral percentage p<0.05, significant statistically difference were observed. This difference especially may result of a sedentary lifestyle.
Yerlikaya, Emrah; Karageçili, Hasan; Aydin, Ruken Zeynep
2016-04-01
Obesity is a key risk for the development of hyperglycemia, hypertension, hyperlipidemia, insulin resistance and is totally referred to as the metabolic disorders. Diabetes mellitus, a metabolic disorder, is related with hyperglycemia, altered metabolism of lipids, carbohydrates and proteins. The minimum defining characteristic feature to identify diabetes mellitus is chronic and substantiated elevation of circulating glucose concentration. In this study, it is aimed to determine the body composition analyze of obese and (obese+diabetes) patients.We studied the datas taken from three independent groups with the body composition analyzer instrument. The body composition analyzer calculates body parameters, such as body fat ratio, body fat mass, fat free mass, estimated muscle mass, and base metabolic rate on the basis of data obtained by Dual Energy X-ray Absorptiometry using Bioelectrical Impedance Analysis. All patients and healthy subjects applied to Siirt University Medico and their datas were taken. The Statistical Package for Social Sciences version 21 was used for descriptive data analysis. When we compared and analyzed three groups datas, we found statistically significant difference between obese, (obese+diabetes) and control groups values. Anova test and tukey test are used to analyze the difference between groups and to do multiple comparisons. T test is also used to analyze the difference between genders. We observed the statistically significant difference in age and mineral amount pdiabetes+obese) and obese groups. Besides, when these patient groups and control group were analyzed, there were significant difference between most parameters. In terms of education level among the illiterate and university graduates; fat mass kg, fat percentage, internal lubrication, body mass index, water percentage, protein mass percentage, mineral percentage p<0.05, significant statistically difference were observed. This difference especially may result of a sedentary
A previous study showed that reported BIA equations for body composition are not suitable for Colombian population. The purpose of this study was to develop and validate a preliminary BIA equation for body composition assessment in young females from Colombia, using hydrodensitometry as reference method. A sample of 30 young females was evaluated. Inclusion and exclusion criteria were defined to minimize the variability of BIA. Height, weight, BIA, residual lung volume (RV) and underwater weight (UWW) were measured. A preliminary BIA equation was developed (r2 = 0.72, SEE = 2.48 kg) by stepwise multiple regression with fat-free mass (FFM) as dependent variable and weight, height and impedance measurements as independent variables. The quality of regression was evaluated and a cross-validation against 50% of sample confirmed that results obtained with the preliminary BIA equation is interchangeable with results obtained with hydrodensitometry (r2 = 0.84, SEE = 2.62 kg). The preliminary BIA equation can be used for body composition assessment in young females from Colombia until a definitive equation is developed. The next step will be increasing the sample, including a second reference method, as deuterium oxide dilution (D2O), and using multi-frequency BIA (MF-BIA). It would also be desirable to develop equations for males and other ethnic groups in Colombia.
Caicedo-Eraso, J. C.; González-Correa, C. H.; González-Correa, C. A.
2013-04-01
A previous study showed that reported BIA equations for body composition are not suitable for Colombian population. The purpose of this study was to develop and validate a preliminary BIA equation for body composition assessment in young females from Colombia, using hydrodensitometry as reference method. A sample of 30 young females was evaluated. Inclusion and exclusion criteria were defined to minimize the variability of BIA. Height, weight, BIA, residual lung volume (RV) and underwater weight (UWW) were measured. A preliminary BIA equation was developed (r2 = 0.72, SEE = 2.48 kg) by stepwise multiple regression with fat-free mass (FFM) as dependent variable and weight, height and impedance measurements as independent variables. The quality of regression was evaluated and a cross-validation against 50% of sample confirmed that results obtained with the preliminary BIA equation is interchangeable with results obtained with hydrodensitometry (r2 = 0.84, SEE = 2.62 kg). The preliminary BIA equation can be used for body composition assessment in young females from Colombia until a definitive equation is developed. The next step will be increasing the sample, including a second reference method, as deuterium oxide dilution (D2O), and using multi-frequency BIA (MF-BIA). It would also be desirable to develop equations for males and other ethnic groups in Colombia.
Several studies have shown that the accuracy of BIA results depends of ethnicity, age, gender, hormonal and genetic variations and, so far, there are not specific equations for Colombian population. The purpose was to evaluate reported BIA equations to determine their usefulness in body composition assessment in young females from Colombia using hydrodensitometry as the reference method. A sample of 30 young females was evaluated. Inclusion and exclusion criteria were defined to minimize the variability of BIA. Height, weight, multi-frequency BIA, residual lung volume (RV) and underwater weight (UWW) were measured. Five BIA equations met the inclusion criteria of this study. Three equations overestimated and two equations underestimated body fat (BF). Paired Student t-test and Bland and Altman analysis (p<0.05) showed significant differences in four BIA equations. However, all standard error of estimate (SEE) to BF was greater than 2.7 kg. This study showed that the five selected BIA equations are not valid for estimation of body composition in young females from Colombia. It is recommended to develop BIA equations to improve BF fat assessment in our population.
Malnutrition in remission of childhood cancers as assessed by bioelectric impedance analysis
M. V. Konovalova
2014-07-01
Full Text Available The results of our cross-sectional bioimpedance study of children aged 7–17 years cured of cancer during follow-up (patients’ group, n = 552, remission time range 0–15 years and of age-matched healthy controls (n = 1,500 show significant intergroup differences in body height and body composition parameters. The most pronounced alterations in the patients’ group were observed in standardized values of phase angle reflecting a sharp decrease in the percentage of metabolically active body cell mass in fat-free mass. Malnutrition, judged from the prevalence of obesity and low phase angle, was observed in 52.7 % of our patients reaching a maximum of 76.8 % in a subgroup of children with CNS tumors. In view of known association that exists between malnutrition and reduced tolerance to chemotherapy, increased susceptibility to infections and adverse outcomes rate, we recommend using bioimpedance analysis in remission of childhood cancers in order to monitoring and timely correction of nutritional state as well as for prevention of delayed cardiovascular risks.
Smart Multi-Frequency Bioelectrical Impedance Spectrometer for BIA and BIVA Applications.
Harder, Rene; Diedrich, Andre; Whitfield, Jonathan S; Buchowski, Macie S; Pietsch, John B; Baudenbacher, Franz J
2016-08-01
Bioelectrical impedance analysis (BIA) is a noninvasive and commonly used method for the assessment of body composition including body water. We designed a small, portable and wireless multi-frequency impedance spectrometer based on the 12 bit impedance network analyzer AD5933 and a precision wide-band constant current source for tetrapolar whole body impedance measurements. The impedance spectrometer communicates via Bluetooth with mobile devices (smart phone or tablet computer) that provide user interface for patient management and data visualization. The export of patient measurement results into a clinical research database facilitates the aggregation of bioelectrical impedance analysis and biolectrical impedance vector analysis (BIVA) data across multiple subjects and/or studies. The performance of the spectrometer was evaluated using a passive tissue equivalent circuit model as well as a comparison of body composition changes assessed with bioelectrical impedance and dual-energy X-ray absorptiometry (DXA) in healthy volunteers. Our results show an absolute error of 1% for resistance and 5% for reactance measurements in the frequency range of 3 kHz to 150 kHz. A linear regression of BIA and DXA fat mass estimations showed a strong correlation (r(2)=0.985) between measures with a maximum absolute error of 6.5%. The simplicity of BIA measurements, a cost effective design and the simple visual representation of impedance data enables patients to compare and determine body composition during the time course of a specific treatment plan in a clinical or home environment. PMID:26863670
Bruni Vincenzina
2008-08-01
Full Text Available Abstract Background As weight gain is one of the most frequently cited reasons for not using and for discontinuing hormonal contraceptives, in an open-label, single-arm, multicentre clinical study we evaluated the effect of the ethinylestradiol/norelgestromin contraceptive patch (EVRA, Janssen-Cilag International, Belgium on body composition using bioelectrical impedance analysis (BIA. Methods Body weight and impedance vector components (resistance (R and reactance (Xc, at 50 kHz frequency, Akern-RJL Systems analyzer were recorded before entry, after 1, 3 and 6 months in 182 Italian healthy women aged 29 yr (18 to 45, and with BMI 21.8 kg/m2 (16 to 31. Total body water (TBW was estimated with a BIA regression equation. Vector BIA was performed with the RXc mean graph method and the Hotelling's T2 test for paired and unpaired data. Results After 6 months body weight increased by 0.64 kg (1.1% and TBW increased by 0.51 L (1.7%. The pattern of impedance vector displacement indicated a small increase in soft tissue hydration (interstitial gel fluid. Body composition changes did not significantly differ among groups of previous contraceptive methods. Arterial blood pressure did not significantly change over time. Conclusion After 6 months of treatment with the ethinylestradiol/norelgestromin contraceptive patch we found a minimal, clinically not relevant, increase in body weight less than 1 kg that could be attributed to an adaptive interstitial gel hydration. This fluctuation is physiological as confirmed by the lack of any effect on blood pressure. This could be useful in increasing women's choice, acceptability and compliance of the ethinylestradiol/norelgestromin contraceptive patch.
Is bioelectrical impedance accurate for use in large epidemiological studies?
Merchant Anwar T
2008-09-01
Full Text Available Abstract Percentage of body fat is strongly associated with the risk of several chronic diseases but its accurate measurement is difficult. Bioelectrical impedance analysis (BIA is a relatively simple, quick and non-invasive technique, to measure body composition. It measures body fat accurately in controlled clinical conditions but its performance in the field is inconsistent. In large epidemiologic studies simpler surrogate techniques such as body mass index (BMI, waist circumference, and waist-hip ratio are frequently used instead of BIA to measure body fatness. We reviewed the rationale, theory, and technique of recently developed systems such as foot (or hand-to-foot BIA measurement, and the elements that could influence its results in large epidemiologic studies. BIA results are influenced by factors such as the environment, ethnicity, phase of menstrual cycle, and underlying medical conditions. We concluded that BIA measurements validated for specific ethnic groups, populations and conditions can accurately measure body fat in those populations, but not others and suggest that for large epdiemiological studies with diverse populations BIA may not be the appropriate choice for body composition measurement unless specific calibration equations are developed for different groups participating in the study.
Wang, Lin; Hui, Stanley Sai-chuen; Wong, Stephen Heung-sang
2014-01-01
Background The current study aimed to examine the validity of various published bioelectrical impedance analysis (BIA) equations in estimating FFM among Chinese children and adolescents and to develop BIA equations for the estimation of fat-free mass (FFM) appropriate for Chinese children and adolescents. Material/Methods A total of 255 healthy Chinese children and adolescents aged 9 to 19 years old (127 males and 128 females) from Tianjin, China, participated in the BIA measurement at 50 kHz...
Sato, Susumu; Demura, Shinichi; Kitabayashi, Tamotsu; Noguchi, Takanori
2007-01-01
This study aimed to determine the accuracy of segmental body composition variables estimated by singlefrequency BIA with 8-point contact electrodes (SF-BIA8), compared with dual-energy X-ray absorptiometry (DXA). Subjects were 72 obese Japanese adults (43 males and 29 females) aged 30 to 66 years. Segmental body composition variables (fat free mass : FFM, fat mass : FM, and percent fat mass : %FAT) were measured by these techniques. The correlations between impedance values and FFM measured b...
Sen, Bandana; Mahalanabis, Dilip; Kurpad, Anura V; Shaikh, Saijuddin; Bose, Kaushik
2010-07-01
The association of early postnatal growth with diseases in adults such as hypertension, type 2 diabetes and CHD has generated interest in studying postnatal growth. Bioelectrical impedance analysis (BIA) is a useful measure to estimate total body water (TBW) and fat-free mass (FFM). We evaluated three published equations (Fjeld et al. (Pediatr Res (1990) 27, 98-102), Bocage (MSc Thesis (1988) University of West Indies) and Kushner et al. (Am J Clin Nutr (1992) 56, 835-839) to measure TBW and derived FFM based on BIA, using 2H2O dilution as a reference method for suitability in infants in India. In a cross-sectional study in seventy-eight apparently healthy infants aged 6-24 months from the urban poor attending an immunisation clinic at a hospital in Kolkata, we measured their length to the nearest 0.1 cm, weight to the nearest 10 g, resistance at 50 kHz using BIA and TBW using 2H2O dilution. TBW was derived using three published BIA-based equations and compared with TBW using 2H2O dilution. Based on the BIA equations of Fjeld et al., Bocage and Kushner et al., the mean TBW values were 2.46 % (P < 0.001), 4.62 % (P < 0.001) and 9.50 % (P < 0.001) lower than the reference 2H2O method, respectively. All three published BIA-based equations consistently underestimated the TBW and FFM and appeared inadequate for studying infants in India. The equation described by Fjeld et al. gave the smallest deviation from the reference method and may be used for field studies. New equations based on population-specific data are desirable for a more precise measure of TBW. PMID:20188001
Christensen, Rasmus Wibæk; Kæstel, Pernille; Skov, R.;
2015-01-01
noninvasive method for assessing BC. However, very little research has been conducted in low- and middle-income populations, where efforts to prevent or treat malnutrition in early life are a public health priority. We aimed to develop equations for predicting fat-free mass (FFM) and fat mass (FM) based on......, age and an impedance index (L(2)/Z50) were predictors. Prediction equations were developed using stepwise multiple linear regression and the accuracy was evaluated with a 10-fold cross-validation approach. RESULTS: A linear regression model based on body weight, age and sex predicted FFM, estimated by...... model fit for predicting FFM compared with a model already comprising weight, sex and age. CONCLUSIONS: The derived equations predicted FFM with acceptable accuracy and may be used in future field surveys, epidemiological studies and clinical trials conducted in similar sub-Saharan African population...
Rebecca Ricci
2010-01-01
Full Text Available In this preliminary study, BIVA has been performed on 17 healthy Italian Hound dogs, 10 males (M and 7 females (F, in order to verify if gender-related differences can be detected. Only in F higher reactance (Xc values (F: 46.4 vs M: 37.7, P<0.05 and a significant negative correlation (-0.80, P<0.05 between BCS and resistance (R values were detected. 50%, 75% and 95% tolerance ellipses were calculated both in M and F using average Xc and R values standardized for withers height. Probably due to the low number of subjects used in the present study, the variability of the individual vector distribution (F: 79.6 vs M: 53.0Ohm/m, as well as the mean impedance vector lengtht (F: 548.2 vs M: 498.9Ohm/m, were similar in F and M. The gender-related difference in phase angle values was not significant (F: 0.168 vs M: 0.157, P=ns. In conclusion, the use of BIVA in dogs indicated differences between males and females which should be confirmed by a larger number of subjects.
Rutherford, W. J.; Diemer, Gary A.; Scott, Eric D.
2011-01-01
Bioelectrical impedance analysis (BIA) is a widely used method for estimating body composition, yet issues concerning its validity persist in the literature. The purpose of this study was to validate percentage of body fat (BF) values estimated from BIA and skinfold (SF) with those obtained from hydrodensitometry (HD). Percent BF values measured…
Yılmaz, Süreyya; Yildirim, Yasar; Taylan, Mahsuk; Demir, Melike; Yilmaz, Zülfükar; Kara, Ali Veysel; Aydin, Fatma; Sen, Hadice Selimoglu; Karabulut, Aziz; Topcu, Fusun
2016-01-01
BACKGROUND Pulmonary arterial hypertension (PAH) is common disease among hemodialysis (HD) patients and is associated with increased morbidity and mortality. However, its pathogenesis has not been completely elucidated. We aimed to evaluate the frequency of PAH in HD patients, as well as the relationship between fluid status and PAH. MATERIAL AND METHODS We enrolled 77 HD patients in this study. Multifrequency bioimpedance analysis (BIA) was used to assess fluid status. BIA was performed before and 30 min after the midweek of HD. Overhydration (OH)/extracellular water (ECW)% ratio was used as an indicator of fluid status. Fluid overload was deﬁned as OH/ECW ≥7%. Echocardiographic examinations were performed before and after the HD. Pulmonary arterial hypertension was defined as systolic pulmonary artery pressure at rest (sPAP) higher than 35 mmHg. RESULTS PAH was found in 33.7% of the HD patients. OH/ECW and the frequency of fluid overload were significantly higher in HD patients with PAH than those without PAH, whereas serum albumin and hemoglobin levels were significantly lower. sPAP level was significantly higher in HD patients with fluid overload than in those without fluid overload after hemodialysis session. Furthermore, sPAP, OH/ECW levels, and the frequency of PAH were significantly reduced after HD. We also found a significant positive correlation between sPAP and OH/ECW. Multivariate logistic regression analysis demonstrated fluid overload to be an independent predictor of PAH after HD. CONCLUSIONS PAH is prevalent among HD patients. This study demonstrated a strong relationship between fluid overload and PAH in HD patients. PMID:26874785
Bindiya Rana
2012-10-01
Full Text Available The present cross-sectional study was carried out to find the association of percent body fat (PBF with blood pressure (BP variables among apparently healthy young females studying in Guru Nanak Dev University, Amritsar. A total of 150 females ranging in age from 20-25 years were personally interviewed. Height and weight of each subject was taken using standard methodology. Their body composition parameters were taken by using body fat analyzer. Subjects were categorized as obese and non-obese according to PBF, in which those having >30% body fat was considered as obese. BP of each subject was measured by using the standard methodology. The prevalence of hypertension was calculated according to JNC VII criteria. In the pooled data, the percentage prevalence of obesity according to PBF was 36%. The percentage prevalence of pre-hypertension and hypertension in the pooled sample was 54% and 12%, respectively. However, it was observed that prevalence of hypertension was slightly more among obese females (7.3% as compared to non-obese (4.7% but the prevalence of pre-hypertension was significantly (p<0.05 more in non-obese females (39.3% as compared to obese females (14.7%. The underline cause of this high prevalence of pre-hypertension in non-obese subjects was not known. It is clear from the correlation analysis that no association was observed between SBP and MAP with PBF in obese and non-obese subjects while DBP is positively and significantly (p<0.05 correlated with weight, fat mass and fat free mass in non-obese subjects only. Thus it is concluded from this study that PBF measured by BIA was not likely to be a good predictor of high BP. Therefore, further large prospective studies on the association of hypertension and whole body fat and abdominal fat should be carried out to confirm the role of fat on BP.
Valencia Mauro E
2007-08-01
Full Text Available Abstract Background The study of body composition in specific populations by techniques such as bio-impedance analysis (BIA requires validation based on standard reference methods. The aim of this study was to develop and cross-validate a predictive equation for bioelectrical impedance using air displacement plethysmography (ADP as standard method to measure body composition in Mexican adult men and women. Methods This study included 155 male and female subjects from northern Mexico, 20–50 years of age, from low, middle, and upper income levels. Body composition was measured by ADP. Body weight (BW, kg and height (Ht, cm were obtained by standard anthropometric techniques. Resistance, R (ohms and reactance, Xc (ohms were also measured. A random-split method was used to obtain two samples: one was used to derive the equation by the "all possible regressions" procedure and was cross-validated in the other sample to test predicted versus measured values of fat-free mass (FFM. Results and Discussion The final model was: FFM (kg = 0.7374 * (Ht2 /R + 0.1763 * (BW - 0.1773 * (Age + 0.1198 * (Xc - 2.4658. R2 was 0.97; the square root of the mean square error (SRMSE was 1.99 kg, and the pure error (PE was 2.96. There was no difference between FFM predicted by the new equation (48.57 ± 10.9 kg and that measured by ADP (48.43 ± 11.3 kg. The new equation did not differ from the line of identity, had a high R2 and a low SRMSE, and showed no significant bias (0.87 ± 2.84 kg. Conclusion The new bioelectrical impedance equation based on the two-compartment model (2C was accurate, precise, and free of bias. This equation can be used to assess body composition and nutritional status in populations similar in anthropometric and physical characteristics to this sample.
Knee bioelectric impedance assessment in healthy/with osteoarthritis subjects
The present study analyzes parameters estimated by bioelectric impedance spectroscopy (BIS) in subjects with healthy and with osteoarthritis (OA) knees. Thirty-two male volunteers, members of the Parachute Military Infantry Brigade of Rio de Janeiro, Brazil, participated in the study (62 knee joints). Clinical specialists used the Dejour scale for OA classification and divided the subjects into a control (without OA) and a pathological group (with different degrees of OA). BIS data were obtained in a standing position using a BIS technique based on the current response to a step voltage excitation. Differences between groups were measured by means of a Wilcoxon–Mann–Whitney test. Results indicate that raw bioimpedance parameters seem to be sensitive to the physiological changes associated with OA. Thus, data indicate that extra-cellular resistance (Re) and reactance of the equivalent capacitance (Xcx) increase according to the disease intensity (p < 0.001). In conclusion, the BIS technique seems to be able to provide the objective and non-invasive basis for helping the diagnosis of knee OA
Bioelectrical impedance spectroscopy in growth hormone-deficient adults
This study evaluated water compartment assessment by bioelectrical impedance spectroscopy (BIS) by Xitron 4000B in 164 growth hormone-deficient adults on growth hormone replacement therapy, examined the assumed constant body density and gender-specific resistivities in BIS methodology and evaluated a published BMI-adjusted BIS equation. Body composition was measured by BIS, total body potassium (TBK), tritium dilution and dual-energy x-ray absorptiometry (DXA). Tritium dilution and TBK were combined to a reference method for water compartments. Average difference for total body water (TBW) by tritium dilution and by BIS was 0.6 l in women (p > 0.05) and −0.2 l in men (p > 0.05). Average extracellular water (ECW) by the reference method and by BIS differed 1.5 l in women (p < 0.05) and 1.2 l in men (p < 0.05). Average intracellular water (ICW) by the reference method and by BIS differed −0.9 l in women (p < 0.05) and −1.3 l in men (p < 0.05). However, average ECW and ICW could be successfully estimated by BIS with use of unisex resistivity constants that were derived from this population, although with large individual variation. Average individual body density was lower than assumed. Application of individual body density did not improve agreement between methods. BMI-adjusted equations were not fully accurate in this population
Phase angle and bioelectrical impedance vectors in adolescent and adult male athletes.
Koury, Josely C; Trugo N, M F; Torres, Alexandre G
2014-09-01
The aim of the current study was to assess phase angle (PA) and bioelectrical impedance vectors (BIVA) in adolescent (n = 105, 12-19 y) and adult (n = 90, 20-50 y) male athletes practicing varied sports modalities. Bioelectrical impedance analysis (BIA) was performed with a single-frequency tetrapolar impedance analyzer after the athletes had fasted overnight for 8 h. PA and BIVA were determined from BIA data. PA presented correlations (P athletes and also with age in adolescent (r = .63) and adult (r = -.27) athletes. Compared with adults, adolescent athletes presented lower PA and higher frequency of PA below the 5th percentile of a reference population (P athletes were different (P athletes were in the 95th percentile of BIVA tolerance ellipses and in quadrants consistent with adequate body cell mass and total body water. The adolescent athletes outside the 95th percentile ellipse were all football and basketball players who showed indications of decreased water retention and body cell mass and of increased water retention, respectively. PA and BIVA ellipses showed that the intense training routine of the athletes changed functional and hydration parameters and that the magnitude of these changes in adolescents may depend on the sport modality practiced. PMID:24414089
Schols, A.M.; Wouters, E.F.; Soeters, P.B.; Westerterp, K.R. (Univ. of Limburg, Maastricht (Netherlands))
1991-02-01
Body composition is an important measure of nutritional status in patients with chronic obstructive pulmonary disease (COPD). We generated a regression model for bioelectrical impedance (BI) by using deuterium dilution (2H2O) as a reference method in 32 COPD patients, aged 63 +/- 9 y (mean +/- SD), in stable pulmonary and cardiac condition. Height squared divided by resistance (Ht2/Res) correlated well with total body water (TBW) as measured by 2H2O (r = 0.93, P less than 0.001, SEE = 1.9 L). The best-fitting regression equation to predict TBW comprised Ht2/Res and body weight (r2 = 0.89, SEE = 1.8 L, P less than 0.001). BI-predicted TBW was used to estimate BI-fat-free mass (FFM) that was compared with skinfold-thickness-based FFM predictions (Anthr-FFM). Relative to BI-FFM a significant overestimation of 4.4 +/- 0.8 kg was found by Anthr-FFM. Our results suggest that BI is a useful measure of body composition in patients with severe COPD.
Chittawatanarat K
2011-11-01
Full Text Available Kaweesak Chittawatanarat1,2, Sakda Pruenglampoo3, Siriphan Kongsawasdi4, Busaba Chuatrakoon4, Vibul Trakulhoon5, Winai Ungpinitpong6, Jayanton Patumanond21Department of Surgery, Faculty of Medicine, 2Clinical Epidemiology Unit, 3Research Institute for Health Sciences, 4Department of Physical Therapy, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, 5Department of Surgery, Bhumibol Adulyadej Hospital, Bangkok, 6Surgical Unit, Surin Hospital, Surin, ThailandBackground: The measurements of body mass index (BMI and percentage of body fat are used in many clinical situations. However, special tools are required to measure body fat. Many formulas are proposed for estimation but these use constant coefficients of age. Age spectrum might affect the predicted value of the body composition due to body component alterations, and the coefficient of age for body fat prediction might produce inconsistent results. The objective of this study was to identify variations of BMI and body fat across the age spectrum as well as compare results between BMI predicted body fat and bioelectrical impedance results on age.Methods: Healthy volunteers were recruited for this study. Body fat was measured by bioelectrical impedance. The age spectrum was divided into three groups (younger: 18–39.9; middle: 40–59.9; and older: ≥60 years. Comparison of body composition covariates including fat mass (FM, fat free mass (FFM, percentage FM (PFM, percentage FFM (PFFM, FM index (FMI and FFM index (FFMI in each weight status and age spectrum were analyzed. Multivariable linear regression coefficients were calculated. Coefficient alterations among age groups were tested to confirm the effect of the age spectrum on body composition covariates. Measured PFM and calculated PFM from previous formulas were compared in each quarter of the age spectrum.Results: A total of 2324 volunteers were included in this study. The overall body composition and weight
Mario Liani
2012-01-01
Full Text Available IntroductionAssessment of renal function based on quantification of the glomerular filtration rate (GFR is essential for early detection of damage and progression of renal diseases. The purpose of our study was to determine the value of cystatin C (Cys C assays in the calculation of the GFR and bioelectrical impedance analysis parameters in obese subjects aged 30-70 years with moderately damaged renal function.Materials and methodsCys C levels were measured with a new immunoturbidimetric kit (Roche Diagnostics and an automated Cobas c6000 analyzer. In the GFR calculation, creatinine and Cys C levels were included. The GFR calculated with the equation that included Cys C in obese and normal-weight patients is not affected by changes in the lean body mass.ResultsObese patients (N = 70 had a mean (± SD serum creatinine level of 1.52 ± 1.0 mg/dL and a mean Cys C level of 1.28 ± 0.59 mg/L. In this group, the GFR calculated on the basis of MDRD, Cys C, and creatinine clearance values showed similar filtered values between MDRD and Cys C and a DS value smaller in the case of Cys C. The correlation (R2 between GFR and its metabolite is higher in the case of Cys C when somatotype parameters (measured with bioelectrical impedance analysis were introduced into the equation.ConclusionsWhen Cys C is included in calculations of GFR, the result shows a higher correlation degree compared to the MDRD system. Given that Cys C shows less intra-individual variability than creatinine, it can be applied in routine diagnostics in a larger number of patients.
In the field of occupational health, health guidance concerning obesity is often conducted in order to prevent lifestyle-related diseases. With recent awareness of the concept of metabolic syndrome, measurement of the visceral fat area (VFA) by CT has been useful for health guidance, but it is difficult in workplace health screening. Presently, the BMI (Body Mass Index), body fat percentage measured by the bioelectrical impedance method, and waist girth at the umbilical level (abdominal girth) are practical indices of obesity used in such health screening. In this study, VAF was measured in 590 clerical or sales workers in the manufacturing industry using a body fat meter capable of a visceral fat measurement by the bioelectrical impedance method. The relationship of this value to the results of biochemical tests and lifestyle was then evaluated using analysis of covariance structures. Analysis indicated that the risk of lifestyle-related disease was closely related to the degree of obesity. Among indices of the degree of obesity, VFA was more closely related than BMI or body fat percentage, and only slightly less closely related than abdominal girth to the risk of lifestyle-related diseases. Since VFA is effective in screening for latent obesity, health guidance based on digital data, and the subjects' body imaging, its measurement by the bioelectrical impedance method is considered useful for workplace health management. (author)
Knechtle, B; A. Wirth; Knechtle, P; Rosemann, T; Rüst, C A; R. Bescós
2011-01-01
Two hundred and fifty seven male Caucasian ultraendurance athletes were recruited, pre-race, before different swimming, cycling, running and triathlon races. Fat mass and skeletal muscle mass were estimated using bioelectrical impedance analysis (BIA) and anthropometric methods in order to investigate whether the use of BIA or anthropometry would be useful under field conditions. Total body fat estimated using BIA was significantly high (P < 0.001) compared with anthropometry. When the result...
Pileggi, V N; Monteiro, J P; Margutti, A V B; Camelo, J S
2016-03-01
Malnutrition constitutes a major public health concern worldwide and serves as an indicator of hospitalized patients' prognosis. Although various methods with which to conduct nutritional assessments exist, large hospitals seldom employ them to diagnose malnutrition. The aim of this study was to understand the prevalence of child malnutrition at the University Hospital of the Ribeirão Preto Medical School, University of São, Brazil. A cross-sectional descriptive study was conducted to compare the nutritional status of 292 hospitalized children with that of a healthy control group (n=234). Information regarding patients' weight, height, and bioelectrical impedance (i.e., bioelectrical impedance vector analysis) was obtained, and the phase angle was calculated. Using the World Health Organization (WHO) criteria, 35.27% of the patients presented with malnutrition; specifically, 16.10% had undernutrition and 19.17% were overweight. Classification according to the bioelectrical impedance results of nutritional status was more sensitive than the WHO criteria: of the 55.45% of patients with malnutrition, 51.25% exhibited undernutrition and 4.20% were overweight. After applying the WHO criteria in the unpaired control group (n=234), we observed that 100.00% of the subjects were eutrophic; however, 23.34% of the controls were malnourished according to impedance analysis. The phase angle was significantly lower in the hospitalized group than in the control group (P<0.05). Therefore, this study suggests that a protocol to obtain patients' weight and height must be followed, and bioimpedance data must be examined upon hospital admission of all children. PMID:26840712
Bioelectrical impedance spectroscopy for the assessment of body fluid volumes of term neonates
Ferreira D.M.
2004-01-01
Full Text Available The assessment of fluid volume in neonates by a noninvasive, inexpensive, and fast method can contribute significantly to increase the quality of neonatal care. The objective of the present study was to calibrate an acquisition system and software to estimate the bioelectrical impedance parameters obtained by a method of bioelectrical impedance spectroscopy based on step response and to develop specific equations for the neonatal population to determine body fluid compartments. Bioelectric impedance measurements were performed by a laboratory homemade instrument. The volumes were estimated in a clinical study on 30 full-term neonates at four different times during the first month of life. During the first 24 hours of life the total body water, extracellular water and intracellular water were 2.09 ± 0.25, 1.20 ± 0.19, and 0.90 ± 0.25 liters, respectively. By the 48th hour they were 1.87 ± 0.27, 1.08 ± 0.17, and 0.79 ± 0.21 liters, respectively. On the 10th day they were 2.02 ± 0.25, 1.29 ± 0.21, and 0.72 ± 0.14 liters, respectively, and after 1 month they were 2.34 ± 0.27, 1.62 ± 0.20, and 0.72 ± 0.13 liters, respectively. The behavior of the estimated volume was correlated with neonatal body weight changes, leading to a better interpretation of such changes. In conclusion, this study indicates the feasibility of bioelectrical impedance spectroscopy as a method to help fluid administration in intensive care neonatal units, and also contribute to the development of new equations to estimate neonatal body fluid contents.
吴冬雪; 孟群; 沈颖
2014-01-01
目的：探讨生物电阻抗原理（bioelectrical impedance analysis, BIA）在评价慢性肾脏病儿童营养方面的临床应用价值。方法选取2009年至2011年期间就诊于北京儿童医院肾脏内科的单中心慢性肾脏病（chronic kid-ney disease, CKD）患儿57例（CKD组），同时选择健康儿童54例作为正常对照组。利用生物电阻抗原理对儿童进行人体成分（主要包括蛋白质、脂肪含量的测定）的评估及比较。结果 CKD组蛋白质相对含量为（14.72±2.44）%，正常对照组为（18.10±3.91）%，两组间差异有统计学意义（t=2.61，P=0.000）；CKD组脂肪相对含量为（24.31±12.52）%，显著高于正常对照组的（16.1±17.34）%，差异有统计学意义（t=3.89，P=0.000）；CKD1~2期患儿蛋白质相对含量为（34.57±7.39）%，CKD3~5期患儿含量为（41.08±5.53）%，两者比较差异有统计学意义（t=3.749，P=0.000）；CKD1~2期患儿相对脂肪含量为（28.73±12.50）%，CKD3~5期患儿含量为（16.13±7.52）%，其差异有统计学意义（t=-4.745，P=0.000）。 CKD组中47例（82.45%）处于营养成分失衡状态；在身高别体重提示营养状况良好的32例CKD患儿中25例（78.12%）存在营养成分不均衡。结论 CKD患儿存在蛋白质、脂肪等人体成分不均衡状态，个体化、针对性的营养管理对CKD患儿的营养状况改善有一定帮助。生物电阻抗原理对于评价CKD患儿营养状况有一定的临床应用价值。%Objectives To evaluate the nutritional status of children with chronic kidney disease(CKD) by bioelec-trical impedance analysis (BIA) and explore the value of BIA in assessing the nutritional status of children with CKD. Methods Fifty-seven patients with CKD who were hospitalized in Beijing Children's Hospital from 2009 to the end of 2011 were enrolled in this study. They were classified to be stages 1-5 according to the recommendation by the National Kidney
New concept of plethysmography instrumentation by means of bioelectrical impedance technology
Číp, Ondřej; Václavík, V.; Jurák, Pavel
Vídeň : Verlag der Technischen Universität Graz, 2002 - (Hutten, H.; Krösl, P.), s. 90 - 91 ISBN 3-901351-62-0. [EMBEC'02. Vídeň (AT), 04.12.2002-08.12.2002] R&D Projects: GA AV ČR IAB2065001; GA ČR GA102/02/1339 Institutional research plan: CEZ:AV0Z2065902 Keywords : bioelectrical impedance * pletysmography * digital signal processing Subject RIV: BH - Optics, Masers, Lasers
ANALYSIS OF INTERNALLY GENERATED NOISE OF BIOELECTRIC AMPLIFIERS
Mashhour Mustafa; Bani Amer
2003-01-01
This paper deals with internally generated noise of bioelectric amplifiers that are usually used for processing of bioelectric events. The main purpose of this paper is to present a procedure for analysis of the effects of internal noise generated by the active circuits and to evaluate the output noise of the author's new designed bioelectric amplifier that caused by internal effects to the amplifier circuit itself in order to compare it with the noise generated by conventional amplifiers. The obtained analysis results of internally generated noise showed that the total output noise of bioelectric active circuits does not increase when some of their resistors have a larger value. This behavior is caused by the different transfer functions for the signal and the respective noise sources associated with these resistors. Moreover, the new designed bioelectric amplifier has an output noise less than that for conventional amplifiers. The obtained analysis results were also experimentally verified and the final conclusions were drawn.
罗毅; 严志新; 汪立; 陈佳佳; 刘宁飞
2014-01-01
Objective To compare the accuracy of multi -frequency bioelectrical impedance analysis and the MoistureMeterD Compact to detect tissue edema in secondary lymphedema of upper limb. Methods Eighteen patients with secondary lymphedema after radical mastectomy, treated by manual lymph drainage, were randomly selected in this study. The measurement of circumference of upper limb was determined as standard, which had an correlation analysis with multi-frequency bioelectrical impedance analysis and MoistureMeterD Compact ’s results on tissue edema change. Results Accoring to the circumference change and the measured results of multi-frequency bioelectrical impedance analysis and the MoistureMeterD Compact, the degree of lymphedema was decreased after treatment. The multifrequency bioelectrical impedance’s test results had an relatively higher correlation (r=0.579, P<0.05) with the results of the standard, comparing to the results of the MoistureMeterD Compact (r=0.490, P<0.05). Conclusion Both multi-frequency bioelectrical impedance analysis and the MoistureMeterD Compact could be used for the measurement of lymphedema of upper limb, and multifrequency bioelectrical impedance analysis have an higher accuracy in the measurement of tissue edema.%目的：以周径测量结果为标准，比较多频生物电阻抗分析仪与接触式水分测量仪检测继发性上肢淋巴水肿的准确性。方法随机选取在我科进行淋巴手法引流治疗乳腺癌根治术后继发性上肢淋巴水肿患者18名，以周径测量获得的上肢增粗程度为标准，将多频生物电阻抗分析仪和接触式水分测量仪对组织水肿的检测结果，与周径改变进行相关性分析。结果患肢周径变化和两种水分测量的结果均显示患者治疗后水肿程度减轻。相比接触式水分测量仪的结果（r=0.490，P<0.05），多频生物电阻抗分析仪的测试结果（r=0.579，P<0.05）与周径测量结果相关性系数更高
Effects of skin blood flow and temperature on bioelectric impedance after exercise.
Liang, M T; Norris, S
1993-11-01
To examine the effects of increased skin blood flow (BFsk) and skin temperature (Tsk) on bioelectric impedance (BIA), 30 young males participated as subjects. All subjects underwent the following measurements: 1) BFsk and Tsk for the chest, biceps, thigh, and calf; 2) body composition using the BIA prediction equations and underwater weighting (UW); and 3) triceps skinfold (SFtri) thickness. After the baseline studies (M1) the subjects exercised for 30 min at approximately 83% of maximal heart rate. The above measurements were repeated immediately after exercise (M2), and at 1-h recovery from exercise (M3). Repeated measures ANOVA showed that mean Tsk and BFsk, and for the four measured sites were significantly increased from M1 to M2 (P measurement for resistance (R) and reactance between M1 and M2 (P > 0.05), and between M2 and M3 (P > 0.05). With regression analysis the following independent variables were identified as strong contributing factors for predicting fat-free mass (FFM): 1) SFtri and total body water for M1 and M3; and 2) WT, SFtri, and Tsk of the chest for M2. Two FFM equations have little multicolinearity (M1 and M2), e.g., they have low root mean square errors ( or = 0.94), and relatively low values for coefficient of variations (< or = 5.65%). Differences (P < 0.05) were observed between the UW method and the Lukasi equation for estimating FFM for M1 and M3, but not for M2.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8289609
Cleary, Jane; Daniells, Suzie; Okely, Anthony D; Batterham, Marijka; Nicholls, Jessie
2008-01-01
Bioelectrical impedance equations are frequently used by food and nutrition professionals to estimate percent fat mass in overweight and obese children. However, it is not known whether they are accurate for such children, as they have been primarily developed for children of varying body weights. The aim of this cross-sectional study was to evaluate the predictive validity of four previously published prediction equations developed for the pediatric population, among a sample of overweight and obese children. Thirty overweight or obese children (mean age=7.57+/-1.28 years) underwent measurement of fat mass, percent fat mass, and fat-free mass using dual-energy x-ray absorptiometry (DEXA) and bioelectrical impedance analysis (BIA). Impedance values from the BIA were entered into the four prediction equations and Pearson correlations used to determine the significance of associations between each of the BIA prediction equations and DEXA for percent fat mass, fat mass, and fat-free mass. For percent fat mass, paired t tests were used to assess differences between the methods and the technique of Bland and Altman was used to determine bias and error. Results showed that the mean percent fat mass as determined by DEXA for this age group was 40.79%. In comparison with other BIA prediction equations, the Schaefer equation had the closest mean value of 41.98%, and was the only equation not to significantly differ from the DEXA (P=0.121). This study suggests that the Schaefer equation is the only accurate BIA prediction equation for assessing percent fat mass in this sample of overweight and obese children from primarily white backgrounds. PMID:18156000
洪海兰; 王莲凤; 杨彩娟; 黄冬玲
2012-01-01
目的:应用生物电阻抗法(BIA)评估维持性血液透析(MHD)患者的营养状况,为临床采取有效的营养干预提供科学依据.方法:测量56例MHD患者与60名健康志愿者的体重(WT)、体质指数(BMI)、体脂肪量(FM)、瘦体重(LBM)(即非脂肪量FFM)和体脂肪率(Fat％),用描述性研究的方法分析不同的性别、年龄及BMI的MHD患者的人体成分.结果:MHD患者人体成分的各项参数值均显著低于健康志愿者.在体质指数无显著差异的前提下,男性MHD患者的FM和Fat％低于女性,≥45岁的MHD患者FM和Fat％明显高于＜45岁的患者.比较不同BMI的MHD患者的人体成分也存在显著差异.结论:应用BIA测定MHD患者的人体成分准确、无创、快捷,对有效评估MHD患者的营养状况有着重要意义.%Objective: Bioelectrical impedance analysis( BIA) was applied to assess nutritional status of maintenance hemodialysis patients( MHD) ,to provide a scientific basis for clinical effective nutrition intervention. Methods:56 cases of MHD patients and 60 healthy volunteers were involved,weight(WT) ,body mass index(BMI) ,fat mass(FM) ,lean body mass(LBM) (that is,fat -free mass,FFM)and body fat percentage were measured. Descriptive research method was used to analyze different gender, age and BMI in MHD patients of different body composition. Results:MHD patients of the body composition were significantly lower than healthy volunteers. Based tin ao significant difference in body mass index, FM and Fat % of male MHD patients were less than that of women, FM and Fat% of patients more than 45 years old were higher than that of the patients less than 45. Comparing the body composition among MHD patients with different BMI, there are significant differences. Conclusion-. Application of BIA in MHD patients was accurate,non - invasive and quick and it has important significance for assessment of the nutritional status of MHD patients.
Rohit Subhedar
2014-12-01
Full Text Available Enormous use of sophisticated technology in daily living has resulted in lifestyle disorders in form of obesity, hypertension, cardiac disorders and musculoskeletal problems in a community as a whole. This significant rise in physically unfit community prompted us to find a most cost-effective, simple, and reliable mode of physical fitness evaluation in form of Bioelectrical Impedance technology. An observational randomized experimental study was conducted at Multispecialty Department of Physiotherapy, Bombay Hospital-Indore-India. Tanita BC-418 working on the principle of Bioelectrical Impedance Technology was used for Body composition Analysis of 100 male and females with age group 40-50 years. Conclusion: BIA has proved to be an advanced diagnostic technology for evaluating human body fitness in today’s fast and rapidly advancing life style. The Body Composition Parameters important in evaluating physical fitness such as Body fat%, Fat Free Mass, Total Body Water%, BMR, segmental fat distribution can be easily assessed with this technique. Multi-frequency segmental Bioelectrical Impedance analysis identifies the Differences in segmental body fat% distribution and these differences signify the presence of regional pain, having musculoskeletal origin.
The mechanical function and size of a muscle may be closely linked. Handgrip strength (HGS) has been used as a predictor of functional performing. Anthropometric measurements have been made to estimate arm muscle area (AMA) and physical muscle mass volume of upper limb (ULMMV). Electrical volume estimation is possible by segmental BIA measurements of fat free mass (SBIA-FFM), mainly muscle-mass. Relationship among these variables is not well established. We aimed to determine if physical and electrical muscle mass estimations relate to each other and to what extent HGS is to be related to its size measured by both methods in normal or overweight young males. Regression analysis was used to determine association between these variables. Subjects showed a decreased HGS (65.5%), FFM, (85.5%) and AMA (74.5%). It was found an acceptable association between SBIA-FFM and AMA (r2 = 0.60) and poorer between physical and electrical volume (r2 = 0.55). However, a paired Student t-test and Bland and Altman plot showed that physical and electrical models were not interchangeable (pt2 = 0.07) and electrical (r2 = 0.192) ULMMV showing that muscle mass quantity does not mean muscle strength. Other factors influencing HGS like physical training or nutrition require more research.
Gonzalez-Correa, C. H.; Caicedo-Eraso, J. C.; Varon-Serna, D. R.
2013-04-01
The mechanical function and size of a muscle may be closely linked. Handgrip strength (HGS) has been used as a predictor of functional performing. Anthropometric measurements have been made to estimate arm muscle area (AMA) and physical muscle mass volume of upper limb (ULMMV). Electrical volume estimation is possible by segmental BIA measurements of fat free mass (SBIA-FFM), mainly muscle-mass. Relationship among these variables is not well established. We aimed to determine if physical and electrical muscle mass estimations relate to each other and to what extent HGS is to be related to its size measured by both methods in normal or overweight young males. Regression analysis was used to determine association between these variables. Subjects showed a decreased HGS (65.5%), FFM, (85.5%) and AMA (74.5%). It was found an acceptable association between SBIA-FFM and AMA (r2 = 0.60) and poorer between physical and electrical volume (r2 = 0.55). However, a paired Student t-test and Bland and Altman plot showed that physical and electrical models were not interchangeable (pt<0.0001). HGS showed a very weak association with anthropometric (r2 = 0.07) and electrical (r2 = 0.192) ULMMV showing that muscle mass quantity does not mean muscle strength. Other factors influencing HGS like physical training or nutrition require more research.
Bioelectrical impedance analysis--part I
Kyle, Ursula G; Bosaeus, Ingvar; De Lorenzo, Antonio D;
2004-01-01
fluid and electrolyte abnormalities, when using appropriate population, age or pathology-specific BIA equations and established procedures. Published BIA equations validated against a reference method in a sufficiently large number of subjects are presented and ranked according to the standard error of...... altered hydration states also requires further research. ESPEN guidelines for the clinical use of BIA measurements are described in a paper to appear soon in Clinical Nutrition....
Nielsen, Birgit Marie; Dencker, M; Ward, L;
2007-01-01
AIM: Predictive equations for estimating body composition from bioelectrical impedance analysis (BIA) among Scandinavian children are lacking. In the present study, equations for estimation of fat-free body mass (FFM) and lean tissue mass (LTM) were developed and cross-validated from BIA using dual...... linear regression and cross-validated against DXA measurements of body composition. RESULTS: FFM was predicted from BIA and anthropometric variables with an adjusted R(2)= 0.95 and root mean square error (RMSE) = 0.84 kg, and LTM was predicted with an adjusted R(2)= 0.95 and RMSE = 0.87 kg. Cross......-validation revealed a mean RMSE = 0.95 kg FFM and a mean RMSE = 0.96 kg LTM. Prediction of body composition from equations developed in previous literature was mixed when applied to the present cohort of children. CONCLUSIONS: FFM and LTM are predicted with sufficient accuracy at the population level. We recommend...
Guricci, S.; Hatriyanti, Y.; Hautvast, J.G.A.J.; Deurenberg, P.
1999-01-01
Three different adult Indonesian population groups living on Sumatra (Palembang), Java (Depok) and Sulawesi (Makale) participated in a study on body composition. Body weight, body height and multifrequency bioelectrical impedance (1, 5, 50 and 100 kHz) were measured and in addition total body water
Małecka-Massalska, Teresa; Mlak, Radoslaw; Smolen, Agata; Morshed, Kamal
2016-05-01
Malnutrition, which can be determined by subjective and objective methods, has a high prevalence in head and neck cancer patients. Subjective Global Assessment is a subjective method of nutritional status evaluation. Phase angle, determined by bioelectrical impedance analysis, is proposed as an objective nutritional marker in various disease conditions. The study was conducted to investigate the association between phase angle and Subjective Global Assessment to validate the determination of the nutrition status in adult patients with head and neck cancer. In a prospective cohort study, patients were classified as either well-nourished or malnourished using the Subjective Global Assessment. Phase angle measured by bioelectrical impedance analysis was planned in 75 naive patients with histologically confirmed head and neck cancer. Receiver operating characteristic curves were estimated using the non-parametric method to determine the optimal cut-off level of phase angle. The study was conducted on a cohort population of 75 patients. Well-nourished patients (n = 45) had a statistically significantly higher (p = 0.005) median phase angle score (5.25º) as compared to those who were malnourished (4.73º) (n = 30). A phase angle cut-off of 4.73 was 80 % sensitive and 56.7 % specific in detecting malnutrition diagnosed by SGA in these populations. Phase angle is considered to be a nutritional indicator in patients with head and neck cancer in detecting malnutrition. Further observations are needed to calculate survival, and validate the prognostic significance of phase angle. For future studies, it is important to indicate the specificity of the PA in comparison to SGA measurement. PMID:25859939
The purpose of this study is to compare measurement errors in two commercially available multi-frequency bioimpedance analyzers, a Xitron 4000B and an ImpediMed SFB7, including electrode impedance mismatch. The comparison was made using resistive electrical models and in ten human volunteers. We used three different electrical models simulating three different body segments: the right-side, leg and thorax. In the electrical models, we tested the effect of the capacitive coupling of the patient to ground and the skin–electrode impedance mismatch. Results showed that both sets of equipment are optimized for right-side measurements and for moderate skin–electrode impedance mismatch. In right-side measurements with mismatch electrode, 4000B is more accurate than SFB7. When an electrode impedance mismatch was simulated, errors increased in both bioimpedance analyzers and the effect of the mismatch in the voltage detection leads was greater than that in current injection leads. For segments with lower impedance as the leg and thorax, SFB7 is more accurate than 4000B and also shows less dependence on electrode mismatch. In both devices, impedance measurements were not significantly affected (p > 0.05) by the capacitive coupling to ground
Drug and bioactive molecule screening based on a bioelectrical impedance cell culture platform
Ramasamy S
2014-12-01
Full Text Available Sakthivel Ramasamy,1 Devasier Bennet,1 Sanghyo Kim1,2 1Department of Bionanotechnology, Gachon University, Gyeonggi-Do, Republic of Korea; 2Graduate Gachon Medical Research Institute, Gil Medical Center, Incheon, Republic of Korea Abstract: This review will present a brief discussion on the recent advancements of bioelectrical impedance cell-based biosensors, especially the electric cell-substrate impedance sensing (ECIS system for screening of various bioactive molecules. The different technical integrations of various chip types, working principles, measurement systems, and applications for drug targeting of molecules in cells are highlighted in this paper. Screening of bioactive molecules based on electric cell-substrate impedance sensing is a trial-and-error process toward the development of therapeutically active agents for drug discovery and therapeutics. In general, bioactive molecule screening can be used to identify active molecular targets for various diseases and toxicity at the cellular level with nanoscale resolution. In the innovation and screening of new drugs or bioactive molecules, the activeness, the efficacy of the compound, and safety in biological systems are the main concerns on which determination of drug candidates is based. Further, drug discovery and screening of compounds are often performed in cell-based test systems in order to reduce costs and save time. Moreover, this system can provide more relevant results in in vivo studies, as well as high-throughput drug screening for various diseases during the early stages of drug discovery. Recently, MEMS technologies and integration with image detection techniques have been employed successfully. These new technologies and their possible ongoing transformations are addressed. Select reports are outlined, and not all the work that has been performed in the field of drug screening and development is covered. Keywords: screening of bioactive agents, impedance-based cell
Bogónez Franco, Francisco; Nescolarde Selva, Lexa Digna; Bragós Bardia, Ramon; Rosell Ferrer, Francisco Javier; Yandiola, Iñigo
2009-01-01
The purpose of this study is to compare measurement errors in two commercially available multi-frequency bioimpedance analyzers, a Xitron 4000B and an ImpediMed SFB7, including electrode impedance mismatch. The comparison was made using resistive electrical models and in ten human volunteers. We used three different electrical models simulating three different body segments: the right-side, leg and thorax. In the electrical models, we tested the effect of the capacitive coupling of the ...
A novel bioelectrical impedance spectroscopy system based on the digital auto-balancing bridge method improved from the conventional analogue auto-balancing method is presented for bioelectrical impedance measurements. The hardware of the proposed system consists of a reference source, a null detector, a variable source, a field programmable gate array, a clock generator, a flash and a USB controller. Software implemented in the field programmable gate array includes three major blocks: clock management, peripheral control and digital signal processing. The principle and realization of the least-mean-squares-based digital auto-balancing algorithm is introduced in detail. The performances of our system were examined by comparing with a commercial impedance analyzer. The results reveal that the proposed system has high speed (less than 3.5 ms per measurement) and high accuracy in the frequency range of 1 kHz–10 MHz. Compared with the commercial instrument based on the traditional analogue auto-balancing method, our system shows advantages in measurement speed, compactness and flexibility, making it suitable for various bioelectrical impedance measurement applications. (paper)
Li, Nan; Xu, Hui; Wang, Wei; Zhou, Zhou; Qiao, Guofeng; D-U Li, David
2013-06-01
A novel bioelectrical impedance spectroscopy system based on the digital auto-balancing bridge method improved from the conventional analogue auto-balancing method is presented for bioelectrical impedance measurements. The hardware of the proposed system consists of a reference source, a null detector, a variable source, a field programmable gate array, a clock generator, a flash and a USB controller. Software implemented in the field programmable gate array includes three major blocks: clock management, peripheral control and digital signal processing. The principle and realization of the least-mean-squares-based digital auto-balancing algorithm is introduced in detail. The performances of our system were examined by comparing with a commercial impedance analyzer. The results reveal that the proposed system has high speed (less than 3.5 ms per measurement) and high accuracy in the frequency range of 1 kHz-10 MHz. Compared with the commercial instrument based on the traditional analogue auto-balancing method, our system shows advantages in measurement speed, compactness and flexibility, making it suitable for various bioelectrical impedance measurement applications.
ANALYSIS OF INTERNALLY GENERATED NOISE OF BIOELECTRIC AMPLIFIERS
MashhourMustafaBaniAmer
2003-01-01
This papenr deals with internally generated noise of bioelectric amplifiers that are usually used for processing of bioelectric events.The main purpose of this paper is to present a procedure for analysis of the effects of internal noise generated by the active circuits and to evaluate the output noise of the author's new designed bioelectric amplifier that caused by internal effects to the amplifier circuit itself in order to compare it with the noise generated by conventional amplifiers.The obtained analysis results of internally generated noise showed that the total output noise of bioelectric active circuits does not increase when some of their resitors have a larger value.This behavior is caused by the different transfer functions for the signal and the respective noise sources associated with these resistors.Moreover,the new designed bioelectric amplifier haws an output noise less than that for conventional amplifiers.The obtained analysis results were also experimentally verified and the final conclusions were drawn.
Ridner, Sheila H.; Shih, Ya-Chen Tina; Doersam, Jennifer K.; Rhoten, Bethany Andrews; Schultze, Benjamin S.; Dietrich, Mary S.
2014-01-01
Background: Less than half of breast cancer survivors with lymphedema perform self-care as directed. Effective lymphedema self-care is required to obtain acceptable health outcomes. Self-Regulation Theory suggests that objective self-measurement of physiological conditions is necessary to promote self-regulation/self-care. Bioelectric Impedance Spectroscopy (BIS) represents a potential self-measurement method for arm lymphedema. The purpose of this pilot study was to examine the impact of arm...
Sawant, Anuradha; House, Andrew A; Chesworth, Bert M.; Connelly, Denise M.; Lindsay, Robert; Gati, Joe; Bartha, Robert; Overend, Tom J.
2015-01-01
Abstract Establishing the effect of fluctuating extracellular fluid (ECF) volume on muscle strength in people with end‐stage renal disease (ESRD) on hemodialysis (HD) is essential, as inadequate hydration of the skeletal muscles impacts its strength and endurance. Bioelectrical impedance spectroscopy (BIS) has been a widely used method for estimating ECF volume of a limb or calf segment. Magnetic resonance imaging (MRI)‐acquired transverse relaxation times (T 2) has also been used for estimat...
Anuradha Sawant; House, Andrew A; Chesworth, Bert M.; Joseph Gati; Robert Lindsay; Connelly, Denise M.; Robert Bartha; Overend, Tom J.
2013-01-01
Purpose. The purpose of this study was to investigate the test-retest reliability, relative variability, and agreement between calf bioelectrical impedance-spectroscopy (cBIS) acquired extracellular fluid (ECF), intracellular fluid (ICF), total water and the ratio of ECF : ICF, magnetic-resonance-imaging (MRI) acquired transverse relaxation times (T2), and apparent diffusion coefficient (ADC) of calf muscles of the same segment in healthy individuals. Methods. Muscle hydration measures were c...
Masae Miyatani; Pearl Yang; Scott Thomas; Catharine Craven, B.; Paul Oh
2012-01-01
We aimed to compare the level of agreement between leg-to-leg bioelectrical impedance analysis (LBIA) and dual-energy X-ray absorptiometry (DXA) for assessing changes in body composition following exercise intervention among individuals with Type 2 diabetes mellitus (T2DM). Forty-four adults with T2DM, age 53.2 ± 9.1 years; BMI 30.8 ± 5.9 kg/m2 participated in a 6-month exercise program with pre and post intervention assessments of body composition. Fat free mass (FFM), % body fat (%FM) and f...
Swartz, Ann M; Swartz, Ann M; Jeremy Evans, M; King, George A; Thompson, Dixie L
2002-08-01
The Tanita TBF-305 (Tanita Corp., Tokyo, Japan) is a commercially available foot-to-foot bioelectrical impedance analysis (BIA) system. The manufacturer-supplied equations incorporate gender, mass, height, activity category and a measured impedance value to determine % body fat (BF). The purpose of the present study was to determine whether the manufacturer-supplied 'adult' and 'athlete' equations provided an accurate estimate of % BF for a group of young men with varying activity levels. Fifty-seven men (18-35 years old) were categorized into the following groups: (1) highly active (HA) (> or = 10.0 h aerobic activity/week); (2) moderately active (MA) (2.5-10.0 h aerobic activity/week); (3) less active (LA) (aerobic activity/week). The % BF was measured using the BIA 'athlete' and 'adult' modes. After BIA measurements, residual volume was measured and hydrostatic weighing (HW) was performed. The amount of activity performed by each group was significantly different (P<0.001). No significant differences were found between the % BF determined by the 'athlete' mode and HW for HA (P=0.309) and MA (P=0.091). However, a significant difference was found for LA (P=0.001). The % BF determined by the 'adult' mode and HW was not different for LA (P=0.395), but was significantly different for MA (P<0.001) and HA (P<0.001). The choice of activity mode on the foot-to-foot BIA significantly alters prediction of % BF. With careful selection of activity mode, there was no statistical difference between % BF determined by HW and the BIA, but the range of individual error scores was large. PMID:12144724
C.M.M. Resende
2011-11-01
Full Text Available The objectives of the present study were to describe and compare the body composition variables determined by bioelectrical impedance (BIA and the deuterium dilution method (DDM, to identify possible correlations and agreement between the two methods, and to construct a linear regression model including anthropometric measures. Obese adolescents were evaluated by anthropometric measures, and body composition was assessed by BIA and DDM. Forty obese adolescents were included in the study. Comparison of the mean values for the following variables: fat body mass (FM; kg, fat-free mass (FFM; kg, and total body water (TBW; % determined by DDM and by BIA revealed significant differences. BIA overestimated FFM and TBW and underestimated FM. When compared with data provided by DDM, the BIA data presented a significant correlation with FFM (r = 0.89; P < 0.001, FM (r = 0.93; P < 0.001 and TBW (r = 0.62; P < 0.001. The Bland-Altman plot showed no agreement for FFM, FM or TBW between data provided by BIA and DDM. The linear regression models proposed in our study with respect to FFM, FM, and TBW were well adjusted. FFM obtained by DDM = 0.842 x FFM obtained by BIA. FM obtained by DDM = 0.855 x FM obtained by BIA + 0.152 x weight (kg. TBW obtained by DDM = 0.813 x TBW obtained by BIA. The body composition results of obese adolescents determined by DDM can be predicted by using the measures provided by BIA through a regression equation.
Grutsch James F
2008-06-01
Full Text Available Abstract Background Bioelectrical Impedance (BIA derived phase angle is increasingly being used as an objective indicator of nutritional status in advanced cancer. Subjective Global Assessment (SGA is a subjective method of nutritional status. The objective of this study was to investigate the association between BIA derived phase angle and SGA in advanced colorectal cancer. Methods We evaluated a case series of 73 stages III and IV colorectal cancer patients. Patients were classified as either well-nourished or malnourished using the SGA. BIA was conducted on all patients and phase angle was calculated. The correlation between phase angle and SGA was studied using Spearman correlation coefficient. Receiver Operating Characteristic curves were estimated using the non-parametric method to determine the optimal cut-off levels of phase angle. Results Well-nourished patients had a statistically significantly higher (p = 0.005 median phase angle score (6.12 as compared to those who were malnourished (5.18. The Spearman rank correlation coefficient between phase angle and SGA was found to be 0.33 (p = 0.004, suggesting better nutritional status with higher phase angle scores. A phase angle cut-off of 5.2 was 51.7% sensitive and 79.5% specific whereas a cut-off of 6.0 was 82.8% sensitive and 54.5% specific in detecting malnutrition. Interestingly, a phase angle cut-off of 5.9 demonstrated high diagnostic accuracy in males who had failed primary treatment for advanced colorectal cancer. Conclusion Our study suggests that bioimpedance phase angle is a potential nutritional indicator in advanced colorectal cancer. Further research is needed to elucidate the optimal cut-off levels of phase angle that can be incorporated into the oncology clinic for better nutritional evaluation and management.
Ejlerskov, Katrine Tschentscher; Jensen, Signe Marie; Christensen, Line B;
2014-01-01
For 3-year-old children suitable methods to estimate body composition are sparse. We aimed to develop predictive equations for estimating fat-free mass (FFM) from bioelectrical impedance (BIA) and anthropometry using dual-energy X-ray absorptiometry (DXA) as reference method using data from 99......-validation approach. Prediction error of FFM was 3.0% for both equations (root mean square error: 360 and 356 g, respectively). The derived equations produced BIA-based prediction of FFM and FM near DXA scan results. We suggest that the predictive equations can be applied in similar population samples aged 2-4 years...
Kerr, Ava; Slater, Gary; Byrne, Nuala; Chaseling, Janet
2015-10-01
The three-compartment (3-C) model of physique assessment (fat mass, fat-free mass, water) incorporates total body water (TBW) whereas the two-compartment model (2-C) assumes a TBW of 73.72%. Deuterium dilution (D2O) is the reference method for measuring TBW but is expensive and time consuming. Multifrequency bioelectrical impedance spectroscopy (BIS SFB7) estimates TBW instantaneously and claims high precision. Our aim was to compare SFB7 with D2O for estimating TBW in resistance trained males (BMI >25kg/m2). We included TBWBIS estimates in a 3-C model and contrasted this and the 2-C model against the reference 3-C model using TBWD2O. TBW of 29 males (32.4 ± 8.5 years; 183.4 ± 7.2 cm; 92.5 ± 9.9 kg; 27.5 ± 2.6 kg/m2) was measured using SFB7 and D2O. Body density was measured by BODPOD, with body composition calculated using the Siri equation. TBWBIS values were consistent with TBWD2O (SEE = 2.65L; TE = 2.6L) as were %BF values from the 3-C model (BODPOD + TBWBIS) with the 3-C reference model (SEE = 2.20%; TE = 2.20%). For subjects with TBW more than 1% from the assumed 73.72% (n = 16), %BF from the 2-C model differed significantly from the reference 3-C model (Slope 0.6888; Intercept 5.093). The BIS SFB7 measured TBW accurately compared with D2O. The 2C model with an assumed TBW of 73.72% introduces error in the estimation of body composition. We recommend TBW should be measured, either via the traditional D2O method or when resources are limited, with BIS, so that body composition estimates are enhanced. The BIS can be accurately used in 3C equations to better predict TBW and BF% in resistance trained males compared with a 2C model. PMID:26011918
Nightingale, Claire M; Rudnicka, Alicja R; Owen, Christopher G; Donin, Angela S.; Newton, Sian L.; Furness, Cheryl A.; Emma L Howard; Gillings, Rachel D.; Jonathan C K Wells; Cook, Derek G.; Whincup, Peter H.
2013-01-01
BACKGROUND: Bioelectrical impedance analysis (BIA) is a potentially valuable method for assessing lean mass and body fat levels in children from different ethnic groups. We examined the need for ethnic- and gender-specific equations for estimating fat free mass (FFM) from BIA in children from different ethnic groups and examined their effects on the assessment of ethnic differences in body fat. METHODS: Cross-sectional study of children aged 8-10 years in London Primary schools including 325 ...
柴林燕; 赵舒; 沙洪
2011-01-01
Objective The Hilbert- Huang transformation (HHT) method was introduced to process the bio-impedance gastric motility signals from subjects.Methods Nonlinear and non-stationary original gastric motility series were decomposed into a number of intrinsic mode function (1MF) components by the empirical mode decomposition method (EMD).Hilbert transformation was carried out then and instantaneous frequency was extracted effectively.Gastric motility signal among 0.03-0.06 Hz was reconstructed from the IMF.Results The results suggested that HHT was a new and applicable time series analysis method based on mode decomposition and could extract impedance signal and remove the disturbances such as blood flow and breathing.Conclusion The new adaptive mode decomposition-based signal processing method provides a new method to investigate clinical gastric motility information.%目的 采用HHT时间序列分析方法处理从人体采集到的胃动力信号.方法 通过经验模态分解(EMD)技术将一非线性、非稳态过程的原始胃动力序列分解为一组内在模态函数(IMFs),对每一个IMF进行Hilbert 变换,得到信号的瞬时频率,然后选择与胃动力相关的频率成分,即0.03-0.06 Hz之间的IMF进行重构提取胃动力信号.结果 使用该方法可以有效去除叠加在阻抗胃动力信号中的呼吸和血流等干扰信号,保留胃动力信号的有效频率成分.结论 此方法是一种更具有自适应的、新型的、基于模态分解的时间序列数据处理方法,可以有效地为临床胃动力信息研究提供一种新途径.
Bioelectrical impedance spectroscopy as a fluid management system in heart failure
Episodes of hospitalization for heart failure patients are frequent and are often accompanied by fluid accumulations. The change of the body impedance, measured by bioimpendace spectroscopy, is an indicator of the water content. The hypothesis was that it is possible to detect edema from the impedance data. First, a finite integration technique was applied to test the feasibility and allowed a theoretical analysis of current flows through the body. Based on the results of the simulations, a clinical study was designed and conducted. The segmental impedances of 25 patients suffering from heart failure were monitored over their recompensation process. The mean age of the patients was 73.8 and their mean body mass index was 28.6. From these raw data the model parameters from the Cole model were deduced by an automatic fitting algorithm. These model data were used to classify the edema status of the patient. The baseline values of the regression lines of the extra- and intracellular resistance from the transthoracic measurement and the baseline value of the regression line of the extracellular resistance from the foot-to-foot measurement were identified as important parameters for the detection of peripheral edema. The rate of change of the imaginary impedance at the characteristic frequency and the mean intracellular resistance from the foot-to-foot measurement were identified as important parameters for the detection of pulmonary edema. To classify the data, two decision trees were considered: One should detect pulmonary edema (npulmonary = 13, nnone = 12) and the other peripheral edema (nperipheral = 12, nnone = 13). Peripheral edema could be detected with a sensitivity of 100% and a specificity of 90%. The detection of pulmonary edema showed a sensitivity of 92.31% and a specificity of 100%. The leave-one-out cross-validation-error for the peripheral edema detection was 12% and 8% for the detection of pulmonary edema. This enables the application of BIS as an early
Single-cell bioelectrical impedance platform for monitoring cellular response to drug treatment
Asphahani, Fareid; Wang, Kui; Thein, Myo; Veiseh, Omid; Yung, Sandy; Xu, Jian; Zhang, Miqin
2011-01-01
The response of cells to a chemical or biological agent in terms of their impedance changes in real-time is a useful mechanism that can be utilized for a wide variety of biomedical and environmental applications. The use of a single-cell based analytical platform could be an effective approach to acquiring more sensitive cell impedance measurements, particularly in applications where only diminutive changes in impedance are expected. Here, we report the development of an on-chip cell impedanc...
Masaharu Kagawa
2014-05-01
Full Text Available The aim of the study was to examine differences in total body water (TBW measured using single-frequency (SF and multi-frequency (MF modes of bioelectrical impedance spectroscopy (BIS in children and adults measured in different postures using the deuterium (2H dilution technique as the reference. Twenty-three boys and 26 adult males underwent assessment of TBW using the dilution technique and BIS measured in supine and standing positions using two frequencies of the SF mode (50 kHz and 100 kHz and the MF mode. While TBW estimated from the MF mode was comparable, extra-cellular fluid (ECF and intra-cellular fluid (ICF values differed significantly (p < 0.01 between the different postures in both groups. In addition, while estimated TBW in adult males using the MF mode was significantly (p < 0.01 greater than the result from the dilution technique, TBW estimated using the SF mode and prediction equation was significantly (p < 0.01 lower in boys. Measurement posture may not affect estimation of TBW in boys and adult males, however, body fluid shifts may still occur. In addition, technical factors, including selection of prediction equation, may be important when TBW is estimated from measured impedance.
Milivoj Dopsaj
2012-12-01
Full Text Available Because of the specificity of given sport and weight categories wrestlers are characterized by specific morphologic characteristics. With the development of new measurement technologies there are some new opportunities for the development of new ways of obtaining information relevant to the sports system. One of the new technologies, which are used in area of measurement of body composition structure, is a method of bioimpedace, and the latest generations use a variant of the multichannel bioelectrical bioimpedance. The goal of this study is to define morphological model of top senior wrestlers by using the latest technological methods that will revalidate the existing knowledge about the given area. The sample of respondents is made of 22 male wrestlers, Greco-Roman style, top senior level athletes from four different countries: Serbia (n = 10, Croatia (n = 9, Montenegro (n = 2 and Greece (n = 1. Measurement of body composition is made with method of multichannel bioelectric impedance with professional apparatus of latest generation - InBody 720 Tetrapolar 8-Point Tactile Electrode System (Biospace, Co., Ltd. The most important result of this research is definition of generic (general four-dimensional model (4D model of body composition with quality international level wrestlers with following characteristics: in regards to average body mass of sample wrestlers – 81.95 kg, the amount of water is 55.08 L or 67.24 %, the amount of proteins is 15.00 kg or 18.33%, minerals 4.98 kg or 5.97% and fat mass 6.99 kg or 8.49 %.
Single-cell bioelectrical impedance platform for monitoring cellular response to drug treatment
The response of cells to a chemical or biological agent in terms of their impedance changes in real-time is a useful mechanism that can be utilized for a wide variety of biomedical and environmental applications. The use of a single-cell-based analytical platform could be an effective approach to acquiring more sensitive cell impedance measurements, particularly in applications where only diminutive changes in impedance are expected. Here, we report the development of an on-chip cell impedance biosensor with two types of electrodes that host individual cells and cell populations, respectively, to study its efficacy in detecting cellular response. Human glioblastoma (U87MG) cells were patterned on single- and multi-cell electrodes through ligand-mediated natural cell adhesion. We comparatively investigated how these cancer cells on both types of electrodes respond to an ion channel inhibitor, chlorotoxin (CTX), in terms of their shape alternations and impedance changes to exploit the fine detectability of the single-cell-based system. The detecting electrodes hosting single cells exhibited a significant reduction in the real impedance signal, while electrodes hosting confluent monolayer of cells showed little to no impedance change. When single-cell electrodes were treated with CTX of different doses, a dose-dependent impedance change was observed. This enables us to identify the effective dose needed for this particular treatment. Our study demonstrated that this single-cell impedance system may potentially serve as a useful analytical tool for biomedical applications such as environmental toxin detection and drug evaluation
Increases in total body water (TBW) are typical of late-stage pregnancy. Because excessive TBW expansion or contraction can lead to adverse outcomes, a safe non-invasive method for routine assessment of TBW would be useful clinically. Impedance vectors are derived from resistance (R) and reactance...
Anuradha Sawant
2013-01-01
Full Text Available Purpose. The purpose of this study was to investigate the test-retest reliability, relative variability, and agreement between calf bioelectrical impedance-spectroscopy (cBIS acquired extracellular fluid (ECF, intracellular fluid (ICF, total water and the ratio of ECF : ICF, magnetic-resonance-imaging (MRI acquired transverse relaxation times (T2, and apparent diffusion coefficient (ADC of calf muscles of the same segment in healthy individuals. Methods. Muscle hydration measures were collected in 32 healthy individuals on two occasions and analyzed by a single rater. On both occasions, MRI measures were collected from tibialis anterior (TA, medial (MG, and lateral gastrocnemius (LG and soleus muscles following the cBIS data acquired using XiTRON Hydra 4200 BIS device. The intraclass correlation coefficients (ICC2,1, coefficient of variation (CV, and agreement between MRI and cBIS data were also calculated. Results. ICC2,1 values for cBIS, T2, and ADC ranged from 0.56 to 0.92, 0.96 to 0.99, and 0.05 to 0.56, respectively. Relative variability between measures (CV ranged from 14.6 to 25.6% for the cBIS data and 4.2 to 10.0% for the MRI-acquired data. The ratio of ECF : ICF could significantly predict T2 of TA and soleus muscles. Conclusion. MRI-acquired measures of T2 had the highest test-retest reliability of muscle hydration with the least error and variation on repeated testing. Hence, T2 of a muscle is the most reliable and stable outcome measure for evaluating individual muscle hydration.
Use of electrocardiogram (ECG) electrodes for Bioelectrical Impedance Analysis (BIA)
BIA is a safe, noninvasive, portable and relatively inexpensive method of estimating body composition that is practical and suitable for individual use and large-scale studies. However, the cost of the electrodes recommended by some BIA manufacturers is too high for developing countries; where very often the long and complicated process of importation reduces the time they can be used. The purpose of this study was to evaluate the use of two types of ECG electrodes (2290 and 2228 by 3M®) in BIA measurements to decrease the costs of the test. The results showed that the 2228 ECG electrodes can be used in BIA measurements for adult's body composition assessment. These electrodes are available in the domestic market and their costs are 92% lower than the electrodes recommended by manufacturer. The results show a new cost-benefit relation for BIA method and make this a more accessible tool for individual tests, large-scale researches and studies in the community.
Statistical Analysis of Plant Bioelectric Potential for Communication with Humans
Shimbo, Tatsuya; Oyabu, Takashi; Hirobayashi, Shigeki; Takenaka, Kozaburo
The bioelectric potential of a foliage plant changes according to an occupant’s behavior, for example entering the room in which the plant is installed, as well as watering and touching the plant. The potential shows the impulse responses due to the behaviors. In this study, the integrated values of the bioelectric potential were adopted to identify those behaviors. There are two types of values. Those were derived by integrating the bioelectric potential characteristics for a minute (vm1) and for an hour (vh1) respectively. The histogram of the values vm1 for the steady state perfectly took a normal distribution. The frequencies of vm1 for the behaviors were different compared with the steady state distribution. The system can identify the behaviors by examining the frequency table of vm1. Conversely, it is thought the plant gives us some suggestions using bioelectric potential characteristics. A clue for communication between humans and plants was also obtained. The vh1 becomes higher as the average room temperature (tr) becomes lower. There was a negative correlation between vm1 and tr. There were two groups in the scatter diagram of the variables vm1 and tr.
Bohannon, Richard W; Chu, Johnson; Steffl, Michal
2016-03-01
[Purpose] The purpose of this study was to describe the relationship between three practical measures used to characterize muscle mass: mid-arm circumference, maximum calf circumference, and muscle mass index determined using bioimpedance analysis. [Subjects and Methods] Thirty-eight ambulatory women residing in a senior center (mean age, 83 years) participated in this cross-sectional study. Their mid-arm circumference and maximum calf circumference were measured bilaterally and they all underwent bioimpedance analysis. Relationships were examined by using Pearson (r) correlations, Cronbach's alpha, and factor analysis. [Results] Circumferential measures correlated significantly with one another (r = 0.745-0.968) and with the muscle mass index determined with bioimpedance analysis (r = 0.480-0.628). The Cronbach's alpha for the measures was 0.905. Factor analysis confirmed that all of the measures were reflective of a common construct. [Conclusion] On the basis of their correlations with one another and the muscle mass index determined with bioimpedance analysis, circumferential measures of the mid-arm or calf may be considered crude indicators of reduced muscle mass. PMID:27134404
Bohannon, Richard W.; Chu, Johnson; Steffl, Michal
2016-01-01
[Purpose] The purpose of this study was to describe the relationship between three practical measures used to characterize muscle mass: mid-arm circumference, maximum calf circumference, and muscle mass index determined using bioimpedance analysis. [Subjects and Methods] Thirty-eight ambulatory women residing in a senior center (mean age, 83 years) participated in this cross-sectional study. Their mid-arm circumference and maximum calf circumference were measured bilaterally and they all underwent bioimpedance analysis. Relationships were examined by using Pearson (r) correlations, Cronbach’s alpha, and factor analysis. [Results] Circumferential measures correlated significantly with one another (r = 0.745–0.968) and with the muscle mass index determined with bioimpedance analysis (r = 0.480–0.628). The Cronbach’s alpha for the measures was 0.905. Factor analysis confirmed that all of the measures were reflective of a common construct. [Conclusion] On the basis of their correlations with one another and the muscle mass index determined with bioimpedance analysis, circumferential measures of the mid-arm or calf may be considered crude indicators of reduced muscle mass.
Bohannon, Richard W; Chu, Johnson; Steffl, Michal
2016-01-01
[Purpose] The purpose of this study was to describe the relationship between three practical measures used to characterize muscle mass: mid-arm circumference, maximum calf circumference, and muscle mass index determined using bioimpedance analysis. [Subjects and Methods] Thirty-eight ambulatory women residing in a senior center (mean age, 83 years) participated in this cross-sectional study. Their mid-arm circumference and maximum calf circumference were measured bilaterally and they all unde...
Objective: To evaluate the association between electrical bioimpedance analysis (BIA) and visceral fat (VF) in adult and elderly patients. Subjects and methods: This was a cross-sectional study, with a sample of 191 subjects (52% women, 49% elderly) stratified by sex, age and body mass. Computerized tomography (VF area) and BIA (percentage of total body fat (%TBF-BIA), phase angle, reactance and resistance) data were generated. Statistical analysis was based on Pearson's Correlation Coefficient, Anova, Pearson's Chi-square, and ROC curves. Results: VF areas ≥ 130 cm2 were more prevalent among the elderly and among men. Adult females showed a stronger correlation between GV and %TBF-BIA. The other groups showed similar results and statistically significant correlations. Correlations between GV and phase angle were weak and not statistically significant. ROC Curves analyzes showed the following %TBF-BIA, which identified excess VF: for male subjects: 21.5% (adults) and 24.25% (elderly); for female subjects: 35.05% (adults) and 38.45% (elderly) with sensitivity of 78.6%, 82.1%, 83.3%, and 66.7%, and specificity of 70.6%, 62.5%, 79.1%, and 69%, respectively. Conclusion: BIA was found to have satisfactory sensitivity and specificity to predict VF; however, other devices and other techniques should be investigated to improve VF prediction. (author)
B. Knechtle
2011-12-01
Full Text Available Two hundred and fifty seven male Caucasian ultraendurance athletes were recruited, pre-race, before different swimming, cycling, running and triathlon races. Fat mass and skeletal muscle mass were estimated using bioelectrical impedance analysis (BIA and anthropometric methods in order to investigate whether the use of BIA or anthropometry would be useful under field conditions. Total body fat estimated using BIA was significantly high (P Se reclutaron a 257 hombres caucasianos que eran atletas de alto rendimiento, antes de competir en diferentes pruebas triatlón de natación, ciclismo y carrera. Se estimaron la masa grasa y la masa de músculo esquelético utilizando un análisis de impedancia bioeléctrica (BIA y métodos antropométricos con el fin de investigar si el uso de BIA o de la antropometría sería útil en tales condiciones de campo. La grasa corporal total estimada por BIA fue significativamente mayor en comparación con la antropometría (P < 0,001. Cuando se compararon los resultados entre BIA y antropometría, se encontraron niveles de concordancia bajos a moderados. Estos resultados concuerdan con las diferencias halladas con el análisis Bland-Altman, lo que indica que la ecuación antropométrica de Ball et al. posee el mayor grado de concordancia (desviación = -3,0 ± 5,8 kg con BIA, con Stewart et al. (desviación = -6,4 ± 6,3 kg, Faulkner (desviación = -4,7 ± 5,8 kg y Wilmore-Siri (desviación = -4,8 ± 6,2 kg. La estimación de la masa de músculo esquelético fue significativamente superior con BIAS que con antropometría (P < 0,001. Los resultados de la ICC y del método Bland-Altman muestran que la ecuación antropométrica de Lee et al. (desviación = -5,4 ± 5,3 kg produjo el mayor grado de concordancia. El método combinado de Janssen et al. entre antropometría y BIA mostró el menor grado de concordancia (desviación = -12,5 ± 5,7 kg. Hubo una diferencia estadísticamente significativa entre los resultados
Pei Ying Sim
2014-01-01
Full Text Available Objective. To compare the measurements of body fat percentage (BF% using the foot-to-foot bioelectrical impedance analysis (FTF-BIA with the direct segmental multifrequency BIA (DSM-BIA. Methods. There were 36 men and 52 women (37.1±14.3 years with 57% Malays, 30% Chinese, and 13% Indian. For children, there were 45 boys and 26 girls (11.5±2.5 years with 52% Malay, 15% Chinese, and 33% Indian. Results. Mean height for men was 168.4 cm, 11 cm taller than women. Men were 10 kg heavier than women at 70 kg. BF% in women was 32% and 33% whereas BF% in men was 23% and 25% when measured using FTF-BIA and DSM-BIA, respectively. In children, BF% measured with FTF-BIA and DSM-BIA was 49% and 46%, respectively. The correlations were significant for men (r=0.92, SEE = 2.80, women (r=0.91, SEE = 3.31, boys (r=0.95, SEE = 5.44, and girls (r=0.96, SEE = 5.27. The BF% in underweight/normal (r=0.92, SEE = 2.47 and that in overweight/obese adults (r=0.89, SEE = 3.61 were strongly correlated. The correlations were significant in normal/underweight (r=0.94, SEE = 3.78 and obese/overweight children (r=0.83, SEE = 6.49. All ethnic groups showed significant correlation with BF%. Malay adults (r=0.92, SEE = 3.27 and children (r=0.94, SEE = 0.88 showed significant mean differences in BF%. Conclusion. The FTF-BIA showed higher accuracy for all normal/underweight and Chinese group with acceptable overestimation in children and underestimation in adults. Caution should be taken when interpreting BF% depending on gender, BMI, and ethnicity.
刘紫锰; 杨春华; 陈娟; 欧阳彬; 管向东
2009-01-01
目的 探讨生物电阻抗法测量无创心输出量(CO)在危重病中应用的准确性和有效性.方法 选择2008年1月至5月间本院外科重症监护中心(SICU)收治的12例需放置SWAN-GANZ导管进行血流动力学监测的患者,同时用生物电阻抗法和SWAN-GANZ导管热稀释法测定患者CO曲线平稳后0、1、6、12、24、48 h的CO值,并应用Pearson相关对两种方法测得的CO值与时间进行分析.结果 生物电阻抗法测最的CO值在所有时间点均低于SWAN-GANZ导管热稀释法的测最值[0 h:(5.5±0.9)L/min比(7.7±1.4)L/min;1h:(5.3±0.7)L/min比(7.4±1.5)L/min;6 h:(4.6±0.6)L/min比(6.8±1.4)L/min;12 h:(5.1±0.9)L/min比(7.6±1.6)L/min;24 h:(6.1±1.1)L/min比(9.0±1.6)L/min;48 h:(6.3±1.3)L/min比(9.5±1.5)L/min;均P<0.05].两种方法测量的CO值均随着时间的延长而呈升高趋势(r=0.818,P=0.047和r=0.884,P=0.020).结论 生物电阻抗法测量的无创CO与SWAN-GANZ导管测定的患者CO同样呈时间依赖性,是一种有效的CO监测方法.%Objective To evaluate the efficacy and accuracy of non-invasive bioelectrical impedance measurement of cardiac output (CO) in critically ill patients. Methods Between January and May 2008, 12 patients who needed hemodynamics monitoring using SWAN-GANZ catheterization in surgical intensive care unit (SICU) of our hospital were measured for CO by bioelectrical impedance and SWAN-GANZ catheterization thermodilution approaches. These values were recorded at 0, 1, 6, 12, 24 and 48 hours after the CO curve became stable in these patients. Pearson correlation analysis was performed for CO values over time recorded by these two approaches. Results At all the time points, CO measurement by bioelectrical impedance yielded lower values than those by SWAN-GANZ catheterization thermodilution approach [0 h: (5.5±0.9) L/min vs (7.7±1.4) L/min; 1 h: (5.3±0.7) L/min vs (7.4±1.5) L/min; 6 h: (4.6±0.6) L/min vs (6.8±1.4) L/min; 12 h: (5.1±0.9) L/min vs (7.6±1.6) L
Villa, Federica; Magnani, Alessandro; Maggioni, Martina A.; Stahn, Alexander; Rampichini, Susanna; Merati, Giampiero; Castiglioni, Paolo
2016-01-01
Bioelectrical Impedance Spectroscopy (BIS) allows assessing the composition of body districts noninvasively and quickly, potentially providing important physiological/clinical information. However, neither portable commercial instruments nor more advanced wearable prototypes simultaneously satisfy the demanding needs of unobtrusively tracking body fluid shifts in different segments simultaneously, over a broad frequency range, for long periods and with high measurements rate. These needs are often required to evaluate exercise tests in sports or rehabilitation medicine, or to assess gravitational stresses in aerospace medicine. Therefore, the aim of this work is to present a new wearable prototype for monitoring multi-segment and multi-frequency BIS unobtrusively over long periods. Our prototype guarantees low weight, small size and low power consumption. An analog board with current-injecting and voltage-sensing electrodes across three body segments interfaces a digital board that generates square-wave current stimuli and computes impedance at 10 frequencies from 1 to 796 kHz. To evaluate the information derivable from our device, we monitored the BIS of three body segments in a volunteer before, during and after physical exercise and postural shift. We show that it can describe the dynamics of exercise-induced changes and the effect of a sit-to-stand maneuver in active and inactive muscular districts separately and simultaneously. PMID:27187389
肖贵遐; 刘国庆; 彭玉平; 朱代谟
2001-01-01
The changes of intracranial components and corr esponding brain impedan ce were analyzed while intracranial pressure was increasing, and the relation of intr acranial pressure pulse wave and brain impedance pulse wave were discussed. A theory of noninvasive intracranial pressure monitoring by bioelectric impedance was put forward. The result of primary experiment suggested that the theory be feasible.%分析了在颅内压增高的过程中，颅内容 物的变化及相应的脑阻抗的变化情况 ，同时讨论了在颅内压升高以后颅内压脉冲波和脑阻抗脉冲波的关系，提出了一个用生物电 阻抗法无创监护颅内压的理论。初步的动物实验表明该理论是可行的。
Villa, Federica; Magnani, Alessandro; Maggioni, Martina A; Stahn, Alexander; Rampichini, Susanna; Merati, Giampiero; Castiglioni, Paolo
2016-01-01
Bioelectrical Impedance Spectroscopy (BIS) allows assessing the composition of body districts noninvasively and quickly, potentially providing important physiological/clinical information. However, neither portable commercial instruments nor more advanced wearable prototypes simultaneously satisfy the demanding needs of unobtrusively tracking body fluid shifts in different segments simultaneously, over a broad frequency range, for long periods and with high measurements rate. These needs are often required to evaluate exercise tests in sports or rehabilitation medicine, or to assess gravitational stresses in aerospace medicine. Therefore, the aim of this work is to present a new wearable prototype for monitoring multi-segment and multi-frequency BIS unobtrusively over long periods. Our prototype guarantees low weight, small size and low power consumption. An analog board with current-injecting and voltage-sensing electrodes across three body segments interfaces a digital board that generates square-wave current stimuli and computes impedance at 10 frequencies from 1 to 796 kHz. To evaluate the information derivable from our device, we monitored the BIS of three body segments in a volunteer before, during and after physical exercise and postural shift. We show that it can describe the dynamics of exercise-induced changes and the effect of a sit-to-stand maneuver in active and inactive muscular districts separately and simultaneously. PMID:27187389
Federica Villa
2016-05-01
Full Text Available Bioelectrical Impedance Spectroscopy (BIS allows assessing the composition of body districts noninvasively and quickly, potentially providing important physiological/clinical information. However, neither portable commercial instruments nor more advanced wearable prototypes simultaneously satisfy the demanding needs of unobtrusively tracking body fluid shifts in different segments simultaneously, over a broad frequency range, for long periods and with high measurements rate. These needs are often required to evaluate exercise tests in sports or rehabilitation medicine, or to assess gravitational stresses in aerospace medicine. Therefore, the aim of this work is to present a new wearable prototype for monitoring multi-segment and multi-frequency BIS unobtrusively over long periods. Our prototype guarantees low weight, small size and low power consumption. An analog board with current-injecting and voltage-sensing electrodes across three body segments interfaces a digital board that generates square-wave current stimuli and computes impedance at 10 frequencies from 1 to 796 kHz. To evaluate the information derivable from our device, we monitored the BIS of three body segments in a volunteer before, during and after physical exercise and postural shift. We show that it can describe the dynamics of exercise-induced changes and the effect of a sit-to-stand maneuver in active and inactive muscular districts separately and simultaneously.
Jendrysek Marek
2015-11-01
Full Text Available Purpose: Body composition evaluation of youth aged 17-18 of a different physical activity with the help of bioelectric impedance method. Material and Methods: 18 boys practicing swimming and 19 boys not practicing it took part in the study, making up a control group. Height, weight, BMI, lean body mass, the content of fat and water, Rohr factor were evaluated. Non-parametric Mann-Whitney test has been used to evaluate the differences in the range of the tissue components between the two groups. Results: Statistically significant differences were found on the p<0,05 level in % fat content. Mean body weight in experimental group was 71.5 kg, while in control group it was 69.4 kg. Minimum and maximum weight in group of swimming-practicing persons was: 56.6-92.2 kg. Increased body weight in the group of swimmers can result from greater amount of active tissue in this group compared with persons of low physical activity. Proportionally, it amounted to 64.3 kg and 61.3 kg. In the tested groups, minimal and maximal values of amount of active tissue proportionately amounted to: 54.1-78 and 49.5-72,3 kg. Conclusions: Physical activity modifies body composition. Active lifestyle is one of the methods for prevention of overweight and obesity.
Analysis of Body Composition Methods in a Community Sample of African American Women
Lopez, Ygnacio; O’Connor, Daniel P.; Ledoux, Tracey A.; Rebecca E. Lee
2011-01-01
The purposes of the authors in this study were: (1) to determine whether published body mass index and bioelectrical impedance analysis equations agreed with dual energy x-ray absorptiometry body fat percentage measures and (2) to estimate new body mass index and bioelectrical impedance analysis equations in a sample of African American women. Linear regression was used to determine how well 10 body mass index and bioelectrical impedance analysis equations reflected dual energy x-ray absorpti...
Laura Augusta Barufaldi
2011-07-01
Full Text Available OBJECTIVE: To describe the nutritional status of indigenous children and adolescents in Rio Grande do Sul, Brazil, through bioelectrical values, and to compare the nutritional classifications of the anthropometric method to those of the body composition method. METHODS: A cross-sectional survey was conducted of 3 204 subjects at 35 schools in the 12 Kaingang indigenous lands of Rio Grande do Sul, Brazil. Following World Health Organization recommendations, the weight and height (H of each subject was measured twice and the body mass index/age (BMI/A was classified. Body composition was assessed by Bioelectrical Impedance Vector Analysis (BIVA. Resistance (R and reactance (Xc were estimated using a bioelectrical impedance analyzer. Divergences between these two methods were performed on RXc graph. RESULTS: Of the sample, 56.8% were adolescents and 50.6% were males. The mean values of phase angle were higher in adolescents, in males, and in individuals overweight by BMI/A. Mean values of R, Xc, R/H, and Xc/H were higher among children and among those with BMI/A OBJETIVO: Describir el estado nutricional de niños y adolescentes indígenas en Rio Grande do Sul, Brasil, mediante los valores de impedancia bioeléctrica y comparar las clasificaciones nutricionales del método antropométrico con las del método de composición corporal. MÉTODOS: Se llevó a cabo un estudio transversal en 3 204 participantes de 35 escuelas de los 12 territorios indígenas habitados por el pueblo kaingang (o guayaná del estado de Rio Grande do Sul (Brasil. Según las recomendaciones de la Organización Mundial de la Salud, se midió el peso y la talla (T de cada participante en dos oportunidades y se clasificó el índice de masa corporal (IMC según la edad. La composición corporal se evaluó mediante análisis vectorial de impedancia bioeléctrica. La resistencia (R y la reactancia (Xc se calcularon con un analizador de impedancia bioeléctrica. Las divergencias
Verney, Julien; Metz, Lore; Chaplais, Elodie; Cardenoux, Charlotte; Pereira, Bruno; Thivel, David
2016-07-01
The aim of this study was to compare total and segmental body composition results between bioimpedance analysis (BIA) and dual x-ray absorptiometry (DXA) scan and to test the reproducibility of BIA in obese adolescents. We hypothesized that BIA offers an accurate and reproducible method to assess body composition in adolescents with obesity. Whole-body and segmental body compositions were assessed by BIA (Tanita MC-780) and DXA (Hologic) among 138 (110 girls and 28 boys) obese adolescents (Tanner stage 3-5) aged 14±1.5years. The BIA analysis was replicated on 3 identical occasions in 32 participants to test the reproducibility of the methods. Whole-body fat mass percentage was significantly higher using the BIA method compared with DXA (40.6±7.8 vs 38.8±4.9%, PBioimpedance analysis offers an acceptable and reproducible alternative to assess body composition in obese adolescents, with however a loss of correlation between BIA and DXA with increasing body fat; its validity remains uncertain for segmental analysis among obese youth. PMID:27333957
Sigmund Martin
2015-07-01
Full Text Available BACKGROUND: Bioelectrical impedance (BIA seems an appropriate method for basic diagnostics of body composition in a practical environment. This is a non-time consuming non-invasive method that provides a high degree of response relevance. However, the values identifi ed by the BIA method are susceptible to a number of factors, which need to be taken into account during the investigation stage and interpretation of the results. One of the signifi cant factors infl uencing the outcomes of measurement is the instrument factor.OBJECTIVE: The objective of the present comparative survey was to analyse the proportions of body fat by means of the BIA hand-to-leg method and BIA leg-to-leg method in a sample of athletic individuals aged 7 to 18 years.METHODS: The survey included a total of 178 ice-hockey players aged 7 to 18 years. The proportion of body fat analysed by means of the BIA hand-to-leg method was measured by the Tanita BC-418 MA instrument. For the purposes of the BIA leg-to-leg method the Tanita BF-350 instrument was used (Tanita, Japan. Both instruments work at a frequency of 50 kHz.RESULTS: The percentage of body fat established by the BIA leg-to-leg method (M = 13.5%; SD = 4.8 indicated signifi cantly lower values of fat percentage than the values measured by the BIA hand-to-leg method (M = 17.1%; SD = 4.3. The overall diff erence represents an average value of 3.6% (standard mode; p < .001; d = 0.8. Regarding the monitored age categories the observed diff erences are in the range of 3.1–4.7% (p < .001; d = 0.7–1.2.CONCLUSION: The present study compares the proportions of body fat by means of the BIA leg-to-leg method and BIA hand-to-leg method in athletic boys aged 7 to 18 years. The results measured by the BIA leg-to-leg method signifi cantly undervalue the proportion of body fat in comparison with the BIA hand-to-leg method. The instrument factor and age factor represented signifi - cant variables infl uencing the results of the
Borges Naida C
2012-07-01
Full Text Available Abstract Background Few equations have been developed in veterinary medicine compared to human medicine to predict body composition. The present study was done to evaluate the influence of weight loss on biometry (BIO, bioimpedance analysis (BIA and ultrasonography (US in cats, proposing equations to estimate fat (FM and lean (LM body mass, as compared to dual energy x-ray absorptiometry (DXA as the referenced method. For this were used 16 gonadectomized obese cats (8 males and 8 females in a weight loss program. DXA, BIO, BIA and US were performed in the obese state (T0; obese animals, after 10% of weight loss (T1 and after 20% of weight loss (T2. Stepwise regression was used to analyze the relationship between the dependent variables (FM, LM determined by DXA and the independent variables obtained by BIO, BIA and US. The better models chosen were evaluated by a simple regression analysis and means predicted vs. determined by DXA were compared to verify the accuracy of the equations. Results The independent variables determined by BIO, BIA and US that best correlated (p r2, 19 equations were selected (12 for FM, 7 for LM; however, only 7 equations accurately predicted FM and one LM of cats. Conclusions The equations with two variables are better to use because they are effective and will be an alternative method to estimate body composition in the clinical routine. For estimated lean mass the equations using body weight associated with biometrics measures can be proposed. For estimated fat mass the equations using body weight associated with bioimpedance analysis can be proposed.
一种基于FPGA的数字EIT系统的实验研究%A Bioelectricity Impedance Measurement System Research Based on FPGA
孙晓彤; 郝会玲; 沙洪
2013-01-01
以FPGA芯片为核心的数字化生物电阻抗测量实验平台,主要完成直接数字频率合成(DDS)的电流源模块、V/I变换和数字解调模块的研究.采用DDS技术生成正弦信号发生器,由THS4021改进的Howland电路设计压控电流源,在不同负载条件下测量其输出电流幅值的频率响应,并在不同频率下测量电流源的输出阻抗,对恒流源性能的稳定性和精度进行测定.解调方法采用数字化解调,测试不同激励频率下的数字正交解调输出误差变化情况.最后采用盐水槽实验系统进行成像实验.结果表明,电流源可在6.1～390.6 kHz范围输出多频激励信号,在600 kHz前保持在190 kΩ的输出阻抗.当信号频率从200 kHz逐渐增加到1.6 MHz时,解调电路输出的I和Q路误差逐渐增加,对应的幅度误差从1.13％增加到7.19％,相位误差从1.03％增大到5.34％.采用相邻激励-相邻测量模式对环氧树脂棒进行盐水槽成像实验,成像结果表明系统能够对单个目标物体实现较准确的定位,验证了本研究平台的可行性.%In this work the digital bioelectricity impedance measurement experiment platform with the core of FPGA was studied and completed the research of the DDS module,V/I conversion and digital demodulation.DDS technology was used to generate a sinusoidal signal generator.Howland circuit improved by THS4021 was used to design a voltage-controlled current source,the amplitude of the output current of the frequency response was measured in different load conditions,and the output impedance of the current source was measured at different frequencies,which proved stability and accuracy of the constant current source.The digital demodulation was used in the study and tested digital quadrature demodulation output error under different excitation frequency.At last we used salt water tank experimental system for imaging experiments.The current source could produce multi-frequency excitation signal in
Wave impedance retrieving via Bloch modes analysis
Andryieuski, Andrei; Ha, S.; Sukhorukov, A.; Malureanu, Radu; Kivshar, Y.; Lavrinenko, Andrei
-ciples violation, like antiresonance behaviour with Im(ε) <0, Im(μ) <0. We employ the Bloch mode analysis of periodic metamaterials to extract the dominating (fundamental) Bloch mode. Then it is possible to determine the Bloch and wave impedances by the surface and volume aver-aging of the electromagnetic field of...... the Bloch mode, respectively. Case studies prove that our ap-proach can determine material and wave effective parameters of lossy and lossless metamaterials. In some examples when the passivity is violated we made further analysis and showed that this is due to the failure of concept of impedance...
Wavelet analysis of the impedance cardiogram waveforms
Podtaev, S.; Stepanov, R.; Dumler, A.; Chugainov, S.; Tziberkin, K.
2012-12-01
Impedance cardiography has been used for diagnosing atrial and ventricular dysfunctions, valve disorders, aortic stenosis, and vascular diseases. Almost all the applications of impedance cardiography require determination of some of the characteristic points of the ICG waveform. The ICG waveform has a set of characteristic points known as A, B, E ((dZ/dt)max) X, Y, O and Z. These points are related to distinct physiological events in the cardiac cycle. Objective of this work is an approbation of a new method of processing and interpretation of the impedance cardiogram waveforms using wavelet analysis. A method of computer thoracic tetrapolar polyrheocardiography is used for hemodynamic registrations. Use of original wavelet differentiation algorithm allows combining filtration and calculation of the derivatives of rheocardiogram. The proposed approach can be used in clinical practice for early diagnostics of cardiovascular system remodelling in the course of different pathologies.
Claire M Nightingale
Full Text Available BACKGROUND: Bioelectrical impedance analysis (BIA is a potentially valuable method for assessing lean mass and body fat levels in children from different ethnic groups. We examined the need for ethnic- and gender-specific equations for estimating fat free mass (FFM from BIA in children from different ethnic groups and examined their effects on the assessment of ethnic differences in body fat. METHODS: Cross-sectional study of children aged 8-10 years in London Primary schools including 325 South Asians, 250 black African-Caribbeans and 289 white Europeans with measurements of height, weight and arm-leg impedance (Z; Bodystat 1500. Total body water was estimated from deuterium dilution and converted to FFM. Multilevel models were used to derive three types of equation {A: FFM = linear combination(height+weight+Z; B: FFM = linear combination(height(2/Z; C: FFM = linear combination(height(2/Z+weight}. RESULTS: Ethnicity and gender were important predictors of FFM and improved model fit in all equations. The models of best fit were ethnicity and gender specific versions of equation A, followed by equation C; these provided accurate assessments of ethnic differences in FFM and FM. In contrast, the use of generic equations led to underestimation of both the negative South Asian-white European FFM difference and the positive black African-Caribbean-white European FFM difference (by 0.53 kg and by 0.73 kg respectively for equation A. The use of generic equations underestimated the positive South Asian-white European difference in fat mass (FM and overestimated the positive black African-Caribbean-white European difference in FM (by 4.7% and 10.1% respectively for equation A. Consistent results were observed when the equations were applied to a large external data set. CONCLUSIONS: Ethnic- and gender-specific equations for predicting FFM from BIA provide better estimates of ethnic differences in FFM and FM in children, while generic equations
Impedance analysis of acupuncture points and pathways
Investigation of impedance characteristics of acupuncture points from acoustic to radio frequency range is addressed. Discernment and localization of acupuncture points in initial single subject study was unsuccessfully attempted by impedance map technique. Vector impedance analyses determined possible resonant zones in MHz region.
Fisher information analysis in electrical impedance tomography
This paper provides a quantitative analysis of the optimal accuracy and resolution in electrical impedance tomography (EIT) based on the Cramér–Rao lower bound. The imaging problem is characterized by the forward operator and its Jacobian. The Fisher information operator is defined for a deterministic parameter in a real Hilbert space and a stochastic measurement in a finite-dimensional complex Hilbert space with a Gaussian measure. The connection between the Fisher information and the singular value decomposition (SVD) based on the maximum likelihood (ML) criterion (the ML-based SVD) is established. It is shown that the eigenspaces of the Fisher information provide a suitable basis to quantify the trade-off between the accuracy and the resolution of the (nonlinear) inverse problem. It is also shown that the truncated ML-based pseudo-inverse is a suitable regularization strategy for a linearized problem, which exploits sufficient statistics for estimation within these subspaces. The statistical-based Cramér–Rao lower bound provides a complement to the deterministic upper bounds and the L-curve techniques that are employed with linearized inversion. To this end, electrical impedance tomography provides an interesting example where the eigenvalues of the SVD usually do not exhibit a very sharp cut-off, and a trade-off between the accuracy and the resolution may be of practical importance. A numerical study of a hypothetical EIT problem is described, including a statistical analysis of the model errors due to the linearization. (paper)
The accuracy of BIA measurements is limited by different sources of error such as physical model, cross sectional area, ethnicity, body hydration, age and level of body fat among other variables. Equation for each population is required as they can produce overestimation when manufacturer's equations are used. The classical measurements hand to foot has shown better correlation against hydrodensitometry than foot to foot or hand to hand. However there is a lack for an accepted standard of BIA procedures. This is compounded when there is not a good report of the BIA study's methodology; hence the comparability between the results is poor and reduces the reliability of the method. Perhaps, standardization of methods would be the first step for BIA studies to move forward and subsequently improve its accuracy. Standardized procedures could also minimize the impact of these variables on studies results. The aim of this study was to propose a protocol as a checklist to standardize BIA procedures and produce comparable results from future studies performed with the classic hand-foot configuration in adults.
Danilov, A. A.; Kramarenko, V. K.; Nikolaev, D. V.; Rudnev, S. G.; Salamatova, V. Yu; Smirnov, A. V.; Vassilevski, Yu V.
2013-04-01
In this work, an adaptive unstructured tetrahedral mesh generation technology is applied for simulation of segmental bioimpedance measurements using high-resolution whole-body model of the Visible Human Project man. Sensitivity field distributions for a conventional tetrapolar, as well as eight- and ten-electrode measurement configurations are obtained. Based on the ten-electrode configuration, we suggest an algorithm for monitoring changes in the upper lung area.
In this work, an adaptive unstructured tetrahedral mesh generation technology is applied for simulation of segmental bioimpedance measurements using high-resolution whole-body model of the Visible Human Project man. Sensitivity field distributions for a conventional tetrapolar, as well as eight- and ten-electrode measurement configurations are obtained. Based on the ten-electrode configuration, we suggest an algorithm for monitoring changes in the upper lung area.
Sarcopenia is defined as a loss of muscle mass depending of ageing and affecting physical function (definition A). A new definition considers excluding mass reduction criterion (definition B). Obesity is pandemic and occurs at all ages. Sarcopenic obesity (SO) implies both processes. The purpose of this study was to compare the results obtained after applying these 2 definitions in 66 aged 22 ± 2.8 years overweight or obese young college women. Percentage body fat (%BF) and skeletal mass index (SMI) were estimated by BIA, muscle function by handgrip strength test (HGS) and physical performance by Harvard step test (HST). There were 9.1% and 90.9% overweight or obese subjects. Twenty nine subjects (43.9%) had decreased HGS and 22 (33.3%) had impaired physical performance. One obese subject (1.5%) met the criteria for sarcopenic obesity by definition A and 9 (13.6%) by definition B. Although a linear regression (α 2 = 0.094, 0.037 and 0.275 respectively) it was observed a tendency for HGS, HST and SMI deterioration when %BF increases. However, other confounding factors must be investigated. Probably as the population gets more obese, the problematic of SO will be found earlier in life.
Use of bioelectrical impedance analysis to assess body composition in rural Gambian children
Prins, M.; Hawkesworth, S.; Wright, A.; Fulford, A.J.C.; Jarjou, L.M.A.; Prentice, A.M.; Moore, S.E.
2008-01-01
Objective: To validate the Tanita BC-418MA Segmental Body Composition Analyser and four-site skinfold measurements for the prediction of total body water (TBW), percentage fat-free mass (% FFM) and percentage body fat (%BF) in a population of rural Gambian children. Subjects/Methods: One hundred and
González-Correa, C. H.; Caicedo-Eraso, J. C.; S, Villada-Gomez J.
2013-04-01
Sarcopenia is defined as a loss of muscle mass depending of ageing and affecting physical function (definition A). A new definition considers excluding mass reduction criterion (definition B). Obesity is pandemic and occurs at all ages. Sarcopenic obesity (SO) implies both processes. The purpose of this study was to compare the results obtained after applying these 2 definitions in 66 aged 22 ± 2.8 years overweight or obese young college women. Percentage body fat (%BF) and skeletal mass index (SMI) were estimated by BIA, muscle function by handgrip strength test (HGS) and physical performance by Harvard step test (HST). There were 9.1% and 90.9% overweight or obese subjects. Twenty nine subjects (43.9%) had decreased HGS and 22 (33.3%) had impaired physical performance. One obese subject (1.5%) met the criteria for sarcopenic obesity by definition A and 9 (13.6%) by definition B. Although a linear regression (α obese, the problematic of SO will be found earlier in life.
Сhanges of brain bioelectric activity by diabetic encephalopathy
Vitaly P. Omelchenko; Elena A. Timoshenko
2011-01-01
This article focuses on the analysis of brain bioelectric activity by diabetic encephalopathy. Paid attention to the establishment of EEG parameters and patients psychological characteristics interrelation.
Impedance analysis of fibroblastic cell layers measured by electric cell-substrate impedance sensing
Lo, Chun-Min; Ferrier, Jack
1998-06-01
Impedance measurements of cell layers cultured on gold electrode surfaces obtained by electric cell-substrate impedance sensing provide morphological information such as junctional resistance and cell-substrate separation. Previously, a model that assumes that cells have a disklike shape and that electric currents flow radially underneath the ventral cell surface and then through the paracellular space has been used to theoretically calculate the impedance of the cell-covered electrode. In this paper we propose an extended model of impedance analysis for cell layers where cellular shape is rectangular. This is especially appropriate for normal fibroblasts in culture. To verify the model, we analyze impedance data obtained from four different kinds of fibroblasts that display a long rectangular shape. In addition, we measure the average cell-substrate separation of human gingival fibroblasts at different temperatures. At temperatures of 37, 22, and 4 °C, the average separation between ventral cell surface and substratum are 46, 55, and 89 nm, respectively.
Hendel, H W; Gotfredsen, A; Højgaard, L;
1996-01-01
measurements were compared with bioimpedance analysis (BIA) by applying 11 predictive BIA equations published in the literature. Predictive equations for the present study population were developed, with the use of fat-free mass (FFM) as assessed by TBK and DXA as references in multiple regression analysis...
M Bayat KASHKOLİ
2011-12-01
Full Text Available The goal of present research is estimating and validity of body density with methods of Body Mass Index, Skin Fold, Bio-Electrical Impedance and Criterion Method of Hydrostatic in men athletes of swimming. The present research has been conducted with semi-experimental and functional method. For doing so 25 men swimming athletes were randomly selected (N= 120. Statistical analysis was conducted with Pearson coefficient, correlated T-test, TE & SEE. The results of statistical analysis show that the method of Skin Fold Stat with hydrostatic criterion method has meaningful difference in society of swimmers. Also there is meaningful difference between body mass index and criterion method. There was not any meaningful difference between bio-electrical impedance and criterion method in swimmers. (TE=3.01, SEE=2.91, R=0.924, P=0.064. The findings show that that bio-electrical impedance in swimmer athletes is more suitable method.
García Breijo, Eduardo; Prats Boluda, Gema; Lidon-Roger, Jose V.; Ye Lin, Yiyao; Garcia Casado, Francisco Javier
2015-01-01
Purpose This paper aims to present a comparison between three types of manufacturing techniques, namely, screen-printed, inkjet and gravure, using different types of inks, for the implementation of concentric ring electrodes which permit estimation of Laplacian potential on the body surface. Design/methodology/approach Flexible concentric ring electrodes not only present lower skin electrode contact impedance and lower baseline wander than rigid electrodes but are also less sens...
Mooney, Angela; Kelsey, Laurel; Fellingham, Gilbert W.; George, James D.; Hager, Ron L.; Myrer, J. William; Vehrs, Pat R.
2011-01-01
To determine the validity and reliability of percent body fat estimates in 177 boys and 154 girls between 12-17 years of age, percent body fat was assessed once using dual-energy X-ray absorptiometry and twice using the sum of two skinfolds and three bioelectrical impedance analysis devices. The assessments were repeated on 79 participants on a…
Application of Vertical Electrodes in Microfluidic Channels for Impedance Analysis
Qiang Li
2016-05-01
Full Text Available This paper presents a microfluidic device with electroplated vertical electrodes in the side walls for impedance measurement. Based on the proposed device, the impedance of NaCl solutions with different concentrations and polystyrene microspheres with different sizes was measured and analyzed. The electroplating and SU-8-PDMS (SU-8-poly(dimethylsiloxane bonding technologies were firstly integrated for the fabrication of the proposed microfluidic device, resulting in a tightly three-dimensional structure for practical application. The magnitude of impedance of the tested solutions in the frequency range of 1 Hz to 100 kHz was analyzed by the Zennium electrochemical workstation. The results show that the newly designed microfluidic device has potential for impedance analysis with the advantages of ease of fabrication and the integration of 3D electrodes in the side walls. The newly designed impedance sensor can distinguish different concentrations of polystyrene microspheres and may have potential for cell counting in biological areas. By integrating with other techniques such as dielectrophoresis (DEP and biological recognition technology, the proposed device may have potential for the assay to identify foodborne pathogen bacteria.
Fiber Materials AC Impedance Characteristics and Principium Analysis
Wang, Jianjun; Li, Xiaofeng
With an invariable amplitude and variable frequency inspiriting, impedance of fiber materials rapidly decrease at first and then increase speedy followed with increasing of signal frequency. For the impedance curve of frequency is section of bathtub, this phenomenon is defined as alternating current electric conductive bathtub effect of fiber material. With analysis tools,of circuit theory and medium polarization theory, the phenomenon can be deeply detected that in AC electric field there are four different kind of currents in fiber material: absorbing current, conductance current, charging current and superficial current. With more analyzing it's discovered this phenomenon can be explained by medium polarize theory. Make using of fiber AC electric conductivity bathtub effect, fast testing equipment on fiber moisture regain can be invent, and disadvantages of conventional impedance technique, such as greatness test error and electrode polarization easily. This paper affords directions to design novel speediness fiber moisture test equipments in theory.
Electrical Modeling and Impedance Analysis of Biological Cells
Gowri Sree V.
2014-03-01
Full Text Available It was proved that the external electric field intensity has significant effects on the biological systems. The applied electric field intensity changes the electrical behavior of the cell systems. The impact of electric field intensity on the cell systems should be studied properly to optimize the electric field treatments of biological systems. Based on the cell dimensions and its dielectric properties, an electrical equivalent circuit for an endosperm cell in rice was developed and its total impedance and capacitance were verified with measurement results. The variations of impedance and conductance with respect to applied impulse voltage at different frequencies were plotted. This impedance analysis method can be used to determine the optimum voltage level for electric field treatment and also to determine the cell rupture due to electric field applications.
An impact analysis of the fault impedance on voltage sags
Ramos, Alessandro Candido Lopes [CELG - Companhia Energetica de Goias, Goiania, GO (Brazil). Generation and Transmission. System' s Operation Center], E-mail: alessandro.clr@celg.com.br; Batista, Adalberto Jose [Federal University of Goias (UFG), Goiania, GO (Brazil)], E-mail: batista@eee.ufg.br; Leborgne, Roberto Chouhy [Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil)], E-mail: rcl@ece.ufrgs.br; Emiliano, Pedro Henrique Mota, E-mail: ph@phph.com.br
2009-07-01
This paper presents an impact analysis of the fault impedance, in terms of its module and angle, on voltage sags caused by faults. Symmetrical and asymmetrical faults are simulated, at transmission and distribution lines, by using a frequency-domain fault simulation software called ANAFAS. Voltage sags are monitored at buses where sensitive end-users are connected. In order to overcome some intrinsic limitations of this software concerning its automatic execution for several cases, a computational tool was developed in Java programming language. This solution allows the automatic simulation of cases including the effect of the fault position, the fault type, and the proper fault impedance. The main conclusion is that the module and angle of the fault impedance can have a significant influence on voltage sag depending on the fault characteristics. (author)
A parametric framework for modelling of bioelectrical signals
Mughal, Yar Muhammad
2016-01-01
This book examines non-invasive, electrical-based methods for disease diagnosis and assessment of heart function. In particular, a formalized signal model is proposed since this offers several advantages over methods that rely on measured data alone. By using a formalized representation, the parameters of the signal model can be easily manipulated and/or modified, thus providing mechanisms that allow researchers to reproduce and control such signals. In addition, having such a formalized signal model makes it possible to develop computer tools that can be used for manipulating and understanding how signal changes result from various heart conditions, as well as for generating input signals for experimenting with and evaluating the performance of e.g. signal extraction methods. The work focuses on bioelectrical information, particularly electrical bio-impedance (EBI). Once the EBI has been measured, the corresponding signals have to be modelled for analysis. This requires a structured approach in order to move...
Thanh-Tuan Ngo
2014-04-01
Full Text Available This paper proposes the design of a biosensor to characterize the dielectric and conductive properties of biological materials (for example blood or water by impedance spectroscopy. Particularly, its design optimized the geometric structure interdigitated electrodes. This optimization allows extending the frequency range of measurement by reducing the polarization effect. Polarization effect is manifested by an interface capability (or double layer from interaction between ions and molecules in the boundary between the surface of the electrolyte and the electrodes, it increases the measurement error at low frequencies. This paper recommends also a novel method to determine the parameters (relative permittivity, thickness and capacitance per unit area of the double layer (DL at the contact surface of the electrode with the solution. CoventorWare software was utilized to modelize of interdigital sensor structure in three dimensions (3D to verify the analytical results and evaluate the influence of geometrical parameters and the dielectric properties of the medium on bioelectrical impedance.
Impedance Analysis of Silicon Nanowire Lithium Ion Battery Anodes
Ruffo, Riccardo
2009-07-02
The impedance behavior of silicon nanowire electrodes has been investigated to understand the electrochemical process kinetics that influences the performance when used as a high-capacity anode in a lithium ion battery. The ac response was measured by using impedance spectroscopy in equilibrium conditions at different lithium compositions and during several cycles of charge and discharge in a half cell vs. metallic lithium. The impedance analysis shows the contribution of both surface resistance and solid state diffusion through the bulk of the nanowires. The surface process is dominated by a solid electrolyte layer (SEI) consisting of an inner, inorganic insoluble part and several organic compounds at the outer interface, as seen by XPS analysis. The surface resistivity, which seems to be correlated with the Coulombic efficiency of the electrode, grows at very high lithium contents due to an increase in the inorganic SEI thickness. We estimate the diffusion coefficient of about 2 × 10 -10 cm 2/s for lithium diffusion in silicon. A large increase in the electrode impedance was observed at very low lithium compositions, probably due to a different mechanism for lithium diffusion inside the wires. Restricting the discharge voltage to 0.7 V prevents this large impedance and improves the electrode lifetime. Cells cycled between 0.07 and 0.70 V vs. metallic lithium at a current density of 0.84 A/g (C/5) showed good Coulombic efficiency (about 99%) and maintained a capacity of about 2000 mAh/g after 80 cycles. © 2009 American Chemical Society.
Dejan Krizaj
2012-10-01
Full Text Available Electrical impedance measurements of the suspensions have to take into account the double layer impedance that is due to a very thin charged layer formed at the electrode-electrolite interface. A dedicated measuring cell that enables variation of the distance between the electrodes was developed for investigation of electrical properties of suspensions using two electrode impedance measurements. By varying the distance between the electrodes it is possible to separate the double layer and the suspension impedance from the measured data. From measured and extracted impedances electrical lumped models have been developed. The error of non inclusion of the double layer impedance has been analyzed. The error depends on the frequency of the measurements as well as on the distance between the electrodes.
Analysis of formulas used in coupling impedance coaxial-wire measurements for distributed impedances
In this paper the authors study the validity of coupling impedance bench measurements for distributed impedances, comparing the commonly used log formula to the result obtained applying a modified version of Bethe's theory of diffraction to a long slot in a coaxial beam pipe. The equations found provide a quantitative expression for the influence of the wire thickness used in the measurement of the real and imaginary part of the longitudinal impedance. The precision achievable in an actual measurement is therefore discussed. The method presented has also been applied in the presence of lumped impedances
Bioelectrical Perchlorate Remediation
Thrash, C.; Achenbach, L. A.; Coates, J. D.
2007-12-01
Several bioreactor designs are currently available for the ex-situ biological attenuation of perchlorate- contaminated waters and recently, some of these reactor designs were conditionally approved by the California Department of Health Services for application in the treatment of perchlorate contaminated drinking water. However, all of these systems are dependent on the continual addition of a chemical electron donor to sustain microbial activity and are always subject to biofouling and downstream water quality issues. In addition, residual labile electron donor in the reactor effluent can stimulate microbial growth in water distribution systems and contribute to the formation of potentially toxic trihalomethanes during disinfection by chlorination. As part of our ongoing studies into microbial perchlorate reduction we investigated the ability of dissimilatory perchlorate reducing bacteria (DPRB) to metabolize perchlorate using a negatively charged electrode (cathode) in the working chamber of a bioelectrical reactor (BER) as the primary electron donor. In this instance the DPRB use the electrons on the electrode surface either directly or indirectly in the form of electrolytically produced H2 as a source of reducing equivalents for nitrate and perchlorate reduction. As part of this investigation our fed-batch studies showed that DPRB could use electrons from a graphite cathode poised at -500mV (vs. Ag/AgCl) for the reduction of perchlorate and nitrate. We isolated a novel organism, Dechlorospirillum strain VDY, from the cathode surface after 70 days operation which readily reduced 100 mg.L-1 perchlorate in a mediatorless batch bioelectrical reactor (BER) in 6 days. Continuous up-flow BERs (UFBERs) seeded with active cultures of strain VDY continuously treated waters containing 100 mg.L-1 perchlorate with almost 100% efficiency throughout their operation achieving a non-optimized volumetric loading of 60 mg.L-1 reactor volume.day-1. The same UFBERs also treated
AC Complex Impedance Analysis of Doped Strontium Titanate Multifunctional Ceramics
无
2002-01-01
Doped SrTiO3 capacitor-varistor multifunctional ceramics were fabricated by a single sintering process. AC compleximpedance analysis was performed to investigate electrical features ofgrains and grain boundaries for both as-reducedceramic and reoxidized ceramics. The results showed that the as-reduced ceramic exhibited inductive response athigh frequencies above 2 MHz, which is attributed to the contribution of electron behavior in semiconducting grains.The high frequency inductive response disappeared in impedance plots of reoxidized ceramics.
Сhanges of brain bioelectric activity by diabetic encephalopathy
Vitaly P. Omelchenko
2011-05-01
Full Text Available This article focuses on the analysis of brain bioelectric activity by diabetic encephalopathy. Paid attention to the establishment of EEG parameters and patients psychological characteristics interrelation.
Zukauskas, G; Dapsys, K; Ilgesviciute, J; Vaitkus, P
1988-01-01
Over 900 experiments on dogs and 135 clinical investigations of healthy people and patients of psychiatric and cardiological departments were performed. With the aid of a 8-channel biopotential amplifier and integrator, bioelectrical potential (BEP) directly from internal organs or from various skin zones were recorded. The quantitative parameters of the BEP--their square values and the sum of the square values of BEP recorded simultaneously from several points of the organism--were measured. The effect of low (1 Hz) and high (28 GHz) frequency electrical stimulation was studied. The stimulation of spleen, liver, stomach, small intestine and corresponding acupuncture points had the greatest effect on the quantitative parameters of the BEP in stomach and small intestine. During patient investigation, the most remarkable changes of the studied parameters were noticed in the BEP recorded from the acupuncture points of the affected internal organ meridians. The existence of the common points between Eastern medicine and Western science are discussed. The analysis of the BEP quantitative parameters proves the existence of electrophysiological equilibrium parameters in the organism--bioelectrical homeostasis. The possible theories of electrical circulation in the organism and their relations with traditional acupuncture theoretical concepts are also discussed. PMID:2904209
Bioelectric Signal Measuring System
We describe a low noise measuring system based on interdigitated electrodes for sensing bioelectrical signals. The system registers differential voltage measurements in order of microvolts. The base noise during measurements was in nanovolts and thus, the sensing signals presented a very good signal to noise ratio. An excitation voltage of 1Vrms with 10 KHz frequency was applied to an interdigitated capacitive sensor without a material under test and to a mirror device simultaneously. The output signals of both devices was then subtracted in order to obtain an initial reference value near cero volts and reduce parasitic capacitances due to the electronics, wiring and system hardware as well. The response of the measuring system was characterized by monitoring temporal bioelectrical signals in real time of biological materials such as embryo chicken heart cells and bovine suprarenal gland cells
Pasaribu, Marthin
2016-01-01
Background: Patients with Chronic Kidney Disease (CKD) undergoing regular haemodialysis often have nutritional deficiencies. The decline nutritional status in patients with CKD occur due to various factors, one of which is the high levels of urea in the blood (uremic malnutrition). Urea in the blood consists of small, medium and large molecular weight. The combination of haemodialysis with haemoperfusion (HD / HF) were able to eliminate the medium and large molecular weight. Nutritional stat...
Design and Analysis of Impedance Pumps Utilizing Electromagnetic Actuation
Yu-Hisang Wang
2010-04-01
Full Text Available This study designs and analyzes an impedance pump utilizing an electromagnetic actuator. The pump is designed to have three major components, namely a lower glass substrate patterned with a copper micro-coil, a microchannel, and an upper glass cover plate attached a magnetic PDMS diaphragm. When a current is passed through the micro-coil, an electromagnetic force is established between the coil and the magnetic diaphragm. The resulting deflection of the PDMS diaphragm creates an acoustic impedance mismatch within the microchannel, which results in a net flow. In performing the analysis, simulated models of the magnetic field, the diaphragm displacement and the flow rate are developed using Ansoft/Maxwell3D, ANSYS FEA and FLUENT 6.3 CFD software, respectively. Overall, the simulated results reveal that a net flow rate of 52.8 μL/min can be obtained using a diaphragm displacement of 31.5 μm induced by a micro-coil input current of 0.5 A. The impedance pump proposed in this study provides a valuable contribution to the ongoing development of Lab-on-Chips (LoCs systems.
王智运; 尹庆水
2011-01-01
背景:现代临床外科操作对减少创伤和提高精确度的要求日益提高,生物电阻抗测量技术能将人体组织的信息转化为数字化信号,识别不同组织、器官,进而达到辅助临床操作的目的.目的:回顾分析生物电阻抗测量技术通过数字化转换辅助临床诊断、治疗以及手术等操作过程的情况.方法:由第一作者检索 1999/2009 PubMed数据及万方数据库有关使用生物电阻抗测量技术辅助临床诊断、治疗以及手术等操作,通过数字化信号的采集和分析达到实时定位、定性、提高精度和疗效评估等方面的文献.结果与结论:生物电阻抗测量技术以其无创、安全、可持续监控、多次测量和重复使用等优点,是一种理想的临床操作辅助手段.随着该技术新理论、新方法的不断发展,许多学者在此基础上对其辅助临床操作的应用进行了大量的研究和尝试,有理由相信其辅助应用的范围也将进一步扩大.%BACKGROUND: Modern chirurgery technique claims less trauma and higher precision. Bioelectical impedance measurement technique, which transfers anthropometric tissue information to digital signal, can afford aid to clinical surgery discriminate different tissue and organ.OBJECTIVE: To summarize the clinical application of bioelectical impedance measurement technique for assistance of the chirurgery operation.METHODS: Literatures about application of bioelectical impedance measu rement technique for the chirurgery operation were searched from Chinese Journal Full-text database and PubMed database, published from 1999 to 2009. Articles that qualitatively improve accuracy and curative effect evaluation using digital signal collection and analysis were analyzed.RESULTS AND CONCLUSION: The bioelectical impedance measurement technique is an ideal aided means, by the advantages of noninvasive, safe, durative monitoring, and repetitive use. With developing theory and methods of this
In designing policies to promote bioenergy, policy makers face challenges concerning uncertainties about the sustainability of bioenergy pathways (including greenhouse gas balances), technology and resource costs, or future energy market framework conditions. New information becomes available with time, but policy adjustments can involve high levels of adaptation costs. To enable an effective steering of technology choices and innovation, policies have to strike a balance between creating a consistent institutional framework, which establishes planning security for investors, and sufficient flexibility to adapt to new information. This paper examines implications of economic theory for handling cost and benefit uncertainty in bioelectricity policy design, focussing on choices between price and quantity instruments, technology differentiation, and policy adjustment. Findings are applied to two case studies, the UK's Renewables Obligation and the German feed-in tariff/feed-in premium scheme. Case study results show the trade-offs that are involved in instrument choice and design – depending on political priorities and a country's specific context, different options can prove more adequate. Combining market-based remuneration with sustainability criteria results in strong incentives for bioenergy producers to search for low-cost solutions; whereas cost-based price instruments with centrally steered technology and feedstock choices offer higher planning security for investors and more direct control for policy makers over what pathways are implemented. Independent of the choice of instrument type and technology differentiation mechanism, findings emphasise the importance of a careful policy design, which determines the exact balance between performance criteria such as cost control, incentive intensity, planning security and adaptive efficiency. - Highlights: • Bioelectricity policy design must deal with simultaneous cost and benefit uncertainty.
V. Martín Moreno
2003-04-01
agreement among the fat-to-fat-free mass ratios obtained by arm anthropometric measures (fat-muscle index, FMI, Siri equation for the sum of four skinfold thickness (body fat-muscle index, BFMI Siri and triceps skinfold (BFMItriceps and bioelectrical impedance (BFMI Omron methods. Methods: This is a cross-sectional study. A total of 145 patients were evaluated by anthropometry and bioelectrical impedance (Omron BF 300(, being estimated the agreement through the Intraclass Correlation Coefficient (ICC and Bland-Altman method. The reference method was BFMI Siri. Results: The ICC between BFMI Siri - BFMItriceps were 0,9304 (0,9035; 0,9498, between BFMI Siri - FMI of 0,7726 (0,6846; 0,8361 and between BFMI Siri - BFMI Omron of 0,9114 (0,8771; 0,9361. BFMItriceps (limits of agreement -0,171 to 0,117 show the best agreement according to Bland-Altman analysis with BFMI Siri, followed by BMFI Siri - BFMI Omron (-0,186; 0,178. The agreement limits between FMI and BFMI Siri (-0,2; 0,42, BFMItriceps (-0,26; 0,42 or BFMI Omron (-0,292; 0,504 were beyond of the established cut-off points (-0,2; 0,2. Conclusions: Due to the nature of the statistical agreement BFMItriceps and BFMI Omron are methods interchangeable methods between them and with BFMI Siri. FMI is not interchangeable with BFMI Siri, BFMI Omron or BFMItriceps. These results suggest that FMI cannot estimate properly the body composition. BFMItriceps and BFMI Omron are valid alternative methods to be used instead BFMI Siri in the fat-to-fat-free mass ratio assessment.
黄陈; 朱文艺; 徐静; 李利; 樊荣; 李琦; 王建
2015-01-01
Objective To examine the body composition of COPD patients by multi - frequency bioelectrical impedance and investigate the relationship between body composition and blood gas indicators in order to provide clinical references for nutritional support for COPD patients. Methods We enrolled 62 patients who was hospitalized and diagnosed with COPD in the Department of Respiratory Medicine of Xinqiao Hospital from January to June in 2011. Multi - frequency bioelectrical impedance was used to detect the patients' physical composition. We collected data of serum total protein,albumin, prealbumin,hemoglobin,lymph cell count,blood gas( PaCO2 ,PaO2 and SpO2 ),HCO -3 ,Cl - ,K + ,Na + ,pH of the subjects at admission. Statistical analysis was conducted on the above indicators. Results The malnutrition rates assessed by ribosomal protein content,body fat content,BMI and MAC were 41. 9% ,17. 7% ,19. 4% and 16. 1% , respectively. According the BMI,the patients with inadequate,normal and excess nutrition were significantly different( P < 0. 05 )in ribosomal TBW,BFM,PBF,FFM,PBFF,protein content and PBP;the subjects with inadequate nutrition were higher(P <0. 05)than those with normal and high nutrition in PBP;the subjects with inadequate nutrition were lower( P < 0. 05)than those with normal and high nutrition in PBF and FFM. TBW,FFM,ribosomal protein,and SMM were negatively correlated with PaO2 ( r = - 0. 311, - 0. 306, - 0. 308, - 0. 306;P < 0. 05),and BMI was negatively correlated with SpO2 ( r =- 0. 304,P < 0. 05). Conclusion COPD patients have high malnutrition rate when assessed by ribosomal protein. FFM is more sensitive than BMI in nutritional evaluation of COPD patients. The increase of FFM in COPD patients may improve hypoxia tolerance.%目的：应用多频生物电阻抗技术分析 COPD 患者人体成分及其与血气分析指标的关系，为 COPD 患者的营养支持提供依据。方法选择2011年1—6月在新桥医院呼吸科住院并诊断为 COPD
Harmonic analysis for identification of nonlinearities in impedance spectroscopy
Kiel, M.; Bohlen, O.; Sauer, D.U. [Electrochemical Energy Conversion and Storage Systems Group, Institute for Power Electronics and Electrical Drives (ISEA), RWTH Aachen University (Germany)
2008-10-30
Though impedance is only defined for linear systems, impedance spectroscopy is also successfully applied to nonlinear systems such as fuel cells and batteries. The influence of nonlinearities on measurement results in impedance spectroscopy is therefore discussed on a theoretical and simulative basis. The basis is a simplified Randles model of an electrochemical cell, on which a simulated impedance spectroscopy in galvanostatic mode is performed. For the investigation the focus is on the Butler-Vollmer equation in order to describe the nonlinearity. Furthermore, a linear model for comparison is used, in which the Butler-Volmer nonlinearity is replaced by a linear resistor to show the differences in impedance measurement. In order to find a correlation, also the occurring harmonics are observed. The results are discussed and several methods are suggested for maintaining a quasi-linear impedance measurement by controlling the amplitude of the excitation signal. (author)
Erem, Burak; Martinez Orellana, Ramon; Hyde, Damon E.; Peters, Jurriaan M.; Duffy, Frank H.; Stovicek, Petr; Warfield, Simon K.; MacLeod, Rob S.; Tadmor, Gilead; Brooks, Dana H.
2016-04-01
This paper addresses the challenge of extracting meaningful information from measured bioelectric signals generated by complex, large scale physiological systems such as the brain or the heart. We focus on a combination of the well-known Laplacian eigenmaps machine learning approach with dynamical systems ideas to analyze emergent dynamic behaviors. The method reconstructs the abstract dynamical system phase-space geometry of the embedded measurements and tracks changes in physiological conditions or activities through changes in that geometry. It is geared to extract information from the joint behavior of time traces obtained from large sensor arrays, such as those used in multiple-electrode ECG and EEG, and explore the geometrical structure of the low dimensional embedding of moving time windows of those joint snapshots. Our main contribution is a method for mapping vectors from the phase space to the data domain. We present cases to evaluate the methods, including a synthetic example using the chaotic Lorenz system, several sets of cardiac measurements from both canine and human hearts, and measurements from a human brain.
Dobrev D.
2009-12-01
Full Text Available Measurement and recording of changes in bioelectrical impedance in vivo has become a widely used method with various clinical applications. It includes basal impedance Zo, relative changes ΔZ or its derivative dZ. Many applications related to cardiac and respiratory function require simultaneous electrocardiogram, impedance cardiogram and/or respiration signals recording and analysis. Accurate recording of body impedance is limited by high common mode voltages at the amplifier inputs combined with the influence of the output impedance of the used current source. A circuit concept for a simultaneous high-quality electrocardiogram and bioimpedance acquisition is proposed, profiting from advantages offered by a previously specially designed amplifier with current-driven inputs, yielding to low common mode and high differential mode input impedances.
H. Siqueira Vassimon
2011-06-01
Full Text Available Introduction: Human immunodeficiency vírus (HIV-associated lipodystrophy syndrome (LS includes body composition and metabolic alterations. Lack of validated criteria and tools make difficult to evaluate body composition in this group. Objective: The aim of the study was to compare different methods to evaluate body composition between Brazilians HIV subjects with (HIV+LIPO+ or without LS (HIV+LIPO- and healthy subjects (Control. Methods: in a cross-sectional analyses, body composition was measured by bioelectrical impedance analysis (BIA, skinfold thickness (SF and dual-energy x-ray absorptiometry (DXA in 10 subjects from HIV+LIPO+ group; 22 subjects from HIV+LIPO- group and 12 from Control group. Results: There were no differences in age and body mass index (BMI between groups. The fat mass (FM (% estimated by SF did not correlate with DXA in HIV+LIPO+ group (r = 0,46/ p > 0,05 and had fair agreement in both HIV groups (HIV+LIPO+ =0,35/ HIV+ LIPO- = 0,40. BIA had significant correlation in all groups (p Introducción: El síndrome de lipodistrofia (SL asociado al virus de inmunodeficiencia humana (HIV incluye alteraciones en la composición corporal y metabólica. La falta de herramientas adecuadas y criterios válidos dificultan la evaluación de la composición corporal en este grupo. Objetivo: El objetivo del estudio fue comparar distintos métodos para evaluar la composición corporal entre individuos brasileños con HIV que teniam (HIV+LIPO+ o no LS (HIV+LIPO- e individuos sanos (control. Métodos: Estudio transversal en el que fue evaluada la composición corporal por análisis de impedancia bioeléctrica (BIA, pliegues cutáneos (SF y absorciometría de rayos X de doble energía (DXA en un grupo de 10 individuos con HIV+LIPO+, 22 individuos del grupo HIV+ LIPO- y 12 individuos del grupo control. Resultados: No hubo diferencias en la edad e índice de masa corporal (IMC entre grupos. La masa grasa (MG (% estimada por SF no se correlacion
Thassila Caccia Feragi Cintra
2010-04-01
Full Text Available A bioimpedância (BIC é um método que aplica à tecnologia da impedância no estudo da composição corporal pela avaliação da diferença da condutividade elétrica dos tecidos. Os resultados da BIC são expressos pelas medidas primárias de resistência (R e reatância (Xc. Neste experimento, o método foi desenvolvido para verificar a viabilidade do uso de três diferentes tipos de eletrodos sobre a reprodutibilidade dos valores de R e Xc em gatos adultos. As médias de R e Xc com adesivos e agulhas de acupuntura não diferiram entre si (p?0,05, e os menores valores dos coeficientes de variação obtidos com estes eletrodos sinalizaram para uma melhor reprodutibilidade dos resultados quando comparados com os da agulha hipodérmica. Os diferentes tipos de eletrodos não interferiram nos valores da massa magra (MM estimada por equação específica, porém a agulha de acupuntura mostrou ser o eletrodo mais estável e de melhor aplicabilidade. A MM determinada com os diferentes tipos de eletrodos foi superior (p?0,05 à obtida com a absorciometria de raios-x de dupla energia (DEXA, provavelmente decorrente da equação utilizada na sua estimativa.
PALAVRAS-CHAVES: Composição corporal, felinos, impedância, massa magra.
The bioelectrical impedance is a method that applies impedance technology in the study of physical composition by evaluation of electrical conductivity difference on each organism tissue. The results of bioelectrical impedance (BIC are expressed by the resistance (R and reactance (Xc primary measures. This study was carried out to verify the viability of the use of three different electrodes on the repeatability of R and Xc values in adult cats. The averages of R and Xc estimated by adhesive and acupuncture needles did not differ from each other (p?0.05 and the smaller values of the variation coefficient acquired with these electrodes signaled for a better reproducibility of the results when compared with
Analysis of impedance characteristics of IMPATT-generators
F. B. Bereziuk
2007-10-01
Full Text Available Model of power solid-state oscillators in a millimeter wave band is presented. This model based on non-stationary impedance characteristics of pulse oscillating impact avalanche transit time diodes.
An Analysis of the Acoustic Input Impedance of the Ear
Withnell, Robert H.; Gowdy, Lauren E.
2013-01-01
Ear canal acoustics was examined using a one-dimensional lossy transmission line with a distributed load impedance to model the ear. The acoustic input impedance of the ear was derived from sound pressure measurements in the ear canal of healthy human ears. A nonlinear least squares fit of the model to data generated estimates for ear canal radius, ear canal length, and quantified the resistance that would produce transmission losses. Derivation of ear canal radius has application to quantify...
Phase angle as bioelectrical marker to identify elderly patients at risk of sarcopenia.
Basile, Claudia; Della-Morte, David; Cacciatore, Francesco; Gargiulo, Gaetano; Galizia, Gianluigi; Roselli, Mario; Curcio, Francesco; Bonaduce, Domenico; Abete, Pasquale
2014-10-01
Several markers have been associated with sarcopenia in the elderly, including bioelectrical indices. Phase angle (PhA) is an impedance parameter and it has been suggested as an indicator of cellular death. Thus, the relationship between PhA and muscle mass and strength was investigated in 207 consecutively elderly participants (mean age 76.2±6.7years) admitted for multidimensional geriatric evaluation. Muscle strength by grip strength using a hand-held dynamometer and muscle mass was measured by bioimpedentiometer. PhA was calculated directly with its arctangent (resistance/reactance×180°/π). Linear relationship among muscular mass and strength and with clinical and biochemical parameters, including PhA at uni- and multivariate analysis were performed. Linear regression analysis demonstrated that lower level of PhA is associated with reduction in grip strength (y=3.16+0.08x; r=0.49; psarcopenia. PMID:25034911
An Impedance-Based Stability Analysis Method for Paralleled Voltage Source Converters
Wang, Xiongfei; Blaabjerg, Frede; Loh, Poh Chiang
2014-01-01
This paper analyses the stability of paralleled voltage source converters in AC distributed power systems. An impedance-based stability analysis method is presented based on the Nyquist criterion for multiloop system. Instead of deriving the impedance ratio as usual, the system stability is asses...
Impedance Interaction Modeling and Analysis for Bidirectional Cascaded Converters
Tian, Yanjun; Deng, Fujin; Chen, Zhe;
2015-01-01
more uncertainty to the system stability. An investigation is performed here for showing that the forward and reverse interactions are prominently different in terms of dynamics and stability even though the cascaded converter control remains unchanged. An important guideline has been drawn for the......For the cascaded converter system, the output impedance of source converter interacts with the input impedance of load converter, and the interaction may cause the system instability. In bidirectional applications, when the power flow is reversed, the impedance interaction also varies, which brings...... control of the cascaded converter. That is when voltage mode converter working as the load converter; the constant power mode converter as the source converter, the system is more stable. The concluded findings have been verified by simulation and experimental results....
Two port network analysis for three impedance based oscillators
Said, Lobna A.
2011-12-01
Two-port network representations are applied to analyze complex networks which can be dissolved into sub-networks connected in series, parallel or cascade. In this paper, the concept of two-port network has been studied for oscillators. Three impedance oscillator based on two port concept has been analyzed using different impedance structures. The effect of each structure on the oscillation condition and the frequency of oscillation have been introduced. Two different implementations using MOS and BJT have been introduced. © 2011 IEEE.
Automated experiment for registration of bioelectrical potentials
D. V. Chernetchenko
2013-11-01
Full Text Available A hardware-software complex automated system of recording bioelectrical potentials, which is based on a USB-device with subsequent processing of signals with PC was developed in this work. We proposed a universal scheme of registration of bioelectrical potentials, which allows one to detect the reaction of biological objects to different stimuli, such as cold, heat, photo- and electrical stimulation, and to different combinations of these stimuli (Motsnyj et al., 2004. They could be applied for deeper understanding of the biological mechanisms of generation of electrical potentials in cells and discovering the accommodation processes of organisms as a whole to these stimuli. The system for registration of bioelectrical potentials consists of hardware and software parts. The software part consists of the client and server sides, which transmit experimental data to the network. The client-side software renders a quantitative analysis and stores the results in a database. An integrated system of registration and biometrical processing was applied for analysis of the electrical responses of maize leaves to heat stimuli. The dynamics of these potentials were studied and a quantitative analysis of the potential level stabilization was made. We found that amplitude relation of responses to the initial response increased and stabilized at the level of 130%. Mathematical models of the plant cell for discovering intracellular mechanisms of biopotentials registration were developed. As a result of modeling, we found that the electrical response of the cells is based on selective conductance of the cell membrane for Н+ and K+ ions. By this way, we show the biophysical relation of plant potentials to intracellular biophysical mechanisms.
Impedance analysis of different cell monolayers grown on gold-film electrodes.
Reiss, Bjoern; Wegener, Joachim
2015-08-01
Impedance analysis of mammalian cells grown on planar film electrodes provides a label-free, non-invasive and unbiased observation of cell-based assays addressing the biological response to drugs, toxins or stressors in general. Whereas the time course of the measured impedance at one particular frequency has been used a lot for quantitative monitoring, in-depth analysis of the frequency-dependent impedance spectra is rarely performed. This study summarizes and validates the existing model for spectral analysis by applying it to eight different cell types from different mammalian tissues. Model parameters correctly predict the functional and/or structural properties of the individual cells under study. PMID:26737923
Architecture, modeling, and analysis of a plasma impedance probe
Jayaram, Magathi
Variations in ionospheric plasma density can cause large amplitude and phase changes in the radio waves passing through this region. Ionospheric weather can have detrimental effects on several communication systems, including radars, navigation systems such as the Global Positioning Sytem (GPS), and high-frequency communications. As a result, creating models of the ionospheric density is of paramount interest to scientists working in the field of satellite communication. Numerous empirical and theoretical models have been developed to study the upper atmosphere climatology and weather. Multiple measurements of plasma density over a region are of marked importance while creating these models. The lack of spatially distributed observations in the upper atmosphere is currently a major limitation in space weather research. A constellation of CubeSat platforms would be ideal to take such distributed measurements. The use of miniaturized instruments that can be accommodated on small satellites, such as CubeSats, would be key to achieving these science goals for space weather. The accepted instrumentation techniques for measuring the electron density are the Langmuir probes and the Plasma Impedance Probe (PIP). While Langmuir probes are able to provide higher resolution measurements of relative electron density, the Plasma Impedance Probes provide absolute electron density measurements irrespective of spacecraft charging. The central goal of this dissertation is to develop an integrated architecture for the PIP that will enable space weather research from CubeSat platforms. The proposed PIP chip integrates all of the major analog and mixed-signal components needed to perform swept-frequency impedance measurements. The design's primary innovation is the integration of matched Analog-to-Digital Converters (ADC) on a single chip for sampling the probes current and voltage signals. A Fast Fourier Transform (FFT) is performed by an off-chip Field-Programmable Gate Array (FPGA
High accuracy particle analysis using sheathless microfluidic impedance cytometry.
Spencer, Daniel; Caselli, Federica; Bisegna, Paolo; Morgan, Hywel
2016-07-01
This paper describes a new design of microfluidic impedance cytometer enabling accurate characterization of particles without the need for focusing. The approach uses multiple pairs of electrodes to measure the transit time of particles through the device in two simultaneous different current measurements, a transverse (top to bottom) current and an oblique current. This gives a new metric that can be used to estimate the vertical position of the particle trajectory through the microchannel. This parameter effectively compensates for the non-uniform electric field in the channel that is an unavoidable consequence of the use of planar parallel facing electrodes. The new technique is explained and validated using numerical modelling. Impedance data for 5, 6 and 7 μm particles are collected and compared with simulations. The method gives excellent coefficient of variation in (electrical) radius of particles of 1% for a sheathless configuration. PMID:27241585
Design and Analysis of Impedance Pumps Utilizing Electromagnetic Actuation
Yu-Hisang Wang; Yao-Wen Tsai; Chien-Hsiung Tsai; Chia-Yen Lee; Lung-Ming Fu
2010-01-01
This study designs and analyzes an impedance pump utilizing an electromagnetic actuator. The pump is designed to have three major components, namely a lower glass substrate patterned with a copper micro-coil, a microchannel, and an upper glass cover plate attached a magnetic PDMS diaphragm. When a current is passed through the micro-coil, an electromagnetic force is established between the coil and the magnetic diaphragm. The resulting deflection of the PDMS diaphragm creates an acoustic impe...
Păunescu, T G; Helman, S I
2001-01-01
Transepithelial electrical impedance analysis provides a sensitive method to evaluate the conductances and capacitances of apical and basolateral plasma membranes of epithelial cells. Impedance analysis is complicated, due not only to the anatomical arrangement of the cells and their paracellular shunt pathways, but also in particular to the existence of audio frequency-dependent capacitances or dispersions. In this paper we explore implications and consequences of anatomically related Maxwel...
NEUROFEEDBACK INFLUENCE ON CEREBRUM BIOELECTRICAL ACTIVITY IN GYMNASTS-WOMEN
T. Yu. Strizhkova; Cherapkina, L. P.; O. Yu. Strizhkova
2013-01-01
The analysis of electroencephalogram (EEG) of highly skilled gymnasts-women (main group – 49, control group – 39) showed the availability of cerebrum bioelectrical activity features of sportswomen connected with left hemisphere dominance, predominance of theta-rhythm power and lower reaction to eyes closing, also character of neurodynamic changes generated by neurofeedback course depended on ovarian-menstrual cycle phases.
Huang, Jun; Li, Zhe; Liaw, Bor Yann; Zhang, Jianbo
2016-03-01
Though it becomes a routine to fit impedance data to an equivalent electric circuit model (EECM) using complex nonlinear least square (CNLS) to extract physical parameters from impedance data, two formidable challenges still remain: to build a physically meaningful EECM and to find good initial estimates for model parameters. In this study, combining graphical analysis of impedance data in both Bode and Nyquist plots, a two-step procedure is proposed to address the challenges: (1) a frequency derivative phase angle method is developed in Bode plot to identify the number of time constants (or electrochemical processes); (2) graphical analysis of impedance data in Nyquist plot is used sequentially for initial parameter determination. Major graphical analysis methods are compared in terms of frequency resolution, accuracy and complexity using synthetic data. The superiority of the proposed procedure is illustrated using the experimental data of a three-electrode lithium-ion cell.
Elliptic cylinder geometry for distinguishability analysis in impedance tomography.
Saka, Birsen; Yilmaz, Atila
2004-01-01
Electrical impedance tomography (EIT) is a technique that computes the cross-sectional impedance distribution within the body by using current and voltage measurements made on the body surface. It has been reported that the image reconstruction is distorted considerably when the boundary shape is considered to be more elliptical than circular as a more realistic shape for the measurement boundary. This paper describes an alternative framework for determining the distinguishability region with a finite measurement precision for different conductivity distributions in a body modeled by elliptic cylinder geometry. The distinguishable regions are compared in terms of modeling error for predefined inhomogeneities with elliptical and circular approaches for a noncircular measurement boundary at the body surface. Since most objects investigated by EIT are noncircular in shape, the analytical solution for the forward problem for the elliptical cross section approach is shown to be useful in order to reach a better assessment of the distinguishability region defined in a noncircular boundary. This paper is concentrated on centered elliptic inhomogeneity in the elliptical boundary and an analytic solution for this type of forward problem. The distinguishability performance of elliptical cross section with cosine injected current patterns is examined for different parameters of elliptical geometry. PMID:14723501
王晓君; 胡小琪; 徐海泉; 郭向晖; 李振英; 刘爱玲
2011-01-01
Objective To develop the bioelectrical impedance analysis (BIA) prediction equation for the assessment of body composition among Chinese children. Methods A total of 409 children (220 boys, 189 girls) aged 7-10 years were recruited in Beijing. Body height, weight, resistance and reactance measured by BIA were collected. Total body water (TBW) and fat-free mass (FFM) measured by deuterium dilution technique was used as reference. The multiple stepwise regression analysis was employed to set up equations. Pure error (PE) and Bland-Altman approach was used to cross-validate the prediction equations. Results The prediction equation for TBW was: -6.893 + 0.410xgender(boy=l, girl=0)+0.273xage(year)+0.174xweight(kg) + 0.081 xheight(cm)+ 0.206xRI (cmVft) [R2=0.90, root mean square error (RMSE) = 1.2 kg ], and for FFM was: -9.742 +0.784x gender (boy=l, girl=0)+0.429xage(year)+0.227xweight (kg)+0.104xheight (cm) + 0.269xRI(cm2/fi) (/?2=0.90, RMSE=1.6 kg). No significant difference between predicted TBW,FFM and measured TBW,FFM was found. PE was 1.4 and 1.8 kg for TBW equation and FFM equation, respectively. However, the mean of predicted and measured TBW,FFM correlated positively with the difference between the predicted and measured values ( correlation coefficient 0.24 for TBW and 0.23 for FFM,P<0.01). The two equations performed well in different BMI groups. Conclusion The developed BIA prediction equations for the estimation of TBW and FFM have a high accuracy and precision and are valid for the assessment of body composition among Chinese children aged 7-10 years.%目的 利用生物电阻抗方法测量儿童的体成分,建立适合我国儿童体成分的预测方程.方法 在北京市采用目的抽样法选取409名7～10岁的儿童(男生220名,女生189名),测量身高和体重,采用生物电阻抗仪测量全身电阻抗和电容抗,采用单标水法测量的总体水(total body water,TBW)和去脂体重(fat-free mass,FFM)作为标准,用多元线性逐步
Membrane Operational Impedance Spectra in Chara corallina Estimated by Laplace Transforms Analysis 1
Homblé, Fabrice; Jenard, André
1986-01-01
The membrane operational impedance spectrum of Chara corallina Klein ex Willd. (R. Brown) cells is investigated using Laplace transform analysis. The spectrum changes with both amplitude and sign of the electrical stimulation when time- and voltage-dependent K+ channels contribute to the membrane conductance. We compare the advantages and disadvantage of this technique for studying membrane impedance with those of the alternating current method and the white noise method. PMID:16664925
Fourier-Domain Analysis of Hydriding Kinetics Using Pneumato-Chemical Impedance Spectroscopy
Millet, P.; C. Decaux; R. Ngameni; Guymont, M.
2007-01-01
Analysis of phase transformation processes observed in hydrogen absorbing materials (pure metals, alloys, or compounds) is still a matter of active research. Using pneumato-chemical impedance spectroscopy (PIS), it is now possible to analyze the mechanism of hydriding reactions induced by the gas phase. Experimental impedance diagrams, measured on activated LaNi5 in single- and two-phase domains, are reported in this paper. It is shown that their shape is mostly affected by the slope of the i...
Sugarcane bio ethanol and bioelectricity
Nogueira, Luiz Augusto Horta; Leal, Manoel Regis Lima Verde
2012-07-01
This chapter approaches the Brazilian sugar cane production and processing model, sugarcane processing, sugarcane reception, sugarcane preparation and juice extraction, juice treatment, fermentation, distillation, sector efficiencies and future improvement - 2007, 2015 and 2025, present situation (considering the 2007/2008 harvesting season), prospective values for 2015 and for 2025, bioelectricity generation, straw recovery, bagasse availability, energy balance, present situation, perspective for improvements in the GHG mitigation potential, bio ethanol production chain - from field to tank, and surplus electricity generation.
Dielectric loss analysis using linear resonators with different impedances
Sarabi, Bahman; Khalil, M. S.; Khasawneh, M. A.; Stoutimore, M. J. A.; Gladchenko, Sergiy; Wellstood, F. C.; Lobb, C. J.; Osborn, K. D.
2012-02-01
It is known that amorphous dielectrics are a major source of decoherence in superconducting qubits due to energy absorption by two-level systems coupled to the electric fields. Linear resonators have been applied extensively to study loss in different dielectrics used in qubit circuits due to their versatility and relative simplicity in design, fabrication and measurement. We have designed linear resonators with multi-turn inductors and parallel-plate capacitors with resonance frequencies of 4.8-6.4 GHz. We achieve substantially different L/C values and capacitor volumes by varying the number of inductance turns and the area of the capacitors. We will present results of continuous wave measurements with SiNx capacitors and show how loss tangent and phase noise are related to impedance and capacitor volume.
Robot impedance control and passivity analysis with inner torque and velocity feedback loops
Michele FOCCHI; Gustavo A MEDRANO-CERDA; Thiago BOAVENTURA; Marco FRIGERIO; Claudio SEMINI; Jonas BUCHLI; Darwin G CALDWELL
2016-01-01
Impedance control is a well-established technique to control interaction forces in robotics. However, real implementations of impedance control with an inner loop may suffer from several limitations. In particular, the viable range of stable stiffness and damping values can be strongly affected by the bandwidth of the inner control loops (e.g., a torque loop) as well as by the filtering and sampling frequency. This paper provides an extensive analysis on how these aspects influence the stability region of impedance parameters as well as the passivity of the system. This will be supported by both simulations and experimental data. Moreover, a methodology for designing joint impedance controllers based on an inner torque loop and a positive velocity feedback loop will be presented. The goal of the velocity feedback is to increase (given the constraints to preserve stability) the bandwidth of the torque loop without the need of a complex controller.
Electrochemical impedance spectroscopy on in-situ analysis of oxide layer formation in liquid metal
Graphical abstract: Some test materials (i.e. Fe, Cr, Y and JLF-1 steel) were immersed to liquid metal lead (Pb) mainly at 773 K as the working electrode of electrochemical impedance spectroscopy (EIS). Some oxide layers formed on the electrodes in liquid Pb were analyzed by EIS. The impedance response was summarized as semicircular Nyquist plot, and the electrical properties and the thickness of the oxide layers were evaluated in non-destructive manner. Large impedance due to the formation of Y oxide formed in liquid Pb was detected by EIS, though impedance of Fe oxide and Cr oxide could not be detected due to their small electro resistance. The time constant of the oxide layers was evaluated from the impedance information, and this value identified the types of oxides. The change of the time constant with the immersion time indicated the change of the electrical properties determined by the chemical composition and the crystal structure. The thickness of the oxide layer estimated by EIS agreed well with that evaluated by metallurgical analysis. The growth of Y oxide layer in the liquid Pb was successfully detected by EIS in non-destructive manner. - Highlights: • The electrical properties and the thickness of lead oxide layer formed in liquid Pb were obtained by electrochemical impedance spectroscopy (EIS). • The Fe oxide, Cr oxide and Fe–Cr oxide formed on the electrodes in liquid Pb were not detected by EIS due to their small electrical resistance. • The formation and the growth of Y oxide formed in liquid Pb was detected by EIS. - Abstract: Some test materials (i.e. Fe, Cr, Y and JLF-1 steel) were immersed to liquid metal lead (Pb) mainly at 773 K as the working electrode of electrochemical impedance spectroscopy (EIS). Some oxide layers formed on the electrodes in liquid Pb were analyzed by EIS. The impedance response was summarized as Nyquist plot, and the electrical properties and the thickness of the oxide layers were evaluated in non
Coupling of impedance functions to nuclear reactor building for soil-structure interaction analysis
Finite element model of a nuclear reactor building is coupled to complex soil impedance functions and soil-structure-interaction analysis is carried out in frequency domain. In the second type of analysis applied in this paper, soil impedance functions are used to evaluate equivalent soil springs and dashpots of soil. These are coupled to the structure model in order to carry out the time marching analysis. Three types of soil profiles are considered: hard, medium and soft. Results of two analyzes are compared on the same structural model. Equivalent soil springs and dashpots are determined using new method based on the least square approximation. (author)
Xu, Shanzhi; Wang, Peng; Dong, Yonggui
2016-01-01
In order to measure the impedance variation process in electrolyte solutions, a method of triangular waveform voltage excitation is investigated together with principal component analysis (PCA). Using triangular waveform voltage as the excitation signal, the response current during one duty cycle is sampled to construct a measurement vector. The measurement matrix is then constructed by the measurement vectors obtained from different measurements. After being processed by PCA, the changing information of solution impedance is contained in the loading vectors while the response current and noise information is contained in the score vectors. The measurement results of impedance variation by the proposed signal processing method are independent of the equivalent impedance model. The noise-induced problems encountered during equivalent impedance calculation are therefore avoided, and the real-time variation information of noise in the electrode-electrolyte interface can be extracted at the same time. Planar-interdigitated electrodes are experimentally tested for monitoring the KCl concentration variation process. Experimental results indicate that the measured impedance variation curve reflects the changing process of solution conductivity, and the amplitude distribution of the noise during one duty cycle can be utilized to analyze the contact conditions of the electrode and electrolyte interface. PMID:27110787
Application of impedance spectroscopy method for analysis of benzanol fuels
Mamykin A. V.
2015-06-01
Full Text Available The authors have developed a method for express control of three component «gasoline-alcohol-water» fuel mixtures based on the spectral impedance investigation of benzanol mixture in the frequency range of 500 Hz — 10 kHz. A correlation dependence between the dielectric constant and the specific resistance of the fuel mixture on content of ethanol and water in the mixture has been found. On the basis of this dependence a calibration nomogram to quantify the gasoline and water-alcohol components content in the test benzanol fuel in the actual range of concentrations has been formed. The nomogram allows determining the water-alcohol and gasoline parts in the analyzed fuel with an error of no more than 1% vol., while the strength of water-alcohol solution is determined with an error of no more than 0.8% vol. The obtained nomogram can also give information about critical water content in the benzanol fuel to prevent its eventual phase separation. It is shown that the initial component composition of different gasoline brands has no significant effect on the electrical characteristics of the studied benzanol fuels, which makes the evaluation of alcohol and water content in the fuel sufficiently accurate. for practical applications.
Impedance-matching analysis in IR leaky-wave antennas
Premkumar, Navaneeth; Xu, Yuancheng; Lail, Brian A.
2015-08-01
Planar leaky-wave antennas (LWA) that are capable of full-space scanning have long since been the pursuit for applications including, but not limited to, integration onto vehicles and into cameras for wide-angle of view beam-steering. Such a leaky-wave surface (LWS) was designed for long-wave infrared frequencies with frequency scanning capability. The LWS is based on a microstrip patch array design of a leaky-wave impedance surface and is made up of gold microstrip patches on a grounded zinc sulphide substrate. A 1D composite right/left-handed (CRLH) metamaterial made by periodically stacking a unit cell of the LWS in the longitudinal direction to form a LWA was designed. This paper deals with loading the LWA with a nickel bolometer to collect leaky-wave signals. The LWA radiates a backward leaking wave at 30 degrees at 28.3THz and scans through broadside for frequencies 20THz through 40THz. The paper deals with effectively placing the bolometer in order for the collected signal to exhibit the designed frequency regime. An effective way to maximize the power coupling into the load from the antenna is also explored. The benefit of such a metamaterial/holographic antennacoupled detector is its ability to provide appreciable capture cross-sections while delivering smart signals to subwavelength sized detectors. Due to their high-gain, low-profile, fast response time of the detector and ease of fabrication, this IR LWA-coupled bolometer harbors great potential in the areas of high resolution, uncooled, infrared imaging.
Eickemberg, Michaela [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil); Roriz, Anna Karla Carneiro [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil); Fontes, Gardenia Abreu Vieira [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil); Sampaio, Lilian Ramos [Universidade Federal de Sao Paulo (Unifesp), Sao Paulo, SP (Brazil)
2013-05-01
Objective: To evaluate the association between electrical bioimpedance analysis (BIA) and visceral fat (VF) in adult and elderly patients. Subjects and methods: This was a cross-sectional study, with a sample of 191 subjects (52% women, 49% elderly) stratified by sex, age and body mass. Computerized tomography (VF area) and BIA (percentage of total body fat (%TBF-BIA), phase angle, reactance and resistance) data were generated. Statistical analysis was based on Pearson's Correlation Coefficient, Anova, Pearson's Chi-square, and ROC curves. Results: VF areas {>=} 130 cm{sup 2} were more prevalent among the elderly and among men. Adult females showed a stronger correlation between GV and %TBF-BIA. The other groups showed similar results and statistically significant correlations. Correlations between GV and phase angle were weak and not statistically significant. ROC Curves analyzes showed the following %TBF-BIA, which identified excess VF: for male subjects: 21.5% (adults) and 24.25% (elderly); for female subjects: 35.05% (adults) and 38.45% (elderly) with sensitivity of 78.6%, 82.1%, 83.3%, and 66.7%, and specificity of 70.6%, 62.5%, 79.1%, and 69%, respectively. Conclusion: BIA was found to have satisfactory sensitivity and specificity to predict VF; however, other devices and other techniques should be investigated to improve VF prediction. (author)
Time-invariant measurement of time-varying bioimpedance using vector impedance analysis.
Sanchez, B; Louarroudi, E; Pintelon, R
2015-03-01
When stepped-sine impedance spectroscopy measurements are carried out on (periodically) time-varying bio-systems, the inherent time-variant (time-periodic) parts are traditionally ignored or mitigated by filtering. The latter, however, lacks theoretical foundation and, in this paper, it is shown that it only works under certain specific conditions. Besides, we propose an alternative method, based on multisine signals, that exploits the non-stationary nature in time-varying bio-systems with a dominant periodic character, such as cardiovascular and respiratory systems, or measurements interfered with by their physiological activities. The novel method extracts the best—in a mean square sense—linear time-invariant (BLTI) impedance approximation ZBLTI(jω) of a periodically time-varying (PTV) impedance ZPTV(jω, t) as well as its time-periodic part. Relying on the geometrical interpretation of the BLTI concept, a new impedance analysis tool, called vector impedance analysis (VIA), is also presented. The theoretical and practical aspects are validated through measurements performed on a PTV dummy circuit and on an in vivo myocardial tissue. PMID:25700023
Analysis of the Impedance Resonance of Piezoelectric Multi-Fiber Composite Stacks
Sherrit, S.; Djrbashian, A.; Bradford, S C
2013-01-01
Multi-Fiber CompositesTM (MFC's) produced by Smart Materials Corp behave essentially like thin planar stacks where each piezoelectric layer is composed of a multitude of fibers. We investigate the suitability of using previously published inversion techniques for the impedance resonances of monolithic co-fired piezoelectric stacks to the MFCTM to determine the complex material constants from the impedance data. The impedance equations examined in this paper are those based on the derivation. The utility of resonance techniques to invert the impedance data to determine the small signal complex material constants are presented for a series of MFC's. The technique was applied to actuators with different geometries and the real coefficients were determined to be similar within changes of the boundary conditions due to change of geometry. The scatter in the imaginary coefficient was found to be larger. The technique was also applied to the same actuator type but manufactured in different batches with some design changes in the non active portion of the actuator and differences in the dielectric and the electromechanical coupling between the two batches were easily measureable. It is interesting to note that strain predicted by small signal impedance analysis is much lower than high field stains. Since the model is based on material properties rather than circuit constants, it could be used for the direct evaluation of specific aging or degradation mechanisms in the actuator as well as batch sorting and adjustment of manufacturing processes.
Theoretical Analysis of Triple Liquid Stub Tuner Impedance Matching for ICRH on Tokamaks
Du, Dan; Gong, Xueyu; Yin, Lan; Xiang, Dong; Li, Jingchun
2015-12-01
The impedance matching is crucial for continuous wave operation of ion cyclotron resonance heating (ICRH) antennae with high power injection into plasmas. A sudden increase in the reflected radio frequency power due to an impedance mismatch of the ICRH system is an issue which must be solved for present-day and future fusion reactors. This paper presents a method for theoretical analysis of ICRH system impedance matching for a triple liquid stub tuner under plasma operational conditions. The relationship of the antenna input impedance with the plasma parameters and operating frequency is first obtained using a global solution. Then, the relations of the plasma parameters and operating frequency with the matching liquid heights are indirectly obtained through numerical simulation according to transmission line theory and matching conditions. The method provides an alternative theoretical method, rather than measurements, to study triple liquid stub tuner impedance matching for ICRH, which may be beneficial for the design of ICRH systems on tokamaks. supported by the National Magnetic Confinement Fusion Science Program of China (Nos. 2014GB108002, 2013GB107001), National Natural Science Foundation of China (Nos. 11205086, 11205053, 11375085, and 11405082), the Construct Program of Fusion and Plasma Physics Innovation Team in Hunan Province, China (No. NHXTD03), the Natural Science Foundation of Hunan Province, China (No. 2015JJ4044)
Hui Yan liu; Qing Ji XIE
2004-01-01
Simultaneous impedance analysis of three one-face sealed resonating piezoelectric quartz crystals (PQCs) in parallel is proposed through admittance measurements of the three PQCs on one impedance analyzer and then non-linear fitting according to the parallel combination of three Butterworth-Van Dyke circuits. Responses of each PQC obtained from the three-PQC mode agreed well with those measured separately in series sucrose aqueous solutions. This novel method has been used for the study of depletion-layer effect during ferri-/ferrocyanide electrochemical reactions.
Seismic Soil-Structure Interaction (SSI) analysis has been performed for a site with deeply embedded multiple power block structures. The new method employed combines the computational advantages of the Continuum Impedance Approach together with the Substructure Deletion/Boundary Element Method to accurately predict the 3-Dimensional seismic response of structures. (author)
A Practical Approach for Analysis of Input and Output Impedances of Feedback Amplifiers
Abramovitz, A.
2009-01-01
This paper suggests a pedagogical approach to teaching the subject of the analysis of feedback amplifiers for electrical engineering students at the undergraduate level. Special attention is given to derivation of the input and output impedances. In order to make the procedure clear and suitable for classroom presentation an alternative proof of…
Mounet, N
2010-01-01
Using B. Zotter’s formalism, we present here a novel, efficient and exact matrix method for the field matching determination of the electromagnetic field components created by an offset point charge travelling at any speed in an infinitely long circular multilayer beam pipe. This method improves by a factor of more than one hundred the computational time with three layers and allows the computation for more layers than three. We also generalize our analysis to any azimuthal mode and finally perform the summation on all such modes in the impedance formulae. In particular the exact multimode direct space-charge impedances (both longitudinal and transverse) are given, as well as the wall impedance to any order of precision.
Bioelectric modulation of macrophage polarization
Li, Chunmei; Levin, Michael; Kaplan, David L.
2016-02-01
Macrophages play a critical role in regulating wound healing and tissue regeneration by changing their polarization state in response to local microenvironmental stimuli. The native roles of polarized macrophages encompass biomaterials and tissue remodeling needs, yet harnessing or directing the polarization response has been largely absent as a potential strategy to exploit in regenerative medicine to date. Recent data have revealed that specific alteration of cells’ resting potential (Vmem) is a powerful tool to direct proliferation and differentiation in a number of complex tissues, such as limb regeneration, craniofacial patterning and tumorigenesis. In this study, we explored the bioelectric modulation of macrophage polarization by targeting ATP sensitive potassium channels (KATP). Glibenclamide (KATP blocker) and pinacidil (KATP opener) treatment not only affect macrophage polarization, but also influence the phenotype of prepolarized macrophages. Furthermore, modulation of cell membrane electrical properties can fine-tune macrophage plasticity. Glibenclamide decreased the secretion and gene expression of selected M1 markers, while pinacidil augmented M1 markers. More interestingly, glibencalmide promoted macrophage alternative activation by enhancing certain M2 markers during M2 polarization. These findings suggest that control of bioelectric properties of macrophages could offer a promising approach to regulate macrophage phenotype as a useful tool in regenerative medicine.
NEUROFEEDBACK INFLUENCE ON CEREBRUM BIOELECTRICAL ACTIVITY IN GYMNASTS-WOMEN
T. Yu. Strizhkova
2013-01-01
Full Text Available The analysis of electroencephalogram (EEG of highly skilled gymnasts-women (main group – 49, control group – 39 showed the availability of cerebrum bioelectrical activity features of sportswomen connected with left hemisphere dominance, predominance of theta-rhythm power and lower reaction to eyes closing, also character of neurodynamic changes generated by neurofeedback course depended on ovarian-menstrual cycle phases.
Calculation of rotor impedance for use in design analysis of helicopter airframe vibrations
Nygren, Kip P.
1990-01-01
Excessive vibration is one of the most prevalent technical obstacles encountered in the development of new rotorcraft. The inability to predict these vibrations is primarily due to deficiencies in analysis and simulation tools. The Langley Rotorcraft Structural Dynamics Program was instituted in 1984 to meet long term industry needs in the area of rotorcraft vibration prediction. As a part of the Langley program, this research endeavors to develop an efficient means of coupling the rotor to the airframe for preliminary design analysis of helicopter airframe vibrations. The main effort was to modify the existing computer program for modeling the dynamic and aerodynamic behavior of rotorcraft called DYSCO (DYnamic System COupler) to calculate the rotor impedance. DYSCO was recently developed for the U.S. Army and has proven to be adaptable for the inclusion of new solution methods. The solution procedure developed to use DYSCO for the calculation of rotor impedance is presented. Verification of the procedure by comparison with a known solution for a simple wind turbine model is about 75 percent completed, and initial results are encouraging. After the wind turbine impedance is confirmed, the verification effort will continue by comparison to solutions of a more sophisticated rotorcraft model. Future work includes determination of the sensitivity of the rotorcraft airframe vibrations to helicopter flight conditions and rotor modeling assumptions. When completed, this research will ascertain the feasibility and efficiency of the impedance matching method of rotor-airframe coupling for use in the analysis of airframe vibrations during the preliminary rotorcraft design process.
Analysis of Conductor Impedances Accounting for Skin Effect and Nonlinear Permeability
Perkins, M P; Ong, M M; Brown, C G; Speer, R D
2011-07-20
It is often necessary to protect sensitive electrical equipment from pulsed electric and magnetic fields. To accomplish this electromagnetic shielding structures similar to Faraday Cages are often implemented. If the equipment is inside a facility that has been reinforced with rebar, the rebar can be used as part of a lighting protection system. Unfortunately, such shields are not perfect and allow electromagnetic fields to be created inside due to discontinuities in the structure, penetrations, and finite conductivity of the shield. In order to perform an analysis of such a structure it is important to first determine the effect of the finite impedance of the conductors used in the shield. In this paper we will discuss the impedances of different cylindrical conductors in the time domain. For a time varying pulse the currents created in the conductor will have different spectral components, which will affect the current density due to skin effects. Many construction materials use iron and different types of steels that have a nonlinear permeability. The nonlinear material can have an effect on the impedance of the conductor depending on the B-H curve. Although closed form solutions exist for the impedances of cylindrical conductors made of linear materials, computational techniques are needed for nonlinear materials. Simulations of such impedances are often technically challenging due to the need for a computational mesh to be able to resolve the skin depths for the different spectral components in the pulse. The results of such simulations in the time domain will be shown and used to determine the impedances of cylindrical conductors for lightning current pulses that have low frequency content.
Increases in TBW are typical of pregnancy with advancing gestation. Because excessive TBW expansion can lead to adverse outcomes, a safe non-invasive method for routine assessment of TBW would be useful clinically. BIVA uses resistance (R) and reactance (Xc) determined with 800 uA at 50 kHz and n...
Electrochemical impedance analysis of spray deposited CZTS thin film: Effect of Se introduction
Patil, Swati J.; Lokhande, Vaibhav C.; Lee, Dong-Weon; Lokhande, Chandrakant D.
2016-08-01
The present work deals with electrochemical impedance analysis of spray deposited Cu2ZnSnS4 (CZTS) thin films grown on fluorine doped tin oxide (FTO) substrates and effect of post Se introduction. The CZTS thin films are characterized using X-ray diffraction (XRD), X-Ray photo spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM) and UV-Vis spectroscopy techniques. The electrochemical measurements are carried out using impedance analysis spectroscopy. The strong peak in XRD pattern along (112) plane confirms the Kestrite crystal structure of CZTS film. The FE-SEM analysis reveals that nanoflakes contain crack-free surface microstructure changes with post Se introucation. The optical study reveals that absorption increases with Se dipping time and observed lower band gap of 1.31 eV. Introduction of Se in CZTS film results an improvement in the grain size and surface morphology which leads to increased electrical conductivity of CZTS film.
Bayram, Baris
2015-08-01
In this study, radiation impedance of a capacitive micromachined ultrasonic transducer composed of square-shaped membranes arranged in m × m configuration (m = 1 - 5) is investigated using finite element analysis (FEA) of a commercially available software package(ANSYS). Radiation impedance is calculated for immersed membranes operating in conventional and collapse modes. Individual membrane response within the multi-membrane configuration is analyzed, and excited modes and their effects on radiation impedance and the pressure spectra are reported. This FEA provides an accurate behavior of the acoustic coupling of a thin membrane in a multi-membrane configuration, and extends above the anti-resonance frequency. The first resonance frequency of the membrane is excited for m × m (m ≥ 3) configuration in conventional mode and for m × m (m ≥ 2) configuration in collapse mode. Therefore, this frequency is determined to be responsible for the adverse effects observed in radiation impedance and pressure spectrum. A membrane configuration, which is missing the central membrane from the full m × m configuration is proposed, and is investigated with the FEA. This study is beneficial for the design of precise transducers suited for biomedical applications. PMID:26328680
Determination of bone mineral volume fraction using impedance analysis and Bruggeman model
Ciuchi, Ioana Veronica; Olariu, Cristina Stefania, E-mail: oocristina@yahoo.com; Mitoseriu, Liliana, E-mail: lmtsr@uaic.ro
2013-11-20
Highlights: • Mineral volume fraction of a bone sample was determined. • Dielectric properties for bone sample and for the collagen type I were determined by impedance spectroscopy. • Bruggeman effective medium approximation was applied in order to evaluate mineral volume fraction of the sample. • The computed values were compared with ones derived from a histogram test performed on SEM micrographs. -- Abstract: Measurements by impedance spectroscopy and Bruggeman effective medium approximation model were employed in order to determine the mineral volume fraction of dry bone. This approach assumes that two or more phases are present into the composite: the matrix (environment) and the other ones are inclusion phases. A fragment of femur diaphysis dense bone from a young pig was investigated in its dehydrated state. Measuring the dielectric properties of bone and its main components (hydroxyapatite and collagen) and using the Bruggeman approach, the mineral volume filling factor was determined. The computed volume fraction of the mineral volume fraction was confirmed by a histogram test analysis based on the SEM microstructures. In spite of its simplicity, the method provides a good approximation for the bone mineral volume fraction. The method which uses impedance spectroscopy and EMA modeling can be further developed by considering the conductive components of the bone tissue as a non-invasive in situ impedance technique for bone composition evaluation and monitoring.
Power flow analysis for droop controlled LV hybrid AC-DC microgrids with virtual impedance
Li, Chendan; Chaudhary, Sanjay; Vasquez, Juan Carlos;
2014-01-01
The AC-DC hybrid microgrid is an effective form of utilizing different energy resources and the analysis of this system requires a proper power flow algorithm. This paper proposes a suitable power flow algorithm for LV hybrid AC-DC microgrid based on droop control and virtual impedance. Droop and...... algorithm makes it a potential method for planning, dispatching and operation of droop controlled LV hybrid AC-DC....... virtual impedance concepts for AC network, DC network and interlinking converter are reviewed so as to model it in the power flow analysis. The validation of the algorithm is verified by comparing it with steady state results from detailed time domain simulation. The effectiveness of the proposed...
Ho, Nhu Thuy; Senthilkumar, V.; Kim, Yong Soo
2014-04-01
In this study, we investigated the resistive switching behavior of pristine graphene oxide and thermally reduced GO. Impedance spectroscopy and current-voltage analysis were used to verify the possible physical mechanism of the switching operation. Our observations demonstrated that, the switching operation originates from the oxidation/reduction at the top interface of Al electrode and oxygen migration inside the active layer. Reversible redox reaction Al+1 + xO-2 ↔ AlOx is ground for the conduction electrons.
Complex impedance and equivalent bolometer, analysis of a low noise bolometer for SAFARI
Lindeman, M.A.; Khosropanah, P.; Hijmering, R.A.; De Ridder, M.; Gottardi, L; de Bruijn, M; van der Kuur, J; de Korte, P.A.J.; Gao, J. R.; Hoevers, H.
2012-01-01
Transition-edge-sensor (TES) bolometers are the chosen detector technology for the SAFARI Imaging Spectrometer on the SPICA telescope. For this mission, SRON is developing bolometers, each consisting of a TiAu TES that is weakly coupled to the thermal bath through thin legs of silicon nitride. In order to understand and optimize the bolometer and to verify our detector models, we characterize the devices using a series of complex impedance measurements. We apply equivalent bolometer analysis ...
Oleksiak, Justyna; Cybulski, Gerard
2014-11-01
The aim of this work was to create a computer program, written in LabVIEW, which enables the visualization and analysis of hemodynamic parameters. It allows the user to import data collected using ReoMonitor, an ambulatory monitoring impedance cardiography (AICG) device. The data include one channel of the ECG and one channel of the first derivative of the impedance signal (dz/dt) sampled at 200Hz and the base impedance signal (Z0) sampled every 8s. The program consist of two parts: a bioscope allowing the presentation of traces (ECG, AICG, Z0) and an analytical portion enabling the detection of characteristic points on the signals and automatic calculation of hemodynamic parameters. The detection of characteristic points in both signals is done automatically, with the option to make manual corrections, which may be necessary to avoid "false positive" recognitions. This application is used to determine the values of basic hemodynamic variables: pre-ejection period (PEP), left ventricular ejection time (LVET), stroke volume (SV), cardiac output (CO), and heart rate (HR). It leaves room for further development of additional features, for both the analysis panel and the data acquisition function.
Liu Shuyi
2016-01-01
Full Text Available The hardware design of tuber electrical resistance tomography (TERT system is one of the key research problems of TERT data acquisition system. The TERT system can be applied to the tuber growth process monitoring in agriculture, i.e., the TERT data acquisition system can realize the real imaging of tuber plants in soil. In TERT system, the imaging tuber and soil multiphase medium is quite complexity. So, the impedance test and analysis of soil multiphase medium is very important to the design of sensitive array sensor subsystem and signals processing circuits. In the paper, the soil impedance test experimental is described and the results are analysed. The data acquisition hardware system is designed based on the result of soil medium impedance test and analysis. In the hardware design, the switch control chip ADG508, the instrumentation amplifier AD620 and programmable amplifier AD526 are employed. In the meantime, the phase locked loop technique for signal demodulation is introduced. The initial data collection is given and discussed under the conditions of existing plant tuber and no existing plant tuber. Conclusions of the hardware design of TERT system are presented.
Label-free single cell analysis with a chip-based impedance flow cytometer
Pierzchalski, Arkadiusz; Hebeisen, Monika; Mittag, Anja; Di Berardino, Marco; Tarnok, Attila
2010-02-01
For description of cellular phenotypes and physiological states new developments are needed. Axetris' impedance flow cytometer (IFC) (Leister) is a new promising label-free alternative to fluorescence-based flow cytometry (FCM). IFC measures single cells at various frequencies simultaneously. The frequencies used for signal acquisition range from 0.1 to 20 MHz. The impedance signal provides information about cell volume (ionophore valinomycin. Changes in membrane potential were detectable at the level of cytoplasm conductivity (>4 MHz) and membrane capacitance (1-4 MHz). Our data indicate that IFC can be a valuable alternative to conventional FCM for various applications in the field of cell death and physiology. The work will be extended to address further potential applications of IFC in biotechnology and biomedical cell analysis, as well as in cell sorting.
Electrochemical Impedance Spectroscopic Analysis of RuO2 Based Thick Film pH Sensors
The conductimetric interdigitated thick film pH sensors based on RuO2 were fabricated and their electrochemical reactions with solutions of different pH values were studied by electrochemical impedance spectroscopy (EIS) technique. The microstructural properties and composition of the sensitive films were examined by scanning electron microscopy, X-ray energy dispersive spectroscopy and Raman spectroscopy. The EIS analysis of the sensor was carried out in the frequency range 10 mHz–2 MHz for pH values of test solutions 2–12. The electrical parameters of the sensor were found to vary with changing pH. The conductance and capacitance of the film were distinctly dependent on pH in the low frequency range. The Nyquist and Bode plots derived from the impedance data for the metal oxide thick film pH sensor provided information about the underlying electrochemical reactions
Role of radiation damping in the impedance function approach to soil-structure interaction analysis
This report was prepared at the request of the Lawrence Livermore Laboratory (LLL) to provide background information for analyzing soil-structure interaction by the frequency-independent impedance function approach. LLL is conducting such analyses as part of its seismic review of selected operating plants under the Systematic Evaluation Program for the US Nuclear Regulatory Commission. The analytical background and basic assumptionsof the impedance function theory are briefly reviewed, and the role of radiation damping in soil-structure interaction analysis is discussed. The validity of modeling soil-structure interaction by using frequency-independent functions is evaluated based on data from several field tests. Finally, the recommended procedures for performing soil-structure interaction analyses are discussed with emphasis on the modal superposition method
Towards microfluidic sperm refinement: impedance-based analysis and sorting of sperm cells.
de Wagenaar, B; Dekker, S; de Boer, H L; Bomer, J G; Olthuis, W; van den Berg, A; Segerink, L I
2016-04-12
The use of high quality semen for artificial insemination in the livestock industry is essential for successful outcome. Insemination using semen with a high number of sperm cells containing morphological defects has a negative impact on fertilization outcome. Therefore, semen with a high number of these abnormal cells is discarded in order to maintain high fertilization potential, resulting in the loss of a large number of morphologically normal sperm cells (up to 70-80% of original sample). A commonly occurring morphological sperm anomaly is the cytoplasmic droplet on the sperm flagella. Currently, no techniques are available to extract morphologically normal sperm cells from rejected samples. Therefore, we aim to develop a microfluidic setup which is able to detect and sort morphologically normal sperm cells label-free and non-invasively. In a proof-of-concept experiment, differential impedance measurements were used to detect the presence of cytoplasmic droplets on sperm flagella, which was quantified by calculating the area under the curve (AUC) of the corresponding impedance peaks. A receiver operating characteristic curve of this electrical analysis method showed the good predictive power of this analysis method (AUC value of 0.85). Furthermore, we developed a label-free cell sorting system using LabVIEW, which is capable of sorting sperm cells based on impedance. In a proof-of-concept experiment, sperm cells and 3 μm beads were sorted label-free and non-invasively using impedance detection and dielectrophoresis sorting. These experiments present our first attempt to perform sperm refinement using microfluidic technology. PMID:27025866
Seçgin, A.; Kara, M.; Ozankan, A.
2016-03-01
A modal impedance technique is introduced for mid frequency vibration analyses. The approach is mainly based on statistical energy analysis (SEA), however loss factors are determined by not only driving but also contributed by transfer mobilities. The mobilities are computed by finite element modal analysis. The technique takes geometrical complexity and boundary condition into account to handle their mid-frequency effects. It is applied to a stiffened composite plate having randomized mass, i.e., uncertain plate. For the verification, several numerical and experimental tests are performed. Internal damping of subsystems is evaluated using power injection and is then fed to finite element software to perform numerical analyses. Monte Carlo simulation is employed for the uncertainty analyses. To imitate plate mass heterogeneity, many small masses are used in both numerical and experimental analysis. It is shown that the proposed technique can reliably be used for vibration analyses of uncertain complex structures from mid to high frequency regions.
Combined impedance and dielectrophoresis portable device for point-of-care analysis
del Moral Zamora, B.; Colomer-Farrarons, J.; Mir-Llorente, M.; Homs-Corbera, A.; Miribel-Català, P.; Samitier-Martí, J.
2011-05-01
In the 90s, efforts arise in the scientific world to automate and integrate one or several laboratory applications in tinny devices by using microfluidic principles and fabrication technologies used mainly in the microelectronics field. It showed to be a valid method to obtain better reactions efficiency, shorter analysis times, and lower reagents consumption over existing analytical techniques. Traditionally, these fluidic microsystems able to realize laboratory essays are known as Lab-On-a-Chip (LOC) devices. The capability to transport cells, bacteria or biomolecules in an aqueous medium has significant potential for these microdevices, also known as micro-Total-Analysis Systems (uTAS) when their application is of analytical nature. In particular, the technique of dielectrophoresis (DEP) opened the possibility to manipulate, actuate or transport such biological particles being of great potential in medical diagnostics, environmental control or food processing. This technique consists on applying amplitude and frequency controlled AC signal to a given microsystem in order to manipulate or sort cells. Furthermore, the combination of this technique with electrical impedance measurements, at a single or multiple frequencies, is of great importance to achieve novel reliable diagnostic devices. This is because the sorting and manipulating mechanism can be easily combined with a fully characterizing method able to discriminate cells. The paper is focused in the electronics design of the quadrature DEP generator and the four-electrode impedance measurement modules. These together with the lab-on-a-chip device define a full conception of an envisaged Point-of-Care (POC) device.
The inverse problem of bioelectricity: an evaluation
Oosterom, A. van
2012-01-01
This invited paper presents a personal view on the current status of the solution to the inverse problem of bioelectricity. Its focus lies on applications in the field of electrocardiography. The topic discussed is also relevant in other medical domains, such as electroencephalography, electroneurog
Baumeister, K. J.
1975-01-01
A finite difference formulation is presented for sound propagation in a rectangular two-dimensional duct without steady flow. Before the difference equations are formulated, the governing Helmholtz equation is first transformed to a form whose solution tends not to oscillate along the length of the duct. This transformation reduces the required number of grid points by an order of magnitude. Example solutions indicate that stepped noise source profiles have much higher attenuation than plane waves in a uniform impedance liner. Also, multiple stepped impedance liners are shown to have higher attenuation than uniform ducts if the impedances are chosen properly. For optimum noise reduction with axial variations in impedance, the numerical analysis indicates that for a plane wave input the resistance should be near zero at the entrance of a suppressor duct, while the reactance should be near the optimum value associated with the least-attenuated mode in a uniform duct.
Solid oxide electrolysis cell analysis by means of electrochemical impedance spectroscopy: A review
Nechache, A.; Cassir, M.; Ringuedé, A.
2014-07-01
High temperature water electrolysis based on Solid Oxide Electrolysis Cell (SOEC) is a very promising solution to produce directly pure hydrogen. However, degradation issues occurring during operation still represent a scientific and technological barrier in view of its development at an industrial scale. Electrochemical Impedance Spectroscopy (EIS) is a powerful in-situ fundamental tool adapted to the study of SOEC systems. Hence, after a quick presentation of EIS principle and data analysis methods, this review demonstrates how EIS can be used: (i) to characterize the performance and mechanisms of SOEC electrodes; (ii) as a complementary tool to study SOEC degradation processes for different cell configurations, in addition to post-test tools such as scanning electron microscopy (SEM) or X-ray diffraction (XRD). The use of EIS to establish a systematic SOEC analysis is introduced as well.
Hydration dynamics of collagen/PVA composites: Thermoporometric and impedance analysis
Porous scaffolds like collagen/PVA (polyvinyl alcohol) composites have potential applications in the field of biomedical engineering. The pore properties and electrical behavior of collagen/PVA composite system were investigated by thermoporometry technique and electrochemical impedance analysis. The porous composites were crosslinked by less cytotoxic genipin due to the versatility in the crosslinking reactivity between the amino groups. Different physicochemical properties like rheological behavior, thermal stability of the protein and morphological changes of the composites were investigated as a function of PVA concentration by viscosity profile, temperature dependant circular dichroic spectroscopic studies, scanning electron microscopy. Bound water constrained within the pores of collagen/PVA composites seems to provide signatures for changes induced by amount of additives on the pore diameter and distribution in composite molecules. Impedance measurements of the composites in the frequency range of 10−2 to 105 Hz reveal that concentration of the additive and crosslinking significantly influence the permittivity of the composites. The tunable physicochemical properties help to gain insight for regulating cellular events for tissue and organ regeneration. - Highlights: • Additive and crosslinker influence pore size distribution of biocomposite. • Pore sizes are shifted to the lower nanometer range with increasing PVA concentration. • Additives influence reorientation of water near the peptide group of collagen. • Increase of tan δ values with the decrease of frequency indicates that the resistive component of biocomposites dominates
Mahmoud Z. Iskandarani
2009-01-01
Full Text Available Problem statement: From the early days of, researchers have developed electronic models of neurons designed to emulate neural behavior with electrical signals that mimic in some ways the measured potentials of biological neurons. Researchers interested in fabricating artificial neurons have long sought a simple and techniques to produce devices that efficiently store synaptic weights, which is behind holding a particular state in relation to conductance parameters. As Engineers become closer to realizing accurate hardware models of neurons, the need for a simple analog memory device grows correspondingly. To determine the storage characteristics of polyethylene oxide based polymer as the base material for high charge storage analogue neural switch. Approach: Various devices prepared under controlled conditions. Each device tested for its impedance characteristics as a function of both frequency and temperature. Mathematical model developed to account for the obtained characteristics. Results: The heat treated devices showed stability, repeatability and ability to store enough charge for long time periods. Impedance analysis proved a similar response to the actual neural switches. Conclusion: The symmetrical behavior for such devices opened a wide application area for the manufacturing of low and high frequency analogue devices for intelligent system applications.
Mariana Orta Duarte
2014-01-01
Full Text Available Introduction: Obesity is considered one of the most serious public health problems of the 21st century in children and adolescents. The percentile or Z-score of the body mass index is widely used in children and adolescents to define and assess overweight and obesity, but it does not determine the percentage of total body fat. Other anthropometric measurements that determine total body fat are skinfold thickness and methods of body composition assessment such as bio impedance analysis, both of which are rapid and inexpensive. Objetive: The aim of the study was to correlate the percentage of body fat determined by the Slaughter equation with the percentage of body fat determined by the bio impedance analysis technique, and the body mass index in schoolchildren. Methods: The design of the study is cross-sectional and it was performed on a random selection of 74 children (9.47 ± 1.55 years old attending a primary school in Colima, Mexico during 2011. The percentage of body fat was measured by the Slaughter equation and bio impedance analysis technique. Body mass index was calculated. Inferential statistics were performed with the non-paired Student's t test, Pearson's correlation for quantitative variables (percentage of body fat by the Slaughter equation and bio impedance analysis and the Fisher exact test for qualitative variables. Results: A significant correlation (r = 0.74; p < 0.001 was identified between the percentage of fat measured by the Slaughter equation and bio impedance analysis. We also identified a significant correlation between the percentage of fat measured by the Slaughter equation and body mass index (r = 0. 85; p < 0.001 and the percentage of fat measured by bio impedance analysis and body mass index (r = 0.78; p < 0.001. Conclusion: Given that we identified a significant positive correlation between BIA and STE, we conclude that both are adequate alternatives for measuring the percentage of body fat among schoolchildren in
Impedance spectroscopy analysis of CeNbO4.25
李琴; 王金玲; 张国光
2013-01-01
Monoclinic CeNbO4.25 was prepared by solid state reaction. Complex impedance analysis indicated the presence of grain interior effect along with the grain boundary contribution. The values of ionic transference number ti below 423 K were calculated to be about 0.5. The activation energies of ionic conductivity and electronic conductivity were deduced to be 36.0 and 37.2 kJ/mol, re-spectively. The real part of the AC conductivity was frequency dependent. At high frequencies corresponding to the grain interior ef-fect, the non-Debye nature of the AC conductivity was interpreted by the correlated hopping of interstitial oxygen with the electron holes on the basis of the correlated barrier hopping (CBH) model.
Impedance analysis of Pb2Sb3LaTi5O18 ceramic
C K Suman; K Prasad; R N P Choudhary
2004-12-01
Polycrystalline sample of Pb2Sb3LaTi5O18, a member of tungsten–bronze (TB) family, was prepared using a high temperature solid-state reaction technique. XRD analysis indicated the formation of a singlephase orthorhombic structure. The dielectric studies revealed the diffuse phase transition and the transition temperature was found to be at 52°C. Impedance plots were used as tools to analyse the sample behaviour as a function of frequency. Cole–Cole plots showed Debye relaxation. The activation energy was estimated to be 0.634 eV from the temperature variation of d.c. conductivity. The nature of variation of d.c. conductivity with temperature suggested NTCR behaviour.
Robot Impedance Control and Passivity Analysis with Inner Torque and Velocity Feedback Loops
Focchi, Michele; Medrano-Cerda, Gustavo A.; Boaventura, Thiago; Frigerio, Marco; Semini, Claudio; Buchli, Jonas; Caldwell, Darwin G.
2014-01-01
Impedance control is a well-established technique to control interaction forces in robotics. However, real implementations of impedance control with an inner loop may suffer from several limitations. Although common practice in designing nested control systems is to maximize the bandwidth of the inner loop to improve tracking performance, it may not be the most suitable approach when a certain range of impedance parameters has to be rendered. In particular, it turns out that the viable range ...
Oz, Alon; Hershkovitz, Shany; Tsur, Yoed
2014-11-01
In this contribution we present a novel approach to analyze impedance spectroscopy measurements of supercapacitors. Transforming the impedance data into frequency-dependent capacitance allows us to use Impedance Spectroscopy Genetic Programming (ISGP) in order to find the distribution function of relaxation times (DFRT) of the processes taking place in the tested device. Synthetic data was generated in order to demonstrate this technique and a model for supercapacitor ageing process has been obtained.
Lim, Jun-Hee; Liu, Tian; Kim, Sung-Soo
2014-06-01
The microwave absorption of metamaterials composed of split cut wire (SCW) on grounded dielectric substrate has been investigated on the basis of equivalent transmission line circuit. S-parameters (S 11 and S 21) and input impedance are numerically simulated with variations of the thickness and dielectric loss of the substrate and the geometry of the SCW. Magnetic resonance resulting from antiparallel currents between SCW and ground plane was observed at the frequency of minimum reflection loss. The simulated resonance frequency and reflection loss can be explained well on the basis of the circuit theory of an LC resonator. Analysis of the input impedance of the high impedance surface has shown that perfect absorption can be obtained at the optimized impedance-matching condition, which is dependent on SCW width, thickness and the dielectric loss of the substrate. Better insight into the absorption mechanism of metamaterial absorbers can be attained through the parametric analysis on complex impedance of SCW and its relationship with reflection loss.
Bioelectric Applications for Treatment of Melanoma
Two new cancer therapies apply bioelectric principles. These methods target tumor structures locally and function by applying millisecond electric fields to deliver plasmid DNA encoding cytokines using electrogene transfer (EGT) or by applying rapid rise-time nanosecond pulsed electric fields (nsPEFs). EGT has been used to locally deliver cytokines such as IL-12 to activate an immune response, resulting in bystander effects. NsPEFs locally induce apoptosis-like effects and affect vascular networks, both promoting tumor demise and restoration of normal vascular homeostasis. EGT with IL-12 is in melanoma clinical trials and nsPEFs are used in models with B16F10 melanoma in vitro and in mice. Applications of bioelectrics, using conventional electroporation and extensions of it, provide effective alternative therapies for melanoma
Bioelectric Applications for Treatment of Melanoma
Beebe, Stephen J., E-mail: sbeebe@odu.edu; Schoenbach, Karl H.; Heller, Richard [Frank Reidy Research Center for Bioelectrics/Old Dominion University 4211 Monarch Way, Suite 300, Norfolk, Virginia 23508 (United States)
2010-09-27
Two new cancer therapies apply bioelectric principles. These methods target tumor structures locally and function by applying millisecond electric fields to deliver plasmid DNA encoding cytokines using electrogene transfer (EGT) or by applying rapid rise-time nanosecond pulsed electric fields (nsPEFs). EGT has been used to locally deliver cytokines such as IL-12 to activate an immune response, resulting in bystander effects. NsPEFs locally induce apoptosis-like effects and affect vascular networks, both promoting tumor demise and restoration of normal vascular homeostasis. EGT with IL-12 is in melanoma clinical trials and nsPEFs are used in models with B16F10 melanoma in vitro and in mice. Applications of bioelectrics, using conventional electroporation and extensions of it, provide effective alternative therapies for melanoma.
Bioelectric Applications for Treatment of Melanoma
Richard Heller
2010-09-01
Full Text Available Two new cancer therapies apply bioelectric principles. These methods target tumor structures locally and function by applying millisecond electric fields to deliver plasmid DNA encoding cytokines using electrogene transfer (EGT or by applying rapid rise-time nanosecond pulsed electric fields (nsPEFs. EGT has been used to locally deliver cytokines such as IL-12 to activate an immune response, resulting in bystander effects. NsPEFs locally induce apoptosis-like effects and affect vascular networks, both promoting tumor demise and restoration of normal vascular homeostasis. EGT with IL-12 is in melanoma clinical trials and nsPEFs are used in models with B16F10 melanoma in vitro and in mice. Applications of bioelectrics, using conventional electroporation and extensions of it, provide effective alternative therapies for melanoma.
An introduction to the memristor - a valuable circuit element in bioelectricity and bioimpedance
Gorm Krogh Johnsen
2012-08-01
Full Text Available The memristor (short for memory resistor is a yet quite unknown circuit element, though equally fundamental as resistors, capacitors, and coils. It was predicted from theory arguments nearly 40 years ago, but not realized as a physical component until recently. The memristor shows many interesting features when describing electrical phenomena, especially at small (molecular or cellular scales and can in particular be useful for bioimpedance and bioelectricity modeling. It can also give us a richer and much improved conceptual understanding of many such phenomena. Up until today the tools available for circuit modeling have been restricted to the three circuit elements (RLC as well as the widely used constant phase element (CPE. However, as one element has been missing in our modeling toolbox, many bioelectrical phenomena may have been described incompletely as they are indeed memristive. Such memristive behavior is not possible to capture within a traditional RLC framework. In this paper we will introduce the memristor and look at potential bioelectrical memristive phenomena. The goal is to explain the new memristor’s properties in a simple manner as well as to highlight its importance and relevance. We conclude that memristors must be included as a readily used building block for bioimpedance and bioelectrical data analysis and modeling.
Small Signal Modeling and Comprehensive Analysis of Magnetically Coupled Impedance Source Converters
Forouzesh, Mojtaba; Siwakoti, Yam Prasad; Blaabjerg, Frede;
2016-01-01
Magnetically coupled impedance-source (MCIS) networks are recently introduced impedance networks intended for various high-boost applications. It employs coupled magnetic in the circuit to achieve higher voltage gain. Various MCIS networks have been proposed in the literature for myriad applicati...
Araya, Samuel Simon; Vang, Jakob Rabjerg; Andreasen, Søren Juhl;
2013-01-01
This work analyses the conditioning of single fuel cell assemblies based on different membrane electrode assembly (MEA) types, produced by different methods. The analysis was done by means of electrochemical impedance spectroscopy, and the changes in the fitted resistances of the all the tested...
Couroussé, Damien
2007-01-01
Mechanical impedance is a transposition to mechanics of the term impedance that is used and defined in circuit theory. The theory of circuit (theory of Kirchhoff networks) is basically applicable to electric networks but can be considered more generally as a unifying simplified theory of physics available in several domains like mechanics, electromagnetism, aero-acoustics and fluids mechanics.
In this work, the hydridation dynamics in presence of impurities is analyzed by pneumato-chemical impedance spectroscopy. The measurements are carried out with a Sieverts volumetric frame. The obtention conditions of the experimental impedances are discussed in relation with the thermodynamic states of the metal-H studied systems. A software of specific modelling has been developed: with this software, it is possible to calculate the experimental impedances and, from model equations, to accede to the microscopic kinetic parameters bound to the hydridation reactions. The results obtained on different materials, in presence of oxygen, are presented and analyzed. (O.M.)
Frequency Synchronization Analysis in Digital lock-in Methods for Bio-impedance Determination
Brajkovič Robert; Žagar Tomaž; Križaj Dejan
2014-01-01
The lock-in method is one of the most frequently used methods for reconstruction of measured signals and as such frequently applied in the (bio)impedance method to determine the modulus and phase of the (bio)impedance. In implementation of the method in a (bio)impedance measurement device one has to consider possible non synchronized frequencies of the reference and the analyzed signals as well as potential sources of noise. In this work we analyzed these errors theoretically and experimental...