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Sample records for bioelectrical impedance spectroscopy

  1. Feasibility of Bioelectrical Impedance Spectroscopy Measurement before and after Thoracentesis

    PubMed Central

    Weyer, Sören; Pauly, Karolin; Napp, Andreas; Dreher, Michael; Leonhardt, Steffen; Marx, Nikolaus; Schauerte, Patrick; Mischke, Karl

    2015-01-01

    Background. Bioelectrical impedance spectroscopy is applied to measure changes in tissue composition. The aim of this study was to evaluate its feasibility in measuring the fluid shift after thoracentesis in patients with pleural effusion. Methods. 45 participants (21 with pleural effusion and 24 healthy subjects) were included. Bioelectrical impedance was analyzed for “Transthoracic,” “Foot to Foot,” “Foot to Hand,” and “Hand to Hand” vectors in low and high frequency domain before and after thoracentesis. Healthy subjects were measured at a single time point. Results. The mean volume of removed pleural effusion was 1169 ± 513 mL. The “Foot to Foot,” “Hand to Hand,” and “Foot to Hand” vector indicated a trend for increased bioelectrical impedance after thoracentesis. Values for the low frequency domain in the “Transthoracic” vector increased significantly (P < 0.001). A moderate correlation was observed between the amount of removed fluid and impedance change in the low frequency domain using the “Foot to Hand” vector (r = −0.7). Conclusion. Bioelectrical impedance changes in correlation with the thoracic fluid level. It was feasible to monitor significant fluid shifts and loss after thoracentesis in the “Transthoracic” vector by means of bioelectrical impedance spectroscopy. The trial is registered with Registration Numbers IRB EK206/11 and NCT01778270. PMID:25861647

  2. Bioelectrical impedance analysis revisited.

    PubMed

    Mikes, D M; Cha, B A; Dym, C L; Baumgaertner, J; Hartzog, A G; Tacey, A D; Calabria, M R

    1999-12-01

    Although total limb volume measurements are used to track the progress of lymphedema and its treatment, these measurements can be confounded by changes other than fluid excess namely muscle or fat gain. Bioelectrical impedance analysis (BIA) is a technique that specifically quantifies both total body fluid and extracellular fluid in extremities. Whereas BIA has potential as a quick, inexpensive, and quantitative technique to measure directly fluid gain or loss from lymphedema, it also has certain shortcomings that must be addressed before it can be validated. this paper examines the back-ground that explains why measuring total limb volume is insufficient to quantify the extent of peripheral lymphedema and explores the advantages and drawbacks of using BIA for this purpose. PMID:10652699

  3. Measurement of nutritional status in simulated microgravity by bioelectrical impedance spectroscopy.

    PubMed

    Bartok, Cynthia; Atkinson, Richard L; Schoeller, Dale A

    2003-07-01

    The potential of bioelectrical impedance spectroscopy (BIS) for assessing nutritional status in spaceflight was tested in two head-down-tilt bed-rest studies. BIS-predicted extracellular water (ECW), intracellular water (ICW), and total body water (TBW) measured using knee-elbow electrode placement were compared with deuterium and bromide dilution (DIL) volumes in healthy, 19- to 45-yr-old subjects. BIS was accurate during 44 h of head-down tilt with mean differences (BIS - DIL) of 0-0.1 kg for ECW, 0.3-0.5 for ICW, and 0.4-0.6 kg for TBW (n = 28). At 44 h, BIS followed the within-individual change in body water compartments with a relative prediction error (standard error of the estimate/baseline volume) of 2.0-3.6% of water space. In the second study, BIS did not detect an acute decrease (-1.41 +/- 0.91 kg) in ICW secondary to 48 h of a protein-free, 800 kcal/day diet (n = 18). BIS's insensitivity to ICW losses may be because they were predominantly (65%) localized to the trunk and/or because there was a general failure of BIS to measure ICW independently of ECW and TBW. BIS may have potential for measuring nutritional status during spaceflight, but its limitations in precision and insensitivity to acute ICW changes warrant further validation studies. PMID:12562674

  4. Measurement of nutritional status in simulated microgravity by bioelectrical impedance spectroscopy

    NASA Technical Reports Server (NTRS)

    Bartok, Cynthia; Atkinson, Richard L.; Schoeller, Dale A.

    2003-01-01

    The potential of bioelectrical impedance spectroscopy (BIS) for assessing nutritional status in spaceflight was tested in two head-down-tilt bed-rest studies. BIS-predicted extracellular water (ECW), intracellular water (ICW), and total body water (TBW) measured using knee-elbow electrode placement were compared with deuterium and bromide dilution (DIL) volumes in healthy, 19- to 45-yr-old subjects. BIS was accurate during 44 h of head-down tilt with mean differences (BIS - DIL) of 0-0.1 kg for ECW, 0.3-0.5 for ICW, and 0.4-0.6 kg for TBW (n = 28). At 44 h, BIS followed the within-individual change in body water compartments with a relative prediction error (standard error of the estimate/baseline volume) of 2.0-3.6% of water space. In the second study, BIS did not detect an acute decrease (-1.41 +/- 0.91 kg) in ICW secondary to 48 h of a protein-free, 800 kcal/day diet (n = 18). BIS's insensitivity to ICW losses may be because they were predominantly (65%) localized to the trunk and/or because there was a general failure of BIS to measure ICW independently of ECW and TBW. BIS may have potential for measuring nutritional status during spaceflight, but its limitations in precision and insensitivity to acute ICW changes warrant further validation studies.

  5. A high-speed bioelectrical impedance spectroscopy system based on the digital auto-balancing bridge method

    NASA Astrophysics Data System (ADS)

    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.

  6. Validation of Bioelectrical Impedance Spectroscopy to Measure Total Body Water in Resistance-Trained Males.

    PubMed

    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

  7. Association between muscle hydration measures acquired using bioelectrical impedance spectroscopy and magnetic resonance imaging in healthy and hemodialysis population

    PubMed Central

    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 (T2) has also been used for estimating ECF volumes of individual skeletal muscles. The purpose of this study was to determine the association between T2 (gold standard) of tibialis anterior (TA), medial (MG), and lateral gastrocnemius (LG), and soleus muscles and calf BIS ECF, in healthy and in people with ESRD/HD. Calf BIS and MRI measures were collected on two occasions before and after HD session in people with ESRD/HD and on a single occasion for the healthy participants. Linear regression analysis was used to establish the association between these measures. Thirty‐two healthy and 22 participants on HD were recruited. The association between T2 of TA, LG, MG, and soleus muscles and ratio of calf BIS‐acquired ECF and intracellular fluids (ICF) were: TA: β = 0.30, P > 0.05; LG: β = 0.37, P = 0.035; MG: β = 0.43, P = 0.014; soleus: β = 0.60, P < 0.001. For the HD group, calf ECF was significantly associated with T2 of TA (β = 0.44, P = 0.042), and medial gastrocnemius (β = 0.47, P = 0.027) following HD only. Hence BIS‐acquired measures cannot be used to measure ECF volumes of a single muscle in the ESRD/HD population; however, BIS could be utilized to estimate ratio of ECF: ICF in healthy population for the LG, MG, and soleus muscles. PMID:25626863

  8. Bioelectrical Impedance and Body Composition Assessment

    ERIC Educational Resources Information Center

    Martino, Mike

    2006-01-01

    This article discusses field tests that can be used in physical education programs. The most common field tests are anthropometric measurements, which include body mass index (BMI), girth measurements, and skinfold testing. Another field test that is gaining popularity is bioelectrical impedance analysis (BIA). Each method has particular strengths…

  9. Bioelectrical impedance spectroscopy to estimate fluid balance in critically ill patients.

    PubMed

    Dewitte, Antoine; Carles, Pauline; Joannès-Boyau, Olivier; Fleureau, Catherine; Roze, Hadrien; Combe, Christian; Ouattara, Alexandre

    2016-04-01

    Fluid management is a crucial issue in intensive-care medicine. This study evaluated the feasibility and reproducibility of bioimpedance spectroscopy to measure body-water composition in critically ill patients, and compared fluid balance and daily changes in total body water (TBW) measured by bioimpedance. This observational study included 25 patients under mechanical ventilation. Fluid balance and bioimpedance measurements were recorded on 3 consecutive days. Whole-body bioimpedance spectroscopy was performed with exact or ideal body weights entered into the device, and with or without ICU monitoring. Reproducibility of bioimpedance spectroscopy was very good in all conditions despite ICU monitoring and mechanical ventilation. Bioimpedance measurements using an ideal body weight varied significantly, making the weighing procedure necessary. Comparison of fluid balance and daily changes in body weight provided the best correlation (ρ = 0.74; P < 0.0001). Daily changes in TBW were correlated with fluid balance (Spearman coefficient ρ = 0.31; P = 0.003) and this correlation was improved after exclusion of patients with a SOFA score >10 (ρ = 0.36; P = 0.05) and with extracorporeal circulation (ρ = 0.50; P = 0.005). Regardless of the technique used to estimate volume status, important limits of agreement were observed. Non-invasive determination of body-water composition using bioimpedance spectroscopy is feasible in critically ill patients but requires knowledge of the patient's weight. The best method to assess volume status after fluid resuscitation and the value gained from information about body composition provided by bioimpedance techniques needs further evaluation. PMID:26018457

  10. Experimental verification of depolarization effects in bioelectrical impedance measurement.

    PubMed

    Chen, Xiaoyan; Lv, Xinqiang; Du, Meng

    2014-01-01

    The electrode polarization effects on bioelectrical impedance measurement at low-frequency cannot be ignored. In this paper, the bioelectrical data of mice livers are measured to specify the polarization effects on the bio-impedance measurement data. We firstly introduce the measurement system and methodology. Using the depolarization method, the corrected results are obtained. Besides, the specific effects of electrode polarization on bio-impedance measurement results are investigated using comparative analysis of the previous and posterior correction results from dielectric spectroscopy, Cole-Cole plot, conductivity and spectroscopy of dissipation tangent. Experimental results show that electrode polarization has a significant influence on the characteristic parameters of mouse liver tissues. To be specific, we see a low-frequency limit resistance R0 increase by 19.29%, a reactance peak XP increase by 8.50%, a low-frequency limit conductivity Kl decrease by 17.65% and a dissipation peak tangent decrease by 160%. PMID:25227082

  11. Bioelectrical Impedance Methods for Noninvasive Health Monitoring: A Review

    PubMed Central

    Bera, Tushar Kanti

    2014-01-01

    Under the alternating electrical excitation, biological tissues produce a complex electrical impedance which depends on tissue composition, structures, health status, and applied signal frequency, and hence the bioelectrical impedance methods can be utilized for noninvasive tissue characterization. As the impedance responses of these tissue parameters vary with frequencies of the applied signal, the impedance analysis conducted over a wide frequency band provides more information about the tissue interiors which help us to better understand the biological tissues anatomy, physiology, and pathology. Over past few decades, a number of impedance based noninvasive tissue characterization techniques such as bioelectrical impedance analysis (BIA), electrical impedance spectroscopy (EIS), electrical impedance plethysmography (IPG), impedance cardiography (ICG), and electrical impedance tomography (EIT) have been proposed and a lot of research works have been conducted on these methods for noninvasive tissue characterization and disease diagnosis. In this paper BIA, EIS, IPG, ICG, and EIT techniques and their applications in different fields have been reviewed and technical perspective of these impedance methods has been presented. The working principles, applications, merits, and demerits of these methods has been discussed in detail along with their other technical issues followed by present status and future trends. PMID:27006932

  12. Bioelectrical impedance analysis for bovine milk: Preliminary results

    NASA Astrophysics Data System (ADS)

    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.

  13. Bioelectrical impedance assessment of wound healing.

    PubMed

    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 theory and application of localized BIA and provides examples of its use among patients with lower leg wounds. This promising method may afford clinicians a novel technique for routine monitoring of interventions and surveillance of wounds. PMID:22401341

  14. Wearable Multi-Frequency and Multi-Segment Bioelectrical Impedance Spectroscopy for Unobtrusively Tracking Body Fluid Shifts during Physical Activity in Real-Field Applications: A Preliminary Study.

    PubMed

    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

  15. Wearable Multi-Frequency and Multi-Segment Bioelectrical Impedance Spectroscopy for Unobtrusively Tracking Body Fluid Shifts during Physical Activity in Real-Field Applications: A Preliminary Study

    PubMed Central

    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

  16. Bioelectrical impedance analysis. What does it measure?

    NASA Technical Reports Server (NTRS)

    Schoeller, D. A.

    2000-01-01

    Bioelectrical impedance analysis (BIA) has been proposed for measuring fat-free mass, total body water, percent fat, body cell mass, intracellular water, and extracellular water: a veritable laboratory in a box. Although it is unlikely that BIA is quite this versatile, correlations have been demonstrated between BIA and all of these body compartments. At the same time, it is known that all of the compartments are correlated among themselves. Because of this, it is difficult to determine whether BIA is specific for any or all of these compartments. To investigate this question, we induced acute changes in total body water and its compartments over a 3-h period. Using this approach, we demonstrated that multifrequency BIA, using the Cole-Cole model to calculate the zero frequency and infinite frequency resistance, measures extracellular and intracellular water.

  17. Anisotropic bioelectrical impedance determination of subcutaneous fat thickness

    NASA Astrophysics Data System (ADS)

    Hernández-Becerra, P. A. I.; Delgadillo-Holtfort, I.; Balleza-Ordaz, M.; Huerta-Franco, M. R.; Vargas-Luna, M.

    2014-11-01

    Preliminary results have shown that bioelectrical impedance measurements performed on different parts of the human body strongly depend upon the subcutaneous fat of the considered region. In this work, a method for the determination of subcutaneous fat thickness is explored. Within this method the measurement of the bioelectrical impedance response of the fat-muscle system, both along the direction defined by the muscle fibers and along the corresponding perpendicular direction, are performed. Measurements have been carried out on human female and male subjects of ages around 25 years old at the region of the biceps. Correlation has been performed with skinfold caliper measurements.

  18. BIOELECTRICAL IMPEDANCE VECTOR ANALYSIS IDENTIFIES SARCOPENIA IN NURSING HOME RESIDENTS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  19. Bioelectrical impedance analysis of bovine milk fat

    NASA Astrophysics Data System (ADS)

    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.

  20. Bioelectrical Impedance Vector Analysis and Muscular Fitness in Healthy Men

    PubMed Central

    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

  1. Bioelectrical Impedance Vector Analysis and Muscular Fitness in Healthy Men.

    PubMed

    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

  2. The Influence of Segmental Impedance Analysis in Predicting Validity of Consumer Grade Bioelectrical Impedance Analysis Devices

    NASA Astrophysics Data System (ADS)

    Sharp, Andy; Heath, Jennifer; Peterson, Janet

    2008-05-01

    Consumer grade bioelectric impedance analysis (BIA) instruments measure the body's impedance at 50 kHz, and yield a quick estimate of percent body fat. The frequency dependence of the impedance gives more information about the current pathway and the response of different tissues. This study explores the impedance response of human tissue at a range of frequencies from 0.2 - 102 kHz using a four probe method and probe locations standard for segmental BIA research of the arm. The data at 50 kHz, for a 21 year old healthy Caucasian male (resistance of 180φ±10 and reactance of 33φ±2) is in agreement with previously reported values [1]. The frequency dependence is not consistent with simple circuit models commonly used in evaluating BIA data, and repeatability of measurements is problematic. This research will contribute to a better understanding of the inherent difficulties in estimating body fat using consumer grade BIA devices. [1] Chumlea, William C., Richard N. Baumgartner, and Alex F. Roche. ``Specific resistivity used to estimate fat-free mass from segmental body measures of bioelectrical impedance.'' Am J Clin Nutr 48 (1998): 7-15.

  3. Bioelectrical impedance changes in regional extracellular fluid alterations.

    PubMed

    Kim, C T; Findley, T W; Reisman, S R

    1997-08-01

    The purpose of this study was to determine whether changes in bioelectrical impedance (BI) can reveal regional extracellular fluid (ECF) alterations. ECF changes were induced by holding various arm positions for ten minutes, and they were evaluated through the measurement of BI in eight normal adult subjects. A low frequency current (100 Hz, 0.50 mA) was applied using an electromyography machine through two current electrodes, and the voltage signals were recorded by two amplitude electrodes. The corresponding BI was calculated by Ohm's law, resistance = voltage/current (R = V/I). There was no significant difference between BI and time interval, but between BI and arm position (two-way ANOVA with replicate, p = 0.954, p < 0.001). BI has a negative correlation with wrist circumference. These results show that this experimental method can be used as reflection of ECF changes and that both position and wrist circumference are major factors for BI in the upper extremity. PMID:9298342

  4. Hydration in older adults: the contribution of bioelectrical impedance analysis.

    PubMed

    Goldberg, Lynette R; Heiss, Cynthia J; Parsons, Susan D; Foley, Amanda S; Mefferd, Antje S; Hollinger, Deborah; Parham, Douglas F; Patterson, Jeremy

    2014-06-01

    The sensory and gastrointestinal changes that occur with ageing affect older adults' food and liquid intake. Any decreased liquid intake increases the risk for dehydration. This increased dehydration risk is compounded in older adults with dysphagia. The availability of a non-invasive and easily administered way to document hydration levels in older adults is critical, particularly for adults in residential care. This pilot study investigated the contribution of bioelectrical impedance analysis to measure hydration in 19 older women in residential care: 13 who viewed themselves as healthy and six with dysphagia. Mann-Whitney U analyses documented no significant between-group differences for Total Body Water (TBW), Fat Free Mass (FFM), Fat Mass (FM), and percentage Body Fat (%BF). However, when compared to previously published data for age-matched women, the TBW and FFM values of the two participant groups were notably less, and FM and %BF values were notably greater than expected. If results are confirmed through continued investigation, such findings may suggest that long-term care facilities are unique environments in which all older residents can be considered at-risk for dehydration and support the use of BIA as a non-invasive tool to assess and monitor their hydration status. PMID:24521507

  5. Bioelectrical impedance analysis: A new tool for assessing fish condition

    USGS Publications Warehouse

    Hartman, Kyle J.; Margraf, F. Joseph; Hafs, Andrew W.; Cox, M. Keith

    2015-01-01

    Bioelectrical impedance analysis (BIA) is commonly used in human health and nutrition fields but has only recently been considered as a potential tool for assessing fish condition. Once BIA is calibrated, it estimates fat/moisture levels and energy content without the need to kill fish. Despite the promise held by BIA, published studies have been divided on whether BIA can provide accurate estimates of body composition in fish. In cases where BIA was not successful, the models lacked the range of fat levels or sample sizes we determined were needed for model success (range of dry fat levels of 29%, n = 60, yielding an R2 of 0.8). Reduced range of fat levels requires an increased sample size to achieve that benchmark; therefore, standardization of methods is needed. Here we discuss standardized methods based on a decade of research, identify sources of error, discuss where BIA is headed, and suggest areas for future research.

  6. Bioelectric Impedance Analysis in the Diagnosis of Vesicoureteral Reflux

    PubMed Central

    Bayram, Meral Torun; Alaygut, Demet; Turkmen, Mehmet; Soylu, Alper; Kavukcu, Salih

    2015-01-01

    Background: Vesicoureteral reflux (VUR) is a common abnormality of the urinary tract in childhood. Objectives: As urine enters the ureters and renal pelvis during voiding in vesicoureteral reflux (VUR), we hypothesized that change in body water composition before and after voiding may be less different in children with VUR. Patients and Methods: Patients were grouped as those with VUR (Group 1) and without VUR (Group 2). Bioelectric impedance analysis was performed before and after voiding, and third space fluid (TSF) (L), percent of total body fluid (TBF%), extracellular fluid (ECF%), and intracellular fluid (ICF%) were recorded. After change of TSF, TBF, ECF, ICF (ΔTSF, ΔTBF%, ΔECF%, ΔICF%), urine volume (mL), and urine volume/body weight (mL/kg) were calculated. Groups 1 and 2 were compared for these parameters. In addition, pre- and post-voiding body fluid values were compared in each group. Results: TBF%, ECF%, ICF%, and TSF in both pre- and post-voiding states and ΔTBF%, ΔECF%, ΔICF%, and ΔTSF after voiding were not different between groups. However, while post-voiding TBF%, ECF% was significantly decreased in Group 1 (64.5 ± 8.1 vs 63.7 ± 7.2, P = 0.013 for TBF%), there was not post-voiding change in TSF in the same group. On the other hand, there was also a significant TSF decrease in Group 2. Conclusions: Bladder and ureter can be considered as the third space. Thus, we think that BIA has been useful in discriminating children with VUR as there was no decreased in patients with VUR, although there was decreased TSF in patients without VUR. However, further studies are needed to increase the accuracy of this hypothesis. PMID:26396698

  7. Active core rewarming avoids bioelectrical impedance changes in postanesthetic patients

    PubMed Central

    2011-01-01

    Background Postoperative hypothermia is a common cause of complications in patients who underwent laparoscopic cholecystectomy. Hypothermia is known to elicit electrophysiological, biochemical, and cellular alterations thus leading to changes in the active and passive membrane properties. These changes might influence the bioelectrical impedance (BI). Our aim was to determine whether the BI depends on the core temperature. Methods We studied 60 patients (52 female and 8 male) age 40 to 80 years with an ASA I-II classification that had undergone laparoscopic cholecystectomy under balanced inhalation anesthesia. The experimental group (n = 30) received active core rewarming during the transanesthetic and postanesthesic periods. The control group (n = 30) received passive external rewarming. The BI was recorded by using a 4-contact electrode system to collect dual sets of measurements in the deltoid muscle. The body temperature, hemodynamic variables, respiratory rate, blood-gas levels, biochemical parameters, and shivering were also measured. The Mann-Whitney unpaired t-test was used to determine the differences in shivering between each group at each measurement period. Measurements of body temperature, hemodynamics variables, respiratory rate, and BI were analyzed using the two-way repeated-measures ANOVA. Results The gradual decrease in the body temperature was followed by the BI increase over time. The highest BI values (95 ± 11 Ω) appeared when the lowest values of the temperature (35.5 ± 0.5°C) were reached. The active core rewarming kept the body temperature within the physiological range (over 36.5°C). This effect was accompanied by low stable values (68 ± 3 Ω) of BI. A significant decrease over time in the hemodynamic values, respiratory rate, and shivering was seen in the active core-rewarming group when compared with the controls. The temporal course of shivering was different from those of body temperatue and BI. The control patients showed a

  8. Smart Multi-Frequency Bioelectrical Impedance Spectrometer for BIA and BIVA Applications.

    PubMed

    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

  9. Bioelectrical impedance analysis as a laboratory activity: At the interface of physics and the body

    NASA Astrophysics Data System (ADS)

    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.

  10. Bioelectrical impedance vector analysis in the critically ill: cool tool or just another 'toy'?

    PubMed

    Forni, Lui G; Hasslacher, Julia; Joannidis, Michael

    2015-01-01

    Assessment of volume and hydration status is far from easy and therefore technology such as bioelectrical impedance vector analysis (BIVA) may complement our examination techniques. This study highlights the fact that clinical assessment of volume balance and BIVA may correlate, but whether the routine use of BIVA will avoid significant volume overload in the critically ill remains unknown. Further studies are needed but at the moment appear a little way off. PMID:26556282

  11. Electrochemical Impedance Spectroscopy

    NASA Astrophysics Data System (ADS)

    Retter, Utz; Lohse, Heinz

    Non-steady-state measuring techniques are known to be extremely suitable for the investigation of the electrode kinetics of more complex electrochemical systems. Perturbation of the electrochemical system leads to a shift of the steady state. The rate at which it proceeds to a new steady state depends on characteristic parameters (reaction rate constants, diffusion coefficients, charge transfer resistance, double-layer capacity). Due to non-linearities caused by the electron transfer, low-amplitude perturbation signals are necessary. The small perturbation of the electrode state has the advantage that the solutions of relevant mathematical equations used are transformed in limiting forms that are normally linear. Impedance spectroscopy represents a powerful method for investigation of electrical properties of materials and interfaces of conducting electrodes. Relevant fields of application are the kinetics of charges in bulk or interfacial regions, the charge transfer of ionic or mixed ionic-ionic conductors, semiconducting electrodes, the corrosion inhibition of electrode processes, investigation of coatings on metals, characterisation of materials and solid electrolyte as well as solid-state devices.

  12. Assessment of adult body composition using bioelectrical impedance: comparison of researcher calculated to machine outputted values

    PubMed Central

    Franco-Villoria, Maria; Wright, Charlotte M; McColl, John H; Sherriff, Andrea; Pearce, Mark S

    2016-01-01

    Objectives To explore the usefulness of Bioelectrical Impedance Analysis (BIA) for general use by identifying best-evidenced formulae to calculate lean and fat mass, comparing these to historical gold standard data and comparing these results with machine-generated output. In addition, we explored how to best to adjust lean and fat estimates for height and how these overlapped with body mass index (BMI). Design Cross-sectional observational study within population representative cohort study. Setting Urban community, North East England Participants Sample of 506 mothers of children aged 7–8 years, mean age 36.3 years. Methods Participants were measured at a home visit using a portable height measure and leg-to-leg BIA machine (Tanita TBF-300MA). Measures Height, weight, bioelectrical impedance (BIA). Outcome measures Lean and fat mass calculated using best-evidenced published formulae as well as machine-calculated lean and fat mass data. Results Estimates of lean mass were similar to historical results using gold standard methods. When compared with the machine-generated values, there were wide limits of agreement for fat mass and a large relative bias for lean that varied with size. Lean and fat residuals adjusted for height differed little from indices of lean (or fat)/height2. Of 112 women with BMI >30 kg/m2, 100 (91%) also had high fat, but of the 16 with low BMI (<19 kg/m2) only 5 (31%) also had low fat. Conclusions Lean and fat mass calculated from BIA using published formulae produces plausible values and demonstrate good concordance between high BMI and high fat, but these differ substantially from the machine-generated values. Bioelectrical impedance can supply a robust and useful field measure of body composition, so long as the machine-generated output is not used. PMID:26743700

  13. Bioelectrical impedance analysis can be a useful screen for excess adiposity in spinal muscular atrophy.

    PubMed

    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

  14. Hydration assessment among marathoners using urine specific gravity and bioelectrical impedance analysis.

    PubMed

    Cutrufello, Paul T; Dixon, Curt B; Zavorsky, Gerald S

    2016-01-01

    The present study examined the relationship between urine specific gravity (Usg), body mass (BM) and bioelectrical impedance determined variables [total body water (TBW), per cent TBW and impedance values] before and after a marathon (n = 25 men; 10 women). A significant reduction in BM (pre: 71.2 ± 12.4 kg; post: 69.6 ± 12.0 kg; p < 0.001) and an increase in Usg (pre: 1.009 ± 0.007; post: 1.018 ± 0.009; p < 0.001) was observed post-race. TBW was not significantly decreased (pre: 42.7 ± 8.0 kg; post: 42.4 ± 7.7 kg) while per cent TBW significantly increased post-race (pre: 60.0 ± 3.9%; post: 60.8 ± 3.8%; p < 0.001). Impedance values were significantly greater post-race (pre: 3288 ± 482; post: 3416 ± 492 Ω; p < 0.001). There was no correlation between the change in Usg and the change in BM or any of the bioelectrical impedance determined variables. On average, BM, Usg and impedance values appear to express changes in hydration; however, the observed changes among these variables for a given individual appear to be inconsistent with one another. PMID:27373703

  15. Tissue electrical properties measured by bioelectrical impedance analysis among healthy and sportsmen population

    NASA Astrophysics Data System (ADS)

    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: p<0.0001, 200 kHz - males: p=0.047, females: p<0.0001) Z200/Z5 index also showed lower value in athletes than in control group (p=0.016 for males, p<0.0001 for females). Conclusion: Lower values of impedance and Z200/Z5 index indicates a better nutrition status and general health condition of athletes than in control group.

  16. Effects of resistance training on classic and specific bioelectrical impedance vector analysis in elderly women.

    PubMed

    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

  17. Phase angle and bioelectrical impedance vectors in adolescent and adult male athletes.

    PubMed

    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 < .01) with body-mass index (r = .58) in all 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 < .001). The adolescents with low PA were mostly football and basketball players. The BIVA confidence ellipses of adult and adolescent athletes were different (P < .001) between them and from their respective reference populations and were closer than those of adult and adolescent nonathletes. About 80% of the 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

  18. Smartphone-Based Bioelectrical Impedance Analysis Devices for Daily Obesity Management.

    PubMed

    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 < 0.0001). 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. PMID:26364636

  19. Comparison of Bioelectrical Impedance and Skinfolds with Hydrodensitometry in the Assessment of Body Composition in Healthy Young Adults

    ERIC Educational Resources Information Center

    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…

  20. Body Composition Comparison: Bioelectric Impedance Analysis with Dual-Energy X-Ray Absorptiometry in Adult Athletes

    ERIC Educational Resources Information Center

    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…

  1. Validation of bioelectrical-impedance analysis as a measurement of change in body composition in obesity

    SciTech Connect

    Kushner, R.F.; Kunigk, A.; Alspaugh, M.; Andronis, P.T.; Leitch, C.A.; Schoeller, D.A. )

    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.

  2. Determination of saleable product in finished cattle and beef carcasses utilizing bioelectrical impedance technology.

    PubMed

    Marchello, M J; McLennan, J E; Dhuyvetter, D V; Slanger, W D

    1999-11-01

    Two experiments were performed to develop prediction equations of saleable beef and to validate the prediction equations. In Exp. 1, 50 beef cattle were finished to typical slaughter weights, and multiple linear regression equations were developed to predict kilograms of trimmed boneless, retail product of live cattle, and hot and cold carcasses. A four-terminal bioelectrical impedance analyzer (BIA) was used to measure resistance (Rs) and reactance (Xc) on each animal and processed carcass. The IMPS cuts plus trim were weighed and recorded. Distance between detector terminals (Lg) and carcass temperature (Tp) at time of BIA readings were recorded. Other variables included live weight (BW), hot carcass weight (HCW), cold carcass weight (CCW), and volume (Lg2/Rs). Regression equations for predicting kilograms of saleable product were [11.87 + (.409 x BW) - (.335 x Lg) + (.0518 x volume)] for live (R2 = .80); [-58.83 + (.589 x HCW) - (.846 x Rs) + (1.152 x Xc) + (.142 x Lg) + (2.608 x Tp)] for hot carcass (R2 = .95); and [32.15 + (.633 x CCW) + (.33 x Xc) - (.83 x Lg) + (.677 x volume)] for cold carcass (R2 = .93). In Exp. 2, 27 beef cattle were finished in a manner similar to Exp. 1, and the prediction equations from Exp. 1 were used to predict the saleable product of these animals. The Pearson correlations between actual saleable product and the predictions based on live and cold carcass data were .91 and .95, respectively. The Spearman and Kendall rank correlations were .95 and .83, respectively, for the cold carcass data. These results provide a practical application of bioelectrical impedance for market-based pricing. They complement previous studies that assessed fat-free mass. PMID:10568465

  3. Lipid and moisture content modeling of amphidromous Dolly Varden using bioelectrical impedance analysis

    USGS Publications Warehouse

    Stolarski, J.T.; Margraf, F.J.; Carlson, J.G.; Sutton, T.M.

    2014-01-01

    The physiological well-being or condition of fish is most commonly estimated from aspects of individual morphology. However, these metrics may be only weakly correlated with nutritional reserves stored as lipid, the primary form of accumulated energy in fish. We constructed and evaluated bioelectrical impedance analysis (BIA) models as an alternative method of assessing condition in amphidromous Dolly Varden Salvelinus malma collected from nearshore estuarine and lotic habitats of the Alaskan Arctic. Data on electrical resistance and reactance were collected from the lateral and ventral surfaces of 192 fish, and whole-body percent lipid and moisture content were determined using standard laboratory methods. Significant inverse relationships between temperature and resistance and reactance prompted the standardization of these data to a constant temperature using corrective equations developed herein. No significant differences in resistance or reactance were detected among spawning and nonspawning females after accounting for covariates, suggesting that electrical pathways do not intersect the gonads. Best-fit BIA models incorporating electrical variables calculated from the lateral and ventral surfaces produced the strongest associations between observed and model-predicted estimates of proximate content. These models explained between 6% and 20% more of the variability in laboratory-derived estimates of proximate content than models developed from single-surface BIA data and 32% more than models containing only length and weight data. While additional research is required to address the potential effects of methodological variation, bioelectrical impedance analysis shows promise as a way to provide high-quality, minimally invasive estimates of Dolly Varden lipid or moisture content in the field with only small increases in handling time.

  4. Drug and bioactive molecule screening based on a bioelectrical impedance cell culture platform

    PubMed Central

    Ramasamy, Sakthivel; Bennet, Devasier; Kim, Sanghyo

    2014-01-01

    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. PMID:25525360

  5. Knowing more by fewer measurements: about the (In)ability of bioelectric impedance to enhance obesity research in children.

    PubMed

    Gelbrich, G; Reich, A; Müller, G; Kiess, W

    2005-03-01

    The prevalence of obesity is increasing worldwide. The implications for human health can already be observed in children. Consequently, it is desirable to provide good quantitative descriptions of the relationship of body fat and health risks, such as hypertension. Bioelectric impedance analysis has been frequently praised to be useful for assessing body fat. Devices to analyse body composition based on this technique seem to be selling well, while the real gain in information they provide is unclear. Here we show in a cohort of 2,218 schoolchildren that the body mass index (which is more easily and less costly to determine) is a better predictor of hypertension than the data delivered by impedance analysis. Moreover, we demonstrate that the output of a random number generator is competitive with impedance measurement for this purpose. It is explained by simple arguments from physics why the formulas for the computation of body fat from bioelectric impedance obliterate rather than clarify the relationship of obesity and hypertension. As a consequence, we suggest questioning the opinion propagated by others that bioelectric impedance analysis is a useful tool in field studies on body fat in children. Measurements requiring more effort (compared to simpler methods) should be proved to add worthwhile information, otherwise they should be avoided. PMID:15813605

  6. Smartphone-Based Bioelectrical Impedance Analysis Devices for Daily Obesity Management

    PubMed Central

    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 < 0.0001). 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. PMID:26364636

  7. Visceral fat estimation method by bioelectrical impedance analysis and causal analysis

    NASA Astrophysics Data System (ADS)

    Nakajima, Hiroshi; Tasaki, Hiroshi; Tsuchiya, Naoki; Hamaguchi, Takehiro; Shiga, Toshikazu

    2011-06-01

    It has been clarified that abdominal visceral fat accumulation is closely associated to the lifestyle disease and metabolic syndrome. The gold standard in medical fields is visceral fat area measured by an X-ray computer tomography (CT) scan or magnetic resonance imaging. However, their measurements are high invasive and high cost; especially a CT scan causes X-ray exposure. They are the reasons why medical fields need an instrument for viscera fat measurement with low invasive, ease of use, and low cost. The article proposes a simple and practical method of visceral fat estimation by employing bioelectrical impedance analysis and causal analysis. In the method, abdominal shape and dual impedances of abdominal surface and body total are measured to estimate a visceral fat area based on the cause-effect structure. The structure is designed according to the nature of abdominal body composition to be fine-tuned by statistical analysis. The experiments were conducted to investigate the proposed model. 180 subjects were hired to be measured by both a CT scan and the proposed method. The acquired model explained the measurement principle well and the correlation coefficient is 0.88 with the CT scan measurements.

  8. Determining blood and plasma volumes using bioelectrical response spectroscopy

    NASA Technical Reports Server (NTRS)

    Siconolfi, S. F.; Nusynowitz, M. L.; Suire, S. S.; Moore, A. D. Jr; Leig, J.

    1996-01-01

    We hypothesized that an electric field (inductance) produced by charged blood components passing through the many branches of arteries and veins could assess total blood volume (TBV) or plasma volume (PV). Individual (N = 29) electrical circuits (inductors, two resistors, and a capacitor) were determined from bioelectrical response spectroscopy (BERS) using a Hewlett Packard 4284A Precision LCR Meter. Inductance, capacitance, and resistance from the circuits of 19 subjects modeled TBV (sum of PV and computed red cell volume) and PV (based on 125I-albumin). Each model (N = 10, cross validation group) had good validity based on 1) mean differences (-2.3 to 1.5%) between the methods that were not significant and less than the propagated errors (+/- 5.2% for TBV and PV), 2) high correlations (r > 0.92) with low SEE (< 7.7%) between dilution and BERS assessments, and 3) Bland-Altman pairwise comparisons that indicated "clinical equivalency" between the methods. Given the limitation of this study (10 validity subjects), we concluded that BERS models accurately assessed TBV and PV. Further evaluations of the models' validities are needed before they are used in clinical or research settings.

  9. Body water measurement in growth disorders: a comparison of bioelectrical impedance and skinfold thickness techniques with isotope dilution.

    PubMed Central

    Gregory, J W; Greene, S A; Scrimgeour, C M; Rennie, M J

    1991-01-01

    Total body water was estimated as part of the assessment of body composition in children with growth disorders, using the newly commercially available method of bioelectrical impedance. This was undertaken to compare the precision and accuracy of the results with those derived from skinfold thickness against measurement of stable isotopically labelled water (H2(18)O) dilution as a standard. The comparisons were carried out to see to what extent the impedance method could be applied with confidence to assessment of children with growth disorders. Total body water was derived from impedance (I) using an association with height (Ht2/I). Impedance and skinfold thickness estimates of total body water were equally precise when compared with values obtained from H2(18)O dilution (limits of agreement -1.9 to +1.3 and -1.7 to +2.0 kg respectively). The mean intraobserver coefficient of variation for repeat measurements of impedance was 0.9% compared with 4.6% for skinfold thickness with an interobserver coefficient of variation for impedance of 2.8%. Bioelectrical impedance estimation of body composition is likely to be of value in the growth clinic when expertise in measurement of skinfold thickness is limited or repeated measurements are to be undertaken by different observers. PMID:2001107

  10. Urinary Creatinine Excretion, Bioelectrical Impedance Analysis, and Clinical Outcomes in Patients with CKD: The CRIC Study

    PubMed Central

    Xie, Dawei; Anderson, Amanda H.; Leonard, Mary B.; Reese, Peter P.; Delafontaine, Patrice; Horwitz, Edward; Kallem, Radhakrishna; Navaneethan, Sankar; Ojo, Akinlolu; Porter, Anna C.; Sondheimer, James H.; Sweeney, H. Lee; Townsend, Raymond R.; Feldman, Harold I.

    2014-01-01

    Background and objectives Previous studies in chronic disease states have demonstrated an association between lower urinary creatinine excretion (UCr) and increased mortality, a finding presumed to reflect the effect of low muscle mass on clinical outcomes. Little is known about the relationship between UCr and other measures of body composition in terms of the ability to predict outcomes of interest. Design, setting, participants, & measurements Using data from the Chronic Renal Insufficiency Cohort (CRIC), the relationship between UCr, fat free mass (FFM) as estimated by bioelectrical impedance analysis, and (in a subpopulation) whole-body dual-energy x-ray absorptiometry assessment of appendicular lean mass were characterized. The associations of UCr and FFM with mortality and ESRD were compared using Cox proportional hazards models. Results A total of 3604 CRIC participants (91% of the full CRIC cohort) with both a baseline UCr and FFM measurement were included; of these, 232 had contemporaneous dual-energy x-ray absorptiometry measurements. Participants were recruited between July 2003 and March 2007. UCr and FFM were modestly correlated (rho=0.50; P<0.001), while FFM and appendicular lean mass were highly correlated (rho=0.91; P<0.001). Higher urinary urea nitrogen, black race, younger age, and lower serum cystatin C level were all significantly associated with higher UCr. Over a median (interquartile range) of 4.2 (3.1–5.0) years of follow-up, 336 (9.3%) participants died and 510 (14.2%) reached ESRD. Lower UCr was associated with death and ESRD even after adjustment for FFM (adjusted hazard ratio for death per 1 SD higher level of UCr, 0.63 [95% confidence interval, 0.56 to 0.72]; adjusted hazard ratio for ESRD per 1 SD higher level of UCr, 0.70 [95% confidence interval, 0.63 to 0.75]). Conclusions Among a cohort of individuals with CKD, lower UCr is associated with death and ESRD independent of FFM as assessed by bioelectrical impedance analysis. PMID

  11. Validation of bioelectrical impedance analysis to hydrostatic weighing in male body builders.

    PubMed

    Volpe, Stella Lucia; Melanson, Edward L; Kline, Gregory

    2010-03-01

    The purpose of this study was to compare bioelectrical impedance analysis (BIA) to hydrostatic weighing (HW) in male weight lifters and body builders. Twenty-two male body builders and weight lifters, 23 +/- 3 years of age (mean +/- SD), were studied to determine the efficacy of BIA to HW in this population. Subjects were measured on two separate occasions, 6 weeks apart, for test-retest reliability purposes. Participants recorded 3-day dietary intakes and average work-out times and regimens between the two testing periods. Subjects were, on average, 75 +/- 8 kg of body weight and 175 +/- 7 cm tall. Validation results were as follows: constant error for HW-BIA = 0.128 +/- 3.7%, r for HW versus BIA = -0.294. Standard error of the estimate for BIA = 2.32% and the total error for BIA = 3.6%. Percent body fat was 7.8 +/- 1% from BIA and 8.5 +/- 2% from HW (P > 0.05). Subjects consumed 3,217 +/- 1,027 kcals; 1,848 +/- 768 kcals from carbohydrates; 604 +/- 300 kcals from protein; and 783 +/- 369 kcals from fat. Although work-outs differed among one another, within subject training did not vary. These results suggest that measurement of percent body fat in male body builders and weight trainers is equally as accurate using BIA or HW. PMID:19219400

  12. Validity of Bioelectrical Impedance Analysis to Estimation Fat-Free Mass in the Army Cadets

    PubMed Central

    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

  13. Comparison of Bioelectrical Impedance Analysis and Air Displacement Plethysmography in Community-Dwelling Older Adults.

    PubMed

    Smale, K Brent; McIntosh, Emily I; Vallis, Lori Ann

    2016-05-01

    Clinicians and researchers use body composition measurements to identify individuals who may be at risk of adverse health complications. This study compared two commonly used two-compartmental anthropometric models (bioelectrical impedance analysis [BIA] and air displacement plethysmography [ADP]) to determine whether these two cost-effective methods would provide similar fat free mass index (FFMI) values in a mixed and sex-separated sample population of healthy older adults. Community-dwelling older adults (N= 37, 18 men) aged 74.5 ± 5.2 years participated. FFMIBIAwas correlated with FFMIADP(r= .916); however, these correlations were markedly reduced when the population was split by sex (r< .60). The level of agreement between the difference values (FFMIBIA- FFMIADP) fluctuated ± 2.1 kg/m(2)(illustrated via Bland-Altman plots), but these differences were not statistically different from 0. Findings from the current work suggest that clinicians must be cautious when using portable devices such as BIA to assess FFMI in an older adult population. PMID:24652918

  14. Bioelectrical impedance vector analysis for evaluating zinc supplementation in prepubertal and healthy children

    PubMed Central

    Dantas, Márcia Marília Gomes; Rocha, Érika Dantas Medeiros; Brito, Naira Josele Neves; Alves, Camila Xavier; França, Mardone Cavalcante; Almeida, Maria das Graças; Brandão-Neto, José

    2015-01-01

    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. PMID:26425922

  15. Body composition analysis in older adults with dementia. Anthropometry and bioelectrical impedance analysis: a critical review.

    PubMed

    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

  16. Estimation of fat-free mass in Asian neonates using bioelectrical impedance analysis.

    PubMed

    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

  17. Estimation of fat-free mass in Asian neonates using bioelectrical impedance analysis

    PubMed Central

    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

    2016-01-01

    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 independent Western cohort. A total of 173 neonates at birth and 140 at week-2 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 were assessed using intra-class correlation and Bland-Altman analyses. L2/R50 was the significant predictor of FFM at week-2 but not at birth. Compared to the model using weight, sex and length, including L2/R50 slightly improved the prediction with a bias of 0.01kg with 2SD limits of agreement (LOA) (0.18, −0.20). Prediction explained 88.9% of variation but not beyond that of anthropometry. Applying these equations to 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 to simple anthropometry in Asian populations. There is a need for population and age appropriate FFM prediction equations. PMID:26856420

  18. Prevalence of child malnutrition at a university hospital using the World Health Organization criteria and bioelectrical impedance data

    PubMed Central

    Pileggi, V.N.; Monteiro, J.P.; Margutti, A.V.B.; Camelo, J.S.

    2016-01-01

    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

  19. Prevalence of child malnutrition at a university hospital using the World Health Organization criteria and bioelectrical impedance data.

    PubMed

    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

  20. Effects of skin blood flow and temperature on bioelectric impedance after exercise.

    PubMed

    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 < 0.05) and decreased from M2 to M3 (P < 0.05). These changes did not affect BIA 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 = 2.6 kg), very high values for R2 (> 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

  1. A Pilot Randomized Trial Evaluating Lymphedema Self-Measurement with Bioelectrical Impedance, Self-Care Adherence, and Health Outcomes

    PubMed Central

    Shih, Ya-Chen Tina; Doersam, Jennifer K.; Rhoten, Bethany Andrews; Schultze, Benjamin S.; Dietrich, Mary S.

    2014-01-01

    Abstract 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 self-measurement on daily self-care activities and health outcomes in breast cancer survivors with lymphedema. Methods and Results: A pilot randomized clinical trial compared outcomes between breast cancer survivors with lymphedema who self-monitored for 3 months and breast cancer survivors with lymphedema who did not self-monitor. Data were collected at baseline, months 1, 2, 3, and 4. Eighty-six women with lymphedema were screened: 62 were eligible, 50 were enrolled, 10 withdrew, and 1 had incomplete data, thus N=39. No between group differences were noted in participant characteristics. The self-monitored group had higher days of garment use (p=0.005) that remained stable after self-monitoring stopped. The median number of days of simple manual lymphatic drainage increased in the intervention group (p=0.004) with a downward trend after self-monitoring ceased. Conclusions: Objective self-monitoring of arms using BIS is possible. Self-monitoring may positively impact self-care behaviors. Highly symptomatic patients may require coaching or other psychological support to improve their self-care. Studies that combine a cognitive behavioral therapy component along with self-measurement should be considered as potential interventions to impact lymphedema self-care. Other applications of self-monitoring warrant investigation. PMID:25412401

  2. Optically stimulated differential impedance spectroscopy

    DOEpatents

    Maxey, Lonnie C; Parks, II, James E; Lewis, Sr., Samuel A; Partridge, Jr., William P

    2014-02-18

    Methods and apparatuses for evaluating a material are described. Embodiments typically involve use of an impedance measurement sensor to measure the impedance of a sample of the material under at least two different states of illumination. The states of illumination may include (a) substantially no optical stimulation, (b) substantial optical stimulation, (c) optical stimulation at a first wavelength of light, (d) optical stimulation at a second wavelength of light, (e) a first level of light intensity, and (f) a second level of light intensity. Typically a difference in impedance between the impedance of the sample at the two states of illumination is measured to determine a characteristic of the material.

  3. Relationships between bioelectric impedance and subcutaneous adipose tissue thickness measured by LIPOMETER and skinfold calipers in children.

    PubMed

    Jürimäe, T; Sudi, K; Payerl, D; Leppik, A; Jürimäe, J; Müller, R; Tafeit, E

    2003-09-01

    The aim of this study was to compare the relationships between bioelectrical impedance and thicknesses of adipose tissue measured by traditional skinfold caliper (double thickness) or a LIPOMETER device (single non-compressed thickness) in 9- to 12-year-old boys ( n=52) and girls ( n=44). In total, nine skinfolds (triceps, subscapular, biceps, iliac crest, supraspinale, abdominal, front thigh, medial calf, mid-axilla) were measured. Measurement for the thickness of subcutaneous adipose tissue layers (SAT-layers) by LIPOMETER were performed at 15 body sites (neck, triceps, biceps, upper back, front chest, lateral chest, upper abdomen, lower abdomen, lower back, hip, front thigh, lateral thigh, rear thigh, inner thigh, calf). Body bioelectrical impedance was measured with a multiple-frequency impedance device Multiscan-5000 (Bodystat, UK). Impedance at 50 kHz highly correlated with body mass ( r=-0.47 in boys, r=-0.46 in girls, r=-0.47 in total group). The relationship with body height was significant only in girls ( r=-0.42). Skinfold thicknesses measured by caliper did not correlate significantly with body impedance at 50 kHz. SAT-layers measured by LIPOMETER at triceps, front thigh, lateral thigh and rear thigh sites in boys and at the lateral thigh site in girls correlated significantly with body impedance measured at 50 kHz. Stepwise multiple regression analysis indicated that the iliac crest and front thigh skinfold thicknesses measured by caliper characterized only 5.7-12.0% of the impedance at 50 kHz in the total group ( n=96). From the measured 15 SAT-layers, the most significant was the lateral thigh layer which characterized 20.0%, 11.9% and 13.6% of the impedance at 50 kHz in boys, girls and the total group, respectively. It was concluded that the influence of subcutaneous adipose tissue on body impedance is relatively low in children. However, SAT-layers have a slightly higher influence on body impedance than skinfold thicknesses measured by caliper. The

  4. Association of Anthropometric and Bioelectrical Impedance Analysis Measures of Adiposity with High Molecular Weight Adiponectin Concentration

    PubMed Central

    Zeng, Wei-Fang; Li, Yan; Sheng, Chang-Sheng; Huang, Qi-Fang; Kang, Yuan-Yuan; Zhang, Lu; Wang, Shuai; Cheng, Yi-Bang; Li, Fei-Ka; Wang, Ji-Guang

    2016-01-01

    Objective To investigate the relationship between adiposity measures and plasma concentration of high molecular weight (HMW) adiponectin. Methods In a Chinese sample (n = 1081), we performed measurements of anthropometry and bioelectrical impedance analysis (BIA). We defined overweight and obesity as a body mass index between 24 and 27.4 kg/m² and ≥ 27.5 kg/m², respectively, and central obesity as a waist circumference ≥ 90 cm in men and ≥ 80 cm in women. Plasma HMW adiponectin concentration was measured by the ELISA method. Results Plasma HMW adiponectin concentration was significantly (P < 0.0001) higher in women (n = 677, 2.47 μg/mL) than men (n = 404, 1.58 μg/mL) and correlated with advancing age in men (r = 0.28) and women (r = 0.29). In adjusted analyses, it was lower in the presence of overweight (n = 159, 1.26 μg/mL in men and n = 227, 2.15μg/mL in women) and obesity (n = 60, 1.31 μg/mL and n = 82, 2.10 μg/mL, respectively) than normal weight subjects (n = 185, 2.07μg/mL and n = 368, 2.94 μg/mL, respectively) and in the presence of central obesity (n = 106, 1.28 μg/mL and n = 331, 2.12 μg/mL, respectively) than subjects with a normal waist circumference (n = 298, 1.74 μg/mL and n = 346, 2.74 μg/mL, respectively). In multiple regression analyses stratified for gender, adjusted for confounders and considered separately each of the adiposity measures, all adiposity measures were significantly (r -0.18 to -0.31, P < 0.001) associated with plasma HMW adiponectin concentration. However, in further stratified and adjusted regression analyses considered stepwise all adiposity measures, only waist-to-hip ratio was significantly (P < 0.05) associated with plasma HMW adiponectin concentration in men (r = -0.10) and women (r = -0.15). Conclusions Anthropometric measures of obesity, such as waist-to-hip ratio, but not BIA measures, are independently associated with plasma adiponectin concentration. PMID:27227680

  5. Predictive validity of four bioelectrical impedance equations in determining percent fat mass in overweight and obese children.

    PubMed

    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

  6. The application of bioelectrical impedance analysis in live tropical hair sheep as a predictor of body composition upon slaughter.

    PubMed

    Avril, Dean H; Lallo, Cicero; Mlambo, Victor; Bourne, Gregory

    2013-11-01

    Animal management for breeding and marketing can be improved by precise measurement of desirable traits. Live animal body composition analysis facilitates the selection of animals that are best suited for the intended purpose. This study was designed to assess the accuracy of bioelectrical impedance analysis (BIA) predicted live body tissue composition, as a proxy for the estimation of carcass quality in Barbados Black Belly lambs. Thirty-four Barbados Black Belly lambs were placed on an 8-week feeding regime and then slaughtered. A randomized experimental design was used to allocate diets to animals, which had been stratified into eight groups by initial live weight. The lambs were fed a basal diet of Brachiaria arrecta fresh forage ad libitum and subjected to one of four diets; NS-non-supplemented diet, TG-Trichantera gigantea-supplemented, C100-concentrate supplemented for maintenance, and C400-concentrate supplemented for growth. Diets NS, TG, C100, and C400 had 7, 9, 11, and 7 animals, respectively. The average age and weight at the time of slaughter were 206 days and 23.7 kg, respectively. A 4-terminal impedance analyzer (RJL Systems®) was used to generate BIA data from live animals immediately before slaughter. The chilled carcasses were then subject to chemical analysis for crude fat, crude protein, and dry matter. Live animal and carcass traits predicted by BIA included fat and fat-free mass, crude fat, crude protein, protein to fat ratio, and tissue distribution. Regression equations were developed from BIA data obtained from the live animal to predict all carcass composition traits measured. Bioelectrical impedance analysis generated favorable results as a practical application to carcass composition evaluation in live tropical hair sheep. PMID:23852279

  7. Validity of segmental multiple-frequency bioelectrical impedance analysis to estimate body composition of adults across a range of body mass indexes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Objective: Compare estimates of body composition using segmental, multiple frequency bioelectrical impedance analysis (MF-BIA) with dual x-ray absorptiometry (DXA) in healthy adults across a range of body mass index (BMI). Methods: Percent body fat (%BF), fat-mass (FM), and fat-free mass (FFM) asses...

  8. Effect of Exercise Intensity on Percent Body Fat Determined by Leg-to-Leg and Segmental Bioelectrical Impedance Analyses in Adults

    ERIC Educational Resources Information Center

    Andreacci, Joseph L.; Nagle, Trisha; Fitzgerald, Elise; Rawson, Eric S.; Dixon, Curt B.

    2013-01-01

    Purpose: We examined the impact that cycle ergometry exercise had on percent body fat (%BF) estimates when assessed using either leg-to-leg or segmental bioelectrical impedance analysis (LBIA; SBIA) and whether the intensity of the exercise bout impacts the %BF magnitude of change. Method: Seventy-four college-aged adults participated in this…

  9. The Effect of an Acute After-School Exercise Bout on Percentage of Body Fat Using Leg-to-Leg Bioelectrical Impedance Analysis in Children

    ERIC Educational Resources Information Center

    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…

  10. Impedance spectroscopy of food mycotoxins

    NASA Astrophysics Data System (ADS)

    Bilyy, Oleksandr I.; Yaremyk, Roman Ya.; Kotsyumbas, Ihor Ya.; Kotsyumbas, Halyna I.

    2012-01-01

    A new analytical method of high-selective detection of mycotoxins in food and feed are considered. A method is based on optical registration the changes of conduct of the electric polarized bacterial agents in solution at the action of the external gradient electric fields. Measuring are conducted in integrated electrode-optical cuvette of the special construction, which provides the photometric analysis of forward motion of the objects registration in liquid solution under act of the enclosed electric field and simultaneous registration of kinetics of change of electrical impedance parameters solution and electrode system.

  11. Electrochemical Impedance Spectroscopy Of Metal Alloys

    NASA Technical Reports Server (NTRS)

    Macdowell, L. G.; Calle, L. M.

    1993-01-01

    Report describes use of electrochemical impedance spectroscopy (EIS) to investigate resistances of 19 alloys to corrosion under conditions similar to those of corrosive, chloride-laden seaside environment of Space Transportation System launch site. Alloys investigated: Hastelloy C-4, C-22, C-276, and B-2; Inconel(R) 600, 625, and 825; Inco(R) G-3; Monel 400; Zirconium 702; Stainless Steel 304L, 304LN, 316L, 317L, and 904L; 20Cb-3; 7Mo+N; ES2205; and Ferralium 255. Results suggest electrochemical impedance spectroscopy used to predict corrosion performances of metal alloys.

  12. Impedance Spectroscopy of Human Blood

    NASA Astrophysics Data System (ADS)

    Mesa, Francisco; Bernal, José J.; Sosa, Modesto A.; Villagómez, Julio C.; Palomares, Pascual

    2004-09-01

    The blood is one of the corporal fluids more used with analytical purposes. When the blood is extracted, immediately it is affected by agents that act on it, producing transformations in its elements. Among the effects of these transformations the hemolysis phenomenon stands out, which consists of the membrane rupture and possible death of the red blood cells. The main purpose of this investigation was the quantification of this phenomenon. A Solartron SI-1260 Impedance Spectrometer was used, which covers a frequency range of work from 1 μHz to 10 MHz, and its accuracy has been tested in the accomplishment of several applications. Measurements were performed on 3 mL human blood samples, from healthy donors. Reactive strips for sugar test of 2 μL, from Bayer, were used as electrodes, which allow gathering a portion of the sample, to be analyzed by the spectrometer. Preliminary results of these measurements are presented.

  13. Bioelectrical impedance phase angle and subjective global assessment in detecting malnutrition among newly diagnosed head and neck cancer patients.

    PubMed

    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

  14. Measuring body composition in dogs using multifrequency bioelectrical impedance analysis and dual energy X-ray absorptiometry.

    PubMed

    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

  15. Single-cell bioelectrical impedance platform for monitoring cellular response to drug treatment.

    PubMed

    Asphahani, Fareid; Wang, Kui; Thein, Myo; Veiseh, Omid; Yung, Sandy; Xu, Jian; Zhang, Miqin

    2011-02-01

    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 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. PMID:21301069

  16. Effective and Timely Evaluation of Pulmonary Congestion: Qualitative Comparison Between Lung Ultrasound and Thoracic Bioelectrical Impedance in Maintenance Hemodialysis Patients

    PubMed Central

    Donadio, Carlo; Bozzoli, Laura; Colombini, Elisa; Pisanu, Giovanna; Ricchiuti, Guido; Picano, Eugenio; Gargani, Luna

    2015-01-01

    Abstract The assessment of pulmonary congestion in maintenance hemodialysis (MHD) patients is challenging. Bioelectrical impedance analysis (BIA) can estimate body water compartments. Natriuretic peptides are markers of hemodynamic stress, neurohormonal activation and extracellular volume overload. Lung ultrasound (LUS) has been proposed for the non-invasive estimation of extravascular lung water through B-lines assessment. Up to now, no study evaluated the correlation between B-lines, segmental thoracic BIA, and natriuretic peptides in MHD patients. The aims of this study were: (1) To validate LUS as a tool for an effective and timely evaluation of pulmonary congestion in MHD patients, in comparison with segmental thoracic BIA, and with natriuretic peptides; (2) To compare a comprehensive whole chest ultrasound scanning with a simplified and timely scanning scheme limited to the lateral chest regions. Thirty-one MHD adult patients were examined. LUS, total body and thoracic BIA, and natriuretic peptides were performed immediately before and after a mid-week dialysis session. The number of B-lines assessed by LUS was compared with total body and thoracic impedance data and with natriuretic peptides. Pre-HD B-lines ranged 0–147 (mean 31) and decreased significantly post-HD (mean 16, P < 0.001). A significant correlation was found between the number of B-lines and extra-cellular water index (ECWI, r = 0.45, P < 0.001), with thoracic impedance (r = 0.30, P < 0.05), and with BNP (r = 0.57, P < 0.01). The dynamic changes in B-lines correlated better with thoracic impedance than with total body impedance, and correlated with extra-cellular but not with intra-cellular water index. The correlation between B-lines and ECWI was similar when LUS was limited to the lateral chest regions or performed on the whole chest. Multivariate analysis showed that only segmental thoracic impedance was an independent predictor of residual pulmonary congestion

  17. Development of bioelectrical impedance analysis-based equations for estimation of body composition in postpartum rural Bangladeshi women.

    PubMed

    Shaikh, Saijuddin; Schulze, Kerry J; Kurpad, Anura; Ali, Hasmot; Shamim, Abu Ahmed; Mehra, Sucheta; Wu, Lee S-F; Rashid, Mahbubar; Labrique, Alain B; Christian, Parul; West, Keith P

    2013-02-28

    Equations for predicting body composition from bioelectrical impedance analysis (BIA) parameters are age-, sex- and population-specific. Currently there are no equations applicable to women of reproductive age in rural South Asia. Hence, we developed equations for estimating total body water (TBW), fat-free mass (FFM) and fat mass in rural Bangladeshi women using BIA, with ²H₂O dilution as the criterion method. Women of reproductive age, participating in a community-based placebo-controlled trial of vitamin A or β-carotene supplementation, were enrolled at 19·7 (SD 9·3) weeks postpartum in a study to measure body composition by ²H₂O dilution and impedance at 50 kHz using multi-frequency BIA (n 147), and resistance at 50 kHz using single-frequency BIA (n 82). TBW (kg) by ²H2O dilution was used to derive prediction equations for body composition from BIA measures. The prediction equation was applied to resistance measures obtained at 13 weeks postpartum in a larger population of postpartum women (n 1020). TBW, FFM and fat were 22·6 (SD 2·7), 30·9 (SD 3·7) and 10·2 (SD 3·8) kg by ²H₂O dilution. Height²/impedance or height²/resistance and weight provided the best estimate of TBW, with adjusted R² 0·78 and 0·76, and with paired absolute differences in TBW of 0·02 (SD 1·33) and 0·00 (SD 1·28) kg, respectively, between BIA and ²H₂O. In the larger sample, values for TBW, FFM and fat were 23·8, 32·5 and 10·3 kg, respectively. BIA can be an important tool for assessing body composition in women of reproductive age in rural South Asia where poor maternal nutrition is common. PMID:22716500

  18. An evaluation of a bioelectrical impedance analyser for the estimation of body fat content.

    PubMed Central

    Maughan, R J

    1993-01-01

    Measurement of body composition is an important part of any assessment of health or fitness. Hydrostatic weighing is generally accepted as the most reliable method for the measurement of body fat content, but is inconvenient. Electrical impedance analysers have recently been proposed as an alternative to the measurement of skinfold thickness. Both these latter methods are convenient, but give values based on estimates obtained from population studies. This study compared values of body fat content obtained by hydrostatic weighing, skinfold thickness measurement and electrical impedance on 50 (28 women, 22 men) healthy volunteers. Mean(s.e.m.) values obtained by the three methods were: hydrostatic weighing, 20.5(1.2)%; skinfold thickness, 21.8(1.0)%; impedance, 20.8(0.9)%. The results indicate that the correlation between the skinfold method and hydrostatic weighing (0.931) is somewhat higher than that between the impedance method and hydrostatic weighing (0.830). This is, perhaps, not surprising given the fact that the impedance method is based on an estimate of total body water which is then used to calculate body fat content. The skinfold method gives an estimate of body density, and the assumptions involved in the conversion from body density to body fat content are the same for both methods. PMID:8457817

  19. Assessment of change in hydration in women during pregnancy and postpartum with bioelectrical impedance vectors

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  20. Inter-sport variability of muscle volume distribution identified by segmental bioelectrical impedance analysis in four ball sports

    PubMed Central

    Yamada, Yosuke; Masuo, Yoshihisa; Nakamura, Eitaro; Oda, Shingo

    2013-01-01

    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. PMID:24379714

  1. Prediction of fat-free body mass from bioelectrical impedance and anthropometry among 3-year-old children using DXA

    PubMed Central

    Ejlerskov, Katrine T.; Jensen, Signe M.; Christensen, Line B.; Ritz, Christian; Michaelsen, Kim F.; Mølgaard, Christian

    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 healthy 3-year-old Danish children. Predictive equations were derived from two multiple linear regression models, a comprehensive model (height2/resistance (RI), six anthropometric measurements) and a simple model (RI, height, weight). Their uncertainty was quantified by means of 10-fold cross-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. The derived equations may prove useful for studies linking body composition to early risk factors and early onset of obesity. PMID:24463487

  2. Validation of bioelectrical impedance analysis (BIA) for estimation of body composition in Black, White and Hispanic adolescent girls.

    PubMed

    Going, S; Nichols, J; Loftin, M; Stewart, D; Lohman, T; Tuuri, G; Ring, K; Pickrel, J; Blew, R; J Stevens

    2006-01-01

    AIM: Equations for estimating % fat mass (%BF) and fat-free mass (FFM) from bioelectrical impedance analysis (BIA) that work in adolescent girls from different racial/ethnic backgrounds are not available. We investigated whether race/ethnicity influences estimation of body composition in adolescent girls. PRINCIPAL PROCEDURES: Prediction equations were developed for estimating FFM and %BF from BIA in 166 girls, 10-15 years old, consisting of 51 Black (B), 45 non-Black Hispanic (H), 55 non-Hispanic White (W) and 15 mixed (M) race/ethnicity girls, using dual energy x-ray absorptiometry (DXA) as the criterion method. FINDINGS: Black girls had similar %BF compared to other groups, yet were heavier per unit of height according to body mass index (BMI: kg.m(-2)) due to significantly greater FFM. BIA resistance index, age, weight and race/ethnicity were all significant predictors of FFM (R(2) = 0.92, SEE = 1.81 kg). Standardized regression coefficients showed resistance index (0.63) and weight (0.34) were the most important predictors of FFM. Errors in %BF (~2%) and FFM (~1.0 kg) were greater when race/ethnicity was not included in the equation, particularly in Black girls. We conclude the BIA-composition relationship in adolescent girls is influenced by race, and consequently have developed new BIA equations for adolescent girls for predicting FFM and %BF. PMID:17848976

  3. Evaluation of a foot-to-foot bioelectrical impedance analyser in highly active, moderately active and less active young men.

    PubMed

    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) (<2.5 h 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

  4. Method for conducting nonlinear electrochemical impedance spectroscopy

    DOEpatents

    Adler, Stuart B.; Wilson, Jamie R.; Huff, Shawn L.; Schwartz, Daniel T.

    2015-06-02

    A method for conducting nonlinear electrochemical impedance spectroscopy. The method includes quantifying the nonlinear response of an electrochemical system by measuring higher-order current or voltage harmonics generated by moderate-amplitude sinusoidal current or voltage perturbations. The method involves acquisition of the response signal followed by time apodization and fast Fourier transformation of the data into the frequency domain, where the magnitude and phase of each harmonic signal can be readily quantified. The method can be implemented on a computer as a software program.

  5. Application of impedance spectroscopy to SOFC research

    SciTech Connect

    Hsieh, G.; Mason, T.O.; Pederson, L.R.

    1996-12-31

    With the resurgence of interest in solid oxide fuel cells and other solid state electrochemical devices, techniques originally developed for characterizing aqueous systems are being adapted and applied to solid state systems. One of these techniques, three-electrode impedance spectroscopy, is particularly powerful as it allows characterization of subcomponent and interfacial properties. Obtaining accurate impedance spectra, however, is difficult as reference electrode impedance is usually non-negligible and solid electrolytes typically have much lower conductance than aqueous solutions. Faidi et al and Chechirlian et al have both identified problems associated with low conductivity media. Other sources of error are still being uncovered. Ford et al identified resistive contacts with large time constants as a possibility, while Me et al showed that the small contact capacitance of the reference electrode was at fault. Still others show that instrument limitations play a role. Using the voltage divider concept, a simplified model that demonstrates the interplay of these various factors, predicts the form of possible distortions, and offers means to minimize errors is presented.

  6. The investigation of the some body parameters of obese and (obese+diabetes) patients with using bioelectrical impedance analysis techniques

    NASA Astrophysics Data System (ADS)

    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 p<0.00 between (diabetes+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

  7. The Association between Muscle Mass Deficits Estimated from Bioelectrical Impedance Analysis and Lumbar Spine Bone Mineral Density in Korean Adults

    PubMed Central

    Jang, Hye-Yeon; Lee, Kye-Bong; Cho, Sul-Bit; Im, In Jae; Kim, Hee Jin

    2016-01-01

    Background Bone mineral density (BMD) is influenced by many factors. Despite the reported association between body components and BMD, most of these studies investigated the relationship between absolute muscle mass or fat mass and BMD in postmenopausal women or elderly subjects. The aim of this study is to investigate the association between muscle mass deficits (MMD) estimated from bioelectrical impedance analysis (BIA) and lumbar spinal BMD in Korean adults 20 to 49 years of age. Methods This cross-sectional study included 1,765 men and women who visited a health promotion center for a routine checkup. The lumbar spinal BMD was measured by dual energy X-ray absorptiometry. Body composition analysis was performed using BIA. Results The mean age of the subjects was 40.2±6.3 years. Ten thousand subjects (56.7%) were males and 126 subjects (7.1%) belonged to the low BMD (Z-score ≤-2.0). MMD had the strongest influence on BMD after adjusting for all covariates. The adjusted odds ratio of Group 3 (MDD >2.6 kg) for low BMD was 2.74 (95% CI, 1.46-5.15) after adjusting for age, gender, body mass index, height, and smoking. Conclusions MMD estimated by BIA showed a significant association with BMD and could be regarded as an independent risk factor for low BMD in adults 20 to 49 years of age. These findings support that interventions such as physical activity or lifestyle changes may simultaneously modify both muscle and bone health in this age group. PMID:27294081

  8. Non-invasive diagnosis of risk in dengue patients using bioelectrical impedance analysis and artificial neural network.

    PubMed

    Ibrahim, F; Faisal, T; Salim, M I Mohamad; Taib, M N

    2010-11-01

    This paper presents a new approach to diagnose and classify early risk in dengue patients using bioelectrical impedance analysis (BIA) and artificial neural network (ANN). A total of 223 healthy subjects and 207 hospitalized dengue patients were prospectively studied. The dengue risk severity criteria was determined and grouped based on three blood investigations, namely, platelet (PLT) count (less than or equal to 30,000 cells per mm(3)), hematocrit (HCT) (increase by more than or equal to 20%), and either aspartate aminotransferase (AST) level (raised by fivefold the normal upper limit) or alanine aminotransferase (ALT) level (raised by fivefold the normal upper limit). The dengue patients were classified according to their risk groups and the corresponding BIA parameters were subsequently obtained and quantified. Four parameters were used for training and testing the ANN which are day of fever, reactance, gender, and risk group's quantification. Day of fever was defined as the day of fever subsided, i.e., when the body temperature fell below 37.5°C. The blood investigation and the BIA data were taken for 5 days. The ANN was trained via the steepest descent back propagation with momentum algorithm using the log-sigmoid transfer function while the sum-squared error was used as the network's performance indicator. The best ANN architecture of 3-6-1 (3 inputs, 6 neurons in the hidden layer, and 1 output), learning rate of 0.1, momentum constant of 0.2, and iteration rate of 20,000 was pruned using a weight-eliminating method. Eliminating a weight of 0.05 enhances the dengue's prediction risk classification accuracy of 95.88% for high risk and 96.83% for low risk groups. As a result, the system is able to classify and diagnose the risk in the dengue patients with an overall prediction accuracy of 96.27%. PMID:20683676

  9. Comparison of Standing Posture Bioelectrical Impedance Analysis with DXA for Body Composition in a Large, Healthy Chinese Population

    PubMed Central

    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

  10. Comparison of Standing Posture Bioelectrical Impedance Analysis with DXA for Body Composition in a Large, Healthy Chinese Population.

    PubMed

    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

  11. Characterization of protein-immobilized polystyrene nanoparticles using impedance spectroscopy.

    PubMed

    Park, Soo-In; Lee, Sang-Yup

    2014-10-01

    A novel approach for characterization of non-conductive protein-immobilized nanoparticles using AC impedance spectroscopy combined with conductive atomic force microscopy was examined. As AC impedance spectroscopy can provide information on diverse electrical properties such as capacitance and inductance, it is applicable to the characterization of non-conductive substances. Several non-conductive protein-immobilized polystyrene nanoparticles were analyzed using AC impedance spectroscopy, and their impedance spectra were used as markers for nanoparticle identification. Analyses of impedance signals using an electrical circuit model established that the capacitance and inductance of each nanoparticle changed with the adsorbed protein and that impedance spectral differences were characteristic properties of the proteins. From this study, AC impedance spectroscopy was shown to be a useful tool for characterization of non-conductive nanoparticles and is expected to be applicable to the development of sensors for nanomaterials. PMID:25942903

  12. Comparison of body fat in Brazilian adult females by bioelectrical impedance analysis

    NASA Astrophysics Data System (ADS)

    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.

  13. Preliminary bioelectrical impedance analysis (BIA) equation for body composition assessment in young females from Colombia

    NASA Astrophysics Data System (ADS)

    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.

  14. Electrochemical Impedance Spectroscopy of Conductive Polymer Coatings

    NASA Technical Reports Server (NTRS)

    Calle, Luz Marina; MacDowell, Louis G.

    1996-01-01

    Electrochemical impedance spectroscopy (EIS) was used to investigate the corrosion protection performance of twenty nine proprietary conductive polymer coatings for cold rolled steel under immersion in 3.55 percent NaCl. Corrosion potential as well as Bode plots of the data were obtained for each coating after one hour immersion, All coatings, with the exception of one, have a corrosion potential that is higher in the positive direction than the corrosion potential of bare steel under the same conditions. Group A consisted of twenty one coatings with Bode plots indicative of the capacitive behavior characteristic of barrier coatings. An equivalent circuit consisting of a capacitor in series with a resistor simulated the experimental EIS data for these coatings very well. Group B consisted of eight coatings that exhibited EIS spectra showing an inflection point which indicates that two time constants are present. This may be caused by an electrochemical process taking place which could be indicitive of coating failing. These coatings have a lower impedance that those in Group A.

  15. Corrosion Study Using Electrochemical Impedance Spectroscopy

    NASA Technical Reports Server (NTRS)

    Farooq, Muhammad Umar

    2003-01-01

    Corrosion is a common phenomenon. It is the destructive result of chemical reaction between a metal or metal alloy and its environment. Stainless steel tubing is used at Kennedy Space Center for various supply lines which service the orbiter. The launch pads are also made of stainless steel. The environment at the launch site has very high chloride content due to the proximity to the Atlantic Ocean. Also, during a launch, the exhaust products in the solid rocket boosters include concentrated hydrogen chloride. The purpose of this project was to study various alloys by Electrochemical Impedance Spectroscopy in corrosive environments similar to the launch sites. This report includes data and analysis of the measurements for 304L, 254SMO and AL-6XN in primarily neutral 3.55% NaCl. One set of data for 304L in neutral 3.55%NaCl + 0.1N HCl is also included.

  16. Protein Aggregation Measurement through Electrical Impedance Spectroscopy

    NASA Astrophysics Data System (ADS)

    Affanni, A.; Corazza, A.; Esposito, G.; Fogolari, F.; Polano, M.

    2013-09-01

    The paper presents a novel methodology to measure the fibril formation in protein solutions. We designed a bench consisting of a sensor having interdigitated electrodes, a PDMS hermetic reservoir and an impedance meter automatically driven by calculator. The impedance data are interpolated with a lumped elements model and their change over time can provide information on the aggregation process. Encouraging results have been obtained by testing the methodology on K-casein, a protein of milk, with and without the addition of a drug inhibiting the aggregation. The amount of sample needed to perform this measurement is by far lower than the amount needed by fluorescence analysis.

  17. Effect of Feeding and Suction on Gastric Impedance Spectroscopy Measurements.

    PubMed

    Beltran, Nohra E; Sánchez-Miranda, Gustavo; Sacristan, Emilio

    2015-01-01

    A specific device and system has been developed and tested for clinical monitoring of gastric mucosal reactance in the critically ill as an early warning of splanchnic hypoperfusion associated with shock and sepsis. This device has been proven effective in clinical trials and is expected to become commercially available next year. The system uses a combination nasogastric tube and impedance spectroscopy probe as a single catheter. Because this device has a double function, the question is: Does enteral feeding or suction affect the gastric reactance measurements? This study was designed to evaluate the effect of feeding and suction on the measurement of gastric impedance spectroscopy in healthy volunteers. Impedance spectra were obtained from the gastric wall epithelia of 18 subjects. The spectra were measured for each of the following conditions: postinsertion of gastric probe, during active suction, postactive suction, and during enteral feeding (236 ml of nutritional supplement). Impedance spectra were reproducible in all volunteers under all conditions tested. There was a slight increase in impedance parameters after suction, and a decrease in impedance after feeding; however, these observed differences were insignificant compared to patient-to-patient variability, and truly negligible compared with previously observed changes associated with splanchnic ischemia in critically ill patients. Our results demonstrate that suction or feeding when using the impedance spectro-metry probe/nasogastric tube does not significantly interfere with gastric impedance spectrometer measurements. PMID:26226020

  18. In vivo impedance spectroscopy of deep brain stimulation electrodes

    NASA Astrophysics Data System (ADS)

    Lempka, Scott F.; Miocinovic, Svjetlana; Johnson, Matthew D.; Vitek, Jerrold L.; McIntyre, Cameron C.

    2009-08-01

    Deep brain stimulation (DBS) represents a powerful clinical technology, but a systematic characterization of the electrical interactions between the electrode and the brain is lacking. The goal of this study was to examine the in vivo changes in the DBS electrode impedance that occur after implantation and during clinically relevant stimulation. Clinical DBS devices typically apply high-frequency voltage-controlled stimulation, and as a result, the injected current is directly regulated by the impedance of the electrode-tissue interface. We monitored the impedance of scaled-down clinical DBS electrodes implanted in the thalamus and subthalamic nucleus of a rhesus macaque using electrode impedance spectroscopy (EIS) measurements ranging from 0.5 Hz to 10 kHz. To further characterize our measurements, equivalent circuit models of the electrode-tissue interface were used to quantify the role of various interface components in producing the observed electrode impedance. Following implantation, the DBS electrode impedance increased and a semicircular arc was observed in the high-frequency range of the EIS measurements, commonly referred to as the tissue component of the impedance. Clinically relevant stimulation produced a rapid decrease in electrode impedance with extensive changes in the tissue component. These post-operative and stimulation-induced changes in impedance could play an important role in the observed functional effects of voltage-controlled DBS and should be considered during clinical stimulation parameter selection and chronic animal research studies.

  19. Plasmonic-Based Electrochemical Impedance Spectroscopy: Application to Molecular Binding

    PubMed Central

    Lu, Jin; Wang, Wei; Wang, Shaopeng; Shan, Xiaonan; Li, Jinghong; Tao, Nongjian

    2012-01-01

    Plasmonic-based electrochemical impedance spectroscopy (P-EIS) is developed to investigate molecular binding on surfaces. Its basic principle relies on the sensitive dependence of surface plasmon resonance (SPR) signal on surface charge density, which is modulated by applying an AC potential to a SPR chip surface. The AC component of the SPR response gives the electrochemical impedance, and the DC component provides the conventional SPR detection. The plasmonic-based impedance measured over a range of frequency is in quantitative agreement with the conventional electrochemical impedance. Compared to the conventional SPR detection, P-EIS is sensitive to molecular binding taking place on the chip surface, and less sensitive to bulk refractive index changes or non-specific binding. Moreover, this new approach allows for simultaneous SPR and surface impedance analysis of molecular binding processes. PMID:22122514

  20. Impedance spectroscopy for the detection and identification of unknown toxins

    NASA Astrophysics Data System (ADS)

    Riggs, B. C.; Plopper, G. E.; Paluh, J. L.; Phamduy, T. B.; Corr, D. T.; Chrisey, D. B.

    2012-06-01

    Advancements in biological and chemical warfare has allowed for the creation of novel toxins necessitating a universal, real-time sensor. We have used a function-based biosensor employing impedance spectroscopy using a low current density AC signal over a range of frequencies (62.5 Hz-64 kHz) to measure the electrical impedance of a confluent epithelial cell monolayer at 120 sec intervals. Madin Darby canine kidney (MDCK) epithelial cells were grown to confluence on thin film interdigitated gold electrodes. A stable impedance measurement of 2200 Ω was found after 24 hrs of growth. After exposure to cytotoxins anthrax lethal toxin and etoposide, the impedance decreased in a linear fashion resulting in a 50% drop in impedance over 50hrs showing significant difference from the control sample (~20% decrease). Immunofluorescent imaging showed that apoptosis was induced through the addition of toxins. Similarities of the impedance signal shows that the mechanism of cellular death was the same between ALT and etoposide. A revised equivalent circuit model was employed in order to quantify morphological changes in the cell monolayer such as tight junction integrity and cell surface area coverage. This model showed a faster response to cytotoxin (2 hrs) compared to raw measurements (20 hrs). We demonstrate that herein that impedance spectroscopy of epithelial monolayers serves as a real-time non-destructive sensor for unknown pathogens.

  1. A Wireless Multi-Sensor Dielectric Impedance Spectroscopy Platform

    PubMed Central

    Ghaffari, Seyed Alireza; Caron, William-O.; Loubier, Mathilde; Rioux, Maxime; Viens, Jeff; Gosselin, Benoit; Messaddeq, Younes

    2015-01-01

    This paper describes the development of a low-cost, miniaturized, multiplexed, and connected platform for dielectric impedance spectroscopy (DIS), designed for in situ measurements and adapted to wireless network architectures. The platform has been tested and used as a DIS sensor node on ZigBee mesh and was able to interface up to three DIS sensors at the same time and relay the information through the network for data analysis and storage. The system is built from low-cost commercial microelectronics components, performs dielectric spectroscopy ranging from 5 kHz to 100 kHz, and benefits from an on-the-fly calibration system that makes sensor calibration easy. The paper describes the microelectronics design, the Nyquist impedance response, the measurement sensitivity and accuracy, and the testing of the platform for in situ dielectric impedance spectroscopy applications pertaining to fertilizer sensing, water quality sensing, and touch sensing. PMID:26393587

  2. A Wireless Multi-Sensor Dielectric Impedance Spectroscopy Platform.

    PubMed

    Ghaffari, Seyed Alireza; Caron, William-O; Loubier, Mathilde; Rioux, Maxime; Viens, Jeff; Gosselin, Benoit; Messaddeq, Younes

    2015-01-01

    This paper describes the development of a low-cost, miniaturized, multiplexed, and connected platform for dielectric impedance spectroscopy (DIS), designed for in situ measurements and adapted to wireless network architectures. The platform has been tested and used as a DIS sensor node on ZigBee mesh and was able to interface up to three DIS sensors at the same time and relay the information through the network for data analysis and storage. The system is built from low-cost commercial microelectronics components, performs dielectric spectroscopy ranging from 5 kHz to 100 kHz, and benefits from an on-the-fly calibration system that makes sensor calibration easy. The paper describes the microelectronics design, the Nyquist impedance response, the measurement sensitivity and accuracy, and the testing of the platform for in situ dielectric impedance spectroscopy applications pertaining to fertilizer sensing, water quality sensing, and touch sensing. PMID:26393587

  3. Effect of the ethinylestradiol/norelgestromin contraceptive patch on body composition. Results of bioelectrical impedance analysis in a population of Italian women

    PubMed Central

    Piccoli, Antonio; Crosignani, PierGiorgio; Nappi, Carmine; Ronsini, Salvatore; Bruni, Vincenzina; Marelli, Silvia

    2008-01-01

    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. PMID:18727825

  4. Relationship between Body mass index (BMI) and body fat percentage, estimated by bioelectrical impedance, in a group of Sri Lankan adults: a cross sectional study

    PubMed Central

    2013-01-01

    Background Body Mass Index (BMI) is used as a useful population-level measure of overweight and obesity. It is used as the same for both sexes and for all ages of adults. The relationship between BMI and body fat percentage (BF %) has been studied in various ethnic groups to estimate the capacity of BMI to predict adiposity. We aimed to study the BMI–BF% relationship, in a group of South Asian adults who have a different body composition compared to presently studied ethnic groups. We examined the influence of age, gender in this relationship and assessed its’ linearity or curvilinearity. Methods A cross sectional study was conducted, where adults of 18–83 years were grouped into young (18–39 years) middle aged (40–59 years) and elderly (>60 years). BF% was estimated from bioelectrical impedance analysis. Pearsons’ correlation coefficient(r) was calculated to see the relationship between BMI-BF% in the different age groups. Multiple regression analysis was performed to determine the effect of age and gender in the relationship and polynomial regression was carried out to see its’ linearity. The relationships between age-BMI, age-BF % were separately assessed. Results Out of 1114 participants, 49.1% were males. The study sample represented a wide range of BMI values (14.8-41.1 kg/m2,Mean 23.8 ± 4.2 kg/m2). A significant positive correlation was observed between BMI-BF%, in males (r =0.75, p < 0.01; SEE = 4.17) and in females (r = 0.82, p < 0.01; SEE = 3.54) of all ages. Effect of age and gender in the BMI-BF% relationship was significant (p < 0.001); with more effect from gender. Regression line found to be curvilinear in nature at higher BMI values where females (p < 0.000) having a better fit of the curve compared to males (p < 0.05). In both genders, with increase of age, BMI seemed to increase in curvilinear fashion, whereas BF% increased in a linear fashion. Conclusions BMI strongly correlate with BF

  5. Monitoring early zeolite formation via in situ electrochemical impedance spectroscopy.

    PubMed

    Brabants, G; Lieben, S; Breynaert, E; Reichel, E K; Taulelle, F; Martens, J A; Jakoby, B; Kirschhock, C E A

    2016-04-01

    Hitherto zeolite formation has not been fully understood. Although electrochemical impedance spectroscopy has proven to be a versatile tool for characterizing ionic solutions, it was never used for monitoring zeolite growth. We show here that EIS can quantitatively monitor zeolite formation, especially during crucial early steps where other methods fall short. PMID:27020096

  6. Transition metal oxide as anode interface buffer for impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Xu, Hui; Tang, Chao; Wang, Xu-Liang; Zhai, Wen-Juan; Liu, Rui-Lan; Rong, Zhou; Pang, Zong-Qiang; Jiang, Bing; Fan, Qu-Li; Huang, Wei

    2015-12-01

    Impedance spectroscopy is a strong method in electric measurement, which also shows powerful function in research of carrier dynamics in organic semiconductors when suitable mathematical physical models are used. Apart from this, another requirement is that the contact interface between the electrode and materials should at least be quasi-ohmic contact. So in this report, three different transitional metal oxides, V2O5, MoO3 and WO3 were used as hole injection buffer for interface of ITO/NPB. Through the impedance spectroscopy and PSO algorithm, the carrier mobilities and I-V characteristics of the NPB in different devices were measured. Then the data curves were compared with the single layer device without the interface layer in order to investigate the influence of transitional metal oxides on the carrier mobility. The careful research showed that when the work function (WF) of the buffer material was just between the work function of anode and the HOMO of the organic material, such interface material could work as a good bridge for carrier injection. Under such condition, the carrier mobility measured through impedance spectroscopy should be close to the intrinsic value. Considering that the HOMO (or LUMO) of most organic semiconductors did not match with the work function of the electrode, this report also provides a method for wide application of impedance spectroscopy to the research of carrier dynamics.

  7. Body composition by bioelectrical-impedance analysis compared with deuterium dilution and skinfold anthropometry in patients with chronic obstructive pulmonary disease

    SciTech Connect

    Schols, A.M.; Wouters, E.F.; Soeters, P.B.; Westerterp, K.R. )

    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.

  8. The value of bioelectrical impedance analysis and phase angle in the evaluation of malnutrition and quality of life in cancer patients--a comprehensive review.

    PubMed

    Grundmann, O; Yoon, S L; Williams, J J

    2015-12-01

    Bioelectrical impedance analysis (BIA) and especially its derived parameter phase angle have been widely used in different populations. The variability of BIA measures has often been cited as a major limitation for its clinical use in evaluating nutritional status and overall health of patients. Cancer patients often present with malnourishment and cachexia, which complicate the course of treatment and affect outcomes. PubMed, CINAHL, EBSCO and Cochrane Library have been searched for relevant publications in English for BIA in cancer patients. Out of 197 total results, 27 original research articles related to BIA measures in cancer patients were included in this review. Studies indicate that the use of BIA and phase angle measures can benefit in the clinical management of cancer patients in multiple ways: in the prevention; diagnosis; prognosis; and outcomes related to treatments that affect nutritional and overall health status. Phase angle and fat-free mass measures were most commonly evaluated and correlated with nutritional status and survival rate. One limitation of BIA measures is the high interpatient variability which requires careful interpretation of results in the context of the individual patient rather than comparison with population data. The BIA and phase angle provide practitioners for the evaluation of nutritional and overall health status in cancer patients with a convenient and non-invasive technique and should be encouraged. PMID:26220573

  9. Body composition of adult cystic fibrosis patients and control subjects as determined by densitometry, bioelectrical impedance, total-body electrical conductivity, skinfold measurements, and deuterium oxide dilution

    SciTech Connect

    Newby, M.J.; Keim, N.L.; Brown, D.L. )

    1990-08-01

    This study contrasts body compositions (by six methods) of eight cystic fibrosis (CF) subjects with those of eight control subjects matched for age, height, and sex. CF subjects weighed 84% as much as control subjects. Densitometry and two bioelectrical impedance-analysis methods suggested that reduced CF weights were due to less lean tissue (10.7, 9.5, and 10.4 kg). Total-body electrical conductivity (TOBEC) and skinfold-thickness measurements indicated that CF subjects were leaner than control subjects and had less fat (5.4 and 3.6 kg) and less lean (5.2 and 7 kg) tissue. D2O dilution showed a pattern similar to TOBEC (8.3 kg less lean, 2.7 kg less fat tissue). Densitometry estimates of fat (mass and percent) were not correlated (r less than 0.74, p greater than 0.05) with any other method for CF subjects but were correlated with all other methods for control subjects. CF subjects contained less fat and lean tissue than did control subjects. Densitometry by underwater weighing is unsuitable for assessing body composition of CF patients.

  10. Prediction of lamb carcass composition by impedance spectroscopy.

    PubMed

    Altmann, M; Pliquett, U; Suess, R; von Borell, E

    2004-03-01

    The objective of this study was to compare impedance spectroscopy with resistance measurements at a single frequency (50 kHz) for the prediction of lamb carcass composition. The impedance spectrum is usually recorded by measuring the complex impedance at various frequencies (frequency domain); however, in this study, we also applied the faster and simpler measurement in the time domain (application of a current step and measurement of the voltage response). The study was carried out on 24 male, German Black-headed Mutton lambs with an average BW of 45 kg. Frequency- and time domain-based impedance measurements were collected at 20 min and 24 h postmortem with different electrode placements. Real and imaginary parts at various frequencies were calculated from the locus diagram. Left sides were dissected into lean, fat, and bone, and right sides were ground to determine actual carcass composition. Crude fat, crude protein, and moisture were chemically analyzed on ground samples. Frequency- and time domain-based measurements did not provide the same absolute impedance values; however, the high correlations (P < 0.001) between these methods for the "real parts" showed that they ranked individuals in the same order. Most of the time domain data correlated higher to carcass composition than did the frequency domain data. The real parts of impedance showed correlations between -0.37 (P > 0.05) and -0.74 (P < 0.001) to water, crude fat, lean, and fatty tissue, whereas the relations to CP were much lower (from 0.00 to -0.47, P < 0.05). Electrode placements at different locations did not substantially improve the correlations with carcass composition. The "imaginary parts" of impedance were not suitable for the prediction of carcass composition. The highest accuracy (R2 = 0.66) was reached for the estimation of crude fat percentage by a regression equation with the time domain-based impedance measured at 24 h postmortem. Furthermore, there was not a clear superiority of

  11. Impedance spectroscopy analysis of cell-electrode interface.

    PubMed

    Jianhui, Lin; Xiaoming, Wu; Pengsheng, Huang; Tianling, Ren; Litian, Liu

    2005-01-01

    Many chronically implanted electrodes suffer sensitivity loss in their applications in brain computer interface systems. It is hard to diagnose the cause of the problem because few measures are available to analyze directly what happened on the cell-electrode interface. In this paper, the impedance characterization of the cell-electrode interface was discussed in detail using equivalent circuit approach, which was used to evaluate the cause of the electrode sensitivity loss. The impedance spectroscopy of the cell-electrode interface acts as a function of several parameters, such as the sealing resistance and the shunt capacitance between the microelectrode and the electrolyte. Changes of the impedance spectroscopy can be traced to the parameter changes of the equivalent circuit, which reflect the status of the cell-electrode interface, such as the cell-electrode gap change, the erosion of microelectrodes, and so on. The circuit impedance simulation results give an important reference for the monitor of the cell-electrode connection, and are also helpful for the improvement of the microelectrode design. PMID:17282042

  12. Determination of soil ionic concentration using impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Pandey, Gunjan; Kumar, Ratnesh; Weber, Robert J.

    2013-05-01

    This paper presents a novel approach to estimate the soil ionic concentration by way of multi-frequency impedance measurements and using the quasi-static dielectric mixing models to infer the various ionic concentrations. In our approach, the permittivity of the soil dielectric mixture is measured using impedance spectroscopy and the results are used as input parameters to dielectric mixing models, combined with the debye-type dielectric relaxation models. We observe that the dielectric mixing models work well for low RF (radio-frequency) range and help in determining the individual ionic concentration in a multi-component soil mixture. Using the fact that the permittivity of a dielectric mixture is proportional to its impedance, we validated our approach by making multi-frequency impedance measurements of a soil mixture at different concentrations of various components. The method provides a good estimate of individual components such as air, water and ions like nitrates. While the paper is written with the perspective of soil constituent concentration determination, the underlying principle of determining individual component concentration using multi-frequency impedance measurement is applicable more generally in areas such as characterizing biological systems like pathogens, quality control of pharmaceuticals etc.

  13. High-precision impedance spectroscopy: a strategy demonstrated on PZT.

    PubMed

    Boukamp, Bernard A; Blank, Dave H A

    2011-12-01

    Electrochemical impedance spectroscopy (EIS) has been recognized as a very powerful tool for studying charge and mass transport and transfer in a wide variety of electrically or electrochemically active systems. Sophisticated modeling programs make it possible to extract parameters from the impedance data, thus contributing to a better understanding of the system or material properties. For an accurate analysis, a correct modeling function is needed; this is often in the form of an equivalent circuit. It is not always possible to define the modeling function from visual inspection of the impedance dispersion. Small contributions to the overall dispersion can be masked, and hence overlooked. In this publication, a strategy is presented for high-precision impedance data analysis. A Kramers-Kronig test is used for the essential data validation. An iterative process of partial analysis and subtraction assists in deconvoluting the impedance spectrum, yielding both a vi- able model function and a set of necessary starting values for the full complex nonlinear least squares (CNLS) modeling. The advantage and possibilities of this strategy are demonstrated with an analysis of the ionic and electronic conductivity of lead zirconate titanate (PZT) as functions of temperature and oxygen partial pressure. PMID:23443688

  14. On-line corrosion monitoring with electrochemical impedance spectroscopy

    SciTech Connect

    Roberge, P.R. . Dept. of Chemistry and Chemical Engineering); Sastri, V.S. )

    1994-10-01

    Electrochemical impedance spectroscopy (EIS) has been found to be a rapid and accurate technique for measuring corrosion rates in the most difficult situations and for yielding information concerning the occurrence of localized corrosion. When used in the absence of potentiostatic control, the technique carries less instrumental overhead, and the danger of damaging the probe by accidental polarization is reduced. Results from two field tests were presented to illustrate the advantages of using EIS for on-line monitoring of general and localized corrosion.

  15. Total body water and fat-free mass: evaluation of equations based on bioelectrical impedance analysis in infants and young children in India.

    PubMed

    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

  16. The Performance of Five Bioelectrical Impedance Analysis Prediction Equations against Dual X-ray Absorptiometry in Estimating Appendicular Skeletal Muscle Mass in an Adult Australian Population

    PubMed Central

    Yu, Solomon C. Y.; Powell, Alice; Khow, Kareeann S. F.; Visvanathan, Renuka

    2016-01-01

    Appendicular skeletal muscle mass (ASM) is a diagnostic criterion for sarcopenia. Bioelectrical impedance analysis (BIA) offers a bedside approach to measure ASM but the performance of BIA prediction equations (PE) varies with ethnicities and body composition. We aim to validate the performance of five PEs in estimating ASM against estimation by dual-energy X-ray absorptiometry (DXA). We recruited 195 healthy adult Australians and ASM was measured using single-frequency BIA. Bland-Altman analysis was used to assess the predictive accuracy of ASM as determined by BIA against DXA. Precision (root mean square error (RMSE)) and bias (mean error (ME)) were calculated according to the method of Sheiner and Beal. Four PEs (except that by Kim) showed ASM values that correlated strongly with ASMDXA (r ranging from 0.96 to 0.97, p < 0.001). The Sergi equation performed the best with the lowest ME of −1.09 kg (CI: −0.84–−1.34, p < 0.001) and the RMSE was 2.09 kg (CI: 1.72–2.47). In men, the Kyle equation performed better with the lowest ME (−0.32 kg (CI: −0.66–0.02) and RMSE (1.54 kg (CI: 1.14–1.93)). The Sergi equation is applicable in adult Australians (Caucasian) whereas the Kyle equation can be considered in males. The need remains to validate PEs in other ethnicities and to develop equations suitable for multi-frequency BIA. PMID:27043617

  17. A Comparison Study of Portable Foot-to-Foot Bioelectrical Impedance Scale to Measure Body Fat Percentage in Asian Adults and Children

    PubMed Central

    Sim, Pei Ying; Su, Tin Tin; Abd Majid, Hazreen; Nahar, Azmi Mohamed; Jalaludin, Muhammad Yazid

    2014-01-01

    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. PMID:25258711

  18. Comparison of Abdominal Visceral Adipose Tissue Area Measured by Computed Tomography with That Estimated by Bioelectrical Impedance Analysis Method in Korean Subjects

    PubMed Central

    Lee, Dong-Hwa; Park, Kyeong Seon; Ahn, Soyeon; Ku, Eu Jeong; Jung, Kyong Yeun; Kim, Yoon Ji; Kim, Kyoung Min; Moon, Jae Hoon; Choi, Sung Hee; Park, Kyong Soo; Jang, Hak Chul; Lim, Soo

    2015-01-01

    We evaluated the concordance between visceral fat area (VFA) estimated by bioelectrical impedance analysis (BIA) or computed tomography (CT) in Korean subjects with a wide range in age and body mass index (BMI). In 1006 individuals (mean age 55.2 ± 11.8 (19–87) years, mean BMI 26.0 ± 3.5 (17–46) kg/m2, 48.9% men), VFA quantified by CT was compared with VFA using multifrequency BIA machines within 15 days. Concordance rates were compared by age or BMI using correlation analysis, Bland-Altman plots, and intraclass correlation coefficient (ICC). Using BIA data, we established a regression formula to reflect CT-VFA. The mean VFAs by CT and BIA were 131.9 ± 57.3 cm2 and 110.5 ± 33.9 cm2, respectively (r = 0.605, p < 0.001). The mean difference was 21.4 ± 45.6 cm2, tending to increase with BMI. In women with BMI <25 kg/m2 or age <50 years, the VFAs by BIA were similar to those by CT (ICC = 0.496 in BMI <25 kg/m2 and ICC = 0.638 in age <50 years). However, the difference was greater in men with BMI ≥25 kg/m2 or age ≥50 years. Applying our formula, the difference between estimations decreased to 0.2 ± 38.2cm2. VFA estimated by BIA correlated well with that by CT, but a more accurate formula is needed to match CT data, particularly in older men or subjects with a high BMI. PMID:26694460

  19. Measuring body composition using the bioelectrical impedance method can predict the outcomes of gemcitabine-based chemotherapy in patients with pancreatobiliary tract cancer

    PubMed Central

    MURAMATSU, MAMI; TSUCHIYA, AYA; OHTA, SEIKO; IIJIMA, YUKIE; MARUYAMA, MIYUKI; ONODERA, YOSHIKO; HAGIHARA, MEGUMI; NAKAYA, NAOKI; SATO, ITARU; OMURA, KENJI; UENO, SOICHIRO; NAKAJIMA, HIDEO

    2015-01-01

    In order to examine the effect on body composition of anticancer drug treatments, the body composition rate in patients being treated with gemcitabine (GEM)-based chemotherapy was measured over time on an outpatient basis with a simple body composition monitor using the bioelectrical impedance (BI) method. The results revealed a significant reduction in the body fat rate (P=0.01) over the course of treatment in patients with pancreatobiliary tract cancer who became unable to continue GEM-based chemotherapy due to progressive disease or a decreased performance status. Meanwhile, no changes were observed in the body composition of control patients with urothelial carcinoma receiving GEM-based chemotherapy. In association with the adverse reactions to GEM and the hematotoxicity profile, a decreased white blood cell count was more likely to occur in body fat-dominant patients (mean fat rate, 25.8%; mean muscle rate, 26.2%), whereas a decreased blood platelet count was more likely to occur in skeletal muscle-dominant patients (mean fat rate, 23.3%; mean muscle rates, 28.7%). The correlation between body composition parameters and the relative dose intensity (RDI) associated with GEM administration was also analyzed. The results revealed a positive correlation between the RDI and basal metabolism amount (P=0.03); however, the RDI did not correlate with the body fat rate, skeletal muscle rate or body mass index (P=0.61, P=0.14 and P=0.20, respectively). In conclusion, the body composition rate measurement using the BI method over time may be useful for predicting the outcome of GEM-based chemotherapy and adverse events in patients with pancreatobiliary tract cancer. In particular, the present findings indicate that the changes in body fat rate may be helpful as an adjunct index for assessing potential continuation of chemotherapy and changes in physical conditions. PMID:26788165

  20. Obesity in young-adult Nigerians: variations in prevalence determined by anthropometry and bioelectrical impedance analysis, and the development of % body fat prediction equations

    PubMed Central

    2012-01-01

    Background Overweight/obesity is a growing global public health concern. The variations in the prevalence of overweight/obesity, defined by Body Mass Index (BMI), Waist Circumference (WC), Waist-to-Height Ratio (WHtR), Waist-to-Hip Ratio (WHpR) and Bioelectrical Impedance Analysis (BIA), were studied and a prediction equation for % body fat (%BF) developed. Methods A total of 1584 subjects (56.4% males) were recruited for the study. Data on age, gender, height, weight, hip circumference and WC were collected from the subjects using standard protocols. BMI, WHtR and WHpR were derived using standard equations. %BF was measured using a BIA device (Omron BF-400). Appropriate statistical tools were used for the data analysis. Results The prevalence of overweight/obesity in the population was 28.4% (36.3% for males; 22.6% for females) (BIA); 20.7% (17.5% for males; 24.8% for females) (BMI); 7.5% (1.3% for males; 16.1% for females) (WC); 2.9% (4.3% for males; 1.2% for females) (WHpR); and 15.4% (14.8% for males; 16.2% females) (WHtR). Taking BIA as the reference point, WC misclassified overweight/obesity the most for males (35%), while for the females, WHpR misclassified both disorders the most (21.4%). Correlation studies showed that only BMI correlated significantly, albeit weakly, with %BF among the males, whereas all the anthropometric measures, but WHpR correlated significantly with % body fat in females. Two prediction equations for %BF were generated, and %BF predicted with the two equations correlated significantly (P < 0.001) with that measured by BIA. Conclusion The prevalence of overweight/obesity in this population vary widely depending on the definition used. The developed prediction equations could be useful in resource-poor settings, but require validation. PMID:22818201

  1. Agreement between bioelectrical impedance and dual energy X-ray absorptiometry in assessing fat, lean and bone mass changes in adults after a lifestyle intervention.

    PubMed

    Macfarlane, Duncan J; Chan, Natalie T-Y; Tse, Michael A; Joe, Glen M

    2016-06-01

    We aimed to assess the agreement of a commercially available bioelectrical impedance analysis (BIA) device in measuring changes in fat, lean and bone mass over a 10-week lifestyle intervention, with dual energy X-ray absorptiometry (DXA) as reference. A sample of 136 volunteers (18-66 years) underwent a physical activity intervention to enhance lean mass and reduce fat mass. BIA (Tanita BC545) and DXA (Hologic Explorer) measures of whole-body composition were taken at baseline and at the end of the intervention. After an average of 74 ± 18 days intervention, DXA showed significant changes in 2 of 3 outcome variables: reduced fat mass of 0.802 ± 1.092 kg (P < 0.001), increased lean mass of 0.477 ± 0.966 kg (P < 0.001); minor non-significant increase of 0.007 ± 0.041 kg of bone mass (P = 0.052). The respective changes in BIA measures were a significant reduction of 0.486 ± 1.539 kg fat (P < 0.001), but non-significant increases of 0.084 ± 1.201 kg lean mass (P = 0.425), and 0.014 ± 0.091 kg bone (P = 0.074). Significant, but moderately weak, correlations were seen in absolute mass changes between DXA and BIA: 0.511 (fat), 0.362 (lean) and 0.172 (bone). Compared to DXA, BIA demonstrated mediocre agreement to changes in fat mass, but poor agreement to lean mass changes. BIA significantly underestimated the magnitude of changes in fat and lean mass compared to DXA. PMID:26451461

  2. Cross-mode bioelectrical impedance analysis in a standing position for estimating fat-free mass validated against dual-energy x-ray absorptiometry.

    PubMed

    Huang, Ai-Chun; Chen, Yu-Yawn; Chuang, Chih-Lin; Chiang, Li-Ming; Lu, Hsueh-Kuan; Lin, Hung-Chi; Chen, Kuen-Tsann; Hsiao, An-Chi; Hsieh, Kuen-Chang

    2015-11-01

    Bioelectrical impedance analysis (BIA) is commonly used to assess body composition. Cross-mode (left hand to right foot, Z(CR)) BIA presumably uses the longest current path in the human body, which may generate better results when estimating fat-free mass (FFM). We compared the cross-mode with the hand-to-foot mode (right hand to right foot, Z(HF)) using dual-energy x-ray absorptiometry (DXA) as the reference. We hypothesized that when comparing anthropometric parameters using stepwise regression analysis, the impedance value from the cross-mode analysis would have better prediction accuracy than that from the hand-to-foot mode analysis. We studied 264 men and 232 women (mean ages, 32.19 ± 14.95 and 34.51 ± 14.96 years, respectively; mean body mass indexes, 24.54 ± 3.74 and 23.44 ± 4.61 kg/m2, respectively). The DXA-measured FFMs in men and women were 58.85 ± 8.15 and 40.48 ± 5.64 kg, respectively. Multiple stepwise linear regression analyses were performed to construct sex-specific FFM equations. The correlations of FFM measured by DXA vs. FFM from hand-to-foot mode and estimated FFM by cross-mode were 0.85 and 0.86 in women, with standard errors of estimate of 2.96 and 2.92 kg, respectively. In men, they were 0.91 and 0.91, with standard errors of the estimates of 3.34 and 3.48 kg, respectively. Bland-Altman plots showed limits of agreement of -6.78 to 6.78 kg for FFM from hand-to-foot mode and -7.06 to 7.06 kg for estimated FFM by cross-mode for men, and -5.91 to 5.91 and -5.84 to 5.84 kg, respectively, for women. Paired t tests showed no significant differences between the 2 modes (P > .05). Hence, cross-mode BIA appears to represent a reasonable and practical application for assessing FFM in Chinese populations. PMID:26409342

  3. Evaluation of bioelectrical impedance analysis (BIA) to measure condition and energy allocated to reproduction in marine fishes

    NASA Astrophysics Data System (ADS)

    Fitzhugh, G. R.; Wuenschel, M. J.; McBride, R. S.

    2010-04-01

    Reliable estimates of fish energy density at specific times prior to spawning may provide suitable proxies for egg production, and thereby help to explain some of the observed annual variation in recruits per spawner. Our goal is to develop and test modifications of BIA technology to measure energy allocation to reproduction for a variety of marine fishes. To date, a newly developed measuring board and probe system stabilized readings, which was demonstrated by a significant reduction in the coefficients of variation for impedance measures. Total body water, wet and dry weights could be predicted with very good precision (r2 = 0.92-0.99) using BIA measures of reactance or resistance for a number of finfish species. While constituent relationships (e.g. body water- body mass functions) did not differ seasonally, we did find that BIA measures are sensitive to body composition changes related to the seasonal spawning cycle. In an examination of monthly samples of tilefish, phase angle decreased below 15° in post-spawning (regressed) females. Such a monthly trend, which suggests available energy had decreased following the spawning season, was not evident from other, more traditional measures of condition including body-muscle water content, Fulton's K or ordinal measures of fat deposition (such as mesenteric fat). These preliminary results show that BIA technology is a promising application for tracking and efficiently predicting energetic condition of marine fishes.

  4. A CMOS Electrochemical Impedance Spectroscopy (EIS) Biosensor Array.

    PubMed

    Manickam, Arun; Chevalier, Aaron; McDermott, Mark; Ellington, Andrew D; Hassibi, Arjang

    2010-12-01

    In this paper, we present a fully integrated biosensor 10 × 10 array in a standard complementary metal-oxide semiconducor process, which takes advantage of electrochemical impedance spectroscopy (EIS). We also show that this system is able to detect various biological analytes, such as DNA and proteins, in real time and without the need for molecular labels. In each pixel of this array, we implement a biocompatible Au electrode transducer and embedded sensor circuitry which takes advantage of the coherent detector to measure the impedance of the associated electrode-electrolyte interface. This chip is capable of concurrently measuring admittance values as small as 10(-8) Ω(-1) within the array with the detection dynamic range of more than 90 dB in the frequency range of 10 Hz-50 MHz. PMID:23850755

  5. Evaluation of non toxic alkyd primers by electrochemical impedance spectroscopy

    SciTech Connect

    Hernandez, L.S.; Garcia, G. |; Lopez, C.

    1998-12-31

    The purpose of this work was to compare the protective capacity of several alkyd primers pigmented with 12.1 volume percent either of calcium phosphate or micronized zinc phosphate as anticorrosive pigments. A paint containing zinc chromate was used as reference. The performance of these paints on steel was assessed through Electrochemical Impedance Spectroscopy (EIS) using a 3% NaCl solution. After 576 hr immersion, the paint with calcium phosphate and specially that with micronized zinc phosphate, showed a better behavior than paint with zinc chromate. Paint rating, using impedance parameters (ionic resistance and capacitance of the paint film, and breakpoint frequency), was in agreement with the visible paint deterioration and corrosion, In addition, there was a good correlation between these parameter and the open circuit corrosion potential of the metallic substrate.

  6. Embedded silver PDMS electrodes for single cell electrical impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Wei, Yuan; Xu, Zhensong; Cachia, Mark A.; Nguyen, John; Zheng, Yi; Wang, Chen; Sun, Yu

    2016-09-01

    This paper presents a microfluidic device with wide channels and embedded AgPDMS electrodes for measuring the electrical properties of single cells. The work demonstrates the feasibility of using a large channel design and embedded electrodes for impedance spectroscopy to circumvent issues such as channel clogging and limited device re-usability. AgPDMS electrodes were formed on channel sidewalls for impedance detection and cell electrical properties measurement. Equivalent circuit models were used to interpret multi-frequency impedance data to quantify each cell’s cytoplasm conductivity and specific membrane capacitance. T24 cells were tested to validate the microfluidic system and modeling results. Comparisons were then made by measuring two leukemia cell lines (AML-2 and HL-60) which were found to have different cytoplasm conductivity values (0.29  ±  0.15 S m‑1 versus 0.47  ±  0.20 S m‑1) and specific membrane capacitance values (41  ±  25 mF m‑2 versus 55  ±  26 mF m‑2) when the cells were flown through the wide channel and measured by the AgPDMS electrodes.

  7. Botulinum neurotoxin serotypes detected by electrochemical impedance spectroscopy.

    PubMed

    Savage, Alison C; Buckley, Nicholas; Halliwell, Jennifer; Gwenin, Christopher

    2015-05-01

    Botulinum neurotoxin is one of the deadliest biological toxins known to mankind and is able to cause the debilitating disease botulism. The rapid detection of the different serotypes of botulinum neurotoxin is essential for both diagnosis of botulism and identifying the presence of toxin in potential cases of terrorism and food contamination. The modes of action of botulinum neurotoxins are well-established in literature and differ for each serotype. The toxins are known to specifically cleave portions of the SNARE proteins SNAP-25 or VAMP; an interaction that can be monitored by electrochemical impedance spectroscopy. This study presents a SNAP-25 and a VAMP biosensors for detecting the activity of five botulinum neurotoxin serotypes (A-E) using electrochemical impedance spectroscopy. The biosensors are able to detect concentrations of toxins as low as 25 fg/mL, in a short time-frame compared with the current standard methods of detection. Both biosensors show greater specificity for their compatible serotypes compared with incompatible serotypes and denatured toxins. PMID:25954998

  8. Improvement of impedance spectroscopy methods: resonance analysis of samples

    NASA Astrophysics Data System (ADS)

    Balmus, Sorin-Bogdan; Ciomaga, Cristina E.; Horchidan, Nadejda; Mitoseriu, Liliana; Dumitru, Ioan

    2015-06-01

    An impedance spectroscopy method, using an Agilent E4991A RF Impedance/Material Analyzer, was employed for the investigation of radiofrequency and microwave dielectric characteristics for some ceramic materials with high dielectric permittivity. Experimental observations recorded single, double and even triple resonances in the permittivity spectra, while for the selected samples significantly different values of permittivity from the ones found in existing literature were directly measured and observed in the frequency range of 100 MHz-1 GHz. The specified material analyzer is designed to work within certain permittivity-frequency domains; working outside these limits leads to significant errors when carrying out direct measurements of permittivity. Having observed that the resonance measurements are not associated with the intrinsic material properties but with the sample resonances, we proposed a dielectric resonance cavity model for sample purposes and we determined the dielectric permittivity at different resonance frequencies. A scaling procedure, based on the computed values of permittivity, was applied in order to correct the directly measured permittivity spectra where the frequency was outside the resonance domains. The corrected data are in good agreement with those measured using other techniques and suggest that the proposed procedure extends the spectroscopy method currently used for high permittivity measurements. The sources of error for the proposed method were investigated.

  9. Studies of deionization and impedance spectroscopy for blood analyzer

    NASA Astrophysics Data System (ADS)

    Kwong, Charlotte C.; Li, Nan; Ho, Chih-Ming

    2005-11-01

    Blood analysis provides vital information for health conditions. For instance, typical infection response is correlated to an elevated White Blood Cell (WBC) count, while low Red Blood Cell (RBC) count, hemoglobin and hematocrit are caused by anemia or internal bleeding. We are developing two essential modules, deionization (DI) chip and microfluidic cytometer with impedance spectroscopy flow, for enabling the realization of a single platform miniaturized blood analyzer. In the proposed analyzer, blood cells are preliminarily sorted by Dielectrophoretic (DEP) means into sub-groups, differentiated and counted by impedance spectroscopy in a flow cytometer. DEP techniques have been demonstrated to stretch DNA, align Carbon Nanotubes (CNT) and trap cells successfully. However, DEP manipulation does not function in biological media with high conductivity. The DI module is designed to account for this challenge. H Filter will serve as an ion extraction platform in a microchamber. Sample and buffer do not mix well in micro scale allowing the ions being extracted by diffusion without increasing the volume. This can keep the downstream processing time short. Micro scale hydrodynamic focusing is employed to place single cell passing along the central plane of the flow cytometer module. By applying an AC electrical field, suspended cells are polarized, membrane capacitance C m, cytoplasm conductivity σ c, and cytoplasm permittivity ɛ c will vary as functions of frequency. Tracing back the monitored current, the numbers of individual cell species can be evaluated.

  10. An Electrochemical Impedance Spectroscopy System for Monitoring Pineapple Waste Saccharification

    PubMed Central

    Conesa, Claudia; Ibáñez Civera, Javier; Seguí, Lucía; Fito, Pedro; Laguarda-Miró, Nicolás

    2016-01-01

    Electrochemical impedance spectroscopy (EIS) has been used for monitoring the enzymatic pineapple waste hydrolysis process. The system employed consists of a device called Advanced Voltammetry, Impedance Spectroscopy & Potentiometry Analyzer (AVISPA) equipped with a specific software application and a stainless steel double needle electrode. EIS measurements were conducted at different saccharification time intervals: 0, 0.75, 1.5, 6, 12 and 24 h. Partial least squares (PLS) were used to model the relationship between the EIS measurements and the sugar determination by HPAEC-PAD. On the other hand, artificial neural networks: (multilayer feed forward architecture with quick propagation training algorithm and logistic-type transfer functions) gave the best results as predictive models for glucose, fructose, sucrose and total sugars. Coefficients of determination (R2) and root mean square errors of prediction (RMSEP) were determined as R2 > 0.944 and RMSEP < 1.782 for PLS and R2 > 0.973 and RMSEP < 0.486 for artificial neural networks (ANNs), respectively. Therefore, a combination of both an EIS-based technique and ANN models is suggested as a promising alternative to the traditional laboratory techniques for monitoring the pineapple waste saccharification step. PMID:26861317

  11. An Electrochemical Impedance Spectroscopy System for Monitoring Pineapple Waste Saccharification.

    PubMed

    Conesa, Claudia; Ibáñez Civera, Javier; Seguí, Lucía; Fito, Pedro; Laguarda-Miró, Nicolás

    2016-01-01

    Electrochemical impedance spectroscopy (EIS) has been used for monitoring the enzymatic pineapple waste hydrolysis process. The system employed consists of a device called Advanced Voltammetry, Impedance Spectroscopy & Potentiometry Analyzer (AVISPA) equipped with a specific software application and a stainless steel double needle electrode. EIS measurements were conducted at different saccharification time intervals: 0, 0.75, 1.5, 6, 12 and 24 h. Partial least squares (PLS) were used to model the relationship between the EIS measurements and the sugar determination by HPAEC-PAD. On the other hand, artificial neural networks: (multilayer feed forward architecture with quick propagation training algorithm and logistic-type transfer functions) gave the best results as predictive models for glucose, fructose, sucrose and total sugars. Coefficients of determination (R²) and root mean square errors of prediction (RMSEP) were determined as R² > 0.944 and RMSEP < 1.782 for PLS and R² > 0.973 and RMSEP < 0.486 for artificial neural networks (ANNs), respectively. Therefore, a combination of both an EIS-based technique and ANN models is suggested as a promising alternative to the traditional laboratory techniques for monitoring the pineapple waste saccharification step. PMID:26861317

  12. Botulinum Neurotoxin Serotypes Detected by Electrochemical Impedance Spectroscopy

    PubMed Central

    Savage, Alison C.; Buckley, Nicholas; Halliwell, Jennifer; Gwenin, Christopher

    2015-01-01

    Botulinum neurotoxin is one of the deadliest biological toxins known to mankind and is able to cause the debilitating disease botulism. The rapid detection of the different serotypes of botulinum neurotoxin is essential for both diagnosis of botulism and identifying the presence of toxin in potential cases of terrorism and food contamination. The modes of action of botulinum neurotoxins are well-established in literature and differ for each serotype. The toxins are known to specifically cleave portions of the SNARE proteins SNAP-25 or VAMP; an interaction that can be monitored by electrochemical impedance spectroscopy. This study presents a SNAP-25 and a VAMP biosensors for detecting the activity of five botulinum neurotoxin serotypes (A–E) using electrochemical impedance spectroscopy. The biosensors are able to detect concentrations of toxins as low as 25 fg/mL, in a short time-frame compared with the current standard methods of detection. Both biosensors show greater specificity for their compatible serotypes compared with incompatible serotypes and denatured toxins. PMID:25954998

  13. Comparisons of a Multi-Frequency Bioelectrical Impedance Analysis to the Dual-Energy X-Ray Absorptiometry Scan in Healthy Young Adults Depending on their Physical Activity Level

    PubMed Central

    Verney, Julien; Schwartz, Chloé; Amiche, Saliha; Pereira, Bruno; Thivel, David

    2015-01-01

    This study aimed at comparing BIA and DXA results in assessing body composition in young adults depending on their physical activity level. Eighty healthy 19–30 years old subjects were enrolled and their body composition (Fat Mass and Fat-Free Mass) was assessed by dual-energy X-ray absorptiometry (DXA) and by a newly developed Bioelectrical Impedance Analyzer (BIA - Tanita MC780). A seven-day physical activity level was assessed using a 3-axial accelerometer. DXA-FM% and BIA-FM% were correlated (p<0.001; r= 0.852; ICC [IC95%]: 0.84 [0.75 – 0.90]; concordance coefficient: 0.844). DXA-FFM and BIA FFM were correlated (p<0.001; r=0.976; ICC [IC95%]: 0.95 [0.93 – 0.97], concordance coefficient: 0.955). DXA and BIA measurements of FM% and FFM were highly correlated in both boys and girls regardless of the physical activity level. Compared with DXA scans, newly developed bioelectrical impedance analyzers provide satisfactory fat mass and lean mass measures in healthy young women and men, despite their physical activity level. PMID:26557191

  14. Optimal multisine excitation design for broadband electrical impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Sanchez, B.; Vandersteen, G.; Bragos, R.; Schoukens, J.

    2011-11-01

    Electrical impedance spectroscopy (EIS) can be used to characterize biological materials in applications ranging from cell culture to body composition, including tissue and organ state. The emergence of cell therapy and tissue engineering opens up a new and promising field of application. While in most cases classical measurement techniques based on a frequency sweep can be used, EIS based on broadband excitations enables dynamic biological systems to be characterized when the measuring time and injected energy are a constraint. Myocardial regeneration, cell characterization in micro-fluidic systems and dynamic electrical impedance tomography are all examples of such applications. The weakness of such types of fast EIS measuring techniques resides in their intrinsic loss of accuracy. However, since most of the practical applications have no restriction over the excitation used, the input power spectrum can be appropriately designed to maximize the accuracy obtained from the measurements. This paper deals with the problem of designing the optimal multisine excitation for electrical bioimpedance measurements. The optimal multisine is obtained by the minimization of the Cramer-Rao lower bound, or what is the same, by maximizing the accuracy obtained from the measurements. Furthermore, because no analytical solution exists for global optimization involving time and frequency domains jointly, this paper presents the multisine optimization approach partially in both domains and then combines the results. As regards the frequency domain approach, a novel contribution is made for the multisine amplitude power spectrum. In the time domain, multisine is optimized by reducing its crest factor. Moreover, the impact on the information and accuracy of the impedance spectrum obtained from using different multisine amplitude power spectra is discussed, as well as the number of frequencies and frequency distributions. The theory is supported by a set of validation measurements when

  15. Using electrical impedance spectroscopy to detect water in planetary regoliths.

    PubMed

    Seshadri, Suresh; Chin, Keith B; Buehler, Martin G; Anderson, Robert C

    2008-08-01

    We present data in examination of the utility of electrical impedance spectroscopy measurements for in situ surveys to determine the water content, distribution, and phase in unconsolidated planetary regolith. We conducted calibration experiments under conditions relevant to Mars: the concentration of electrolytes in solution was varied up to 1 M to simulate the effects of unsaturated dissolved minerals and brines. We also varied the water content of heterogeneous water/sand mixtures, made with these electrolytic solutions from 0.01 wt% to 10 wt%. Tests were performed at temperatures from +25 degrees C to -65 degrees C. Conductivity and dielectric permittivity calculated from the impedance measurements indicate an expected dependence on electrolyte concentration and relative independence from electrolyte type for both liquid water and water ice. Conductivity and calculated dielectric relaxation times for these aqueous solutions agree with existing data in the literature. The relative permittivity for heterogeneous water/sand mixtures is dominated by polarization effects for the electrode configuration used. However, the characteristic orientational relaxation of ice is still visible. The conductivity retains the strong dependence on electrolyte concentration, and the permittivity is still not affected by electrolyte type. A "universal" curve between conductivity and water content establishes detectability limits of <0.01 wt% and approximately 0.3 wt% for water/sand mixtures containing liquid water and ice, respectively. PMID:18752458

  16. Impedance Spectroscopy of Liquid-Phase Sintered Silicon Carbide

    SciTech Connect

    McLachlan, D.S.; Sauti, G.; Vorster, A.; Hermann, M.

    2004-02-26

    Liquid-Phase Sintered Silicon Carbide (LPSSiC) materials were produced with different Y2O3: Al2O3 and Y2O3: SiO2 sintering additive ratios. Densification was achieved by hot pressing (HP). The ratio of the polytypes and the amount and crystalline composition of the grain boundary phases was determined using Rietveld analysis. Microstructures of the materials were related to the mechanical properties (hardness, fracture toughness and strength), which are not presented. The impedance Spectroscopy measurements were made at temperatures between 100 deg. C and 400 deg. C and analyzed using Effective Media Theories and the Brick Layer Model. In some cases, in order to correctly fit the results, it was necessary to use or model the frequency dependence of the conductivity or dielectric constant of the SiC grains using various theoretical models. The impedance arcs for the SiC grains in the different samples varied widely, probably more due to the 'semiconductor' doping of the grains or nonstoichiometry, than the SiC polytypes in the grains. The SiC grains all showed an Arrhenius behavior with energy gaps in the range 0.3 to 0.5eV.

  17. Impedance Spectroscopy of Liquid-Phase Sintered Silicon Carbide

    NASA Astrophysics Data System (ADS)

    McLachlan, D. S.; Sauti, G.; Vorster, A.; Hermann, M.

    2004-02-01

    Liquid-Phase Sintered Silicon Carbide (LPSSiC) materials were produced with different Y2O3: Al2O3 and Y2O3: SiO2 sintering additive ratios. Densification was achieved by hot pressing (HP). The ratio of the polytypes and the amount and crystalline composition of the grain boundary phases was determined using Rietveld analysis. Microstructures of the materials were related to the mechanical properties (hardness, fracture toughness and strength), which are not presented. The impedance Spectroscopy measurements were made at temperatures between 100°C and 400°C and analyzed using Effective Media Theories and the Brick Layer Model. In some cases, in order to correctly fit the results, it was necessary to use or model the frequency dependence of the conductivity or dielectric constant of the SiC grains using various theoretical models. The impedance arcs for the SiC grains in the different samples varied widely, probably more due to the "semiconductor" doping of the grains or nonstoichiometry, than the SiC polytypes in the grains. The SiC grains all showed an Arrhenius behavior with energy gaps in the range 0.3 to 0.5eV.

  18. Analysis of bio-anode performance through electrochemical impedance spectroscopy.

    PubMed

    ter Heijne, Annemiek; Schaetzle, Olivier; Gimenez, Sixto; Navarro, Lucia; Hamelers, Bert; Fabregat-Santiago, Francisco

    2015-12-01

    In this paper we studied the performance of bioanodes under different experimental conditions using polarization curves and impedance spectroscopy. We have identified that the large capacitances of up to 1 mF·cm(-2) for graphite anodes have their origin in the nature of the carbonaceous electrode, rather than the microbial culture. In some cases, the separate contributions of charge transfer and diffusion resistance were clearly visible, while in other cases their contribution was masked by the high capacitance of 1 mF·cm(-2). The impedance data were analyzed using the basic Randles model to analyze ohmic, charge transfer and diffusion resistances. Increasing buffer concentration from 0 to 50mM and increasing pH from 6 to 8 resulted in decreased charge transfer and diffusion resistances; lowest values being 144 Ω·cm(2) and 34 Ω·cm(2), respectively. At acetate concentrations below 1 mM, current generation was limited by acetate. We show a linear relationship between inverse charge transfer resistance at potentials close to open circuit and saturation (maximum) current, associated to the Butler-Volmer relationship that needs further exploration. PMID:25869113

  19. Chronic impedance spectroscopy of an endovascular stent-electrode array

    NASA Astrophysics Data System (ADS)

    Opie, Nicholas L.; John, Sam E.; Rind, Gil S.; Ronayne, Stephen M.; Grayden, David B.; Burkitt, Anthony N.; May, Clive N.; O’Brien, Terence J.; Oxley, Thomas J.

    2016-08-01

    Objective. Recently, we reported a minimally invasive stent-electrode array capable of recording neural signals from within a blood vessel. We now investigate the use of electrochemical impedance spectroscopy (EIS) measurements to infer changes occurring to the electrode–tissue interface from devices implanted in a cohort of sheep for up to 190 days. Approach. In a cohort of 15 sheep, endovascular stent-electrode arrays were implanted in the superior sagittal sinus overlying the motor cortex for up to 190 days. EIS was performed routinely to quantify viable electrodes for up to 91 days. An equivalent circuit model (ECM) was developed from the in vivo measurements to characterize the electrode–tissue interface changes occurring to the electrodes chronically implanted within a blood vessel. Post-mortem histological assessment of stent and electrode incorporation into the wall of the cortical vessels was compared to the electrical impedance measurements. Main results. EIS could be used to infer electrode viability and was consistent with x-ray analysis performed in vivo, and post-mortem evaluation. Viable electrodes exhibited consistent 1 kHz impedances across the 91 day measurement period, with the peak resistance frequency for the acquired data also stable over time. There was a significant change in 100 Hz phase angles, increasing from ‑67.8° ± 8.8° at day 0 to ‑43.8° ± 0.8° at day 91, which was observed to stabilize after eight days. ECM’s modeled to the data suggested this change was due to an increase in the capacitance of the electrode–tissue interface. This was supported by histological assessment with >85% of the implanted stent struts covered with neointima and incorporated into the blood vessel within two weeks. Conclusion. This work demonstrated that EIS could be used to determine the viability of electrode implanted chronically within a blood vessel. Impedance measurements alone were not observed to be a useful predictor of alterations

  20. Diagnosis of PEMFC stack failures via electrochemical impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Merida-Donis, Walter Roberto

    Two failure modes related to water management in Proton Exchange Membrane fuel cells (dehydration and flooding) were investigated using electrochemical impedance spectroscopy as a diagnosis tool. It was hypothesised that each failure mode corresponds to changes in the overall stack impedance that are observable in different frequency ranges. This hypothesis was corroborated experimentally. The experimental implementation required new testing hardware and techniques. A four-cell stack capable of delivering individually conditioned reactants to each cell was designed, built, tested, and characterised under a variety of operating conditions. This stack is the first reported prototype of its type. The stack was used to perform galvanostatic, impedance measurements in situ. The measurements were made at three different temperatures (62, 70 and 80°C), covering the current density range 0.1 to 1.0 A cm-2 , and the frequency range 0.1 to 4 x 105 Hz. The recorded data represent the first reported set of measurements covering these ranges. The failure modes were simulated on individual cells within the stack. The effects on individual cell and stack impedance were studied by measuring the changes in stack and cell impedances under flooding or dehydration conditions. Dehydration effects were measurable over a wide frequency range (0.5 to 105 Hz). In contrast, flooding effects were measurable in a narrower frequency range (0.5 to 102 Hz). Using these results, separate or concurrent impedance measurements in these frequency ranges (or narrow bands thereof) can be used to discern and identify the two failure modes quasi-instantaneously. Such detection was not possible with pre-existing, do techniques. The measured spectra were modelled by a simple equivalent circuit whose time constants corresponded to ideal (RC) and distributed (Warburg) components. The model was robust enough to fit all the measured spectra (for single cells and the stack), under normal and simulated

  1. Impact of nutritional supplementation on immune response, body mass index and bioelectrical impedance in HIV-positive patients starting antiretroviral therapy

    PubMed Central

    2013-01-01

    Background Challenges to HIV care in resource limited settings (RLS) include malnutrition. Limited evidence supports the benefit of nutritional supplementation when starting antiretroviral therapy (ART) in RLS. Methods Randomized controlled pilot study. HIV-positive ART-naive adults with self-reported weight loss were randomized to receive ART plus FutureLife porridge® nutritional supplement (NS) (388 kcal/day) or ART alone (Controls) for 6 months. Patients returned for monthly assessments and blood was drawn at enrolment and 6 months on ART. Differences in body composition, biochemical and laboratory parameters were estimated at 6 months on treatment. Results Of the 36 randomized patients, 26 completed the 6 month follow-up (11 NS vs 15 Controls). At enrolment, groups were similar in terms of age, gender, body mass index (BMI) and bioelectrical impedance. NS patients had a lower median CD4 count (60 cells/mm3 [IQR 12–105 vs 107 cells/mm3 [IQR 63–165]; p = 0.149) and hemoglobin (10.3 g/dL [IQR 9.0-11.3] vs 13.1 g/dL [IQR 11.1-14.7]; p = 0.001). At 6 months, NS patients increased their median CD4 count by 151 cells/mm3 [IQR 120–174) vs 77 cells/mm3 [IQR 33–145] in the Controls. NS patients had higher mean percentage change in body weight (12.7% vs 4.9%; p = 0.047), BMI (7.8% vs 5.5%; p = 0.007), absolute CD4 count (83.0% vs 46.4%, p = 0.002) and hemoglobin (9.5% vs 1.0%; p = 0.026). Patients in the NS arm had a higher mean percentage fat-free mass (16.7% vs −3.5%, p = 0.036), total body water (13.0% vs −1.9%, p = 0.026), intracellular water (16.1% vs −4.1%, p = 0.010) and basal metabolic rate (5.3% vs −0.2%, p = 0.014) compared to Controls. Patients in the NS arm also showed an improvement in physical activity at 6 months post-ART initiation compared to Controls (p = 0.037). Conclusion Preliminary results are encouraging and suggest that NS taken concurrently with ART can promote weight gain

  2. Electrochemical impedance spectroscopy of supercapacitors: A novel analysis approach using evolutionary programming

    NASA Astrophysics Data System (ADS)

    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.

  3. Investigation of defects in thermal sprayed coatings using impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Marzban, Ali

    Thermal spray (TS) coatings and materials including thermal barrier, tribological and anti-corrosive coatings have established application across a number of engineering fields. TS is attractive for these systems due to its low cost, ability to coat large areas and flexibility in material feedstock. These attributes, along with improvements in process diagnostics have spurred the exploration of TS for more functional applications including fuel cells, conformal electronic sensors and biomedical implants. Successful implementation of TS coatings in these systems will require more robust characterization of their mechanical behavior; to date this has been limited and in practice most measurements are carried out in a pass/fail manner. Little is known about the intrinsic or progressive behavior of the coatings under repeated loading. This is important as the microstructure of TS coatings comprises layers of micron-thick flattened particles ('splats') separated by interfaces, the bonding between which is not well understood. These interfaces represent potential short crack growth sites throughout the material. A lot of works has demonstrated that microstructurally short cracks propagate at substantially higher growth rates than long cracks at equivalent driving forces under both quasi-static and cycling loading conditions in ceramics and their composites and metals. Short cracks in a naturally broken material like TS will have a different mechanism. Mechanical properties and fracture behavior have been examined in TS, but via conventional methods. That is to say, a large notch is introduced and allowed to propagate. This method completely neglects the existing microstructure of a TS material, which is lamellar and contains a number of near-horizontal cracks. In this study, a new approach to damage monitoring in TS coatings, using through thickness impedance spectroscopy to detect changes in dielectric properties is introduced. The goal of this research is to understand

  4. Dielectric and Impedance Spectroscopy of Barium Bismuth Vanadate Ferroelectrics

    NASA Astrophysics Data System (ADS)

    Sutar, B. C.; Choudhary, R. N. P.; Das, Piyush R.

    2014-07-01

    Structural, micro-structural and electrical properties of barium bismuth vanadate Ba(Bi0.5V0.5)O3 ceramics were investigated. X-ray diffraction (XRD) analysis of the prepared material confirmed the formation of the compound with monoclinic crystal system. Scanning electron microscopy (SEM) of the compound exhibits well-defined grains that are uniformly distributed throughout the surface of the sample. Dielectric properties of the compound were studied as a function of temperature at different frequencies. An observation of dielectric anomaly at 295 °C is due to ferroelectric phase transition that was later confirmed by the appearance of hysteresis loop. Detailed studies of complex impedance spectroscopy have provided a better understanding of the relaxation process and correlations between the microstructure-electrical properties of the materials. The nature of frequency dependence of ac conductivity obeys the Debye power law. The dc conductivity, calculated from the ac conductivity spectrum, shows the negative temperature coefficient of resistance behavior similar to that of a semiconductor.

  5. Investigation of polypyrrole degradation using electrochemical impedance spectroscopy.

    PubMed

    Marchesi, L F Q P; Simões, F R; Pocrifka, L A; Pereira, E C

    2011-08-11

    In this paper, the electrochemical degradation of polypyrrole film was studied by means of overpotential application. The overpotential was 0.58 V versus SCE, and after every 5 min of application of 0.58 V, a cyclic voltammogram was recorded in the range of -0.7 to 0.5 V as well as an electrochemical impedance spectroscopy and electrochemical quartz crystal microbalance (EIS and EQCM). The main characteristic is the huge increase in the charge transfer resistance (r(ct)), which indicates that the insertion process of ions in the polymer matrix is hindered by the electrochemical degradation. Once the process of insertion is damaged, the number of intercalated ions in the matrix should decrease, which is expressed by the low-frequency capacitance, which is proportional to the number of intercalated ions in the polymeric matrix. The decrease of intercalated ions has an influence in the mass variation of the polymer film, which is confirmed by EQCM measurements. PMID:21721565

  6. Non-destructive evaluation of TBC by electrochemical impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhang, Jianqi

    The objectives of this work focus on studying the feasibility of developing electrochemical impedance spectroscopy as an NDE methodology for quality assurance and post exposure inspection of TBC. Principally air plasma sprayed TBC was investigated while APS dense vertically cracked TBC and electron beam physical vapor deposition sprayed TBC were also studied using EIS. It has been found that EIS has a great promise in TBC quality assurance and post-exposure assessment. In the quality evaluation, EIS can detect TBC topcoat thickness, porosity, and kinds of defects (pore shape, cracks, or delamination). The TBC topcoat thickness shows a linear relationship with ceramic resistance. The TBC porosity has a linear relationship with ceramic capacitance. The kinds of defects in TBC topcoat can be assessed by the value of pore resistance. In the post-exposure inspection, EIS can monitor the evolution of defects in the topcoat, porosity, the growth of TGO and thermal conductivity of TBC. There is an exponential relationship between thermal conductivity and electrochemical impedance or a logarithmic relationship between thermal conductivity and electrochemical conductance. Investigation on thermal conductivity of TBC showed the specific heat or thermal conductivity of TBC has a logarithmic relationship with temperature, respectively. Exposure temperature and time are two important factors for an increase in thermal conductivity. The higher temperature and longer the exposure, the greater increase the thermal conductivity. High temperature exposure of TBC results in phase transformations, t-ZrO2 → m-ZrO2 and t-ZrO2 → c-ZrO2 and evolution of defect (ceramic sintering). Both the phase transformations and the sintering cause an increase in thermal conductivity. However, it has been found the phase transformations are only a conservative factor while the sintering is a substantial reason for an increase in thermal conductivity. A failure mode of TBC due to sintering was

  7. A unified approach to dielectric single cell analysis: impedance and dielectrophoretic force spectroscopy.

    PubMed

    Valero, Ana; Braschler, Thomas; Renaud, Philippe

    2010-09-01

    In this review we present a unified approach for single cell dielectric spectroscopy. Impedance spectroscopy and dielectrophoretic cell sorting, current microtechnologies applied in electrical analysis of single cells are discussed based on their closely related physical principles. In addition, examples of microfluidic devices will be presented: a microfabricated flow cytometer for single cell discrimination based on impedance analysis and a miniaturized continuous dielectrophoretic cell sorter, both using the concept of liquid electrodes. Using the experimental results obtained from both microdevices, we give a comparative overview over the dielectrophoretic sorting and impedance spectroscopy. PMID:20664865

  8. Revisiting the electrochemical impedance spectroscopy of magnesium with online inductively coupled plasma atomic emission spectroscopy.

    PubMed

    Shkirskiy, Viacheslav; King, Andrew D; Gharbi, Oumaïma; Volovitch, Polina; Scully, John R; Ogle, Kevin; Birbilis, Nick

    2015-02-23

    The electrochemical impedance of reactive metals such as magnesium is often complicated by an obvious inductive loop with decreasing frequency of the AC polarising signal. The characterisation and ensuing explanation of this phenomenon has been lacking in the literature to date, being either ignored or speculated. Herein, we couple electrochemical impedance spectroscopy (EIS) with online atomic emission spectroelectrochemistry (AESEC) to simultaneously measure Mg-ion concentration and electrochemical impedance spectra during Mg corrosion, in real time. It is revealed that Mg dissolution occurs via Mg(2+) , and that corrosion is activated, as measured by AC frequencies less than approximately 1 Hz approaching DC conditions. The result of this is a higher rate of Mg(2+) dissolution, as the voltage excitation becomes slow enough to enable all Mg(2+) -enabling processes to adjust in real time. The manifestation of this in EIS data is an inductive loop. The rationalisation of such EIS behaviour, as it relates to Mg, is revealed for the first time by using concurrent AESEC. PMID:25425247

  9. A mathematical model for electrical impedance spectroscopy of zwitterionic hydrogels.

    PubMed

    Feicht, Sarah E; Khair, Aditya S

    2016-08-17

    We report a mathematical model for ion transport and electrical impedance in zwitterionic hydrogels, which possess acidic and basic functional groups that carry a net charge at a pH not equal to the isoelectric point. Such hydrogels can act as an electro-mechanical interface between a relatively hard biosensor and soft tissue in the body. For this application, the electrical impedance of the hydrogel must be characterized to ensure that ion transport to the biosensor is not significantly hindered. The electrical impedance is the ratio of the applied voltage to the measured current. We consider a simple model system, wherein an oscillating voltage is applied across a hydrogel immersed in electrolyte and sandwiched between parallel, blocking electrodes. We employ the Poisson-Nernst-Planck (PNP) equations coupled with acid-base dissociation reactions for the charge on the hydrogel backbone to model the ionic transport across the hydrogel. The electrical impedance is calculated from the numerical solution to the PNP equations and subsequently analyzed via an equivalent circuit model to extract the hydrogel capacitance, resistance, and the capacitance of electrical double layers at the electrode-hydrogel interface. For example, we predict that an increase in pH from the isoelectric point, pH = 6.4 for a model PCBMA hydrogel, to pH = 8 reduces the resistance of the hydrogel by ∼40% and increases the double layer capacitance by ∼250% at an electrolyte concentration of 0.1 mM. The significant impact of charged hydrogel functional groups to the impedance is damped at higher electrolyte concentration. PMID:27464763

  10. Potassium polytitanate gas-sensor study by impedance spectroscopy.

    PubMed

    Fedorov, F S; Varezhnikov, A S; Kiselev, I; Kolesnichenko, V V; Burmistrov, I N; Sommer, M; Fuchs, D; Kübel, C; Gorokhovsky, A V; Sysoev, V V

    2015-10-15

    Nanocrystalline potassium polytitanates K2O·nTiO2·mH2O represent a new type of semiconducting compounds which are characterized by a high specific surface that makes them promising for use in gas sensors. In this work, we have studied potassium polytitanate mesoporous nanoparticle agglomerates placed over a SiO2/Si substrate equipped with multiple coplanar electrodes to measure the electrical response to various organic vapors, 1000 ppm of concentration, mixed with air by impedance spectrometry in range of the 10(-2)-10(6) Hz. The recorded impedance data for each sensor segment are associated with RC components of an equivalent circuit which are applied to selectively recognize the test vapors exploiting a "multisensor array" approach. PMID:26515008

  11. Constituent phases of the passive film formed on 2205 stainless steel by dynamic electrochemical impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Cheng, Xue-Qun; Li, Cheng-Tao; Dong, Chao-Fang; Li, Xiao-Gang

    2011-02-01

    The passive film formed on 2205 duplex stainless steel (DSS) in 0.5 M NaHCO3+0.5 M NaCl aqueous solution was characterized by electrochemical measurements, including potentiodynamic anodic polarization and dynamic electrochemical impedance spectroscopy (DEIS). The results demonstrate that there is a great difference between the passive film evolutions of ferrite and austenite. The impedance values of ferrite are higher than those of austenite. The impedance peaks of ferritic and austenitic phases correspond to the potential of 0.15 and 0.25 V in the low potential range and correspond to 0.8 and 0.75 V in the high potential range. The evolutions of the capacitance of both phases are reverse compared to the evolutions of impedance. The thickness variations obtained from capacitance agree well with those of impedance analysis. The results can be used to explain why pitting corrosion occurs more easily in austenite phase than in ferrite phase.

  12. Assessing Body Fat of Children by Skinfold Thickness, Bioelectrical Impedance Analysis, and Dual-Energy X-Ray Absorptiometry: A Validation Study Among Malay Children Aged 7 to 11 Years.

    PubMed

    Noradilah, Mohd Jonit; Ang, Yeow Nyin; Kamaruddin, Nor Azmi; Deurenberg, Paul; Ismail, Mohd Noor; Poh, Bee Koon

    2016-07-01

    This study aims to validate skinfold (SKF) and bioelectrical impedance analysis (BIA) against dual-energy X-ray absorptiometry (DXA) in determining body fat percentage (BF%) of Malay children aged 7 to 11 years. A total of 160 children had their BF% assessed using SKF and BIA, with DXA as the criterion method. Four SKF equations (SKFBray, SKFJohnston, SKFSlaughter, and SKFGoran) and 4 BIA equations (BIAManufacturer, BIAHoutkooper, BIARush, and BIAKushner) were used to estimate BF%. Mean age, weight, and height were 9.4 ± 1.1years, 30.5 ± 9.9 kg, and 131.3 ± 8.4 cm. All equations significantly underestimated BF% (P < .05). BIA equations had reasonable agreement with DXA and were independent of BF% with BIAManufacturer being the best equation. Although BIA underestimates BF% as compared with DXA, BIA was more suitable to measure BF% in a population that is similar to this study sample than SKF, suggesting a need to develop new SKF equations that are population specific. PMID:27073201

  13. Is chronic hypoxemia in patients with chronic obstructive pulmonary disease associated with more marked nutritional deficiency? A study of the fat-free mass evaluated by anthropometry and bioelectrical impedance methods.

    PubMed

    Godoy, I; Castro E Silva, M H; Togashi, R H; Geraldo, R R; Campana, A O

    2000-01-01

    In order to determine wheter blood gases abnormalities, specially hypoxemia, are associated with more marked changes in fat-free mass in patients with chronic obstructive pulmonary disease (CPOD), nutritional assessment was performed on 16 normoxemic (PaO2 > 55 mm Hg) and 16 hypoxemic (PaO2 < 55 mm Hg) COPD patients in stable clinical condition. Body weight was expressed as percentage of the ideal body weight. Fat-free mass was estimated by anthropometry (FFM-Anthr) and by bioelectrical impedance (FFM-BI). Handgrip-strength was assessed as a measure of peripheral skeletal muscle strength. Patients were age-matched and presented similar degree of airway obstruction. Malnutrition, defined as body weight less than 90% of the ideal, was observed in 19% of the normoxemic patients and in 25% of the hypoxemic patients (p>0,05). FFM values in hypoxemic patients, estimated by both methods, were not different from those observed in normoxemic patients. No significant difference was observed on handgrip values between the two groups. No correlation was found between nutritional indices and pulmonary function and gases exchange parameters. FFM correlated positively with values of peripheral muscle function in normoxemic and hypoxemic patients. These data add further evidence to the hypothesis that hypoxemia is not a primary cause of the nutritional deficiency observed in COPD patients. PMID:10842422

  14. Electrochemical impedance spectroscopy of lithium-titanium disulfide rechargeable cells

    NASA Technical Reports Server (NTRS)

    Narayanan, S. R.; Shen, D. H.; Surampudi, S.; Attia, A. I.; Halpert, G.

    1993-01-01

    The two-terminal alternating current impedance of Li/TiS2 rechargeable cells was studied as a function of frequency, state-of-charge, and extended cycling. Analysis based on a plausible equivalent circuit model for the Li/TiS2 cell leads to evaluation of kinetic parameters for the various physicochemical processes occurring at the electrode/electrolyte interfaces. To investigate the causes of cell degradation during extended cycling, the parameters evaluated for cells cycled 5 times were compared with the parameters of cells cycled over 600 times. The findings are that the combined ohmic resistance of the electrolyte and electrodes suffers a tenfold increase after extended cycling, while the charge-transfer resistance and diffusional impedance at the TiS2/electrolyte interface are not significantIy affected. The results reflect the morphological change and increase in area of the anode due to cycling. The study also shows that overdischarge of a cathode-limited cell causes a decrease in the diffusion coefficient of the lithium ion in the cathode.

  15. Simplified signal processing for impedance spectroscopy with spectrally sparse sequences

    NASA Astrophysics Data System (ADS)

    Annus, P.; Land, R.; Reidla, M.; Ojarand, J.; Mughal, Y.; Min, M.

    2013-04-01

    Classical method for measurement of the electrical bio-impedance involves excitation with sinusoidal waveform. Sinusoidal excitation at fixed frequency points enables wide variety of signal processing options, most general of them being Fourier transform. Multiplication with two quadrature waveforms at desired frequency could be easily accomplished both in analogue and in digital domains, even simplest quadrature square waves can be considered, which reduces signal processing task in analogue domain to synchronous switching followed by low pass filter, and in digital domain requires only additions. So called spectrally sparse excitation sequences (SSS), which have been recently introduced into bio-impedance measurement domain, are very reasonable choice when simultaneous multifrequency excitation is required. They have many good properties, such as ease of generation and good crest factor compared to similar multisinusoids. Typically, the usage of discrete or fast Fourier transform in signal processing step is considered so far. Usage of simplified methods nevertheless would reduce computational burden, and enable simpler, less costly and less energy hungry signal processing platforms. Accuracy of the measurement with SSS excitation when using different waveforms for quadrature demodulation will be compared in order to evaluate the feasibility of the simplified signal processing. Sigma delta modulated sinusoid (binary signal) is considered to be a good alternative for a synchronous demodulation.

  16. In situ anodization of aluminum surfaces studied by x-ray reflectivity and electrochemical impedance spectroscopy

    SciTech Connect

    Bertram, F. Evertsson, J.; Messing, M. E.; Mikkelsen, A.; Lundgren, E.; Zhang, F.; Pan, J.; Carlà, F.; Nilsson, J.-O.

    2014-07-21

    We present results from the anodization of an aluminum single crystal [Al(111)] and an aluminum alloy [Al 6060] studied by in situ x-ray reflectivity, in situ electrochemical impedance spectroscopy and ex situ scanning electron microscopy. For both samples, a linear increase of oxide film thickness with increasing anodization voltage was found. However, the slope is much higher in the single crystal case, and the break-up of the oxide film grown on the alloy occurs at a lower anodization potential than on the single crystal. The reasons for these observations are discussed as are the measured differences observed for x-ray reflectivity and electrochemical impedance spectroscopy.

  17. In situ anodization of aluminum surfaces studied by x-ray reflectivity and electrochemical impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Bertram, F.; Zhang, F.; Evertsson, J.; Carlà, F.; Pan, J.; Messing, M. E.; Mikkelsen, A.; Nilsson, J.-O.; Lundgren, E.

    2014-07-01

    We present results from the anodization of an aluminum single crystal [Al(111)] and an aluminum alloy [Al 6060] studied by in situ x-ray reflectivity, in situ electrochemical impedance spectroscopy and ex situ scanning electron microscopy. For both samples, a linear increase of oxide film thickness with increasing anodization voltage was found. However, the slope is much higher in the single crystal case, and the break-up of the oxide film grown on the alloy occurs at a lower anodization potential than on the single crystal. The reasons for these observations are discussed as are the measured differences observed for x-ray reflectivity and electrochemical impedance spectroscopy.

  18. Determination of salt content in various depth of pork chop by electrical impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Kaltenecker, P.; Szöllösi, D.; Friedrich, L.; Vozáry, E.

    2013-04-01

    The salt concentration was determined inside of pork chop both by electrical impedance spectroscopy and by a conventional chemical method (according to Mohr). The pork chop in various depths (4 mm, 10 mm, 20 mm and 25 mm) was punctured with two stainless steel electrodes. The length of electrodes was 60 mm, and they were insulated along the length except 1 cm section on the end, so the measurement of impedance was realized in various depths. The magnitude and phase angle of impedance were measured with a HP 4284A and a HP 4285A LCR meters from 30 Hz up to 1 MHz and from 75 kHz up to 30 MHz frequency range, respectively at 1 V voltage. The distance between the electrodes was 1 cm. The impedance magnitude decreased as the salt concentration increased. The magnitude of open-short corrected impedance values at various frequencies (10 kHz, 100 kHz, 125 kHz, 1.1 MHz and 8 MHz) showed a good correlation with salt content determined by chemical procedure. The electrical impedance spectroscopy seems a prospective method for determination the salt concentration inside the meat in various depths during the curing procedure.

  19. MONITORING ANTIBODY-ANTIGEN REACTIONS AT CONDUCTING POLYMER-BASED IMMUNOSENSORS USING IMPEDANCE SPECTROSCOPY. (R825323)

    EPA Science Inventory

    Abstract

    The mechanisms of antibody¯antigen (Ab¯Ag) interactions at conducting polypyrrole electrodes have been investigated using impedance spectroscopy techniques. The effects of the variation in ion exchange, solution composition, and...

  20. Electrical impedance tomography spectroscopy method for characterising particles in solid-liquid phase

    NASA Astrophysics Data System (ADS)

    Zhao, Yanlin; Wang, Mi; Yao, Jun

    2014-04-01

    Electrical impedance tomography (EIT) is one of the process tomography techniques to provide an on-line non-invasive imaging for multiphase flow measurement. With EIT measurements, the images of impedance real part, impedance imaginary part, phase angle, and magnitude can be obtained. However, most of the applications of EIT in the process industries rely on the conductivity difference between two phases in fluids to obtain the concentration profiles. It is not common to use the imaginary part or phase angle due to the dominant change in conductivity or complication in the use of other impedance information. In a solid-liquid two phases system involving nano- or submicro-particles, characterisation of particles (e.g. particle size and concentration) have to rely on the measurement of impedance phase angle or imaginary part. Particles in a solution usually have an electrical double layer associated with their surfaces and can form an induced electrical dipole moment due to the polarization of the electrical double layer under the influence of an alternating electric field. Similar to EIT, electrical impedance spectroscopy (EIS) measurement can record the electrical impedance data, including impedance real part, imaginary part and phase angle (θ), which are caused by the polarization of the electrical double layer. These impedance data are related to the particle characteristics e.g. particle size, particle and ionic concentrations in the aqueous medium, therefore EIS method provides a capability for characterising the particles in suspensions. Electrical impedance tomography based on EIS measurement or namely, electrical impedance tomography spectroscopy (EITS) could image the spatial distribution of particle characteristics. In this paper, a new method, including test set-up and data analysis, for characterisation of particles in suspensions are developed through the experimental approach. The experimental results on tomographic imaging of colloidal particles

  1. Electrical impedance tomography spectroscopy method for characterising particles in solid-liquid phase

    SciTech Connect

    Zhao, Yanlin; Wang, Mi; Yao, Jun

    2014-04-11

    Electrical impedance tomography (EIT) is one of the process tomography techniques to provide an on-line non-invasive imaging for multiphase flow measurement. With EIT measurements, the images of impedance real part, impedance imaginary part, phase angle, and magnitude can be obtained. However, most of the applications of EIT in the process industries rely on the conductivity difference between two phases in fluids to obtain the concentration profiles. It is not common to use the imaginary part or phase angle due to the dominant change in conductivity or complication in the use of other impedance information. In a solid-liquid two phases system involving nano- or submicro-particles, characterisation of particles (e.g. particle size and concentration) have to rely on the measurement of impedance phase angle or imaginary part. Particles in a solution usually have an electrical double layer associated with their surfaces and can form an induced electrical dipole moment due to the polarization of the electrical double layer under the influence of an alternating electric field. Similar to EIT, electrical impedance spectroscopy (EIS) measurement can record the electrical impedance data, including impedance real part, imaginary part and phase angle (θ), which are caused by the polarization of the electrical double layer. These impedance data are related to the particle characteristics e.g. particle size, particle and ionic concentrations in the aqueous medium, therefore EIS method provides a capability for characterising the particles in suspensions. Electrical impedance tomography based on EIS measurement or namely, electrical impedance tomography spectroscopy (EITS) could image the spatial distribution of particle characteristics. In this paper, a new method, including test set-up and data analysis, for characterisation of particles in suspensions are developed through the experimental approach. The experimental results on tomographic imaging of colloidal particles

  2. Electrical Impedance Spectroscopy for Electro-Mechanical Characterization of Conductive Fabrics

    PubMed Central

    Bera, Tushar Kanti; Mohamadou, Youssoufa; Lee, Kyounghun; Wi, Hun; Oh, Tong In; Woo, Eung Je; Soleimani, Manuchehr; Seo, Jin Keun

    2014-01-01

    When we use a conductive fabric as a pressure sensor, it is necessary to quantitatively understand its electromechanical property related with the applied pressure. We investigated electromechanical properties of three different conductive fabrics using the electrical impedance spectroscopy (EIS). We found that their electrical impedance spectra depend not only on the electrical properties of the conductive yarns, but also on their weaving structures. When we apply a mechanical tension or compression, there occur structural deformations in the conductive fabrics altering their apparent electrical impedance spectra. For a stretchable conductive fabric, the impedance magnitude increased or decreased under tension or compression, respectively. For an almost non-stretchable conductive fabric, both tension and compression resulted in decreased impedance values since the applied tension failed to elongate the fabric. To measure both tension and compression separately, it is desirable to use a stretchable conductive fabric. For any conductive fabric chosen as a pressure-sensing material, its resistivity under no loading conditions must be carefully chosen since it determines a measurable range of the impedance values subject to different amounts of loadings. We suggest the EIS method to characterize the electromechanical property of a conductive fabric in designing a thin and flexible fabric pressure sensor. PMID:24892493

  3. Electrical Impedance Spectroscopy-Based Defect Sensing Technique in Estimating Cracks

    PubMed Central

    Zhang, Tingting; Zhou, Liangdong; Ammari, Habib; Seo, Jin Keun

    2015-01-01

    A defect sensing method based on electrical impedance spectroscopy is proposed to image cracks and reinforcing bars in concrete structures. The method utilizes the frequency-dependent behavior of thin insulating cracks: low-frequency electrical currents are blocked by insulating cracks, whereas high-frequency currents can pass through thin cracks to probe the conducting bars. From various frequency-dependent electrical impedance tomography (EIT) images, we can show its advantage in terms of detecting both thin cracks with their thickness and bars. We perform numerical simulations and phantom experiments to support the feasibility of the proposed method. PMID:26007713

  4. Impedance spectroscopy study of anodic growth of zirconium oxide film in NaOH medium

    NASA Astrophysics Data System (ADS)

    Pauporté, T.; Finne, J.; Lincot, D.

    2005-06-01

    The growth of anodic oxide films on zirconium metal has been followed up to 300 V by electrochemical impedance spectroscopy and scanning electron microscopy. The maximum layer thickness is 720 nm, the dielectric constant of the film is measured at 19.5 and the growth constant is 2.4 nm V-1. Above 50 V, the presence of two impedance relaxations between 1 Hz and 200 kHz reveals a bilayered structure. This may be a consequence of a lower resistivity of the outer layer induced by some electrolytic solution infiltration into film defects.

  5. Effects of Nitrogen on Passivity of Nickel-Free Stainless Steels by Electrochemical Impedance Spectroscopy Analysis

    NASA Astrophysics Data System (ADS)

    Wu, Xinqiang; Fu, Yao; Ke, Wei; Xu, Song; Feng, Bing; Hu, Botao

    2015-09-01

    The effects of different nitrogen contents on the passivity of nickel-free stainless steels in 0.5 M sulfuric acid + 0.5 M sodium chloride solution were investigated by electrochemical impedance spectroscopy in the potential ranges of active dissolution and active-passive transition. A simplified reaction model containing adsorbed intermediates involved dissolution process, and passivation process was proposed to explain the impedance characteristics. Based on both equivalent circuit and mathematical model analysis, the effects of nitrogen on the passivity of stainless steels are discussed.

  6. Angiotensin-converting enzyme/vitamin D receptor gene polymorphisms and bioelectrical impedance analysis in predicting athletic performances of Italian young soccer players.

    PubMed

    Micheli, Matteo Levi; Gulisano, Massimo; Morucci, Gabriele; Punzi, Tiziana; Ruggiero, Marco; Ceroti, Marco; Marella, Mario; Castellini, Elena; Pacini, Stefania

    2011-08-01

    We evaluated the association between 2 genetic polymorphisms known to be involved in fitness and performance, and anthropometric features, body composition, and athletic performances in young male soccer players with the goal of identifying genetic profiles that can be used to achieve maximal results from training. One hundred twenty-five medium-high-level male soccer players were genotyped for angiotensin-converting enzyme (ACE) I/D, and vitamin D receptor (VDR) FokI gene polymorphisms and scored for anthropometric measurements, body composition, and athletic performance. Body mass index, fat mass, fat-free mass, resistance, reactance, impedance, phase angle (PA), and body cell mass were measured. Athletic performance was evaluated by squat jump, countermovement jump (CMJ), 2-kg medicine ball throw, 10- and 20-m sprint time. We observed that the homozygous ff genotype of the VDR gene was significantly more represented in young soccer players than in a matched sedentary population. Values of reactance and PA were differently distributed in ACE and VDR genotypes with high mean values in subjects with DD (ACE) and FF (VDR) genotypes. No correlation was observed between ACE or VDR genotypes and 2-kg medicine ball throw, 10- and 20-m sprint times. The ID genotype of ACE was associated with the best performances in squat jump and CMJ. Our results suggest that determination of ACE and VDR genotypes might help select those young athletes harboring the most favorable genetic potential to succeed in soccer. PMID:21747292

  7. The influence of nanopore dimensions on the electrochemical properties of nanopore arrays studied by impedance spectroscopy.

    PubMed

    Kant, Krishna; Priest, Craig; Shapter, Joe G; Losic, Dusan

    2014-01-01

    The understanding of the electrochemical properties of nanopores is the key factor for better understanding their performance and applications for nanopore-based sensing devices. In this study, the influence of pore dimensions of nanoporous alumina (NPA) membranes prepared by an anodization process and their electrochemical properties as a sensing platform using impedance spectroscopy was explored. NPA with four different pore diameters (25 nm, 45 nm and 65 nm) and lengths (5 μm to 20 μm) was used and their electrochemical properties were explored using different concentration of electrolyte solution (NaCl) ranging from 1 to 100 μM. Our results show that the impedance and resistance of nanopores are influenced by the concentration and ion species of electrolytes, while the capacitance is independent of them. It was found that nanopore diameters also have a significant influence on impedance due to changes in the thickness of the double layer inside the pores. PMID:25393785

  8. Mitochondrial Membrane Studies Using Impedance Spectroscopy with Parallel pH Monitoring

    PubMed Central

    Padmaraj, Divya; Pande, Rohit; Miller, John H.; Wosik, Jarek; Zagozdzon-Wosik, Wanda

    2014-01-01

    A biological microelectromechanical system (BioMEMS) device was designed to study complementary mitochondrial parameters important in mitochondrial dysfunction studies. Mitochondrial dysfunction has been linked to many diseases, including diabetes, obesity, heart failure and aging, as these organelles play a critical role in energy generation, cell signaling and apoptosis. The synthesis of ATP is driven by the electrical potential across the inner mitochondrial membrane and by the pH difference due to proton flux across it. We have developed a tool to study the ionic activity of the mitochondria in parallel with dielectric measurements (impedance spectroscopy) to gain a better understanding of the properties of the mitochondrial membrane. This BioMEMS chip includes: 1) electrodes for impedance studies of mitochondria designed as two- and four-probe structures for optimized operation over a wide frequency range and 2) ion-sensitive field effect transistors for proton studies of the electron transport chain and for possible monitoring other ions such as sodium, potassium and calcium. We have used uncouplers to depolarize the mitochondrial membrane and disrupt the ionic balance. Dielectric spectroscopy responded with a corresponding increase in impedance values pointing at changes in mitochondrial membrane potential. An electrical model was used to describe mitochondrial sample’s complex impedance frequency dependencies and the contribution of the membrane to overall impedance changes. The results prove that dielectric spectroscopy can be used as a tool for membrane potential studies. It can be concluded that studies of the electrochemical parameters associated with mitochondrial bioenergetics may render significant information on various abnormalities attributable to these organelles. PMID:25010497

  9. Microelectrical Impedance Spectroscopy for the Differentiation between Normal and Cancerous Human Urothelial Cell Lines: Real-Time Electrical Impedance Measurement at an Optimal Frequency

    PubMed Central

    Park, Yangkyu; Kim, Hyeon Woo; Yun, Joho; Seo, Seungwan; Park, Chang-Ju; Lee, Jeong Zoo; Lee, Jong-Hyun

    2016-01-01

    Purpose. To distinguish between normal (SV-HUC-1) and cancerous (TCCSUP) human urothelial cell lines using microelectrical impedance spectroscopy (μEIS). Materials and Methods. Two types of μEIS devices were designed and used in combination to measure the impedance of SV-HUC-1 and TCCSUP cells flowing through the channels of the devices. The first device (μEIS-OF) was designed to determine the optimal frequency at which the impedance of two cell lines is most distinguishable. The μEIS-OF trapped the flowing cells and measured their impedance at a frequency ranging from 5 kHz to 1 MHz. The second device (μEIS-RT) was designed for real-time impedance measurement of the cells at the optimal frequency. The impedance was measured instantaneously as the cells passed the sensing electrodes of μEIS-RT. Results. The optimal frequency, which maximized the average difference of the amplitude and phase angle between the two cell lines (p < 0.001), was determined to be 119 kHz. The real-time impedance of the cell lines was measured at 119 kHz; the two cell lines differed significantly in terms of amplitude and phase angle (p < 0.001). Conclusion. The μEIS-RT can discriminate SV-HUC-1 and TCCSUP cells by measuring the impedance at the optimal frequency determined by the μEIS-OF. PMID:26998490

  10. Low cost soil sensor based on impedance spectroscopy for in-situ measurement

    NASA Astrophysics Data System (ADS)

    Umar, Lazuardi; Setiadi, Rahmondia N.

    2015-04-01

    Soil moisture is a significant element in the water cycle, on an agricultural and in land interaction. In crop production, soil plays a key role as a physical support and a reservoir of water and nutrients. Decisions for optimized input rates of water are largely based on physical, chemical, and biological properties of soils. The aim of this work is to develop a low cost soil moisture sensor (SMS) based on impedance spectroscopy by means of magnitude ratio and phase difference detection method. Using impedance spectroscopy, more information can be delivered from real and imaginary part of the complex permittivity for several frequencies at the same moisture value. For this purpose, a probe has been designed which uses a simplified impedance measuring system to determine soil water content. The circuit sweeps at pre-programmed frequencies from 10 KHz to 10MHz with 10 mV AC amplitude. A local inceptisol soil of East Sumatra was especially selected for this investigation because measurements of soil moisture in peat swamp area were generally reported as challenging to analyze. Samples at defined soil moisture of 2%, 8%, 15% measured using commercial soil sensor Lutron PMS-714, was characterized. A model has been developed in order to correct the frequency influence upon the measurement. The results obtained by the sensor show good results with an overall mean error of 0.21% in impedance.

  11. Sensing of NO2 with Zirconium Hydroxide via Electrical Impedance Spectroscopy

    NASA Astrophysics Data System (ADS)

    Harris, Coleman; Soliz, Jennifer; Klevitch, Andrew; Rossin, Joseph; Fountain, Augustus, III; Peterson, Gregory; Hauser, Adam

    Nitrogen Dioxide (NO2) is a brown gas mainly produced as a byproduct of burning fossil fuels, such as automobiles and power plants. Nitrogen oxides can form acid rain and smog by reacting with air, can form toxic organic nitrates by reacting with soil, and can react with oxygen in water, destroying marine life due to a lack of breathable oxygen. Any concentration beyond 53 ppb (air quality standard) can cause irritation to the lungs and respiratory infections, and higher dosages can be fatal. As such, research in NO2 detection is incredibly important to human welfare. Zirconium hydroxide (Zr(OH)4) has been investigated as a candidate NO2 dielectric sensor using impedance spectroscopy analysis. Impedance changes of several orders of magnitude are seen down to our dosage minimum of 50 ppmhr. Changes in impedance correlate with nitrogen and oxygen atomic ratio increases observed via X-ray photoelectron spectroscopy (XPS). The results indicate that Zr(OH)4 may be a strong candidate for use in impedance-based NO2 detection devices. A.J.H., J.R.S., A.W.F. and G.W. P. acknowledge funding under Army Research Office STIR Award #W911F-15-1-0104. J.R.S. acknowledges funding under a NRC fellowship and is advised by Dr. Christopher Karwacki, ECBC.

  12. Effects of Surface and Morphological Properties of Zeolite on Impedance Spectroscopy-Based Sensing Performance

    PubMed Central

    Zhang, Jianwei; Li, Xiaogan; White, Jeremy; Dutta, Prabir K.

    2012-01-01

    Measurement by impedance spectroscopy of the changes in intrazeolitic cation motion of pressed pellets of zeolite particles upon adsorption of dimethylmethylphosphonate (DMMP) provides a strategy for sensing DMMP, a commonly used simulant for highly toxic organophosphate nerve agents. In this work, two strategies for improving the impedance spectroscopy based sensing of DMMP on zeolites were investigated. The first one is the use of cerium oxide (CeO2) coated on the zeolite surface to neutralize acidic groups that may cause the decomposition of DMMP, and results in better sensor recovery. The second strategy was to explore the use of zeolite Y membrane. Compared to pressed pellets, the membranes have connected supercages of much longer length scales. The zeolite membranes resulted in higher sensitivity to DMMP, but recovery of the device was significantly slower as compared to pressed zeolite pellets. PMID:23201996

  13. Evaluation of doped polyaniline as a carbon steel protective coating using electrochemical impedance spectroscopy

    SciTech Connect

    Calle, L.M.; MacDowell, L.G. III

    1997-12-01

    Electrochemical Impedance Spectroscopy (EIS) was used to evaluate the performance of two doped polyanilines, PAN, in the emeraldine base form, EB, as protective coatings for carbon steel under immersion in 3.55% NaCl. Coatings A and B consisted of EB doped with tetracyanoethylene (TCNE) and with p-toluenesulfonic acid (PTSA) respectively. The equivalent circuit R{sub e}(C{sub c}[R{sub c}(QR{sub 1})]) provided a satisfactory fit for the EIS data.

  14. Development of a new rapid measurement technique for fish embryo membrane permeability studies using impedance spectroscopy

    PubMed Central

    Zhang, T.; Wang, R.Y.; Bao, Q-Y.; Rawson, D.M.

    2006-01-01

    Information on fish embryo membrane permeability is vital in their cryopreservation. Whilst conventional volumetric measurement based assessment methods have been widely used in fish embryo membrane permeability studies, they are lengthy and reduce the capacity for multi-embryo measurement during an experimental run. A new rapid ‘real-time’ measurement technique is required to determine membrane permeability during cryoprotectant treatment. In this study, zebrafish (Danio rerio) embryo membrane permeability to cryoprotectants was investigated using impedance spectroscopy. An embryo holding cell, capable of holding up to 10 zebrafish embryos was built incorporating the original system electrods for measuring the impedance spectra. The holding cell was tested with deionised water and a series of KCl solutions with known conductance values to confirm the performance of the modified system. Untreated intact embryos were then tested to optimise the loading capacity and sensitivity of the system. To study the impedance changes of zebrafish embryos during cryoprotectant exposure, three, six or nine embryos at 50% epiboly stage were loaded into the holding cell in egg water, which was then removed and replaced by 0.5, 1.0, 2.0 or 3 M methanol or dimethyl sulfoxide (DMSO). The impedance changes of the loaded embryos in different cryoprotectant solutions were monitored over 30 min at 22 °C, immediately following embryo exposure to cryoprotectants, at the frequency range of 10–106 Hz. The impedance changes of the embryos in egg water were used as controls. Results from this study showed that the optimum embryo loading level was six embryos per cell for each experimental run. The optimum frequency was identified at 103.14 or 1380 Hz which provided good sensitivity and reproducibility. Significant impedance changes were detected after embryos were exposed to different concentrations of cryoprotectants. The results agreed well with those obtained from conventional

  15. Characterization of Molybdate Conversion Coatings for Aluminum Alloys by Electrochemical Impedance Spectroscopy

    NASA Technical Reports Server (NTRS)

    Calle, Luz Marina

    2000-01-01

    Electrochemical impedance spectroscopy (EIS) was used to investigate the corrosion inhibiting properties of newly developed proprietary molybdate conversion coatings on aluminum alloy 2024-T3 under immersion in aerated 5% (w/w) NaCl. Corrosion potential and EIS measurements were gathered for six formulations of the coating at several immersion times for two weeks. Nyquist as well as Bode plots of the data were obtained. The conversion-coated alloy panels showed an increase in the corrosion potential during the first 24 hours of immersion that later subsided and approached a steady value. Corrosion potential measurements indicated that formulations A, D, and F exhibit a protective effect on aluminum 2024-T3. The EIS spectra of the conversion-coated alloy were characterized by an impedance that is higher than the impedance of the bare alloy at all the immersion times. The low frequency impedance, Z(sub lf) (determined from the value at 0.05 Hz) for the conversion-coated alloy was higher at all the immersion times than that of the bare panel. This indicates improvement of corrosion resistance with addition of the molybdate conversion coating. Scanning electron microscopy (SEM) revealed the presence of cracks in the coating and the presence of cubic crystals believed to be calcium carbonate. Energy dispersive spectroscopy (EDS) of the test panels revealed the presence of high levels of aluminum, oxygen, and calcium but did not detect the presence of molybdenum on the test panels. X-ray photoelectron spectroscopy (XPS) indicated the presence of less than 0.01 atomic percent molybdenum on the surface of the coating.

  16. Electrical transport properties of Mn-Ni-Zn ferrite using complex impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Azizar Rahman, M.; Hossain, A. K. M. Akther

    2014-02-01

    Polycrystalline Mn0.45Ni0.05Zn0.50Fe2O4 was prepared by a standard solid state reaction technique. We report the electrical properties of this ferrite using ac impedance spectroscopy as a function of frequency (20 Hz-10 MHz) at different temperatures (50-350 °C). X-ray diffraction patterns reveal the formation of cubic spinel structure. Complex impedance analysis has been used to separate the grain and grain boundary resistance of this ferrite. The variation of grain and grain boundary conductivities with temperature confirms semiconducting behavior. The dielectric permittivity shows dielectric dispersion at lower frequency and reveals that it has almost the same value on the high-frequency side. The non-coincidence of peaks corresponding to modulus and impedance indicates deviation from Debye-type relaxation. A similar value of activation energy is obtained from impedance and modulus spectra, indicating that charge carriers overcome the same energy barrier during relaxation. Electron hopping is responsible for ac conduction in this ferrite. The electron hopping shifts toward higher frequency with increasing temperature, below which the conductivity is frequency independent. The frequency-independent ac conductivity has been observed at and above 300 °C in the frequency range 20 Hz-1 MHz. This frequency-independent ac conductivity is due to the long-range movement of the mobile charge carriers.

  17. Electrochemical impedance spectroscopy of metal alloys in the space transportation system launch environment

    NASA Technical Reports Server (NTRS)

    Calle, Luz

    1990-01-01

    AC impedance measurements were performed to investigate the corrosion resistance of 18 alloys under conditions similar to the Space Transportation System (STS) launch environment. The alloys were: (1) zirconium 702; (2) Hastelloy C-22, C-276, C-4, and B-2; (3) Inconel 600 and 825; (4) Ferralium 255; (5) Inco Alloy G-3; (6) 20Cb-3; (7) SS 904L, 304LN, 316L, 317L, and 304L; (8) ES 2205; and (9) Monel 400. AC impedance data were gathered for each alloy at various immersion times in 3.55 percent NaCl-0.1N HCl. Polarization resistance values were obtained for the Nyguist plots at each immersion time using the EQUIVALENT CIRCUIT software package available with the 388 electrochemical impedance software. Hastelloy C-22 showed the highest overall values for polarization resistance while Monel 400 and Inconel 600 had the lowest overall values. There was good general correlation between the corrosion performance of the alloys at the beach corrosion testing site, and the expected rate of corrosion as predicted based on the polarization resistance values obtained. The data indicate that electrochemical impedance spectroscopy can be used to predict the corrosion performance of metal alloys.

  18. A study on the impact of lithium-ion cell relaxation on electrochemical impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Barai, Anup; Chouchelamane, Gael H.; Guo, Yue; McGordon, Andrew; Jennings, Paul

    2015-04-01

    Lithium-ion (Li-ion) batteries are of great interest to the automotive industry due to their higher power and energy density, higher cell voltage, longer cycle life and lower self-discharge compared to other battery chemistries. Electrochemical impedance spectroscopy is a powerful tool employed to investigate the fundamental electrochemical reactions within a Li-ion battery cell, which relates to state of charge, internal temperature and state of health. Its effectiveness has established it as a core method to study electrochemical behaviour of batteries in both off-line and on-line applications. In this work it is shown that in addition to state of charge, internal temperature and state of health, the time period between the removal of an electrical load and the impedance measurement affects the results. The study of five commercially available cells of varying capacities and electrode chemistries show that, regardless of cell type, maximum impedance change takes place within the first 4 h of the relaxation period. The root cause of this impedance change has been discussed from an electrochemical perspective.

  19. Performance of an implantable impedance spectroscopy monitor using ZigBee

    NASA Astrophysics Data System (ADS)

    Bogónez-Franco, P.; Bayés-Genís, A.; Rosell, J.; Bragós, R.

    2010-04-01

    This paper presents the characterization measurements of an implantable bioimpedance monitor with ZigBee. Such measurements are done over RC networks, performing short and long-term measurements, with and without mismatch in electrodes and varying the temperature and the RF range. The bioimpedance monitor will be used in organ monitoring through electrical impedance spectroscopy in the 100 Hz - 200 kHz range. The specific application is the study of the viability and evolution of engineered tissue in cardiac regeneration in an experimental protocol with pig models. The bioimpedance monitor includes a ZigBee transceiver to transmit the measured data outside the animal chest. The bioimpedance monitor is based in the 12 Bit Impedance Converter and Network Analyzer AD5933, improved with an analog front-end that implements a 4-electrode measurement structure and allows to measure small impedances. In the debugging prototype, the system autonomy exceeds 1 month when a 14 frequencies impedance spectrum is acquired every 5 minutes. The receiver side consists of a ZigBee transceiver connected to a PC to process the received data. In the current implementation, the effective range of the RF link was of a few centimeters, then needing a range extender placed close to the animal. We have increased it by using an antenna with higher gain. Basic errors in the phantom circuit parameters estimation after model fitting are below 1%.

  20. A new lithium-ion battery internal temperature on-line estimate method based on electrochemical impedance spectroscopy measurement

    NASA Astrophysics Data System (ADS)

    Zhu, J. G.; Sun, Z. C.; Wei, X. Z.; Dai, H. F.

    2015-01-01

    The power battery thermal management problem in EV (electric vehicle) and HEV (hybrid electric vehicle) has been widely discussed, and EIS (electrochemical impedance spectroscopy) is an effective experimental method to test and estimate the status of the battery. Firstly, an electrochemical-based impedance matrix analysis for lithium-ion battery is developed to describe the impedance response of electrochemical impedance spectroscopy. Then a method, based on electrochemical impedance spectroscopy measurement, has been proposed to estimate the internal temperature of power lithium-ion battery by analyzing the phase shift and magnitude of impedance at different ambient temperatures. Respectively, the SoC (state of charge) and temperature have different effects on the impedance characteristics of battery at various frequency ranges in the electrochemical impedance spectroscopy experimental study. Also the impedance spectrum affected by SoH (state of health) is discussed in the paper preliminary. Therefore, the excitation frequency selected to estimate the inner temperature is in the frequency range which is significantly influenced by temperature without the SoC and SoH. The intrinsic relationship between the phase shift and temperature is established under the chosen excitation frequency. And the magnitude of impedance related to temperature is studied in the paper. In practical applications, through obtaining the phase shift and magnitude of impedance, the inner temperature estimation could be achieved. Then the verification experiments are conduced to validate the estimate method. Finally, an estimate strategy and an on-line estimation system implementation scheme utilizing battery management system are presented to describe the engineering value.

  1. Nonlinear electrical impedance spectroscopy of viruses using very high electric fields created by nanogap electrodes

    PubMed Central

    Hatsuki, Ryuji; Honda, Ayae; Kajitani, Masayuki; Yamamoto, Takatoki

    2015-01-01

    Our living sphere is constantly exposed to a wide range of pathogenic viruses, which can be either known, or of novel origin. Currently, there is no methodology for continuously monitoring the environment for viruses in general, much less a methodology that allows the rapid and sensitive identification of a wide variety of viruses responsible for communicable diseases. Traditional approaches, based on PCR and immunodetection systems, only detect known or specifically targeted viruses. We here describe a simple device that can potentially detect any virus between nanogap electrodes using nonlinear impedance spectroscopy. Three test viruses, differing in shape and size, were used to demonstrate the general applicability of this approach: baculovirus, tobacco mosaic virus (TMV), and influenza virus. We show that each of the virus types responded differently in the nanogap to changes in the electric field strength, and the impedance of the virus solutions differed depending both on virus type and virus concentration. These preliminary results show that the three virus types can be distinguished and their approximate concentrations determined. Although further studies are required, the proposed nonlinear impedance spectroscopy method may achieve a sensitivity comparable to that of more traditional, but less versatile, virus detection systems. PMID:26441875

  2. Electrochemical Impedance Spectroscopy Investigation on the Clinical Lifetime of ProTaper Rotary File System

    PubMed Central

    Pirvu, Cristian; Demetrescu, Ioana

    2014-01-01

    The main objective of the current paper is to show that electrochemical impedance spectroscopy (EIS) could be a method for evaluating and predicting of ProTaper rotary file system clinical lifespan. This particular aspect of everyday use of the endodontic files is of great importance in each dental practice and has profound clinical implications. The method used for quantification resides in the electrochemical impedance spectroscopy theory and has in its main focus the characteristics of the surface titanium oxide layer. This electrochemical technique has been adapted successfully to identify the quality of the Ni-Ti files oxide layer. The modification of this protective layer induces changes in corrosion behavior of the alloy modifying the impedance value of the file. In order to assess the method, 14 ProTaper sets utilized on different patients in a dental clinic have been submitted for testing using EIS. The information obtained in regard to the surface oxide layer has offered an indication of use and proves that the said layer evolves with each clinical application. The novelty of this research is related to an electrochemical technique successfully adapted for Ni-Ti file investigation and correlation with surface and clinical aspects. PMID:24605336

  3. SURFACE SEGREGATION STUDIES OF SOFC CATHODES: COMBINING SOFT X-RAYS AND ELECTROCHEMICAL IMPEDENCE SPECTROSCOPY

    SciTech Connect

    Miara, Lincoln J.; Piper, L.F.J.; Davis, Jacob N.; Saraf, Laxmikant V.; Kaspar, Tiffany C.; Basu, Soumendra; Smith, K. E.; Pal, Uday B.; Gopalan, Srikanth

    2010-12-01

    A system to grow heteroepitaxial thin-films of solid oxide fuel cell (SOFC) cathodes on single crystal substrates was developed. The cathode composition investigated was 20% strontium-doped lanthanum manganite (LSM) grown by pulsed laser deposition (PLD) on single crystal (111) yttria-stabilized zirconia (YSZ) substrates. By combining electrochemical impedance spectroscopy (EIS) with x-ray photoemission spectroscopy (XPS) and x-ray absorption spectroscopy XAS measurements, we conclude that electrically driven cation migration away from the two-phase gas-cathode interface results in improved electrochemical performance. Our results provide support to the premise that the removal of surface passivating phases containing Sr2+ and Mn2+, which readily form at elevated temperatures even in O2 atmospheric pressures, is responsible for the improved cathodic performance upon application of a bias.

  4. Design of a wideband CMOS impedance spectroscopy ASIC analog front-end for multichannel biosensor interfaces.

    PubMed

    Valente, Virgilio; Dai Jiang; Demosthenous, Andreas

    2015-08-01

    This paper presents the preliminary design and simulation of a flexible and programmable analog front-end (AFE) circuit with current and voltage readout capabilities for electric impedance spectroscopy (EIS). The AFE is part of a fully integrated multifrequency EIS platform. The current readout comprises of a transimpedance stage and an automatic gain control (AGC) unit designed to accommodate impedance changes larger than 3 order of magnitude. The AGC is based on a dynamic peak detector that tracks changes in the input current over time and regulates the gain of a programmable gain amplifier in order to optimise the signal-to-noise ratio. The system works up to 1 MHz. The voltage readout consists of a 2 stages of fully differential current-feedback instrumentation amplifier which provide 100 dB of CMRR and a programmable gain up to 20 V/V per stage with a bandwidth in excess of 10MHz. PMID:26736404

  5. Impedance Spectroscopy Study of Composite Thin Films of Hydrated Polyethylene Glycol

    SciTech Connect

    Al-Hamarneh, Ibrahim F.; Pedrow, Patrick D.; Goheen, Steven C.; Hartenstine, M. J.

    2007-05-01

    A polythelene glycol (PEG) polymer was synthesized using a dip coating procedure on 316L stainless steel (SS) substrate pre coated by radio frequency RF inductively coupled plasma polymerization with di (ethylene glycol) vinyl ether (EO2V) monomer that was used as a primer coat. The primer and PEG composite film was studied with profilometer, visible-light microscope, scanning electron microscope (SEM) and a tape test to evaluate thickness, stability, morphology and adhesion. Response of the PEG composite film to an AC electric perturbation was studied as a function of hydration state using impedance spectroscopy (IS). A resistor/capacitor network was used to interpret the impedance spectra. The capacitance of the PEG film decreased with an exponentially decaying term as dehydration progressed. PEG film capacitance decay was consistent with a model describing water molecules diffusing through the PEG film.

  6. Impedance Spectroscopy Study of Composite Thin Films of Hydrated Polyethylene Glycol

    SciTech Connect

    Al-Hamarneh, Ibrahim F.; Pedrow, Patrick D.; Goheen, Steven C.; Hartenstine, M. J.

    2007-10-01

    A polyethylene glycol (PEG) polymer was synthesized using a dip coating procedure on 316L stainless steel (SS) substrate pre-coated with a primer that consisted of radio frequency RF inductively coupled plasma-polymerized di (ethylene glycol) vinyl ether (EO2V). The primer and PEG composite film was studied with profilometer, optical microscope, scanning electron microscope (SEM), and a tape test to evaluate thickness, coverage, morphology, and adhesion, respectively. Response of the PEG composite film to an applied AC voltage was studied as a function of hydration state using impedance spectroscopy (IS). A resistor/capacitor network was used to interpret the impedance spectra. Electrical capacitance of the PEG film decreased with an exponentially decaying term as dehydration progressed. PEG film capacitance decay was consistent with a model describing water molecules diffusing through the PEG film.

  7. Microstructural studies of AgNbO{sub 3} ceramic by using complex impedance spectroscopy

    SciTech Connect

    Gangaprasad, K.; Rao, T. Durga; Niranjan, Manish K.; Asthana, Saket

    2015-06-24

    Lead-free piezoelectric silver niobate ceramic was synthesized by conventional solid state route. Room temperature X-ray diffraction pattern revealed that the sample crystallizes in single phase orthorhombic perovskite structure. Scanning electron micrographs of AgNbO{sub 3} ceramic showed that the average grain size is in the range 2–3 µm. The electrical properties were investigated by using impedance spectroscopy. Appearance of single semicircular arc in the Nyquist plot indicated the presence of grain contribution in the sample. Single RC parallel circuit model was employed to extract bulk capacitance (C{sub b}), resistance (R{sub b}) and electrical conductivity (σ{sub b}). The activation energy calculated from impedance and modulus data indicate that same types of charge carriers (oxygen vacancy movements) are responsible for conduction and relaxation.

  8. Electrical Impedance Spectroscopy as Electrical Biopsy for Monitoring Radiation Sequelae of Intestine in Rats

    PubMed Central

    Chao, Pei-Ju; Huang, Eng-Yen; Cheng, Kuo-Sheng; Huang, Yu-Jie

    2013-01-01

    Electrical impedance is one of the most frequently used parameters for characterizing material properties. The resistive and capacitive characteristics of tissue may be revealed by electrical impedance spectroscopy (EIS) as electrical biopsy. This technique could be used to monitor the sequelae after irradiation. In this study, rat intestinal tissues after irradiation were assessed by EIS system based on commercially available integrated circuits. The EIS results were fitted to a resistor-capacitor circuit model to determine the electrical properties of the tissue. The variations in the electrical characteristics of the tissue were compared to radiation injury score (RIS) by morphological and histological findings. The electrical properties, based on receiver operation curve (ROC) analysis, strongly reflected the histological changes with excellent diagnosis performance. The results of this study suggest that electrical biopsy reflects histological changes after irradiation. This approach may significantly augment the evaluation of tissue after irradiation. It could provide rapid results for decision making in monitoring radiation sequelae prospectively. PMID:24093111

  9. RTEMIS: Real-time Tumoroid and Environment Monitoring Using Impedance Spectroscopy and pH Sensing

    NASA Astrophysics Data System (ADS)

    Alexander, Frank A., Jr.

    This research utilizes Electrical Impedance Spectroscopy, a technique classically used for electrochemical analysis and material characterization, as the basis for a non-destructive, label-free assay platform for three dimensional (3D) cellular spheroids. In this work, a linear array of microelectrodes is optimized to rapidly respond to changes located within a 3D multicellular model. In addition, this technique is coupled with an on chip micro-pH sensor for monitoring the environment around the cells. Finally, the responses of both impedance and pH are correlated with physical changes within the cellular model. The impedance analysis system realized through this work provides a foundation for the development of high-throughput drug screening systems that utilize multiple parallel sensing modalities including pH and impedance sensing in order to quickly assess the efficacy of specific drug candidates. The slow development of new drugs is mainly attributed to poor predictability of current chemosensitivity and resistivity assays, as well as genetic differences between the animal models used for tests and humans. In addition, monolayer cultures used in early experimentation are fundamentally different from the complex structure of organs in vivo. This requires the study of smaller 3D models (spheroids) that more efficiently replicate the conditions within the body. The main objective of this research was to develop a microfluidic system on a chip that is capable of deducing viability and morphology of 3D tumor spheroids by monitoring both the impedance of the cellular model and the pH of their local environment. This would provide a fast and reliable method for screening pharmaceutical compounds in a high-throughput system.

  10. Impedance spectroscopy of resistance switching in a Pt/NiO/Pt capacitor

    NASA Astrophysics Data System (ADS)

    Na, Sang-Chul; Chun, Min Chul; Kim, Jae-Jun; Shon, Jungwook; Jo, Sunkak; Kim, Hyunjin; Kang, Bo Soo

    2013-12-01

    A unipolar resistance switching (URS) Pt/NiO/Pt thin film structure was successfully deposited by sputtering. Each state was analyzed by using impedance spectroscopy. The equivalent circuit of the pristine state consists of resistor-capacitor parallel circuit. The low-resistance state could be described by using a single resistor. The high-resistance state comprised parallelly-connected resistor and constant-phase element, plus a serial inductor. Our results are in good agreement with a model for the formation/rupture of conducting filaments in the URS phenomenon.

  11. The peculiar electrical response of liquid crystal-carbon nanotube systems as seen by impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    García-García, A.; Vergaz, R.; Algorri, J. F.; Geday, M. A.; Otón, J. M.

    2015-09-01

    Conductive nanoparticles, especially elongated ones such as carbon nanotubes, dramatically modify the electrical behavior of liquid crystal cells. These nanoparticles are known to reorient with liquid crystals in electric fields, causing significant variations of conductivity at minute concentrations of tens or hundreds ppm. The above notwithstanding, impedance spectroscopy of doped cells in the frequency range customarily employed by liquid crystal devices, 100 Hz-10 kHz, shows a relatively simple resistor/capacitor response where the components of the cell can be univocally assigned to single components of the electrical equivalent circuit. However, widening the frequency range up to 1 MHz or beyond reveals a complex behavior that cannot be explained with the same simple EEC. Moreover, the system impedance varies with the application of electric fields, their effect remaining after removing the field. Carbon nanotubes are reoriented together with liquid crystal reorientation when applying voltage, but barely reoriented back upon liquid crystal relaxation once the voltage is removed. Results demonstrate a remarkable variation in the impedance of the dielectric blend formed by liquid crystal and carbon nanotubes, the irreversible orientation of the carbon nanotubes and possible permanent contacts between electrodes.

  12. Creating dynamic equivalent PV circuit models with impedance spectroscopy for arc-fault modeling.

    SciTech Connect

    Johnson, Jay Dean; Kuszmaul, Scott S.; Strauch, Jason E.; Schoenwald, David Alan

    2011-06-01

    Article 690.11 in the 2011 National Electrical Code{reg_sign} (NEC{reg_sign}) requires new photovoltaic (PV) systems on or penetrating a building to include a listed arc fault protection device. Currently there is little experimental or empirical research into the behavior of the arcing frequencies through PV components despite the potential for modules and other PV components to filter or attenuate arcing signatures that could render the arc detector ineffective. To model AC arcing signal propagation along PV strings, the well-studied DC diode models were found to inadequately capture the behavior of high frequency arcing signals. Instead dynamic equivalent circuit models of PV modules were required to describe the impedance for alternating currents in modules. The nonlinearities present in PV cells resulting from irradiance, temperature, frequency, and bias voltage variations make modeling these systems challenging. Linearized dynamic equivalent circuits were created for multiple PV module manufacturers and module technologies. The equivalent resistances and capacitances for the modules were determined using impedance spectroscopy with no bias voltage and no irradiance. The equivalent circuit model was employed to evaluate modules having irradiance conditions that could not be measured directly with the instrumentation. Although there was a wide range of circuit component values, the complex impedance model does not predict filtering of arc fault frequencies in PV strings for any irradiance level. Experimental results with no irradiance agree with the model and show nearly no attenuation for 1 Hz to 100 kHz input frequencies.

  13. Impedance spectroscopy of bacterial membranes: Co-enzyme Q diffusion in a finite diffusion layer

    PubMed Central

    Jeuken, Lars J.C.; Weiss, Sophie A; Henderson, Peter J.F.; Evans, Stephen D.; Bushby, Richard J.

    2013-01-01

    The inner membrane of Escherichia coli, over-expressing an ubiquinol oxidase, cytochrome bo3 (cbo3), was tethered in a planar configuration to a gold electrode. Electron transfer to cbo3 was achieved via native ubiquinol-8 or added ubiquinol-10 and impedance spectroscopy was used to characterise the diffusion properties of the ubiquinol/ubiquinone in the tethered membrane system. Spectra were obtained at varying DC potentials covering the potential window in which the voltammetric catalytic wave of cbo3 is visible. These spectra were compared to those obtained after addition of a potent inhibitor of cbo3, cyanide, and the difference in impedance was analysed using a derived equivalent circuit, which is similar to that of Open Finite-Length Diffusion (OFLD) or the finite Warburg circuit, but with the boundary conditions modified to account for the fact that ubiquinol reoxidation is limited by enzyme activity. Analysis of the impedance spectra of the tethered membrane system gave kinetic parameters that are consistent with values obtained using cyclic voltammetry. Importantly, the diffusion rate of ubiquinone (10−13 - 10−12 cm2/s) was found to be orders of magnitude lower than accepted values for lateral diffusion (10−8 - 10−7 cm2/s). It is hypothesised that this result represent perpendicular diffusion of quinone across the membrane, corresponding to a ‘flip’ time between 0.05 and 1 s. PMID:19551979

  14. Energy Dispersive X-Ray and Electrochemical Impedance Spectroscopies for Performance and Corrosion Analysis of PEMWEs

    NASA Astrophysics Data System (ADS)

    Steen, S. M., Iii; Zhang, F.-Y.

    2014-11-01

    Proton exchange membrane water electrolyzers (PEMWEs) are a promising energy storage technology due to their high efficiency, compact design, and ability to be used in a renewable energy system. Before they are able to make a large commercial impact, there are several hurdles facing the technology today. Two powerful techniques for both in-situ and ex- situ characterizations to improve upon their performance and better understand their corrosion are electrochemical impedance spectroscopy and energy dispersive x-ray spectroscopy, respectively. In this paper, the authors use both methods in order to characterize the anode gas diffusion layer (GDL) in a PEMWE cell and better understand the corrosion that occurs in the oxygen electrode during electrolysis.

  15. Wideband Fully-Programmable Dual-Mode CMOS Analogue Front-End for Electrical Impedance Spectroscopy.

    PubMed

    Valente, Virgilio; Demosthenous, Andreas

    2016-01-01

    This paper presents a multi-channel dual-mode CMOS analogue front-end (AFE) for electrochemical and bioimpedance analysis. Current-mode and voltage-mode readouts, integrated on the same chip, can provide an adaptable platform to correlate single-cell biosensor studies with large-scale tissue or organ analysis for real-time cancer detection, imaging and characterization. The chip, implemented in a 180-nm CMOS technology, combines two current-readout (CR) channels and four voltage-readout (VR) channels suitable for both bipolar and tetrapolar electrical impedance spectroscopy (EIS) analysis. Each VR channel occupies an area of 0.48 mm 2 , is capable of an operational bandwidth of 8 MHz and a linear gain in the range between -6 dB and 42 dB. The gain of the CR channel can be set to 10 kΩ, 50 kΩ or 100 kΩ and is capable of 80-dB dynamic range, with a very linear response for input currents between 10 nA and 100 μ A. Each CR channel occupies an area of 0.21 mm 2 . The chip consumes between 530 μ A and 690 μ A per channel and operates from a 1.8-V supply. The chip was used to measure the impedance of capacitive interdigitated electrodes in saline solution. Measurements show close matching with results obtained using a commercial impedance analyser. The chip will be part of a fully flexible and configurable fully-integrated dual-mode EIS system for impedance sensors and bioimpedance analysis. PMID:27463721

  16. Electrochemical impedance spectroscopy based MEMS sensors for phthalates detection in water and juices

    NASA Astrophysics Data System (ADS)

    Zia, Asif I.; Mohd Syaifudin, A. R.; Mukhopadhyay, S. C.; Yu, P. L.; Al-Bahadly, I. H.; Gooneratne, Chinthaka P.; Kosel, Jǘrgen; Liao, Tai-Shan

    2013-06-01

    Phthalate esters are ubiquitous environmental and food pollutants well known as endocrine disrupting compounds (EDCs). These developmental and reproductive toxicants pose a grave risk to the human health due to their unlimited use in consumer plastic industry. Detection of phthalates is strictly laboratory based time consuming and expensive process and requires expertise of highly qualified and skilled professionals. We present a real time, non-invasive, label free rapid detection technique to quantify phthalates' presence in deionized water and fruit juices. Electrochemical impedance spectroscopy (EIS) technique applied to a novel planar inter-digital (ID) capacitive sensor plays a vital role to explore the presence of phthalate esters in bulk fluid media. The ID sensor with multiple sensing gold electrodes was fabricated on silicon substrate using micro-electromechanical system (MEMS) device fabrication technology. A thin film of parylene C polymer was coated as a passivation layer to enhance the capacitive sensing capabilities of the sensor and to reduce the magnitude of Faradic current flowing through the sensor. Various concentrations, 0.002ppm through to 2ppm of di (2-ethylhexyl) phthalate (DEHP) in deionized water, were exposed to the sensing system by dip testing method. Impedance spectra obtained was analysed to determine sample conductance which led to consequent evaluation of its dielectric properties. Electro-chemical impedance spectrum analyser algorithm was employed to model the experimentally obtained impedance spectra. Curve fitting technique was applied to deduce constant phase element (CPE) equivalent circuit based on Randle's equivalent circuit model. The sensing system was tested to detect different concentrations of DEHP in orange juice as a real world application. The result analysis indicated that our rapid testing technique is able to detect the presence of DEHP in all test samples distinctively.

  17. The in-situ characterization of a transesterification reaction using electrical impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Cho, Sungjin

    Impedance Spectroscopy has been used in the in-situ monitoring of a transesterfication reaction of soybean biodiesel. This paper describes the application of Electrical Impedance Spectroscopy (EIS) to observe and characterize the transesterfication reaction and its interfacial behavior phenomena electrically. In particular, the dielectric properties of soybean biodiesel were measured at broad range frequencies from 10-2 to 106 Hz at different temperatures, methanol molar ratio to biodiesel, concentration of catalyst and reaction time. Measurement of dielectric property have provided an important approach to understanding the structure of matter. Measurements of the dielectric properties are a reliable and efficient method for evaluating the biodiesel production to determine their quality and yield for reducing the production cost. The dielectric constant (epsilon') and loss (epsilon") are the most convenient indicators for quality control in commercial biodiesel manufacturing. Dielectric properties were correlated with chemically measured changes in soybean oil such as free fatty acids, amount of catalyst and alcohols at different temperatures as well as reaction times. It was observed that there is a good correlation between the dielectric constant (epsilon') and loss (epsilon") in soybean biodiesel. The result indicated that the dielectric properties increased with the (1) increasing temperature (2) increasing methanol; (3) increasing catalyst; (4) increasing reaction time. Dielectric properties was a useful index for the rapid quality evaluation of soybean biodiesel. Dielectric properties were compared to conventional methods of analysis (Infrared Spectroscopy) for evaluating the quality of soybean biodiesel. The results indicated that dielectric constant and dielectric loss are essential measurement for predicting the best biodiesel yield. Moreover, the electrical impedance parameters such as bulk resistance (Rb), bulk capacitance (Cb) and time constant(tau b

  18. High sensitivity and label-free detection of Enterovirus 71 by nanogold modified electrochemical impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Wang, Fang-Yu; Li, Hsing-Yuan; Tseng, Shing-Hua; Cheng, Tsai-Mu; Chu, Hsueh-Liang; Yang, Jyh-Yuan; Chang, Chia-Ching

    2013-03-01

    Enterovirus 71 (EV71), which is the most fulminant and invasive species of enterovirus, can cause children neurologic complications and death within 2-3 days after fever and rash developed. Besides, EV71 has high sequence similarity with Coxsackie A 16 (CA16) that makes differential diagnosis difficult in clinic and laboratory. Since conventional viral diagnostic method cannot diagnose EV71 quickly and EV71 can transmit at low viral titer, the patients might delay in treatment. A quick, high sensitive, and high specific test for EV71 detection is pivotal. Electrochemical impedance spectroscopy (EIS) has been applied for detecting bio-molecules as biosensors recently. In this study, we try to build a detection platform for EV71 detection by nanogold modified EIS probe. The result shows that our probe can detect 3.6 VP1/50 μl (one EV71 particle has 60 VP1) in 3 minutes. The test can also distinguish EV71 from CA16 and lysozyme. Diagnosis of enterovirus 71 by electrochemical impedance spectroscopy has the potential to apply in clinic.

  19. Application of electrochemical impedance spectroscopy: A phase behavior study of babassu biodiesel-based microemulsions.

    PubMed

    Pereira, Thulio C; Conceição, Carlos A F; Khan, Alamgir; Fernandes, Raquel M T; Ferreira, Maira S; Marques, Edmar P; Marques, Aldaléa L B

    2016-11-01

    Microemulsions are thermodynamically stable systems of two immiscible liquids, one aqueous and the other of organic nature, with a surfactant and/or co-surfactant adsorbed in the interface between the two phases. Biodiesel-based microemulsions, consisting of alkyl esters of fatty acids, open a new means of analysis for the application of electroanalytical techniques, and is advantageous as it eliminates the required pre-treatment of a sample. In this work, the phase behaviours of biodiesel-based microemulsions were investigated through the electrochemical impedance spectroscopy (EIS) technique. We observed thatan increase in the amount of biodiesel in the microemulsion formulation increases the resistance to charge transfer at the interface. Also, the electrical conductivity measurements revealed that a decrease or increase in electrical properties depends on the amount of biodiesel. EIS studies of the biodiesel-based microemulsion samples showed the presence of two capacitive arcs: one high-frequency and the other low-frequency. Thus, the formulation of microemulsions plays an important role in estimating the electrical properties through the electrochemical impedance spectroscopy technique. PMID:27276278

  20. Energy resolved electrochemical impedance spectroscopy for electronic structure mapping in organic semiconductors

    SciTech Connect

    Nádaždy, V. Gmucová, K.; Schauer, F.

    2014-10-06

    We introduce an energy resolved electrochemical impedance spectroscopy method to map the electronic density of states (DOS) in organic semiconductor materials. The method consists in measurement of the charge transfer resistance of a semiconductor/electrolyte interface at a frequency where the redox reactions determine the real component of the impedance. The charge transfer resistance value provides direct information about the electronic DOS at the energy given by the electrochemical potential of the electrolyte, which can be adjusted using an external voltage. A simple theory for experimental data evaluation is proposed, along with an explanation of the corresponding experimental conditions. The method allows mapping over unprecedentedly wide energy and DOS ranges. Also, important DOS parameters can be determined directly from the raw experimental data without the lengthy analysis required in other techniques. The potential of the proposed method is illustrated by tracing weak bond defect states induced by ultraviolet treatment above the highest occupied molecular orbital in a prototypical σ-conjugated polymer, poly[methyl(phenyl)silylene]. The results agree well with those of our previous DOS reconstruction by post-transient space-charge-limited-current spectroscopy, which was, however, limited to a narrow energy range. In addition, good agreement of the DOS values measured on two common π-conjugated organic polymer semiconductors, polyphenylene vinylene and poly(3-hexylthiophene), with the rather rare previously published data demonstrate the accuracy of the proposed method.

  1. A novel strategy to monitor microfluidic in-vitro blood-brain barrier models using impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Yeste, J.; Illa, X.; Guimerà, A.; Villa, R.

    2015-06-01

    In this work, we present the use of interdigitated electrodes (IDEs) for performing electrical impedance spectroscopy (EIS) measurements to monitor a microfluidic blood brain barrier model. In particular, an electrode configuration which would not impair the optical visualization of the cell culture is proposed. Numerical studies have been performed to evaluate the electrical impedance sensitivity of the proposed tetrapolar configuration along the cell barrier in a given microfluidic chamber geometry. The system has been validated using a home-made cyclo olefin polymer (COP) bioreactor and perforated poly (methyl methacrylate) (PMMA) sheets with different pore densities in order to simulate different cell barrier impedances.

  2. Equivalent circuits of a self-assembled monolayer-based tunnel junction determined by impedance spectroscopy.

    PubMed

    Sangeeth, C S Suchand; Wan, Albert; Nijhuis, Christian A

    2014-08-01

    The electrical characteristics of molecular tunnel junctions are normally determined by DC methods. Using these methods it is difficult to discriminate the contribution of each component of the junctions, e.g., the molecule-electrode contacts, protective layer (if present), or the SAM, to the electrical characteristics of the junctions. Here we show that frequency-dependent AC measurements, impedance spectroscopy, make it possible to separate the contribution of each component from each other. We studied junctions that consist of self-assembled monolayers (SAMs) of n-alkanethiolates (S(CH2)(n-1)CH3 ≡ SC(n) with n = 8, 10, 12, or 14) of the form Ag(TS)-SC(n)//GaO(x)/EGaIn (a protective thin (~0.7 nm) layer of GaO(x) forms spontaneously on the surface of EGaIn). The impedance data were fitted to an equivalent circuit consisting of a series resistor (R(S), which includes the SAM-electrode contact resistance), the capacitance of the SAM (C(SAM)), and the resistance of the SAM (R(SAM)). A plot of R(SAM) vs n(C) yielded a tunneling decay constant β of 1.03 ± 0.04 n(C)(-1), which is similar to values determined by DC methods. The value of C(SAM) is similar to previously reported values, and R(S) (2.9-3.6 × 10(-2) Ω·cm(2)) is dominated by the SAM-top contact resistance (and not by the conductive layer of GaO(x)) and independent of n(C). Using the values of R(SAM), we estimated the resistance per molecule r as a function of n(C), which are similar to values obtained by single molecule experiments. Thus, impedance measurements give detailed information regarding the electrical characteristics of the individual components of SAM-based junctions. PMID:25036915

  3. Testing the bioelectric shield.

    PubMed

    Blackmore, Susan J; Rose, Nicholas

    2002-01-01

    A pendant was claimed to provide numerous health benefits, including reduced stress, increased strength, and protection from electromagnetic radiation from computers and mobile phones. Three experiments tested the effectiveness of this pendant's effect as a bioelectric shield. In the first experiment, 12 subjects who work with computers wore shields (6 real, 6 sham) for several weeks and were regularly tested for hand strength and mood changes. Both types of shield increased calmness, but the real shields did not have any greater effect. In 2 further studies (in each N=40) hand strength was measured at baseline, with mobile phone, and with mobile phone and bioelectric or sham shield. The shields did not differ in their effects. Both studies showed a significant correlation between the change in strength with and without the shield and subjects'scores on a questionnaire concerning their belief in and use of alternative therapies. The shields appear to produce a measurable placebo effect but are otherwise ineffective. PMID:12233804

  4. Bioelectric Signal Measuring System

    NASA Astrophysics Data System (ADS)

    Guadarrama-Santana, A.; Pólo-Parada, L.; García-Valenzuela, A.

    2015-01-01

    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.

  5. Cracking the bioelectric code

    PubMed Central

    Tseng, AiSun; Levin, Michael

    2013-01-01

    Patterns of resting potential in non-excitable cells of living tissue are now known to be instructive signals for pattern formation during embryogenesis, regeneration and cancer suppression. The development of molecular-level techniques for tracking ion flows and functionally manipulating the activity of ion channels and pumps has begun to reveal the mechanisms by which voltage gradients regulate cell behaviors and the assembly of complex large-scale structures. A recent paper demonstrated that a specific voltage range is necessary for demarcation of eye fields in the frog embryo. Remarkably, artificially setting other somatic cells to the eye-specific voltage range resulted in formation of eyes in aberrant locations, including tissues that are not in the normal anterior ectoderm lineage: eyes could be formed in the gut, on the tail, or in the lateral plate mesoderm. These data challenge the existing models of eye fate restriction and tissue competence maps, and suggest the presence of a bioelectric code—a mapping of physiological properties to anatomical outcomes. This Addendum summarizes the current state of knowledge in developmental bioelectricity, proposes three possible interpretations of the bioelectric code that functionally maps physiological states to anatomical outcomes, and highlights the biggest open questions in this field. We also suggest a speculative hypothesis at the intersection of cognitive science and developmental biology: that bioelectrical signaling among non-excitable cells coupled by gap junctions simulates neural network-like dynamics, and underlies the information processing functions required by complex pattern formation in vivo. Understanding and learning to control the information stored in physiological networks will have transformative implications for developmental biology, regenerative medicine and synthetic bioengineering. PMID:23802040

  6. Corrosion characterization of durable silver coatings by electrochemical impedance spectroscopy and accelerated environmental testing.

    PubMed

    Chu, Chung-Tse; Fuqua, Peter D; Barrie, James D

    2006-03-01

    Highly reflective front-surface silver mirrors are needed for many optical applications. While various protective dielectric coating schemes have been developed, the long-term durability of Ag mirrors is still of great concern in the optics community for a variety of applications under harsh environments. The corrosion protection behavior of a SiNx-coated silver-mirror coating scheme was tested with electrochemical impedance spectroscopy (EIS) and accelerated environmental testing, including humidity and salt fog tests. The EIS data obtained were fitted with different equivalent circuit models. The results suggested that the 100A thick SiNx coating produced by rf magnetron sputtering was porous and acted as a leaky capacitor on the Ag film, whereas the addition of a NiCrNx interlayer as thin as 3A between SiNx and Ag films resulted in a much denser SiNx coating with a low-frequency impedance value of 2 orders of magnitude higher than that without the interlayer. Humidity and salt fog testing of different silver coatings showed similar results. The 100A SiNx/3A-NiCrNx/Ag coating exhibited excellent corrosion resistance against the corrosive environments used in this study. PMID:16539267

  7. Measurement of Electrical Activation Energy in Black CVD Diamond Using Impedance Spectroscopy

    NASA Astrophysics Data System (ADS)

    Ye, Haitao; Williams, Oliver A.; Jackman, Richard B.

    Dc current-voltage (I-V) measurement, Hall measurement, Deep-level transient-spectroscopy (DLTS), and flatband capacitance measurement have been used to investigate electrical activation energies in diamond. However, the deviations still exist in the published activation energies obtained by these methods. In this paper, we report the first measurement of impedance on free-standing diamond films from 0.1Hz to 10MHz up to 300°C. A wide range of CVD materials have been investigated, but here we concentrate on `black' diamond grown by MWPECVD. The Cole-Cole (Z' via Z'') plots are well fitted to a RC parallel circuit model and the equivalent Resistance and Capacitance for the diamond films have been estimated using the Zview curve fitting. The results show only one single semicircle response at each temperature measured. It was found that the resistance decreases from 62 MΩ at room temperature to 4 KΩ at 300°C, with an activation energy around 0.15eV. The equivalent capacitance is maintained at the level of 102 pF up to 300°C suggesting that the diamond grain boundaries are dominating the conduction. At 400°C, the impedance at low frequencies shows a linear tail, which can be explained that the AC polarization of diamond/Au interface occurs.

  8. Investigation on silicon alloying kinetics during lithiation by galvanostatic impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Ko, Younghoon; Hwang, Chihyun; Song, Hyun-Kon

    2016-05-01

    The parameters characterizing lithiation processes in silicon anodes of lithium ion batteries (LIBs) are compared between μm- and nm-sized silicon particles. Galvanostatic electrochemical impedance spectroscopy (GS-EIS) is used to investigate the silicon-lithium alloying reaction in a practical charging operation (galvanostatic lithiation). Effective kinetic parameters depending on lithiation C-rates are obtained along lithiation progress from a large body of impedance data. Nanosizing benefits of nanoparticles over micro-particles are confirmed such as lower polarization resistance (Rp) and thinner solid-electrolyte interphase layer (SEI layer) over the whole lithiation range. Based on the kinetic information obtained from the non-stationary conditions, a lithiation strategy consisting of multiple galvanostatic steps is designed to lithiate silicon anodes in a faster way. 75% of full capacity is lithiated by a galvanostatic sequence of 4C-2C-1C-0.5C within 20 min. However, only 43% and 21% are achieved by a single-rate galvanostatic lithiation at 1 C and 0.5 C, respectively.

  9. A new resonance-frequency based electrical impedance spectroscopy and its application in biomedical engineering

    NASA Astrophysics Data System (ADS)

    Dhurjaty, Sreeram; Qiu, Yuchen; Tan, Maxine; Zheng, Bin

    2014-03-01

    Electrical Impedance Spectroscopy (EIS) has shown promising results for differentiating between malignant and benign tumors, which exhibit different dielectric properties. However, the performance of current EIS systems has been inadequate and unacceptable in clinical practice. In the last several years, we have been developing and testing a new EIS approach using resonance frequencies for detection and classification of suspicious tumors. From this experience, we identified several limitations of current technologies and designed a new EIS system with a number of new characteristics that include (1) an increased A/D (analog-to-digital) sampling frequency, 24 bits, and a frequency resolution of 100 Hz, to increase detection sensitivity (2) automated calibration to monitor and correct variations in electronic components within the system, (3) temperature sensing and compensation algorithms to minimize impact of environmental change during testing, and (4) multiple inductor-switching to select optimum resonance frequencies. We performed a theoretical simulation to analyze the impact of adding these new functions for improving performance of the system. This system was also tested using phantoms filled with variety of liquids. The theoretical and experimental test results are consistent with each other. The experimental results demonstrated that this new EIS device possesses the improved sensitivity and/or signal detection resolution for detecting small impedance or capacitance variations. This provides the potential of applying this new EIS technology to different cancer detection and diagnosis tasks in the future.

  10. Use of electrical impedance spectroscopy to detect malignant and potentially malignant oral lesions

    PubMed Central

    Murdoch, Craig; Brown, Brian H; Hearnden, Vanessa; Speight, Paul M; D’Apice, Katy; Hegarty, Anne M; Tidy, John A; Healey, T Jamie; Highfield, Peter E; Thornhill, Martin H

    2014-01-01

    The electrical properties of tissues depend on their architecture and cellular composition. We have previously shown that changes in electrical impedance can be used to differentiate between different degrees of cervical dysplasia and cancer of the cervix. In this proof-of-concept study, we aimed to determine whether electrical impedance spectroscopy (EIS) could distinguish between normal oral mucosa; benign, potentially malignant lesions (PML); and oral cancer. EIS data were collected from oral cancer (n=10), PML (n=27), and benign (n=10) lesions. EIS from lesions was compared with the EIS reading from the normal mucosa on the contralateral side of the mouth or with reference spectra from mucosal sites of control subjects (n=51). Healthy controls displayed significant differences in the EIS obtained from different oral sites. In addition, there were significant differences in the EIS of cancer and high-risk PML versus low-risk PML and controls. There was no significant difference between benign lesions and normal controls. Study subjects also deemed the EIS procedure considerably less painful and more convenient than the scalpel biopsy procedure. EIS shows promise at distinguishing among malignant, PML, and normal oral mucosa and has the potential to be developed into a clinical diagnostic tool. PMID:25285005

  11. Equivalent circuit model analysis on electrochemical impedance spectroscopy of lithium metal batteries

    NASA Astrophysics Data System (ADS)

    Gao, Peng; Zhang, Cuifen; Wen, Guangwu

    2015-10-01

    Lithium metal electrode is pretreated with 1,3-dioxolane or 1,4-dioxane to improve its properties. The components and morphology of the surface films formed in the above two pretreatment liquids are studied using FTIR and SEM respectively. Li-LiCoO2 coin cells are then fabricated and their cycle and discharge performance are tested. It is found that the battery performance is greatly improved by such pretreatment. Interestingly, the 1,4-dioxane pretreatment is more effective than 1,3-dioxolane in improving the lithium metal electrode performance. To explore the mechanism(s) behind, the electrochemical impedance spectroscopy (EIS) is employed and an equivalent circuit model is designed for EIS analysis. The fitting curves are aligned well with the experimental curves, suggesting that the proposed equivalent circuit model is an ideal model for lithium battery. Next, the corresponding relationship between the impedance components and every individual semicircle in the Nyquist curves is inferred theoretically and the result is satisfying. Based on the analysis using this model, we conclude that the structural stability of SEI film is increased and the interfacial compatibility between the lithium substrate and the SEI film is improved by 1,3-dioxolane or 1,4-dioxane pretreatment.

  12. Comprehensive characterization of all-solid-state thin films commercial microbatteries by Electrochemical Impedance Spectroscopy

    NASA Astrophysics Data System (ADS)

    Larfaillou, S.; Guy-Bouyssou, D.; le Cras, F.; Franger, S.

    2016-07-01

    Constant miniaturization of electronic devices opens the way to the development of thin film microbatteries (TFB). For this type of devices, the use of an all-solid-state thin film technology has many advantages over conventional lithium cells. These microbatteries are thin, bendable and can be produced with a customizable shape for integration in microelectronic devices. Moreover, without liquid electrolyte, they are safer. With the aim to support the industrial production of these TFBs, adequate tools for understanding the electrochemical behavior of the complete microbattery and the identification of their possible failures that can occur have to be developed. In this context, the Electrochemical Impedance Spectroscopy seems to be a good compromise for cells characterization. Widely used for the characterization of liquid electrolyte-based batteries, this technique has been less applied to all solid state batteries, mainly because of the difficulty to work with a two-electrode system. There has been no comprehensive study deeply explaining the impedance evolution during the entire life of a microbattery. In this paper, physical characterizations of individual active materials and aging experiments have been performed in order to undoubtedly assign each EIS contributions, and to propose a more comprehensive electrical model for this family of commercial all-solid-state microbatteries.

  13. Investigation of electrical properties of Mn doped tin oxide nanoparticles using impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Azam, Ameer; Ahmed, Arham S.; Chaman, M.; Naqvi, A. H.

    2010-11-01

    Manganese doped tin oxide nanoparticles with manganese content varying from 0 to 15 mol % were synthesized using sol-gel method. The structural and compositional analysis was carried out using x-ray diffraction (XRD), scanning electron microscope (SEM), and energy dispersive x-ray analysis (EDAX). Dielectric and impedance spectroscopy was carried out at room temperature to explore the electrical properties of Mn doped SnO2. XRD analysis indicated the formation of single phase rutile type tetragonal structure of all the samples. The crystallite size was observed to vary from 16.2 to 7.1 nm as the Mn content was increased. The XRD, SEM, and EDAX results corroborated the successful doping of Mn in the SnO2 matrix. Complex impedance analysis was used to distinguish the grain and grain boundary contributions to the system, suggesting the dominance of grain boundary resistance in the doped samples. The dielectric constant ɛ', dielectric loss tan δ and ac conductivity σac were studied as a function of frequency and composition and the behavior has been explained on the basis of Maxwell-Wagner interfacial model. All the dielectric parameters were found to decrease with the increase in doping concentration. Moreover, it has been observed that the dielectric loss approaches to zero in case of high dopant concentration (9%, 15%) at high frequencies.

  14. Characterization of bioelectric potentials

    NASA Technical Reports Server (NTRS)

    Jorgensen, Charles C. (Inventor); Wheeler, Kevin R. (Inventor)

    2004-01-01

    Method and system for recognizing and characterizing bioelectric potential or electromyographic (EMG) signals associated with at least one of a coarse gesture and a fine gesture that is performed by a person, and use of the bioelectric potentials to enter data and/or commands into an electrical and/or mechanical instrument. As a gesture is performed, bioelectric signals that accompany the gesture are subjected to statistical averaging, within selected time intervals. Hidden Markov model analysis is applied to identify hidden, gesture-related states that are present. A metric is used to compare signals produced by a volitional gesture (not yet identified) with corresponding signals associated with each of a set of reference gestures, and the reference gesture that is closest to the volitional gesture is identified. Signals representing the volitional gesture are analyzed and compared with a database of reference gestures to determine if the volitional gesture is likely to be one of the reference gestures. Electronic and/or mechanical commands needed to carry out the gesture may be implemented at an interface to control an instrument. Applications include control of an aircraft, entry of data from a keyboard or other data entry device, and entry of data and commands in extreme environments that interfere with accurate entry.

  15. Determining charge carrier mobility in Schottky contacted single-carrier organic devices by impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Tang, Ying; Peng, Yingquan; Sun, Lei; Wei, Yi; Xu, Sunan

    2015-10-01

    Impedance spectroscopy (IS) is one of the most important methods for analyzing transport properties of semiconducting thin films. At present carrier mobility can be determined by IS methods only for Ohmic contacted single-carrier devices, which hinders the use of the IS method for determining the carrier mobility of thin films with high-lying lowest unoccupied molecular orbits or low-lying highest occupied molecular orbits. Based on the theory of space charge limited current conduction and thermionic emission at metal-organic interface, we developed a numerical IS model for single-carrier organic devices with Schottky injection contact. With the help of this model, a concise empirical formula is obtained from which the carrier mobility can be determined from the characteristic frequency of the negative differential susceptance and the Schottky energy barrier height at the injection contact.

  16. Degradation of Bilayer Organic Light-Emitting Diodes Studied by Impedance Spectroscopy.

    PubMed

    Sato, Shuri; Takata, Masashi; Takada, Makoto; Naito, Hiroyoshi

    2016-04-01

    The degradation of bilayer organic light-emitting diodes (OLEDs) with a device structure of N,N'-di(1-naphthyl)-N,N'-diphenylbenzidine (α-NPD) (hole transport layer) and tris-(8-hydroxyquinolate)aluminum (Alq3) (emissive layer and electron transport layer) has been studied by impedance spectroscopy and device simulation. Two modulus peaks are found in the modulus spectra of the OLEDs below the electroluminescence threshold. After aging of the OLEDs, the intensity of electroluminescence is degraded and the modulus peak due to the Alq3 layer is shifted to lower frequency, indicating that the resistance of the Alq3 layer is increased. Device simulation reveals that the increase in the resistance of the Alq3 layer is due to the decrease in the electron mobility in the Alq3 layer. PMID:27451634

  17. Impedance spectroscopy of Cu2SnS3 material for photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Essaleh, L.; Chehouani, H.; Belaqziz, M.; Djessas, K.; Gauffier, J. L.

    2015-09-01

    The complex impedance spectroscopy in the frequency range 100-1 MHz and temperature range 300-475 K is used to study the electrical properties of the bulk ternary semiconductor compound Cu2SnS3. The dynamic electrical conductivity study shows that correlated barrier hopping model may be appropriate to describe the transport mechanism in our material. The dependences of dielectric parameters by fitting data with Cole-Cole equations on temperature have been discussed in detail. Relaxation time was found to decrease with increasing temperature and to obey the Arrhenius relationship. The values of calculated resistances for bulk were found to be smaller compared with that of grain boundary contributions.

  18. Investigation of the suppression effect of polyethylene glycol on copper electroplating by electrochemical impedance spectroscopy

    SciTech Connect

    Hung, C.-C.; Lee, W.-H.; Wang, Y.-L.; Chan, D.-Y.; Hwang, G.-J.

    2008-09-15

    Polyethylene glycol (PEG) is an additive that is commonly used as a suppressor in the semiconductor copper (Cu)-electroplating process. In this study, electrochemical impedance spectroscopy (EIS) was used to analyze the electrochemical behavior of PEG in the Cu-electroplating process. Polarization analysis, cyclic-voltammetry stripping, and cell voltage versus plating time were examined to clarify the suppression behavior of PEG. The equivalent circuit simulated from the EIS data shows that PEG inhibited the Cu-electroplating rate by increasing the charge-transfer resistance as well as the resistance of the adsorption layer. The presence of a large inductance demonstrated the strong adsorption of cuprous-PEG-chloride complexes on the Cu surface during the Cu-electroplating process. Increasing the PEG concentration appears to increase the resistances of charge transfer, the adsorption layer, and the inductance of the electroplating system.

  19. Wide-Range Filter-Based Sinusoidal Wave Synthesizer for Electrochemical Impedance Spectroscopy Measurements.

    PubMed

    Chia-Ling Wei; Yi-Wen Wang; Bin-Da Liu

    2014-06-01

    A filter-based wide-range programmable sinusoidal wave synthesizer for electrochemical impedance spectroscopy measurement is proposed. The adopted filter is implemented with switched-capacitor circuits, so its corner frequency is accurate and adjustable by changing its switching frequency. The proposed sine wave synthesizer is implemented by using a 0.35 μm 2P4M 3.3 V mixed-signal polycide process. According to the measured results, the output frequency of the proposed synthesizer is 40 mHz-40 kHz . The measured total harmonic distortion is 0.073% at 10 Hz and 0.075% at 10 kHz, both of which are better than that of a typical function generator. PMID:24043398

  20. Electrical impedance spectroscopy device for measurement of moisture gradients in wood

    NASA Astrophysics Data System (ADS)

    Tiitta, M.; Olkkonen, H.

    2002-08-01

    A prototype of the electrical impedance spectroscopy (EIS) device for the measurement of internal moisture gradients in wood was developed. The EIS device consists of a hand-held probe connected to a control unit interfaced with a portable personal computer and a power unit. In the measurement, parallel flat electrodes of the measuring probe are laid against the wood specimen and the sine wave excitation is applied in the frequency range 1-100 kHz. The measured amplitude and phase spectral data were analyzed using the model based on constant phase elements. A spectral analysis software package was designed for measurement of subsurface transverse moisture gradients. The EIS device was tested with many types of uniform, desorption, and absorption gradients in lumber, pulpwood, and log specimens from spruce, pine, and birch. The EIS device can be easily transferred in a small case allowing field measurements.

  1. Interface Design for CMOS-Integrated Electrochemical Impedance Spectroscopy (EIS) Biosensors

    PubMed Central

    Manickam, Arun; Johnson, Christopher Andrew; Kavusi, Sam; Hassibi, Arjang

    2012-01-01

    Electrochemical Impedance Spectroscopy (EIS) is a powerful electrochemical technique to detect biomolecules. EIS has the potential of carrying out label-free and real-time detection, and in addition, can be easily implemented using electronic integrated circuits (ICs) that are built through standard semiconductor fabrication processes. This paper focuses on the various design and optimization aspects of EIS ICs, particularly the bio-to-semiconductor interface design. We discuss, in detail, considerations such as the choice of the electrode surface in view of IC manufacturing, surface linkers, and development of optimal bio-molecular detection protocols. We also report experimental results, using both macro- and micro-electrodes to demonstrate the design trade-offs and ultimately validate our optimization procedures. PMID:23202170

  2. Estimation of Parameters Obtained by Electrochemical Impedance Spectroscopy on Systems Containing High Capacities

    PubMed Central

    Stević, Zoran; Vujasinović, Mirjana Rajčić; Radunović, Milan

    2009-01-01

    Electrochemical systems with high capacities demand devices for electrochemical impedance spectroscopy (EIS) with ultra-low frequencies (in order of mHz), that are almost impossible to accomplish with analogue techniques, but this becomes possible by using a computer technique and accompanying digital equipment. Recently, an original software and hardware for electrochemical measurements, intended for electrochemical systems exhibiting high capacities, such as supercapacitors, has been developed. One of the included methods is EIS. In this paper, the method of calculation of circuit parameters from an EIS curve is described. The results of testing on a physical model of an electrochemical system, constructed of known elements (including a 1.6 F capacitor) in a defined arrangement, proved the validity of the system and the method. PMID:22400000

  3. Solid oxide electrolysis cell analysis by means of electrochemical impedance spectroscopy: A review

    NASA Astrophysics Data System (ADS)

    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.

  4. The Pt(111)/electrolyte interface under oxygen reduction reaction conditions: an electrochemical impedance spectroscopy study.

    PubMed

    Bondarenko, Alexander S; Stephens, Ifan E L; Hansen, Heine A; Pérez-Alonso, Francisco J; Tripkovic, Vladimir; Johansson, Tobias P; Rossmeisl, Jan; Nørskov, Jens K; Chorkendorff, Ib

    2011-03-01

    The Pt(111)/electrolyte interface has been characterized during the oxygen reduction reaction (ORR) in 0.1 M HClO(4) using electrochemical impedance spectroscopy. The surface was studied within the potential region where adsorption of OH* and O* species occur without significant place exchange between the adsorbate and Pt surface atoms (0.45-1.15 V vs RHE). An equivalent electric circuit is proposed to model the Pt(111)/electrolyte interface under ORR conditions within the selected potential window. This equivalent circuit reflects three processes with different time constants, which occur simultaneously during the ORR at Pt(111). Density functional theory (DFT) calculations were used to correlate and interpret the results of the measurements. The calculations indicate that the coadsorption of ClO(4)* and Cl* with OH* is unlikely. Our analysis suggests that the two-dimensional (2D) structures formed in O(2)-free solution are also formed under ORR conditions. PMID:21244087

  5. Impedance spectroscopy of concrete cover on bridge decks with reinforcing steel

    NASA Astrophysics Data System (ADS)

    Bartholomew, Paul; Blankenagel, Bryan; Guthrie, Spencer; Mazzeo, Brian

    2011-10-01

    Chloride-induced corrosion of reinforcing steel is a major problem for aging bridge structures near marine environments or in cold regions where deicing salts are applied as part of winter maintenance. Corrosion is the result of the interaction of diffused chloride ions with the embedded steel. One property of affected decks that facilitates detection of chloride ions is their ability to conduct electricity. Impedance spectroscopy can be used to measure concrete conductivity and thereby identify areas of increased chloride concentration characterized by elevated risks of corrosion. A new probe and measurement apparatus has been engineered to measure large areas of concrete on bridge decks. Comparison between measurements obtained in the laboratory and in the field will be presented.

  6. Interface electric properties of Si/organic hybrid solar cells using impedance spectroscopy analysis

    NASA Astrophysics Data System (ADS)

    Wang, Dan; Zhu, Juye; Ding, Li; Gao, Pingqi; Pan, Xiaoyin; Sheng, Jiang; Ye, Jichun

    2016-05-01

    The internal resistance and capacitance of Si/organic hybrid solar cells (Si-HSC) based on poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) are investigated by electrochemical impedance spectroscopy (EIS). Three types of Nyquist plots in Si-HSC are observed firstly at different bias voltages, while suitable equivalent circuit models are established to evaluate the details of interface carrier transfer and recombination. In particular, the carrier transport property of the PEDOT:PSS film responds at a high frequency (6 × 104-1 × 106 Hz) in three-arc spectra. Therefore, EIS could help us deeply understand the electronic properties of Si-HSC for developing high performance devices.

  7. Impedance-derived electrochemical capacitance spectroscopy for the evaluation of lectin-glycoprotein binding affinity.

    PubMed

    Santos, Adriano; Carvalho, Fernanda C; Roque-Barreira, Maria-Cristina; Bueno, Paulo R

    2014-12-15

    Characterization of lectin-carbohydrate binding using label-free methods such as impedance-derived electrochemical capacitance spectroscopy (ECS) is desirable to evaluate specific interactions, for example, ArtinM lectin and horseradish peroxidase (HRP) glycoprotein, used here as a model for protein-carbohydrate binding affinity. An electroactive molecular film comprising alkyl ferrocene as a redox probe and ArtinM as a carbohydrate receptive center to target HRP was successfully used to determine the binding affinity between ArtinM and HRP. The redox capacitance, a transducer signal associated with the alkyl ferrocene centers, was obtained by ECS and used in the Langmuir adsorption model to obtain the affinity constant (1.6±0.6)×10(8) L mol(-1). The results shown herein suggest the feasibility of ECS application for lectin glycoarray characterization. PMID:24994505

  8. A comparison of electrochemical noise and impedance spectroscopy for the detection of corrosion in reinforced concrete

    SciTech Connect

    Bertocci, U.

    1996-12-31

    Electrochemical impedance spectroscopy (EIS) and electrochemical noise measurements (ENM) were carried out on small concrete blocks with embedded steel rods, immersed in solutions of highway deicers, mainly sodium or magnesium chlorides with corrosion inhibitors added. Voltage and current fluctuations between identical electrodes were recorded, and different signal-processing schemes were tested. Various problems experienced in the course of the work are described. Corrosion polarization resistances obtained by EIS are compared with values of the ratio of the standard deviations of the voltage and current fluctuations. The results suggest that the type of ENM used in this work is subject to considerable uncertainties, and further work would be necessary before the method can be applied with sufficient confidence to corrosion monitoring.

  9. The evaluation of corrosion inhibitor film persistency using electrochemical impedance spectroscopy and electrochemical noise analysis

    SciTech Connect

    Tan, Y.J.; Kinsella, B.; Bailey, S.

    1996-10-01

    Electrochemical impedance spectroscopy (EIS) and electrochemical noise analysis (ENA) were used as combined techniques to study and evaluate the film persistency of several commercial batch treatment inhibitors which are used for protecting oil-wells, gas-wells or pipelines from CO{sub 2} corrosion. It was found that the inhibitors film deterioration was accompanied by typical changes in the EIS spectra, which could be used as indicators for monitoring inhibitor film breakdown. ENA was shown to be able to continuously follow and monitor the inhibitor film deterioration processes. The noise resistance (R{sub noise}) was confirmed to be strongly correlated to linear polarization resistance (R{sub p}) and this correlation was explained based on a concept called statistical linear polarization. The presence of the hydrocarbon phase and CO{sub 2} corrosion product scale were found to be factors which greatly affect batch treatment inhibitor film persistency.

  10. Corrosion Behavior of Stainless Steels in Neutral and Acidified Sodium Chloride Solutions by Electrochemical Impedance Spectroscopy

    NASA Technical Reports Server (NTRS)

    Calle, L. M.; Kolady, M. R.; Vinje, R. D.

    2004-01-01

    The objective of this work was to evaluate the corrosion performance of three alloys by Electrochemical Impedance Spectroscopy (EIS) and to compare the results with those obtained during a two-year atmospheric exposure study.' Three alloys: AL6XN (UNS N08367), 254SM0 (UNS S32154), and 304L (UNS S30403) were included in the study. 304L was included as a control. The alloys were tested in three electrolyte solutions which consisted of neutral 3.55% NaC1, 3.55% NaC1 in 0.lN HC1, and 3.55% NaC1 in 1.ON HC1. These conditions were expected to be less severe, similar, and more severe respectively than the conditions at NASA's Kennedy Space Center launch pads.

  11. Protein-G-based human immunoglobulin G biosensing by electrochemical impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Tsugimura, Kaiki; Ohnuki, Hitoshi; Endo, Hideaki; Tsuya, Daijyu; Izumi, Mitsuru

    2016-02-01

    A highly sensitive biosensor based on electrochemical impedance spectroscopy (EIS) was developed for the determination of human immunoglobulin G (IgG). Protein G, which specifically binds to IgG, was employed as the molecular receptor. Protein G was covalently immobilized on interdigitated electrodes through a mixed self-assembled monolayer (SAM) composed of 11-mercaptoundecanoic acid (MUA) and 6-mercaptohexanol. It was found that the mixing ratio of the SAM markedly affected the sensor performance. The sample prepared on 25% MUA SAM exhibited a linear behavior in the concentration range of 0.01-10 ng/mL, which is a record low detection for EIS-based IgG sensors. On the other hand, the sample on 100% MUA SAM showed no IgG-sensing action. A possible mechanism of the mixing ratio that affects the sensing performance was proposed.

  12. AC impedance spectroscopy - A dynamic tool for the design of corrosion inhibitors

    SciTech Connect

    Growcock, F.B.; Jasinski, R.J.

    1988-05-01

    Corrosion of steel during oil well acidizing or acid pickling treatments can be controlled effectively and economically with corrosion inhibitors. It is generally accepted that these additives function by forming an adherent barrier on the steel surface, the nature of which depends on various physiochemical properties of the inhibitor. Work to date has established that acetylenic alcohols first chemisorb and subsequently polymerize on steel surfaces. ..cap alpha.., BETA-Unsaturated aldehydes and ..cap alpha..-alkenylphenones behave in a similar manner. On the other hand, quaternary nitrogen salts adsorb electrostatically and do not appear to form macroscopic films. In this paper, the authors describe some AC impedance spectroscopy studies they have undertaken with the objective of elucidating the roles that adsorption and film formation play in the inhibition mechanisms of the compounds mentioned above.

  13. In Situ Representation of Soil/Sediment Conductivity Using Electrochemical Impedance Spectroscopy.

    PubMed

    Li, Xiaojing; Wang, Xin; Zhao, Qian; Zhang, Yueyong; Zhou, Qixing

    2016-01-01

    The electrical conductivity (EC) of soil is generally measured after soil extraction, so this method cannot represent the in situ EC of soil (e.g., EC of soils with different moisture contents) and therefore lacks comparability in some cases. Using a resistance measurement apparatus converted from a configuration of soil microbial fuel cell, the in situ soil EC was evaluated according to the Ohmic resistance (Rs) measured using electrochemical impedance spectroscopy. The EC of soils with moisture content from 9.1% to 37.5% was calculated according to Rs. A significant positive correlation (R² = 0.896, p < 0.01) between the soil EC and the moisture content was observed, which demonstrated the feasibility of the approach. This new method can not only represent the actual soil EC, but also does not need any pretreatment. Thus it may be used widely in the measurement of the EC for soils and sediments. PMID:27144567

  14. Electrochemical impedance spectroscopy and laser photoselectivity with gold nanoparticles for food applications

    NASA Astrophysics Data System (ADS)

    Chee, Grace

    With consistently higher and stricter standards for food quality and safety, it is becoming increasingly necessary to be able to quickly and easily determine certain properties of products in order to keep up with and maintain these standards. This master’s thesis is presented in three chapters. First, an overview of the theoretical background, current applications, and new technologies related to taking physiochemical property measurements of food, and various treatment methods used for food safety purposes. In the second chapter, electrochemical impedance spectroscopy (EIS) is used to find the dielectric (DE) constants and other physiochemical properties of potatoes in order to make quick adjustments to improve the microwave processing technique used for potato chipping. Finally, the third chapter introduces the use of a carbon dioxide laser system in conjunction with a two-ZnSe lens beam expander and functionalized gold nanoparticles to specifically target and kill E. coli in food samples.

  15. Electrochemical characterization of gelatinized starch dispersions: voltammetry and electrochemical impedance spectroscopy on platinum surface.

    PubMed

    Hernandez-Jaimes, C; Lobato-Calleros, C; Sosa, E; Bello-Pérez, L A; Vernon-Carter, E J; Alvarez-Ramirez, J

    2015-06-25

    The electrochemical properties of gelatinized starch dispersions (GSD; 5% w/w) from different botanical sources were studied using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) tests over a platinum surface. The phenomenological modelling of EIS data using equivalent circuits indicated that after gelatinization the electrical resistance was determined mainly by the resistance of insoluble material (i.e., ghosts). Sonication of the GSD disrupted the ghost microstructure, and produced an increase in electrical conductivity by reducing the resistance of the insoluble material. The CV data showed three oxidation peaks at potentials where glucose solutions displayed oxidation waves. It is postulated that hydrolysis at the bulk and electrocatalyzed oxidation on the Pt-surface are reactions involved in the starch transformation. Starches peak intensity increased with the amylose content, suggesting that the amylose-rich matrix played an important role in the charge transfer in the electrolytic system. PMID:25839788

  16. Estimation of parameters obtained by electrochemical impedance spectroscopy on systems containing high capacities.

    PubMed

    Stević, Zoran; Vujasinović, Mirjana Rajčić; Radunović, Milan

    2009-01-01

    Electrochemical systems with high capacities demand devices for electrochemical impedance spectroscopy (EIS) with ultra-low frequencies (in order of mHz), that are almost impossible to accomplish with analogue techniques, but this becomes possible by using a computer technique and accompanying digital equipment. Recently, an original software and hardware for electrochemical measurements, intended for electrochemical systems exhibiting high capacities, such as supercapacitors, has been developed. One of the included methods is EIS. In this paper, the method of calculation of circuit parameters from an EIS curve is described. The results of testing on a physical model of an electrochemical system, constructed of known elements (including a 1.6 F capacitor) in a defined arrangement, proved the validity of the system and the method. PMID:22400000

  17. Label-Free Toxin Detection by Means of Time-Resolved Electrochemical Impedance Spectroscopy

    PubMed Central

    Chai, Changhoon; Takhistov, Paul

    2010-01-01

    The real-time detection of trace concentrations of biological toxins requires significant improvement of the detection methods from those reported in the literature. To develop a highly sensitive and selective detection device it is necessary to determine the optimal measuring conditions for the electrochemical sensor in three domains: time, frequency and polarization potential. In this work we utilized a time-resolved electrochemical impedance spectroscopy for the detection of trace concentrations of Staphylococcus enterotoxin B (SEB). An anti-SEB antibody has been attached to the nano-porous aluminum surface using 3-aminopropyltriethoxysilane/glutaraldehyde coupling system. This immobilization method allows fabrication of a highly reproducible and stable sensing device. Using developed immobilization procedure and optimized detection regime, it is possible to determine the presence of SEB at the levels as low as 10 pg/mL in 15 minutes. PMID:22315560

  18. Determination of carrier lifetime and mobility in colloidal quantum dot films via impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Rath, Arup K.; Lasanta, Tania; Bernechea, Maria; Diedenhofen, Silke L.; Konstantatos, Gerasimos

    2014-02-01

    Impedance Spectroscopy (IS) proves to be a powerful tool for the determination of carrier lifetime and majority carrier mobility in colloidal quantum dot films. We employ IS to determine the carrier lifetime in PbS quantum dot Schottky solar cells with Al and we verify the validity of the technique via transient photovoltage. We also present a simple approach based on an RC model that allows the determination of carrier mobility in PbS quantum dot films and we corroborate the results via comparison with space charge limited measurements. In summary, we demonstrate the potential of IS to characterize key-to-photovoltaics optoelectronic properties, carrier lifetime, and mobility, in a facile way.

  19. In Situ Representation of Soil/Sediment Conductivity Using Electrochemical Impedance Spectroscopy

    PubMed Central

    Li, Xiaojing; Wang, Xin; Zhao, Qian; Zhang, Yueyong; Zhou, Qixing

    2016-01-01

    The electrical conductivity (EC) of soil is generally measured after soil extraction, so this method cannot represent the in situ EC of soil (e.g., EC of soils with different moisture contents) and therefore lacks comparability in some cases. Using a resistance measurement apparatus converted from a configuration of soil microbial fuel cell, the in situ soil EC was evaluated according to the Ohmic resistance (Rs) measured using electrochemical impedance spectroscopy. The EC of soils with moisture content from 9.1% to 37.5% was calculated according to Rs. A significant positive correlation (R2 = 0.896, p < 0.01) between the soil EC and the moisture content was observed, which demonstrated the feasibility of the approach. This new method can not only represent the actual soil EC, but also does not need any pretreatment. Thus it may be used widely in the measurement of the EC for soils and sediments. PMID:27144567

  20. Determination of carrier lifetime and mobility in colloidal quantum dot films via impedance spectroscopy

    SciTech Connect

    Rath, Arup K.; Lasanta, Tania; Bernechea, Maria; Diedenhofen, Silke L.; Konstantatos, Gerasimos

    2014-02-10

    Impedance Spectroscopy (IS) proves to be a powerful tool for the determination of carrier lifetime and majority carrier mobility in colloidal quantum dot films. We employ IS to determine the carrier lifetime in PbS quantum dot Schottky solar cells with Al and we verify the validity of the technique via transient photovoltage. We also present a simple approach based on an RC model that allows the determination of carrier mobility in PbS quantum dot films and we corroborate the results via comparison with space charge limited measurements. In summary, we demonstrate the potential of IS to characterize key-to-photovoltaics optoelectronic properties, carrier lifetime, and mobility, in a facile way.

  1. Impedance spectroscopy of organic magnetoresistance devices—Effect of interface disorder

    SciTech Connect

    Fayolle, M.; Yamaguchi, M.; Ohto, T.; Tada, H.

    2015-02-21

    Organic magnetoresistance (OMAR) can be caused by either single carrier (bipolaron) or double carriers (electron-hole)-based mechanisms. In order to consider applications for OMAR, it is important to control the mechanism present in the device. In this paper, we report the effect of traps on OMAR resulting of disorder at the interface between the organic active layer with the hole injection layer [poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate): PEDOT:PSS]. It has been found that while the single carriers OMAR is enhanced by the presence of traps, the double carriers OMAR is totally removed in a sample with a high interface trap density. The reasons for these results are discussed based on the impedance spectroscopy measurements. First, the mechanism (single or double carriers) responsible of the OMAR was determined with the support of the capacitance measurement. Then, the influence of traps was discussed with the Nyquist diagrams and phase angle-frequency plots of the samples. The results suggested that with a rough interface and thus high disorder, the presence of traps enhanced the bipolaron formation. Traps also acted as recombination centers for electron-hole pairs, which prevented the double carriers OMAR in devices with a rough interface. On the other hand, with a low trap density, i.e., with a smooth surface, the single carrier OMAR decreased, and double carriers OMAR appeared. The sign of the OMAR could then be controlled by simply sweeping the bias voltage. This work demonstrated that the roughness at the interface is important for controlling OMAR and its reproducibility, and that the combination of OMAR measurement and impedance spectroscopy is helpful for clarifying the processes at the interface.

  2. Impedance Spectroscopy and Electroabsorption Studies of PCPDTBT-PCBM Bulk-Heterojunction Solar Cells

    NASA Astrophysics Data System (ADS)

    Green, Christopher; Cohick, Zane; Tzolov, Marian

    2014-03-01

    Bulk heterojunction polymer solar cells, consisting of PCPDTBT and PCBM, offer the potential for high light absorption and effective charge collection in sub-micron thick films. An understanding of the behavior of photo-generated charge transfer complexes in the polymer/small molecule blend is needed for further increases in the efficiency of such devices. In this study, we present experimental results on impedance spectroscopy indicating the formation of trapped electrical charges upon illumination. The population of the related energy states depends on the applied voltage. These results are supported by electroabsorption spectroscopy of the solar cells and of the films of the constituting materials. They indicate an additional electroabsorption feature not present in the individual films of the PCPDTBT and PCBM. The voltage dependence of the electroabsorption signal resulted in estimation of the built-in voltage in our solar cells of 1.1 eV. Our comparison of the photocurrent spectrum with the optical absorption spectrum of the solar cells indicate more efficient energy conversion for the light absorbed in the PCPDTBT compared to the light absorbed in PCBM.

  3. Aptamer-based biosensor for label-free detection of ethanolamine by electrochemical impedance spectroscopy.

    PubMed

    Liang, Gang; Man, Yan; Jin, Xinxin; Pan, Ligang; Liu, Xinhui

    2016-09-14

    A label-free sensing assay for ethanolamine (EA) detection based on G-quadruplex-EA binding interaction is presented by using G-rich aptamer DNA (Ap-DNA) and electrochemical impedance spectroscopy (EIS). The presence of K(+) induces the Ap-DNA to form a K(+)-stabilized G-quadruplex structure which provides binding sites for EA. The sensing mechanism was further confirmed by circular dichroism (CD) spectroscopy and EIS measurement. As a result, the charge transfer resistance (RCT) is strongly increased as demonstrated by using the ferro/ferricyanide ([Fe(CN)6](3-/4-)) as a redox probe. Under the optimized conditions, a linear relationship between ΔRCT and EA concentration was obtained over the range of 0.16 nM and 16 nM EA, with a detection limit of 0.08 nM. Interference by other selected chemicals with similar structure was negligible. Analytical results of EA spiked into tap water and serum by the sensor suggested the assay could be successfully applied to real sample analysis. With the advantages of high sensitivity, selectivity and simple sensor construction, this method is potentially suitable for the on-site monitoring of EA contamination. PMID:27566359

  4. Thermal effect on E/M impedance spectroscopy of piezoelectric wafer active sensors

    NASA Astrophysics Data System (ADS)

    Kamas, Tuncay; Frankforter, Erik; Yu, Lingyu Lucy; Lin, Bin; Giurgiutiu, Victor

    2015-03-01

    This paper presents theoretical predictive modeling and experimental evaluation of the structural health monitoring capability of piezoelectric wafer active sensors (PWAS) at elevated temperatures. Electromechanical impedance spectroscopy (EMIS) method is first qualified using circular PWAS resonators under traction-free boundary condition and in an ambience with increasing temperature. The theoretical study is conducted regarding temperature dependence of the electrical parameters, the capacitance C0, d31 and g31; and the elastic parameters, the in-plane compliance s11 and Young's modulus c11, of piezoelectric materials. The Curie transition temperature must be well above the operating temperature; otherwise, the piezoelectric material may depolarize under combined temperature and pressure conditions. The material degradation is investigated by introducing the temperature effects on the material parameters that are obtained from experimental observations as well as from related work in literature. The preliminary results from the analytical 2-D circular PWAS-EMIS simulations are presented and validated by the experimental PWAS-EMIS measurements at elevated temperatures. Temperature variation may produce pyro-electric charges, which may interfere with the piezoelectric effect. Therefore, analytical simulations are carried out to simulate the pyro-electric response from the temperature effects on a free circular PWAS-EMIS in in-plane mode. For the experimental validation, PWAS transducers are placed in a fixture that provides the traction-free boundary condition. The fixture is then located in an oven integrated with PID temperature controller. The EMIS measurement is conducted during the temperature increase and the first resonance frequency peak in admittance and impedance spectra was acquired.

  5. A new application of electrical impedance spectroscopy for measuring glucose metabolism: a phantom study

    NASA Astrophysics Data System (ADS)

    Dhurjaty, Sreeram; Qiu, Yuchen; Tan, Maxine; Liu, Hong; Zheng, Bin

    2015-03-01

    Glucose metabolism relates to biochemical processes in living organisms and plays an important role in diabetes and cancer-metastasis. Although many methods are available for measuring glucose metabolism-activities, from simple blood tests to positron emission tomography, currently there is no robust and affordable device that enables monitoring of glucose levels in real-time. In this study we tested feasibility of applying a unique resonance-frequency based electronic impedance spectroscopy (REIS) device that has been, recently developed to measure and monitor glucose metabolism levels using a phantom study. In this new testing model, a multi-frequency electrical signal sequence is applied and scanned through the subject. When the positive reactance of an inductor inside the device cancels out the negative reactance of the capacitance of the subject, the electrical impedance reaches a minimum value and this frequency is defined as the resonance frequency. The REIS system has a 24-bit analog-to-digital signal convertor and a frequency-resolution of 100Hz. In the experiment, two probes are placed inside a 100cc container initially filled with distilled water. As we gradually added liquid-glucose in increments of 1cc (250mg), we measured resonance frequencies and minimum electrical signal values (where A/D was normalized to a full scale of 1V). The results showed that resonance frequencies monotonously decreased from 243kHz to 178kHz, while the minimum voltages increased from 405mV to 793mV as the added amount of glucose increased from 0 to 5cc. The study demonstrated the feasibility of applying this new REIS technology to measure and/or monitor glucose levels in real-time in future.

  6. Estimation of defect activation energy around pn interfaces of Cu(In,Ga)Se2 solar cells using impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Sakakura, Hidenori; Itagaki, Masayuki; Sugiyama, Mutsumi

    2016-01-01

    We investigate the defect activation energy around the pn interface of Cu(In,Ga)Se2 (CIGS)-based solar cells using a simple electrochemical impedance spectroscopy. By applying AC and DC voltages to the solar cells, we observed an “inductive” element around the pn interface, which is ignored in conventional deep-level transient spectroscopy or admittance spectroscopy. A defect model is evaluated by proposing an equivalent circuit that includes a positive/negative constant phase element (CPE) to represent the area around the CdS/CIGS interface. By fitting the impedance data, the CPE index and CPE constant show a relationship with the defect activation energy or defect concentration. This result is significant because it may help reveal the defect properties of CIGS solar cells or any other semiconductor devices.

  7. Electrochemical impedance spectroscopy system and methods for determining spatial locations of defects

    DOEpatents

    Glenn, David F.; Matthern, Gretchen E.; Propp, W. Alan; Glenn, Anne W.; Shaw, Peter G.

    2006-08-08

    A method and apparatus for determining spatial locations of defects in a material are described. The method includes providing a plurality of electrodes in contact with a material, applying a sinusoidal voltage to a select number of the electrodes at a predetermined frequency, determining gain and phase angle measurements at other of the electrodes in response to applying the sinusoidal voltage to the select number of electrodes, determining impedance values from the gain and phase angle measurements, computing an impedance spectrum for an area of the material from the determined impedance values, and comparing the computed impedance spectrum with a known impedance spectrum to identify spatial locations of defects in the material.

  8. The application of electrochemical impedance spectroscopy for characterizing the degradation of Ni(OH)2/NiOOH electrodes

    NASA Technical Reports Server (NTRS)

    Macdonald, Digby D.

    1989-01-01

    The use of wide-band electrochemical impedance spectroscopy is described for characterizing the degradation of porous Ni(OH)2/NiOOH electrodes in concentrated KOH electrolyte solutions. The impedance spectra are interpreted in terms of a finite electrical transmission line and the changes in the components of the electrical analog are followed as a function of cycle number. The degradation of the capacity of rolled and bonded Ni(OH)2/NiOOH electrodes is caused by rupture of ohmic contacts within the active mass and by restructuring which results in a decrease in the number of active pores.

  9. Human haptoglobin phenotypes and concentration determination by nanogold-enhanced electrochemical impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Cheng, Tsai-Mu; Lee, Tzu-Cheng; Tseng, Shin-Hua; Chu, Hsueh-Liang; Pan, Ju-Pin; Chang, Chia-Ching

    2011-06-01

    Haptoglobin (Hp) is an acute phase protein that binds free hemoglobin (Hb), preventing Hb-induced oxidative damage in the vascular system. There are three phenotypes in human Hp, whose heterogeneous polymorphic structures and varying concentrations in plasma have been attributed to the cause of diseases and outcome of clinical treatments. Different phenotypes of Hp may be composed of the same subunits but different copy numbers, rendering their determination difficult by a single procedure. In this study, we have developed a simple, fast, reliable and sensitive method, using label-free nanogold-modified bioprobes coupled with self-development electrochemical impedance spectroscopy (EIS). By this method, probe surface charge transfer resistance is detected. The relative charge transfer resistance ratios for Hp 1-1, Hp 2-1 and Hp 2-2 were characterized. We were able to determine protein size difference within 3 nm, and the linear region of the calibration curve for Hp levels in the range of 90 pg ml - 1 and 90 µg ml - 1 (~1 fM to 1 pM). We surmise that similar approaches can be used to investigate protein polymorphism and altered protein-protein interaction associated with diseases.

  10. DNA Hybridization Sensors Based on Electrochemical Impedance Spectroscopy as a Detection Tool

    PubMed Central

    Park, Jin-Young; Park, Su-Moon

    2009-01-01

    Recent advances in label free DNA hybridization sensors employing electrochemical impedance spectroscopy (EIS) as a detection tool are reviewed. These sensors are based on the modulation of the blocking ability of an electrode modified with a probe DNA by an analyte, i.e., target DNA. The probe DNA is immobilized on a self-assembled monolayer, a conducting polymer film, or a layer of nanostructures on the electrode such that desired probe DNA would selectively hybridize with target DNA. The rate of charge transfer from the electrode thus modified to a redox indicator, e.g., [Fe(CN)6]3−/4−, which is measured by EIS in the form of charge transfer resistance (Rct), is modulated by whether or not, as well as how much, the intended target DNA is selectively hybridized. Efforts made to enhance the selectivity as well as the sensitivity of DNA sensors and to reduce the EIS measurement time are briefly described along with brief future perspectives in developing DNA sensors. PMID:22303136