Change search
Refine search result
1 - 13 of 13
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Buendia, Ruben
    et al.
    University of Borås, School of Engineering.
    Gil-Pita, Roberto
    Seoane, Fernando
    University of Borås, School of Engineering.
    Cole Parameter Estimation from the Modulus of the Electrical Bioimpeadance for Assessment of Body Composition. A Full Spectroscopy Approach2011In: Journal of Electrical Bioimpedance, ISSN 1891-5469, E-ISSN 1891-5469, Vol. 2, p. 72-78Article in journal (Refereed)
    Abstract [en]

    Activities around applications of Electrical Bioimpedance Spectroscopy (EBIS) have proliferated in the past decade significantly. Most of these activities have been focused in the analysis of the EBIS measurements, which eventually might enable novel applications. In Body Composition Assessment (BCA), the most common analysis approach currently used in EBIS is based on the Cole function, which most often requires curve fitting. One of the most implemented approaches for obtaining the Cole parameters is performed in the impedance plane through the geometrical properties that the Cole function exhibit in such domain as depressed semi-circle. To fit the measured impedance data to a semi-circle in the impedance plane, obtaining the Cole parameters in an indirect and sequential manner has several drawbacks. Applying a Non-Linear Least Square (NLLS) iterative fitting on the spectroscopy measurement, obtains the Cole parameters considering the frequency information contained in the measurement. In this work, from experimental total right side EBIS measurements, the BCA parameters have been obtained to assess the amount and distribution of whole body fluids. The values for the BCA parameters have been obtained using values for the Cole parameters estimated with both approaches: circular fitting on the impedance plane and NLLS impedance-only fitting. The comparison of the values obtained for the BCA parameters with both methods confirms that the NLLS impedance-only is an effective alternative as Cole parameter estimation method in BCA from EBIS measurements. Using the modulus of the Cole function as the model for the fitting would eliminate the need for performing phase detection in the acquisition process, simplifying the hardware specifications of the measurement instrumentation when implementing a bioimpedance spectrometer.

  • 2.
    Buendia, Ruben
    et al.
    University of Borås, School of Engineering.
    Gil-Pita, Roberto
    Seoane, Fernando
    University of Borås, School of Engineering.
    Cole parameter estimation from total right side electrical bioimpedance spectroscopy measurements: Influence of the number of frequencies and the upper limit2011In: Engineering in Medicine and Biology Society,EMBC, 2011 Annual International Conference of the IEEE, IEEE , 2011, p. 1843-1846Conference paper (Refereed)
    Abstract [en]

    Applications based on measurements of Electrical Bioimpedance Spectrocopy (EBIS) analysis are proliferating. The most spread and known application of EBIS is the non-invasive assessment of body composition. Fitting to the Cole function to obtain the Cole parameters, R0 and R∞, is the core of the EBIS analysis to obtain the body fluid distribution. An accurate estimation of the Cole parameters is essential for the Body Composition Assessment (BCA) and the estimation process depends on several factors. One of them is the upper frequency limit used for the estimation and the other is the number of measured frequencies in the measurement frequency range. Both of them impose requirements on the measurement hardware, influencing largely in the complexity of the bioimpedance spectrometer. In this work an analysis of the error obtained when estimating the Cole parameters with several frequency ranges and different number of frequencies has been performed. The study has been done on synthetic EBIS data obtained from experimental Total Right Side (TRS) measurements. The results suggest that accurate estimations of R0 and R∞ for BCA measurements can be achieved using much narrower frequency ranges and quite fewer frequencies than electrical bioimpedance spectrometers commercially available nowadays do.

  • 3.
    Buendia, Ruben
    et al.
    Chalmers University of Technology.
    Seoane, Fernando
    University of Borås, Faculty of Caring Science, Work Life and Social Welfare. KTH-School of Technology and Health.
    Lindecrantz, Kaj
    KTH-School of Technology and Health.
    Bosaeus, Ingvar
    University of Gothenburg.
    Gil-Pita, Roberto
    Universidad de Alcala.
    Johannsson, Gudmundur
    University of Gothenburg.
    Ellegård, Lars
    University of Gothenburg.
    Ward, Leigh
    University of Queensland.
    Estimation of body fluids with bioimpedance spectroscopy: state of the art methods and proposal of novel methods2015In: Physiological Measurement, ISSN 0967-3334, E-ISSN 1361-6579, Vol. 36, no 10Article in journal (Refereed)
  • 4.
    Buendia, Ruben
    et al.
    University of Borås, School of Engineering.
    Seoane Martinéz, Fernando
    University of Borås, School of Engineering.
    Harris, M.
    Caffarel, J.
    Gil, R.
    Hook Effect Correction & Resistance-based Cole Fitting Prior Cole Model-based Analysis: Experimental Validation2010Conference paper (Refereed)
  • 5.
    Buendia, Ruben
    et al.
    University of Borås, School of Engineering.
    Seoane Martínez, Fernando
    University of Borås, School of Engineering.
    Gil-Pita, R.
    A Novel Approach for Removing the Hook Effect Artefact from Electrical Bioimpedance Spectroscopy Measurements2010Conference paper (Refereed)
    Abstract [en]

    Very often in Electrical Bioimpedance (EBI) spectroscopy measurements the presence of stray capacitances creates a measurement artefact commonly known as Hook Effect. Such an artefact creates a hook-alike deviation of the EBI data noticeable when representing the measurement on the impedance plane. Such Hook Effect is noticeable at high frequencies but it also causes a data deviation at lower measurement frequencies. In order to perform any accurate analysis of the EBI spectroscopy data, the influence of the Hook Effect must be removed. An established method to compensate the hook effect is the well known Td compensation, which consists on multiplying the obtained spectrum, Zmeas(ω) by a complex exponential in the form of exp[jωTd]. Such a method cannot correct entirely the Hook Effect since the hook-alike deviation occurs a broad frequency range in both magnitude and phase of the measured impedance, and by using a scalar value for Td. First a scalar only modifies the phase of the measured impedance and second, a single value can truly corrects the Hook Effect only at a single frequency. In addition, the process to select a value for the scalar Td by an iterative process with the aim to obtain the best Cole fitting lacks solid scientific grounds. In this work the Td compensation method is revisited and a modified approach for correcting the Hook Effect including a novel method for selecting the correcting values is proposed. The initial validation results confirm that the proposed method entirely corrects the Hook Effect at all frequencies.

  • 6.
    Buendia, Ruben
    et al.
    University of Borås, School of Engineering.
    Seoane Martínez, Fernando
    University of Borås, School of Engineering.
    Gil-Pita, R.
    Experimental Validation of a Method for Removing the Capacitive Leakage Artifact from Electrical Bioimpedance Spectroscopy Measurements2010In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 21, no 11, p. 115802-Article in journal (Refereed)
    Abstract [en]

    Often when performing electrical bioimpedance (EBI) spectroscopy measurements, the obtained EBI data present a hook-like deviation, which is most noticeable at high frequencies in the impedance plane. The deviation is due to a capacitive leakage effect caused by the presence of stray capacitances. In addition to the data deviation being remarkably noticeable at high frequencies in the phase and the reactance spectra, the measured EBI is also altered in the resistance and the modulus. If this EBI data deviation is not properly removed, it interferes with subsequent data analysis processes, especially with Cole model-based analyses. In other words, to perform any accurate analysis of the EBI spectroscopy data, the hook deviation must be properly removed. Td compensation is a method used to compensate the hook deviation present in EBI data; it consists of multiplying the obtained spectrum, Zmeas(ω), by a complex exponential in the form of exp(–jωTd). Although the method is well known and accepted, Td compensation cannot entirely correct the hook-like deviation; moreover, it lacks solid scientific grounds. In this work, the Td compensation method is revisited, and it is shown that it should not be used to correct the effect of a capacitive leakage; furthermore, a more developed approach for correcting the hook deviation caused by the capacitive leakage is proposed. The method includes a novel correcting expression and a process for selecting the proper values of expressions that are complex and frequency dependent. The correctness of the novel method is validated with the experimental data obtained from measurements from three different EBI applications. The obtained results confirm the sufficiency and feasibility of the correcting method.

  • 7.
    Buendía López, Rubén
    University of Borås, School of Engineering.
    Improvements in Bioimpedance Spectroscopy Data Analysis: Artifact Correction, Cole Parameters and Body Fluid Estimation2013Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The estimation of body fluids is a useful and common practice in the status assessment of disease mechanisms and treatments. Electrical bioimpedance spectroscopy (EBIS) methods are non-invasive, inexpensive, and efficient alternatives for the estimation of body fluids. However, these methods are indirect, and their robustness and validity are unclear. Regarding the recording of measurements, a controversy developed regarding a spectrum deviation in the impedance plane, which is caused by capacitive leakage. This deviation is frequently compensated for by the extended Cole model, which lacks a theoretical basis; however, there is no method published to estimate the parameters. In this thesis, a simplified model to correct the deviation was proposed and tested. The model consists of an equivalent capacitance in parallel with the load. Subsequently, two other measurement artefacts were considered. Both artefacts were frequently disregarded with regard to total body and segmental EBIS measurements as their influence is insignificant with suitable skin-electrode contact. However, this case is not always valid, particularly from a textile-enabled measurement system perspective. In the estimation of body fluids, EBIS data are fitted to a model to obtain resistances at low and high frequencies. These resistances can be related to body fluid volumes. In order to minimise the influence of all three artefacts on the estimation of body fluids and improve the robustness and suitability of the model fitting the different domains of immittance were used and tested. The conductance in a reduced frequency spectrum was proposed as the most robust domain against the artefacts considered. The robustness and accuracy of the method did not increase, even though resistances at low and high frequencies can be robustly estimated against measurement artefacts. Thus, there is likely error in the relation between the resistances and volumes. Based on a theoretical analysis, state of the art methods were reviewed and their limitations were identified. New methods were also proposed. All methods were tested using a clinical database of patients involved in growth hormone replacement therapy. The results indicated EBIS are accurate methods to estimate body fluids, however they have robustness limits. It is hypothesized that those limits in extra-cellular fluid are primarily due to anisotropy, in total body fluid they are primarily due to the uncertainty ρi, and errors in intra-cellular fluid are primarily due to the addition of errors in extracellular and total body fluid. Currently, these errors cannot be prevented or minimised. Thus, the limitations for robustness must be predicted prior to applying EBIS to estimate body fluids.

  • 8.
    Buendía, Rubén
    et al.
    University of Borås, School of Engineering.
    Bogónez-Franco, Paco
    Nescolarde, Lexa
    Seoane, Fernando
    University of Borås, School of Engineering.
    Influence of electrode mismatch on Cole parameter estimation from Total Right Side Electrical Bioimpedance Spectroscopy measurements2012In: Medical Engineering and Physics, ISSN 1350-4533, E-ISSN 1873-4030, Vol. 34, no 7, p. 1024-1028Article in journal (Refereed)
    Abstract [en]

    Applications based on measurements of Electrical Bioimpedance (EBI) spectroscopy analysis, like assessment of body composition, have proliferated in the past years. Currently Body Composition Assessment (BCA) based in Bioimpedance Spectroscopy (BIS) analysis relays on an accurate estimation of the Cole parameters R0 and R∞. A recent study by Bogonez-Franco et al. has proposed electrode mismatch as source of remarkable artefacts in BIS measurements. Using Total Right Side BIS measurements from the aforementioned study, this work has focused on the influence of electrode mismatch on the estimation of R0 and R∞ using the Non-Linear Least Square curve fitting technique on the modulus of the impedance. The results show that electrode mismatch on the voltage sensing electrodes produces an overestimation of the impedance spectrum leading to a wrong estimation of the parameters R0 and R∞, and consequently obtaining values around 4% larger that the values obtained from BIS without electrode mismatch. The specific key factors behind electrode mismatch or its influence on the analysis of single and spectroscopy measurements have not been investigated yet, no compensation or correction technique is available to overcome the deviation produced on the EBI measurement. Since textile-enabled EBI applications using dry textrodes, i.e. textile electrodes with dry skin–electrode interfaces and potentially large values of electrode polarization impedance are more prone to produce electrode mismatch, the lack of a correction or compensation technique might hinder the proliferation of textile-enabled EBI applications for personalized healthcare monitoring.

  • 9. Reza Atefi, Seyed
    et al.
    Seoane, Fernando
    University of Borås, School of Engineering.
    Buendia, Ruben
    University of Borås, School of Engineering.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Cole Function and Conductance-Based Parasitic Capacitance Compensation for Cerebral Electrical Bioimpedance Measurements2012Conference paper (Refereed)
    Abstract [en]

    One of the most common measurement artifacts present in Electrical Bioimpedance Spectroscopy measurements (EBIS) comes from the capacitive leakage effect resulting from parasitic stray capacitances. This artifact produces a deviation in the measured impedance spectrum that is most noticeable at higher frequencies. The artifact taints the spectroscopy measurement increasing the difficulty of producing reliable EBIS measurements at high frequencies. In this work, an approach for removing such capacitive influence from the spectral measurement is presented making use of a novel method to estimate the value of the parasitic capacitance equivalent that causes the measurement artifact. The proposed method has been tested and validated theoretically and experimentally and it gives a more accurate estimation of the value of the parasitic capacitance than the previous methods. Once a reliable value of parasitic capacitance has been estimated the capacitive influence can be easily compensated in the EBIS measured data. Thus enabling analysis of EBIS data at higher frequencies, i.e. in the range of 300-500 kHz like measurements intended for cerebral monitoring, where the characteristic frequency is remarkably higher than EBIS measurements i.e. within the range 30 to 50 kHz, intended for body composition assessment.

  • 10.
    Seoane, Fernando
    et al.
    University of Borås, School of Engineering.
    Ferreira, Javier
    University of Borås, School of Engineering.
    Buendia, Ruben
    University of Borås, School of Engineering.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Adaptive Frequency Distribution for Electrical Bioimpedance Spectroscopy Measurements2012Conference paper (Refereed)
    Abstract [en]

    This paper presents a novel frequency distribution scheme intended to provide more accurate estimations of Cole parameters. Nowadays a logarithmic frequency distribution is mostly used in Electrical Bioimpedance Spectroscopy (EBIS) applications. However it is not optimized following any criterion. Our hypothesis is that an EBIS signal contains more information where the variation of the measurement regarding the frequency is larger; and that there ought to be more measuring frequencies where there is more information. Results show that for EBIS data with characteristic frequencies up to 200 kHz the error obtained with both frequency distribution schemes is similar. However, for EBIS data with higher values of characteristic frequency the error produced when estimating the values from EBIS measurements using an adaptive frequency distribution is smaller. Thus it may usefull for EBIS applications with high values of characteristic frequency, e.g. cerebral bioimpedance.

  • 11.
    Seoane Martínez, Fernando
    et al.
    University of Borås, School of Engineering.
    Buendia, Ruben
    University of Borås, School of Engineering.
    Gil-Pita, R.
    Cole Parameter Estimation from Electrical Bioconductance Spectroscopy Measurements2010Conference paper (Refereed)
    Abstract [en]

    Several applications of Electrical Bioimpedance (EBI) make use of Cole parameters as base of their analysis, therefore Cole parameters estimation has become a very common practice within Multifrequency- and EBI spectroscopy. EBI measurements are very often contaminated with the influence of parasitic capacitances, which contributes to cause a hook-alike measurement artifact at high frequencies in the EBI obtained data. Such measurement artifacts might cause wrong estimations of the Cole parameters, contaminating the whole analysis process and leading to wrong conclusions. In this work, a new approach to estimate the Cole parameters from the real part of the admittance, i.e. the conductance, is presented and its performance is compared with the results produced with the traditional fitting of complex impedance to a depressed semi-circle. The obtained results prove that is feasible to obtain the full Cole equation from only the conductance data and also that the estimation process is safe from the influence capacitive leakage.

  • 12.
    Seoane Martínez, Fernando
    et al.
    University of Borås, School of Engineering.
    Marquez, J. C.
    University of Borås, School of Engineering.
    Ferreira, Javier
    University of Borås, School of Engineering.
    Buendia, Ruben
    University of Borås, School of Engineering.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    The Challenge of the Skin-Electrode Contact in Textile-enabled Electrical Bioimpedance Measurements for Personalized Healthcare Monitoring Applications2011In: Biomedical Engineering, Trends in Materials Science / [ed] AN Laskovski, InTech , 2011Chapter in book (Other academic)
    Abstract [en]

    Textile technology has gone through a remarkable development in the field of Smart Textiles and more specifically in the area of conductive fabrics and yarns. Important research efforts have been done worldwide and especially in Europe, where the EUcommission has supported several research projects in the near past e.g. BIOTEX IST-2004- 016789, CONTEXT IST- 2004-027291 and MyHeart IST-2002-507816. As a result of such worldwide R&D efforts, textile sensors and electrodes are currently available commercially. Nowadays there are even consumer products with textile sensing technology for heart rate monitoring integrated in the apparel e.g. Adistar Fusion T-shirt from Adidas or the Numetrex’s Cardio shirt. Since one of the main areas of focus where R&D efforts have been concentrated is Personalized Healthcare Monitoring (PHM) and the fact that most of the efforts developing textile sensors have been focused on developing electrodes for biopotential signals recording, it is natural that the main targeted application has been the acquisition of electrical biopotentials and especially monitoring the ElectroCardioGraphic activity, but also other types of textile sensors have been investigated e.g. textile stretching sensor (Mattmann et al., 2008). Nowadays textile-enable stretch sensors are available commercially like the one manufactured by Merlin Systems. While the application of this type of sensor aims at other applications than biopotential recordings, an important area of application of stretch sensors still is PHM and fitness. This type of sensors can be used for respiration monitoring or plethysmography applications.

  • 13.
    Seoane Martínez, Fernando
    et al.
    University of Borås, School of Engineering.
    Marquez, J. C.
    Ferreira, Javier
    University of Borås, School of Engineering.
    Buendia, Ruben
    University of Borås, School of Engineering.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    The Challenge of the Skin-Electrode Contact in Textile-enabled Electrical Bioimpedance Measurements for Personalized Healthcare Monitoting Application2010Conference paper (Refereed)
1 - 13 of 13
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf