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  • 1.
    Abtahi, Farhad
    et al.
    KTH, School of Technology and Health (STH), Patient Safety (Closed 20130701).
    Gyllensten, Illapha Cuba
    KTH, School of Technology and Health (STH).
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701).
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701).
    Software tool for analysis of breathing-related errors in transthoracic electrical bioimpedance spectroscopy measurements2012In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 407, no 1, p. 012028-Article in journal (Refereed)
    Abstract [en]

    During the last decades, Electrical Bioimpedance Spectroscopy (EBIS) has been applied in a range of different applications and mainly using the frequency sweep-technique. Traditionally the tissue under study is considered to be timeinvariant and dynamic changes of tissue activity are ignored and instead treated as a noise source. This assumption has not been adequately tested and could have a negative impact and limit the accuracy for impedance monitoring systems. In order to successfully use frequency-sweeping EBIS for monitoring time-variant systems, it is paramount to study the effect of frequency-sweep delay on Cole Model-based analysis. In this work, we present a software tool that can be used to simulate the influence of respiration activity in frequency-sweep EBIS measurements of the human thorax and analyse the effects of the different error sources. Preliminary results indicate that the deviation on the EBIS measurement might be significant at any frequency, and especially in the impedance plane. Therefore the impact on Cole-model analysis might be different depending on method applied for Cole parameter estimation.

  • 2.
    Atefi, Seyed Reza
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701).
    Buendia, Ruben
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701).
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701).
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701).
    Cole Function and Conductance-Based Parasitic Capacitance Compensation for Cerebral Electrical Bioimpedance Measurements2012In: Engineering in Medicine and Biology Society (EMBC), 2012 Annual International Conference of the IEEE, San Diego: IEEE press , 2012, p. 3368-3371Conference 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.

  • 3.
    Atefi, Seyed Reza
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Electrical Bioimpedance cerebral monitoring. Preliminary results from measurements on stroke patients2012In: Engineering in Medicine and Biology Society (EMBC), 2012 Annual International Conference of the IEEE, IEEE , 2012, p. 126-129Conference paper (Refereed)
    Abstract [en]

    Electrical Bioimpedance Spectroscopy (EBIS) is currently used in different tissue characterization applications. In this work we aim to use EBIS to study changes in electrical properties of the cerebral tissues after an incident of hemorrhage/ischemic stroke. To do so a case-control study was conducted using six controls and three stroke cases. The preliminary results of this study show that by using Cole-based analysis on EBIS measurements and analyzing the Cole parameters R0 and R∞, it is possible to detect changes on electrical properties of cerebral tissue after stroke. 

  • 4.
    Ayllon, David
    et al.
    Department of Signal Theory and Communications.
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Gil-Pita, Roberto
    Department of Signal Theory and Communications.
    Cole equation and parameter estimation from electrical bioimpedance spectroscopy measurements: A comparative study2009In: EMBC: 2009 ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY, VOLS 1-20, Buenos Aires: IEEE Engineering in Medicine and Biology , 2009, p. 3779-3782Conference paper (Refereed)
    Abstract [en]

    Since there are several applications of Electrical Bioimpedance (EBI) that use the Cole parameters as base of the analysis, to fit EBI measured data onto the Cole equation is a very common practice within Multifrequency-EBI and spectroscopy. The aim of this paper is to compare different fitting methods for EBI data in order to evaluate their suitability to fit the Cole equation and estimate the Cole parameters. Three of the studied fittings are based on the use of Non-Linear Least Squares on the Cole model, one using the real part only, a second using the imaginary part and the third using the complex impedance. Furthermore, a novel fitting method done on the impedance plane, without using any frequency information has been implemented and included in the comparison. Results show that the four methods perform relatively well but the best fitting in terms of standard error of estimate is the fitting obtained from the resistance only. The results support the possibility of measuring only the resistive part of the bioimpedance to accurately fit Cole equation and estimate the Cole parameters, with entailed advantages.

  • 5.
    Berglund, Anders
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Integrated Product Development.
    Sturm, Dennis
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Parida, Vinit
    Luleå University of Technology.
    Embracing Entrepreneurial Behaviour in a Research School2009Conference paper (Refereed)
    Abstract [en]

    The Product Innovation Engineering program (PIEp) has recently established a Research School withthe aim to increase innovation capabilities in Swedish industries and to promote entrepreneurialbehaviour. By following a bottom-up approach PIEp has been able to both embrace and fosterentrepreneurship. As a result, the research school has already been able to change preexisting mindsetsand to encourage PhD students to be more proactive, risk-taking and innovative. Through descriptions of their own experiences and of key cases along the way, the authors illustratethe transformation from the initial idea to the research school as it is today. This paper seeks toprovide insight and draw comparisons with other research schools to further research and assist policymakers interested in founding new research schools.

  • 6.
    Buendia, Ruben
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Improvements in Bioimpedance SpectroscopyData Analysis: Artefact Correction, ColeParameters, and Body Fluid Estimation2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The estimation of body fluids is a useful and common practice in the status assessment of diseasemechanisms and treatments. Electrical bioimpedance spectroscopy (EBIS) methods are non-invasive,inexpensive, and efficient alternatives for the estimation of body fluids. However, these methods areindirect, and their robustness and validity are unclear.Regarding the recording of measurements, a controversy developed regarding a spectrum deviationin the impedance plane, which is caused by capacitive leakage. This deviation is frequentlycompensated for by the extended Cole model, which lacks a theoretical basis; however, there is nomethod published to estimate the parameters. In this thesis, a simplified model to correct thedeviation was proposed and tested. The model consists of an equivalent capacitance in parallel withthe load.Subsequently, two other measurement artefacts were considered. Both artefacts were frequentlydisregarded with regard to total body and segmental EBIS measurements as their influence isinsignificant with suitable skin-electrode contact. However, this case is not always valid, particularlyfrom a textile-enabled measurement system perspective. In the estimation of body fluids, EBIS dataare fitted to a model to obtain resistances at low and high frequencies. These resistances can berelated to body fluid volumes. In order to minimise the influence of all three artefacts on theestimation of body fluids and improve the robustness and suitability of the model fitting the differentdomains of immittance were used and tested. The conductance in a reduced frequency spectrum wasproposed 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 highfrequencies can be robustly estimated against measurement artefacts. Thus, there is likely error in therelation between the resistances and volumes. Based on a theoretical analysis, state of the artmethods were reviewed and their limitations were identified. New methods were also proposed. Allmethods were tested using a clinical database of patients involved in growth hormone replacementtherapy. The results indicated EBIS are accurate methods to estimate body fluids, however they haverobustness limits. It is hypothesized that those limits in extra-cellular fluid are primarily due toanisotropy, in total body fluid they are primarily due to the uncertainty ρi, and errors in intra-cellularfluid are primarily due to the addition of errors in extracellular and total body fluid. Currently, theseerrors cannot be prevented or minimised. Thus, the limitations for robustness must be predicted priorto applying EBIS to estimate body fluids.

  • 7.
    Buendia, Ruben
    et al.
    University of Borås, Sweden.
    bogonez-franco, Paco
    Technical University of Catalonia.
    Nescolarde, Lexa
    Technical University of Catalonia.
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    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 R-0 and R-infinity. 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 R-0 and R-infinity 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 R-0 and R-infinity, 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.

  • 8.
    Buendia, Ruben
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Gil-Pita, Roberto
    Department of Theory of the Signal and Communications.
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    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 a phase detection in the acquisition process, simplifying the hardware specifications of the measurement instrumentation when implementing a bioimpedance spectrometer.

  • 9.
    Buendia, Ruben
    et al.
    School of Engineering, University of Borås.
    Gil-Pita, Roberto
    Department of Theory of the Signal and Communications, University of Alcala, Madrid, Spain.
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Cole parameter estimation from total right side electrical bioimpedance spectroscopy measurements: Influence of the number of frequencies and the upper limit2011In: 2011 ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY (EMBC), 2011, p. 1843-1846Conference paper (Refereed)
    Abstract [en]

    Applications based on measurements of Electrical Bioimpedance Spectroscopy (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, R<sub>0</sub> and R<sub>&#x221E;</sub>, 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 R<sub>0</sub> and R<sub>&#x221E;</sub> for BCA measurements can be achieved using much narrower frequency ranges and quite fewer frequencies than electrical bioimpedance spectrometers commercially available nowadays do.

  • 10.
    Buendia, Ruben
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Bosacus, I.
    University of Gothenburg.
    Gil-Pita, Roberto
    Department of Theory of the Signal and Communications, University of Alcala, Madrid, Spain.
    Johannsson, G.
    Ellegård, L.
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Robust approach against capacitive coupling for the estimation of body fluids using clinical bioimpedance spectroscopy measurementsManuscript (preprint) (Other academic)
  • 11.
    Buendia, Ruben
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Gil-Pita, Roberto
    Department of Theory of the Signal and Communications, University of Alcala, Madrid, Spain.
    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 11Article 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, Z meas (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.

  • 12.
    Buendia, Ruben
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Harris, Matthew
    Phillips Research.
    Caffarel, Jeniffer
    Phillips Research.
    Gil-Pita, Roberto
    Department of Theory of the Signal and Communications, University of Alcala, Madrid, Spain.
    Hook Effect correction & resistance-based Cole fitting prior Cole model-based analysis: Experimental validation2010In: Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2010, IEEE Engineering in Medicine and Biology , 2010, p. 6563-6566Conference paper (Refereed)
    Abstract [en]

    The analysis of measurements of Electrical Bioimpedance (EBI) is on the increase for performing non-invasive assessment of health status and monitoring of pathophysiological mechanisms. EBI measurements might contain measurements artefacts that must be carefully removed prior to any further analysis. Cole model-based analysis is often selected when analysing EBI data and might lead to miss-conclusion if it is applied on data contaminated with measurement artefacts. The recently proposed Correction Function to eliminate the influence of the Hook Effect from EBI data and the fitting to the real part of the Cole model to extract the Cole parameters have been validated on experimental measurements. The obtained results confirm the feasible experimental use of these promising pre-processing tools that might improve the outcome of EBI applications using Cole model-based analysis.

  • 13.
    Buendia, Ruben
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701). University of Alcala, Spain; Chalmers University of Technology, Sweden; University of Boras, Sweden.
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701). University of Boras, Sweden.
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701). University of Boras, Sweden; Karolinska Instituet, Sweden.
    Bosacus, I.
    University of Gothenburg.
    Gil-Pita, Roberto
    Department of Theory of the Signal and Communications, University of Alcala, Madrid, Spain.
    Johannsson, G.
    Ellegård, L.
    Ward, L.
    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)
    Abstract [en]

    Determination of body fluids is a useful common practice in determination of disease mechanisms and treatments. Bioimpedance spectroscopy (BIS) methods are non-invasive, inexpensive and rapid alternatives to reference methods such as tracer dilution. However, they are indirect and their robustness and validity are unclear. In this article, state of the art methods are reviewed, their drawbacks identified and new methods are proposed. All methods were tested on a clinical database of patients receiving growth hormone replacement therapy. Results indicated that most BIS methods are similarly accurate (e.g. < 0.5 +/- 3.0% mean percentage difference for total body water) for estimation of body fluids. A new model for calculation is proposed that performs equally well for all fluid compartments (total body water, extra-and intracellular water). It is suggested that the main source of error in extracellular water estimation is due to anisotropy, in total body water estimation to the uncertainty associated with intracellular resistivity and in determination of intracellular water a combination of both.

  • 14.
    Buendía López, Rubén
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Model Based Enhancement of Bioimpedance Spectroscopy Analysis: Towards Textile Enabled Applications2011Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Several signal processing approaches have been developed to overcome the effect of stray capacitances in Electrical Bioimpedance Spectroscopy (EBIS) measurements. EBIS measurements obtained with textile-enabled instrumentation are more vulnerable to stray capacitances. Currently, the most widespread approach for correcting the effect of stray capacitances in EBIS is the time delay (

    Td) compensation method, which also has several drawbacks. In this study, the Td method is revisited and its limitations and its lack of a scientific basis are demonstrated. To determine better ways to overcome the effect of stray capacitances, a simplified measurement model is proposed that is based on previous models of artefacts in EBIS measurements described in the literature. The model consists of a current divider with a parasitic capacitance (Cpar) in parallel with the load. Cpar creates a pathway for the measurement current to leak away from the load, provoking a capacitive leakage effect. In this thesis, three approaches with different limitations are proposed to overcome the capacitive leakage effect. The first approach estimates Cpar and subtracts it from the measurements, thus finding the load. Cpar can be estimated because the susceptance of biological tissue is null at infinite frequency. Therefore, at high frequencies, the susceptance of the tissue can be neglected, and the slope of the susceptance of the measurement is Cpar. The accuracy of Cpar depends on the maximum frequency measured and the value of Cpar. Therefore, it may not be possible to accurately estimate small values of Cpar in the typical frequency ranges used in EBIS. The second and third approaches use the Cole fitting process to estimate the Cole parameters, which form the basis for most EBIS applications. Because the conductance of the measurement is free from the effect of Cpar, performing Cole fitting on the conductance avoids the effect of Cpar in the fitting process. With a poor skin-electrode contact, this approach may not be sufficiently accurate. The third approach would be to perform the Cole fitting on the modulus with a reduced upper frequency limit because the modulus and the low-medium frequencies are very robust against the effect of artefacts. In this approach, a slight capacitive leakage effect is unavoidable. Since it is common to find tainted measurements, especially among those obtained with textile-enabled instrumentation, it is important to find viable methods to avoid their effect. The three methods studied showed that they could reduce the effect of tainted measurements.

  • 15. Ekblom, M. M.
    et al.
    Eriksson, Martin
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Concurrent EMG feedback acutely improves strength and muscle activation2012In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 112, no 5, p. 1899-1905Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to investigate the acute effects of electromyographic (EMG) feedback on muscle activation and strength during maximal voluntary concentric and eccentric muscle actions. 15 females performed two sets of three lengthening and three shortening maximal voluntary isokinetic knee extensions at 20A degrees A s(-1) over 60A degrees range of motion. After the first set, subjects were randomized to either a control group (n = 8) or a feedback group (n = 7). In the second set, the control group performed tasks identical to those in the first set, whereas the feedback group additionally received concurrent visual feedback of the EMGrms from Vastus Medialis (VM). Knee extensor strength and EMG activation of VM, Vastus lateralis (VL) and hamstrings (HAM) were measured during the MVCs. Analyses were performed separately in a 1 s preactivation phase, a 1 s initial movement phase and a 1 s late movement phase. EMG feedback was associated with significantly higher knee extensor strength in all phases (20.5% p < 0.05, 18.2% p < 0.001 and 19% p < 0.001, respectively) for the eccentric MVCs and in the preactivation phase (16.3%, p < 0.001) and initial movement phases (7.2%, p < 0.05) for concentric MVCs. EMG feedback from VM further improved activation in VM and HAM but not VL. These findings suggested that concurrent visual EMG feedback from VM could acutely enhance muscle strength and activation. Before recommending implementation of EMG feedback in resistance training paradigms, the feedback parameters needs to be optimized and its long-term effects needs to be scrutinized.

  • 16.
    Eriksson, Martin
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701).
    Bresin, Roberto
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Music Acoustics.
    Improving running mechanics by use of interactive sonification2010In: Proceedings of the Interaction Sonification workshop (ISon) 2010 / [ed] Bresin, Roberto; Hermann, Thomas; Hunt, Andy, Stockholm, Sweden: KTH Royal Institute of Technology, 2010, p. 95-98Conference paper (Refereed)
    Abstract [en]

    Running technique has a large effect on running economy interms of consumed amount of oxygen. Changing the naturalrunning technique, though, is a difficult task. In this paper, a method based on sonification is presented, that will assist the runner in obtaining a more efficient running style. The system is based on an accelerometer sending data to a mobile phone.Thus the system is non-obtrusive and possible to use in theeveryday training. Specifically, the feedback given is based on the runner’s vertical displacement of the center of mass. As this is the main source of energy expenditure during running, it is conjectured that a reduced vertical displacement should improve running economy.

  • 17.
    Eriksson, Martin
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Sturm, Dennis
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Halvorsen, Kjartan
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Gullstrand, Lennart
    Swedish Sports Confederation.
    Wireless Vertical Displacement Measurement during Running using an Accelerometer and a Mobile Phone2011Conference paper (Refereed)
    Abstract [en]

    The purpose of this study was to investigate in the usability of a wireless accelerometer linked to a mobile phone via Bluetooth radio for measuring vertical displacement in running athletes. Five experienced runners were monitored during lactate threshold testing at three to five different velocities. Accelerometer data was received, processed and stored on the phone to be compared to simultaneous position transducer (ground truth) recordings after data collection. A paired t-test and statistical analysis show no significant differences in the reliability of the recordings. While further investigations are encouraged, the accelerometer and algorithm (running in J2ME on the mobile phone) proof as aflexible, easy-to-use tool for out-of-the-lab monitoring and to provide real-time feedback for running technique experiments.

  • 18.
    Ferreira Gonzalez, Javier
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Textile-enabled Bioimpedance Instrumentation for Personalised Health Monitoring Applications2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    A growing number of factors, including the costs, technological advancements, an ageing population, and medical errors are leading industrialised countries to invest in research on alternative solutions to improving their health care systems and increasing patients’ life quality. Personal Health System (PHS) solutions envision the use of information and communication technologies that enable a paradigm shift from the traditional hospital-centred healthcare delivery model toward a preventive and person-centred approach. PHS offers the means to follow patient health using wearable, portable or implantable systems that offer ubiquitous, unobtrusive bio-data acquisition, allowing remote access to patient status and treatment monitoring.

    Electrical Bioimpedance (EBI) technology is a non-invasive, quick and relatively affordable technique that can be used for assessing and monitoring different health conditions, e.g., body composition assessments for nutrition. EBI technology combined with state-of-the-art advances in sensor and textile technology are fostering the implementation of wearable bioimpedance monitors that use functional garments for the implementation of personalised healthcare applications.

    This research studies the development of a portable EBI spectrometer that can use dry textile electrodes for the assessment of body composition for the purposes of clinical uses. The portable bioimpedance monitor has been developed using the latest advances in system-on-chip technology for bioimpedance spectroscopy instrumentation. The obtained portable spectrometer has been validated against commercial spectrometer that performs total body composition assessment using functional textrode garments.

    The development of a portable Bioimpedance spectrometer using functional garments and dry textile electrodes for body composition assessment has been shown to be a feasible option. The availability of such measurement systems bring closer the real implementation of personalised healthcare systems.

  • 19.
    Ferreira, Javier
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    AD5933-based electrical bioimpedance spectrometer: Towards textile-enabled applications2011In: Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS, 2011, Vol. 2011, p. 3282-3285Conference paper (Refereed)
    Abstract [en]

    Advances on System-On-Chip and Textile technology allows the development of Textile-enabled measurement instrumentation. Textile Electrodes (Textrodes) have been proven reliable for performing Electrical Bioimpedance Spectroscopy (EBIS) measurements, and the availability of a integrated circuit impedance spectrometer, the AD5933, has allowed the implementation of small size EBIS spectrometers. In this work an AD5933-based spectrometer has been implemented, and its performance on 2R1C circuits and for tetrapolar total right side EBIS measurements has been compared against the commercially available spectrometer SFB7. The study has been focused on the working upper frequency range and the estimation of the Cole parameters required for assessment of body fluid distribution: R(0) and R(∞). The results indicate that AD5933-based spectrometer implemented in this work can perform accurate impedance measurements well above the upper limits recommended in the datasheet. The AD5933-EBIS presents a good performance compared with the SFB7 on the 2R1C circuit and the total right side measurements, showing a smaller error in the resistance spectrum and small deviation error in the reactance when measuring over 270 kHz. The comparison on the Cole parameters estimation obtained with the SFB7 and the AD5933-based spectrometer exhibit a difference below 1% for the estimation of R(0) and R(∞). Consequently the overall measurement performance shown by the implemented AD5933-based spectrometer suggests its feasible use for EBIS measurements using dry Textrodes. This is of special relevance for the proliferation of EBI-based personalized health monitoring systems for patients that require to monitor the distribution of body fluids, like in dialysis.

  • 20.
    Flisberg, A.
    et al.
    Department of Pediatrics, Queen Silvia Children's Hospital, Sahlgrenska University Hospital, Sweden.
    Kjellmer, I.
    Department of Pediatrics, Queen Silvia Children's Hospital, Sahlgrenska University Hospital, Sweden.
    Löfhede, J.
    School of Engineering, University of Borås, Sweden.
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701).
    Thordstein, M.
    Department of Clinical Neurophysiology, Institute of Neuroscience and Physiology, Sahlgrenska University Hospital, Göteborg, Sweden.
    Prognostic capacity of automated quantification of suppression time in the EEG of post-asphyctic full-term neonates2011In: Acta Paediatrica, ISSN 0803-5253, E-ISSN 1651-2227, Vol. 100, no 10, p. 1338-1343Article in journal (Refereed)
    Abstract [en]

    Aim: To evaluate the prognostic capacity of a new method for automatic quantification of the length of suppression time in the electroencephalogram (EEG) of a group of asphyxiated newborn infants. Methods: Twenty-one full-term newborn infants who had been resuscitated for severe birth asphyxia were studied. Eight channel continuous EEG was recorded for prolonged time periods during the first days of life. Artefact detection or rejection was not applied to the signals. The signals were fed through a pretrained classifier and then segmented into burst and suppression periods. Total suppression length per hour was calculated. All surviving patients were followed with structured neurodevelopmental assessments to at least 18 months of age. Results: The patients who developed neurodevelopmental disability or died had significant suppression periods in their EEG during the first days of life while the patients who had a normal follow-up had no or negligible amount of suppression. Conclusions: This new method for automatic quantification of suppression periods in the raw, neonatal EEG discriminates infants with good from those with poor outcome.

  • 21.
    Flisberg, A.
    et al.
    Department of Pediatrics, Queen Silvia Children's Hospital, Sahlgrenska University Hospital-Östra.
    Kjellmer, I.
    Department of Pediatrics, Queen Silvia Children's Hospital, Sahlgrenska University Hospital-Östra.
    Löfhede, J.
    School of Engineering, University of Borås.
    Löfgren, N.
    Neoventa Medical AB, Göteborg.
    Rosa-Zurera, M.
    Department of Signal Theory and Communications, University of Alcalá.
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701).
    Thordstein, M.
    Department of Clinical Neurophysiology, Institute of Neuroscience and Physiology, Sahlgrenska University Hospital, Göteborg, Sweden.
    Does indomethacin for closure of patent ductus arteriosus affect cerebral function?2010In: Acta Paediatrica, ISSN 0803-5253, E-ISSN 1651-2227, Vol. 99, no 10, p. 1493-1497Article in journal (Refereed)
    Abstract [en]

    Objective: To study whether indomethacin used in conventional dose for closure of patent ductus arteriosus affects cerebral function measured by Electroencephalograms (EEG) evaluated by quantitative measures. Study design: Seven premature neonates with haemodynamically significant persistent ductus arteriosus were recruited. EEG were recorded before, during and after an intravenous infusion of 0.2 mg/kg indomethacin over 10 min. The EEG was analysed by two methods with different degrees of complexity for the amount of low-activity periods (LAP, "suppressions") as an indicator of affection of cerebral function. Results: Neither of the two methods identified any change in the amount of LAPs in the EEG as compared to before the indomethacin infusion. Conclusion: Indomethacin in conventional dose for closure of patent ductus arteriosus does not affect cerebral function as evaluated by quantitative EEG.

  • 22. Frykberg, Gunilla E.
    et al.
    Thierfelder, Tomas
    Aberg, Anna Cristina
    Halvorsen, Kjartan
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Borg, Jorgen
    Hirschfeld, Helga
    Impact of stroke on anterior-posterior force generation prior to seat-off during sit-to-walk2012In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 35, no 1, p. 56-60Article in journal (Refereed)
    Abstract [en]

    Force generation during sit-to-walk (STW) post-stroke is a poorly studied area, although STW is a common daily transfer giving rise to a risk of falling in persons with disability. The purpose of this study was to describe and compare strategies for anterior-posterior (AP) force generation prior to seat-off during the STW transfer in both subjects with stroke and in matched controls. During STW at self-selected speed, AP force data were collected by 4 force plates, beneath the buttocks and feet from eight subjects with stroke '(>6 months after onset) and 8 matched controls. Subjects with post-stroke hemiparesis and matched controls generated a similar magnitude of total AP force impulses (F-1.71 = 0.67; p = 0.42) beneath buttocks and feet prior to seat-off during STW. However, there were significant group differences in AP force impulse generation beneath the stance buttock (i.e. the non-paretic buttock in the stroke group), with longer duration (F-1.71 = 8.78; p <0.005), larger net AP impulse (F-1.71 = 6.76; p < 0.05) and larger braking impulse (F-1.71 = 7.24; p <0.05) in the stroke group. The total braking impulse beneath buttocks and feet was about 4.5 times larger in the stroke group than in the control group (F-1.71 = 8.84; p < 0.005). An intra-and inter-limb dys-coordination with substantial use of braking impulses was demonstrated in the stroke group. This motor strategy differed markedly from the smooth force interaction in the control group. These results might be important in the development of treatment models related to locomotion post-stroke.

  • 23. Gund, Anna
    et al.
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Schaufelberger, Maria
    Patel, Harshida
    Sjöqvist, Bengt Arne
    Attitudes among healthcare professionals towards ICT and home follow-up in chronic heart failure care2012In: BMC Medical Informatics and Decision Making, ISSN 1472-6947, E-ISSN 1472-6947, Vol. 12, no 1, p. 138-Article in journal (Refereed)
    Abstract [en]

    Background: eHealth applications for out-of-hospital monitoring and treatment follow-up have been advocated for many years as a promising tool to improve treatment compliance, promote individualized care and obtain a person-centred care. Despite these benefits and a large number of promising projects, a major breakthrough in everyday care is generally still lacking. Inappropriate organization for eHealth technology, reluctance from users in the introduction of new working methods, and resistance to information and communication technology (ICT) in general could be reasons for this. Another reason may be attitudes towards the potential in out-of-hospital eHealth applications. It is therefore of interest to study the general opinions among healthcare professionals to ICT in healthcare, as well as the attitudes towards using ICT as a tool for patient monitoring and follow-up at home. One specific area of interest is in-home follow-up of elderly patients with chronic heart failure (CHF). The aim of this paper is to investigate the attitudes towards ICT, as well as distance monitoring and follow-up, among healthcare professionals working with this patient group. Method: This paper covers an attitude survey study based on responses from 139 healthcare professionals working with CHF care in Swedish hospital departments, i.e. cardiology and medicine departments. Comparisons between physicians and nurses, and in some cases between genders, on attitudes towards ICT tools and follow-up at home were performed. Results: Out of the 425 forms sent out, 139 were collected, and 17 out of 21 counties and regions were covered in the replies. Among the respondents, 66% were nurses, 30% physicians and 4% others. As for gender, 90% of nurses were female and 60% of physicians were male. Internet was used daily by 67% of the respondents. Attitudes towards healthcare ICT were found positive as 74% were positive concerning healthcare ICT today, 96% were positive regarding the future of healthcare ICT, and 54% had high confidence in healthcare ICT. Possibilities for distance monitoring/follow-up are good according to 63% of the respondents, 78% thought that this leads to increased patient involvement, and 80% thought it would improve possibilities to deliver better care. Finally, 72% of the respondents said CHF patients would benefit from home monitoring/follow-up to some extent, and 19% to a large extent. However, the best method of follow-up was considered to be home visits by nurse, or phone contact. Conclusion: The results indicate that a majority of the healthcare professionals in this study are positive to both current and future use of ICT tools in healthcare and home follow-up. Consequently other factors have to play an important role in the slow penetration of out-of-hospital eHealth applications in daily healthcare practice.

  • 24. Gund, Anna
    et al.
    Sjöqvist, Bengt Arne
    Wigert, Helena
    Hentz, Elisabet
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Bry, Kristina
    A randomized controlled study about the use of eHealth in the home health care of premature infants2013In: BMC Medical Informatics and Decision Making, ISSN 1472-6947, E-ISSN 1472-6947, Vol. 13, no 1, p. 22-Article in journal (Refereed)
    Abstract [en]

    Background: One area where the use of information and communication technology (ICT), or eHealth, could be developed is the home health care of premature infants. The aim of this randomized controlled study was to investigate whether the use of video conferencing or a web application improves parents' satisfaction in taking care of a premature infant at home and decreases the need of home visits. In addition, nurses' attitudes regarding the use of these tools were examined. Method: Thirty-four families were randomized to one of three groups before their premature infant was discharged from the hospital to home health care: a control group receiving standard home health care (13 families); a web group receiving home health care supplemented with the use of a web application (12 families); a video group with home health care supplemented with video conferencing using Skype (9 families). Families and nursing staff answered questionnaires about the usefulness of ICT. In addition, semi-structured interviews were conducted with 16 families. Results: All the parents in the web group found the web application easy to use. 83% of the families thought it was good to have access to their child's data through the application. All the families in the video group found Skype easy to use and were satisfied with the video calls. 88% of the families thought that video calls were better than ordinary phone calls. 33% of the families in the web group and 75% of those in the video group thought the need for home visits was decreased by the web application or Skype. 50% of the families in the web group and 100% of those in the video group thought the web application or the video calls had helped them feel more confident in caring for their child. Most of the nurses were motivated to use ICT but some were reluctant and avoided using the web application and video conferencing. Conclusion: The families were satisfied with both the web application and video conferencing. The families readily embraced the use of ICT, whereas motivating some of the nurses to accept and use ICT was a major challenge.

  • 25.
    Halvorsen, Kjartan
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Brechbühl, Simon
    ETH Zurich, Switzerland.
    Minimal set of markers for center of mass estimation in gravitational fall2009In: Proceedings of the ISB XXII Congress, 2009Conference paper (Refereed)
  • 26.
    Halvorsen, Kjartan
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Eriksson, Martin
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Nilsson, Johnny
    The Swedish School of Sport and Health Sciences.
    Tinmark, Fredrik
    The Swedish School of Sport and Health Sciences.
    Gullstrand, Lennart
    The Swedish Sport Confederation.
    The antero-posterior movement of the sacrum as an indicator of the antero-posterior movement of center of mass in running2011In: Proceedings of ECSS 16th Congress, 2011Conference paper (Refereed)
  • 27.
    Larsson, Malin
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering.
    Bjällmark, Anna
    KTH, School of Technology and Health (STH), Medical Engineering.
    Larsson, Matilda
    KTH, School of Technology and Health (STH), Medical Engineering.
    Caidahl, Kenneth
    Karolinska Institutet.
    Winter, Reidar
    KTH, School of Technology and Health (STH), Medical Engineering.
    Brodin, Lars-Åke
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    A new ultrasound-based approach to visualize target specific polymeric contrast agent2011In: 2011 IEEE International Ultrasonics Symposium (IUS), IEEE , 2011, p. 1626-1629Conference paper (Refereed)
    Abstract [en]

    There are advantages of using a polymeric shelled contrast agent (CA) during ultrasound imaging instead of lipid shelled CA, e.g. particles can be attached to the surface, which enables an introduction of antibodies to the surface making the CA target specific. For this application it is essential to have a sensitive imaging technique suitable for polymeric CA. However, previously presented results have indicated difficulties in visualizing polymeric CA with commercially available contrast algorithms. Therefore a new subtraction algorithm (SA), was developed that define the difference between contrast and reference images. The aim of this study was to evaluate the response from a polymeric CA, when using the SA and compare it with existing contrast algorithms. Moreover, the possibility to detect a thin layer of CA was tested using the SA.

    Ultrasound short-axis images of a tissue-mimicking vessel phantom with a pulsating flow were obtained using a GE Vivid7 system (M12L) and a Philips iE33 system (S5-1). Repeated (n=91) contrast to tissue ratios (CTR) calculated at various mechanical index (MI) using the contrast algorithms pulse inversion (PI), power modulation (PM) and SA at a concentration of 105microbubbles/ml.

    The developed SA showed improvements in CTR compared to existing contrast algorithms. The CTRs were -0.99 dB ± 0.67 (MI 0.2), 9.46 dB ± 0.77 (MI 0.4) and 2.98 dB ± 0.60 (MI 0.8) with PI, 8.17 dB ± 1.15 (MI 0.2), 15.60 dB ± 1.29 (MI0.4) and 11.60 dB ± 0.73 (MI 0.8) with PM and 14.97 dB ± 3.97 (MI 0.2), 20.89 dB ± 3.54 (MI 0.4) and 21.93 dB ± 4.37 (MI 0.8) with the SA. In addition to this, the layer detection, when using the SA was successful.

  • 28.
    Löfhede, Johan
    et al.
    University of Borås.
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Thordstein, Magnus
    Göteborg Universitet .
    Textile Electrodes for EEG Recording: A Pilot Study2012In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 12, no 12, p. 16907-16919Article in journal (Refereed)
    Abstract [en]

    The overall aim of our research is to develop a monitoring system for neonatal intensive care units. Long-term EEG monitoring in newborns require that the electrodes don’t harm the sensitive skin of the baby, an especially relevant feature for premature babies. Our approach to EEG monitoring is based on several electrodes distributed over the head of the baby, and since the weight of the head always will be on some of them, any type of hard electrode will inevitably cause a pressure-point that can irritate the skin. Therefore, we propose the use of soft conductive textiles as EEG electrodes, primarily for neonates, but also for other kinds of unobtrusive long-term monitoring. In this paper we have tested two types of textile electrodes on five healthy adults and compared them to standard high quality electrodes. The acquired signals were compared with respect to morphology, frequency distribution, spectral coherence, correlation and power line interference sensitivity, and the signals were found to be similar in most respects. The good measurement performance exhibited by the textile electrodes indicates that they are feasible candidates for EEG recording, opening the door for long-term EEG monitoring applications.

  • 29.
    Marquez, Juan Carlos
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Ferreira, Javier
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Buendia, Ruben
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Textile electrode straps for wrist-to-ankle bioimpedance measurements for Body Composition Analysis: Initial validation & experimental results2010In: 2010 ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY (EMBC), IEEE Engineering in Medicine and Biology Society , 2010, p. 6385-6388Conference paper (Refereed)
    Abstract [en]

    Electrical Bioimpedance (EBI) is one of the non-invasive monitoring technologies that could benefit from the emerging textile based measurement systems. If reliable and reproducible EBI measurements could be done with textile electrodes, that would facilitate the utilization of EBI-based personalized healthcare monitoring applications. In this work the performance of a custom-made dry-textile electrode prototype is tested. Four-electrodes ankle-to-wrist EBI measurements have been taken on healthy subjects with the Impedimed spectrometer SFB7 in the frequency range 5 kHz to 1 MHz. The EBI spectroscopy measurements taken with dry electrodes were analyzed via the Cole and Body Composition Analysis (BCA) parameters, which were compared with EBI measurements obtained with standard electrolytic electrodes. The analysis of the obtained results indicate that even when dry textile electrodes may be used for EBI spectroscopy measurements, the measurements present remarkable differences that influence in the Cole parameter estimation process and in the final production of the BCA parameters. These initial results indicate that more research work must be done to in order to obtain a textile-based electrode that ensures reliable and reproducible EBI spectroscopy measurements.

  • 30.
    Marquez, Juan Carlos
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Skin-electrode contact area in electrical bioimpedance spectroscopy. Influence in total body composition assessment2011In: Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS, IEEE Engineering In Medicine and Biology Society , 2011, Vol. 2011, p. 1867-1870Conference paper (Refereed)
    Abstract [en]

    Electrical Bioimpedance Spectroscopy (EBIS) has been widely used for assessment of total body composition and fluid distribution. (EBIS) measurements are commonly performed with electrolytic electrodes placed on the wrist and the ankle with a rather small skin-electrode contact area. The use of textile garments for EBI requires the integration of textrodes with a larger contact area surrounding the limbs in order to compensate the absence of electrolytic medium commonly present in traditional Ag/AgCl gel electrodes. Recently it has been shown that mismatch between the measurements electrodes might cause alterations on the EBIS measurements. When performing EBIS measurements with textrodes certain differences have been observed, especially at high frequencies, respect the same EBIS measurements using Ag/AgCl electrodes. In this work the influence of increasing the skin-electrode area on the estimation of body composition parameters has been studied performing experimental EBIS measurement. The results indicate that an increment on the area of the skin-electrode interface produced noticeable changes in the bioimpedance spectra as well as in the body composition parameters. Moreover, the area increment showed also an apparent reduction of electrode impedance mismatch effects. This influence must be taken into consideration when designing and testing textile-enable EBIS measurement systems.

  • 31. Marquez, Juan Carlos
    et al.
    Seoane, Fernando
    Välimäki, Elina
    University of Borås.
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Comparison of dry-textile electrodes for electrical bioimpedance spectroscopy measurements2010Conference paper (Refereed)
    Abstract [en]

    Textile Electrodes have been widely studied for biopotentials recordings, specially for monitoring the cardiac activity. Commercially available applications, such as Adistar T-shirt and Textronics Cardioshirt, have proved a good performance for heart rate monitoring and are available worldwide. Textile technology can also be used for Electrical Bioimpedance Spectroscopy measurements enabling home and personalized health monitoring applications however solid ground research about the measurement performance of the electrodes must be done prior to the development of any textile-enabled EBI application. In this work a comparison of the measurement performance of two different types of dry-textile electrodes and manufacturers has been performed against standardized RedDot 3M Ag/AgCl electrolytic electrodes. 4-Electrode, whole body, Ankle-to-Wrist EBI measurements have been taken with the Impedimed spectrometer SFB7 from healthy subjects in the frequency range of 3kHz to 500kHz. Measurements have been taken with dry electrodes at different times to study the influence of the interaction skin-electrode interface on the EBI measurements. The analysis of the obtained complex EBI spectra shows that the measurements performed with textile electrodes produce constant and reliable EBI spectra. Certain deviation can be observed at higher frequencies and the measurements obtained with Textronics and Ag/AgCl electrodes present a better resemblance. Textile technology, if successfully integrated it, may enable the performance of EBI measurements in new scenarios allowing the rising of novel wearable monitoring applications for home and personal care as well as car safety.

  • 32.
    Marquez Ruiz, Juan Carlos
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701).
    Sensor-Based Garments that Enable the Use of Bioimpedance Technology: Towards PersonalizedHealthcare Monitoring.2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Functional garments for physiological sensing purposes have been utilized in several disciplinesi.e. sports, firefighting, military and medical. In most of the cases textile electrodes (Textrodes)embedded in the garment are employed to monitor vital signs and other physiologicalmeasurements. Electrical Bioimpedance (EBI) is a non-invasive and effective technology that canbe used for detection and supervision of different health conditions. In some specific applicationssuch as body composition assessment EBIS has shown encouraging results proving good degreeof effectiveness and reliability. In a similar way Impedance Cardiography (ICG) is anothermodality of EBI primarily concerned with the determination of Stroke Volume SV, indices ofcontractility, and other aspects of hemodynamics.EBI technology in the previously mentioned modalities can benefit from a integration with agarment; however, a successful implementation of EBI technology depends on the goodperformance of textile electrodes. The main weakness of Textrodes is a deficient skin-electrodeinterface which produces a high degree of sensitivity to signal disturbances. This sensitivity canbe reduced with a suitable selection of the electrode material and an intelligent and ergonomicgarment design that ensures an effective skin-electrode contact area.This research work studies the performance of textile electrodes and garments for EBIspectroscopy for Total Body Assessment and Transthoracic Electrical Bioimpedance (TEB) forcardio monitoring. Their performance is analyzed based on impedance spectra, estimation ofparameters, influence of electrode polarization impedance Zep and quality of the signals using asreference Ag/AgCl electrodes. The study includes the analysis of some characteristics of thetextile electrodes such as conductive material, skin-electrode contact area size and fabricconstruction.The results obtained in this research work present evidence that textile garments with a dry skinelectrodeinterface like the ones used in research produce reliable EBI measurements in bothmodalities: BIS for Total Body Assessment and TEB for Impedance Cardiography. Textiletechnology, if successfully integrated, may enable the utilization of EBI in both modalities andconsequently implementing wearable applications for home and personal health monitoring.

  • 33.
    Marquez Ruiz, Juan Carlos
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701). University of Borås, Sweden.
    Rempfler, Markus
    University of Borås, Sweden.
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701). University of Borås, Sweden.
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701). Karolinska Institutet, Sweden.
    Textrode-enabled transthoracic electrical bioimpedance measurements: towards wearable applications of impedance cardiography2013In: Journal of Electrical Bioimpedance, ISSN 1891-5469, E-ISSN 1891-5469, Vol. 4, p. 45-50Article in journal (Refereed)
    Abstract [en]

    During the last decades the use of Electrical Bioimpedance (EBI) in the medical field has been subject of extensive research, especially since it is an affordable, harmless and non-invasive technology.

    In some specific applications such as body composition assessment where EBI has proven a good degree of effectiveness and reliability, the use of textile electrodes and measurement garments have shown a good performance and reproducible results.

    Impedance Cardiography (ICG) is another modality of EBI that can benefit from the implementation and use of wearable sensors. ICG technique is based on continuous impedance measurements of a longitudinal segment across the thorax taken at a single frequency. The need for specific electrode placement on the thorax and neck can be easily ensured with the use of a garment with embedded textile electrodes, textrodes. The first step towards the implementation of ICG technology into a garment is to find out if ICG measurements with textile sensors give a good enough quality of the signal to allow the estimation of the fundamental ICG parameters.

    In this work, the measurement performance of a 2-belt set with incorporated textrodes for thorax and neck was compared against ICG measurements obtained with Ag/AgCl electrodes. The analysis was based on the quality of the fundamental ICG signals (∆Z, dZ/dt and ECG), systolic time intervals and other ICG parameters. The obtained results indicate the feasibility of using textrodes for ICG measurements with consistent measurements and relatively low data dispersion. Thus, enabling the development of measuring garments for ICG measurements.

  • 34.
    Marquez Ruiz, Juan Carlos
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Textrode functional straps for bioimpedance measurements-experimental results for body composition analysis2013In: European Journal of Clinical Nutrition, ISSN 0954-3007, E-ISSN 1476-5640, Vol. 67, no SUPPL. 1, p. S22-S27Article in journal (Refereed)
    Abstract [en]

    Background/Objectives:Functional garments for physiological sensing purposes have been used in several disciplines, that is, sports, firefighting, military and medicine. In most of the cases, textile electrodes (textrodes) embedded in the garment are used to monitor vital signs and other physiological measurements. Electrical bioimpedance (EBI) is a non-invasive and effective technology that can be used for the detection and supervision of different health conditions.EBI technology could make use of the advantages of garment integration; however, a successful implementation of EBI technology depends on the good performance of textrodes. The main drawback of textrodes is a deficient skin-electrode interface that produces a high degree of sensitivity to signal disturbances. This sensitivity can be reduced with a suitable selection of the electrode material and an intelligent and ergonomic garment design that ensures an effective skin-electrode contact area.Subjects/Methods:In this work, textrode functional straps for total right side EBI measurements for body composition are presented, and its measurement performance is compared against the use of Ag/AgCl electrodes. Shieldex sensor fabric and a tetra-polar electrode configuration using the ImpediMed spectrometer SFB7 in the frequency range of 3-500 kHz were used to obtain and analyse the impedance spectra and Cole and body composition parameters.Results:The results obtained show stable and reliable measurements; the slight differences obtained with the functional garment do not significantly affect the computation of Cole and body composition parameters.Conclusions:The use of a larger sensor area, a high conductive material and an appropriate design can compensate, to some degree, for the charge transfer deficiency of the skin-electrode interface.

  • 35.
    Márquez Ruiz, Juan Carlos
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    On the Feasibility of Using Textile Electrodes for Electrical Bioimpedance Measurements2011Licentiate thesis, comprehensive summary (Other academic)
  • 36. Nilsson, Johnny
    et al.
    Tinmark, Fredrik
    Halvorsen, Kjartan
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Arndt, Anton
    Kinematic, kinetic and electromyographic adaptation to speed and resistance in double poling cross country skiing2013In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 113, no 6, p. 1385-1394Article in journal (Refereed)
    Abstract [en]

    This study incorporated variations in speed and the horizontal resistance acting upon elite female skiers during double poling (DP) on a treadmill and specifically analyzed biomechanical adaptations to these variations. Whole body kinematics and pole force data were recorded and used to calculate the moment of force acting on the shoulder and elbow joints. Data were obtained with a 3D optoelectronic system using reflective markers at given anatomical landmarks. Forces along the long axis of the right pole were measured with a piezoelectric force transducer. Surface electrodes were used to record EMG activity in the rectus femoris, rectus abdominis, latissimus dorsi and triceps brachii muscles. In a first set of recordings, the participants double poled with zero elevation at five different speeds from 8 to 17 km h(-1). In a second set of recordings, horizontal resistance was added by weights (0.4-1.9 kg) attached to a pulley system pulling the skier posteriorly during DP at 14 km h(-1). Results showed increasing relative duration of the thrust phase with increasing resistance, but not with speed. Significant kinematic differences occurred with increase in both speed and resistance. The mean (+/- SD) horizontal force components ranged between 1.7 (+/- 1.3) and 2.8 (+/- 1.1) percent (%) bodyweight (BW) in the speed adaptation and 3.1 (+/- 0.6) and 4.0 (+/- 1.3) % BW in the adaptation to horizontal resistance. Peak muscle activity showed a central to peripheral (proximo-distal) activation sequence. The temporal cycle phase pattern in the adaptation to speed and horizontal resistance differed.

  • 37.
    Parida, Vinit
    et al.
    Luleå University of Technology.
    Berglund, Anders
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Integrated Product Development.
    Sturm, Dennis
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Grimheden, Martin
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Facilitating the Learning Environment: Initiatives within the PIEp Research School2009Conference paper (Refereed)
    Abstract [en]

    Research schools have become common phenomena in the academic world. However, we find lack of studies investigating their influence and role in the academia. This study attempts to address this gap by describing how a specific research school has evolved into an effective learning environment for the enrolled PhD students. The Product Innovation Engineering program (PIEp) is currently the largest research initiative in Product Innovation in Sweden. The PIEp research school is a part of this program, with the aim to increase innovation capabilities in the Swedish industries. Through an action-based research approach the authors, who are research school participants themselves, present the processes and the chain of events to offer knowledge transfer and to give insight into this special research environment. In this pursuit, the findings are presented in three different themes,1) the role of common interest groups, 2) common interest group activities, and c) a tiger team workshop. This paper holds major implications for other research schools and funding organizations.

  • 38.
    Pau, Ivan
    et al.
    Universidad Politecnica de Madrid.
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701).
    Lindecrantz, Kaj
    Valero, Miguel Angel
    Universidad Politecnica de Madrid.
    Carracedo, Justo
    Universidad Politecnica de Madrid.
    Home e-health system integration in the Smart Home through a common media server.2009In: EMBC: 2009 ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY, VOLS 1-20, 2009, Vol. 2009, p. 6171-6174Conference paper (Refereed)
    Abstract [en]

    Home e-health systems and services are revealed as one of the most important challenges to promote Quality of Life related to Health in the Information Society. Leading companies have worked on e-health systems although the majority of them are addressed to hospital or primary care settings. The solution detailed in this paper offers a personal health system to be integrated with Smart Home services platform to support home based e-care. Thus, the home e-health system and architecture detailed in this research work is ready to supply a seamless personal care solution both from the biomedical data analysis, service provision, security guarantee and information management s point of view. The solution is ready to be integrated within the Accessible Digital Home, a living lab managed by Universidad Politécnica de Madrid for R&D activities.

  • 39.
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701).
    Electrical Bioimpedance Cerebral Monitoring: Fundamental Steps towards Clinical Application2007Doctoral thesis, comprehensive summary (Other academic)
  • 40.
    Seoane, Fernando
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Bouwstra, Sibrecht
    Technical University of Eindovhen.
    Marquez, Juan Carlos
    löfhede, johan
    Högskolan i Borås.
    Lindecrantz, Kaj
    Smart Textiles in Neonatal Monitoring: Enabling Unobtrusive Monitoring at the NICU2012In: Neonatal Monitoring Technologies: : Design for Integrated Solutions / [ed] W. Chen, S. Oetomo, & L. Feijs, IGI Global, 2012, p. -55Chapter in book (Other academic)
  • 41.
    Seoane, Fernando
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701).
    Bragós, Ramon
    Technical University of Catalonia.
    Lindecrantz, Kaj
    Current Source for Wideband Electrical Bioimpedance Spectroscopy Based on a Single Operational Amplifier2006In: WORLD CONGRESS ON MEDICAL PHYSICS AND BIOMEDICAL ENGINEERING 2006, VOL 14, PTS 1-6 / [ed] Kim, SI; Suh, TS, 2006, p. 707-710Conference paper (Refereed)
    Abstract [en]

    Traditionally, measurements of electrical bioimpedance for medical diagnostic purposes have used only low frequencies, usually below 100 kHz. The analysis focused only on the resistive part of the impedance; very often at low frequencies the reactive part of the impedance is negligible. Recent studies of the electrical bioimpedance spectrum, both real and imaginary parts, have indicated new potential applications e.g. detection of meningitis, skin cancer assessment and brain cellular edema detection. An important functional unit in a wideband impedance spectrometer is the current source used to inject the current into the tissue under study. A current source must provide an output current virtually constant over the frequency range of interest and independent of the load at the output. Several designs have been proposed over the years but the performance of them all degraded markedly near bellow 1 MHz e.g. Ackmann in 1993, Bragos et al in 1994 and Bertemes-Filho et al in 2000. The development of electronic technology has made available devices that allow us to obtain a current source with large output impedance, larger than 100 k Omega, above I MHz and based in a simple single Op-Amp circuit topology. Simulation results and experimental measurements are compared and the most important parameters of the VCCS are analytically studied and experimentally tested, including the dependency to changes in the circuit elements and the incidence of the Op-Amp parameters on the current source features.

  • 42.
    Seoane, Fernando
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Buendia, Ruben
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Gil-Pita, Roberto
    Department of Theory of the Signal and Communications, University of Alcala, Madrid, Spain.
    Cole parameter estimation from electrical bioconductance spectroscopy measurements2010In: 2010 ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY (EMBC), IEEE Press, 2010, Vol. 2010, p. 3495-3498Conference 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.

  • 43.
    Seoane, Fernando
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Ferreira, Javier
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Buendia, Ruben
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Adaptive frequency distribution for Electrical Bioimpedance Spectroscopy measurements2012In: Engineering in Medicine and Biology Society (EMBC), 2012 Annual International Conference of the IEEE, IEEE , 2012, p. 562-565Conference 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 useful for EBIS applications with high values of characteristic frequency, e.g. cerebral bioimpedance.

  • 44.
    Seoane, Fernando
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Ferreira, Javier
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Marquez, Juan Carlos
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Skrifvars, Mikael
    University of Borås.
    Conductive Polymer Films as Textrodes for Biopotential Sensing2011Conference paper (Other academic)
    Abstract [en]

    Introduction: After several years of progresses in textile technology and wearable measurement instrumentation, applications of wearable textile-electronics systems are arising providing a stable background for commercial applications. So far, the available commercial solutions are centered on fitness applications and mostly based in the acquisition of heart rate through Textile Electrodes (Textrodes) based on metallic threads or on conductive rubber compounds. Methods and Materials: In this work a novel material approach is presented to produce Textrodes for acquisition of Electrocardiographic (ECG) signals using a conductive polypropylene (PP1386 from Premix, Finland) polymer material. The polymer was film extruded into thin films, and used as such in the Textrode. Conductive Polymer Films (CPF) have been used to produce Textrodes, and its measurement performance has been compared with the ECG signals obtained with commercial Textrode fabrics and conventional Ag/AgCl electrodes. In order to set up the same measurement conditions, a chest strap tailored to host the testing electrodes has been used. Results: The close resemblance of the ECG acquired with the textile fabric electrodes, the Ag/AgCl electrodes and the PP1386 CPF electrodes suggest that the Polymer Electrodes PP1386 are a feasible alternative to the current textile fabrics that use silver thread as conductive material and also to conductive rubber material. Discussion & Conclusion: The availability of the Conductive Polymer Electrode PP1386 in a film form allows the manufacturing of electrodes by conventional textile processes, like lamination or sewing, therefore facilitating the transition from lab prototyping to industrial manufacturing. Replacing the traditional silver thread as conductive element in the fabrication of Textrodes will definitely reduce the material cost per Textrode. Biocompatibility issues and manufacturability issues must be addressed but the exhibited functional performance is showing encouraging results.

  • 45.
    Seoane, Fernando
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Ferreira, Javier
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Sanchéz, Juan José
    Bragós, Ramon
    Technical University of Catalonia.
    An analog front-end enables electrical impedance spectroscopy system on-chip for biomedical applications2008In: Physiological Measurement, ISSN 0967-3334, E-ISSN 1361-6579, Vol. 29, no 6, p. S267-78Article in journal (Refereed)
    Abstract [en]

    The increasing number of applications of electrical bioimpedance measurements in biomedical practice, together with continuous advances in textile technology, has encouraged several researchers to make the first attempts to develop portable, even wearable, electrical bioimpedance measurement systems. The main target of these systems is personal and home monitoring. Analog Devices has made available AD5933, a new system-on-chip fully integrated electrical impedance spectrometer, which might allow the implementation of minimum-size instrumentation for electrical bioimpedance measurements. However, AD5933 as such is not suitable for most applications of electrical bioimpedance. In this work, we present a relatively simple analog front-end that adapts AD5933 to a four-electrode strategy, allowing its use in biomedical applications for the first time. The resulting impedance measurements exhibit a very good performance in aspects like load dynamic range and accuracy. This type of minimum-size, system-on-chip-based bioimpedance measurement system would lead researchers to develop and implement light and wearable electrical bioimpedance systems for home and personal health monitoring applications, a new and huge niche for medical technology development.

  • 46.
    Seoane, Fernando
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701).
    Gawell, Johan
    Inerventions AB.
    Ferreira, Javier
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701).
    Wirstrand, Jonas
    Inerventions AB.
    Stretchable Circuit Board Technology enabling Seamless Textile-Electronic Integration for Electrical Muscle Stimulation Therapy2012Conference paper (Other academic)
  • 47.
    Seoane, Fernando
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701).
    Lindecrantz, Kaj
    Influence of the Skull and the Scalp on the Electrical Impedance of the Head and the Implications on Detection of Brain Cellular Edema2005In: IFMBE proceedings of the 12th International Conference on Biomedical Engineering, Singapore: Springer , 2005Conference paper (Refereed)
  • 48.
    Seoane, Fernando
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701).
    Lindecrantz, Kaj
    Olsson, Torsten
    Kjellmer, Ingemar
    Mallard, Carina
    Evolution of Cerebral Bioelectrical Resistance at Various Frequencies During Hypoxia in Fetal Sheep2004In: Australasian Physical & Engineering Sciences in Medicine, ISSN 0158-9938, Vol. 27, no 4Article in journal (Refereed)
  • 49.
    Seoane, Fernando
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Macias, Raul
    Technical University of Catalonia.
    Bragós, Ramon
    Technical University of Catalonia.
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Simple voltage-controlled current source for wideband electrical bioimpedance spectroscopy: circuit dependences and limitations2011In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 22, no 11Article in journal (Refereed)
    Abstract [en]

    In this work, the single Op-Amp with load-in-the-loop topology as a current source is revisited. This circuit topology was already used as a voltage-controlled current source (VCCS) in the 1960s but was left unused when the requirements for higher frequency arose among the applications of electrical bioimpedance (EBI). The aim of the authors is not only limited to show that with the currently available electronic devices it is perfectly viable to use this simple VCCS topology as a working current source for wideband spectroscopy applications of EBI, but also to identify the limitations and the role of each of the circuit components in the most important parameter of a current for wideband applications: the output impedance. The study includes the eventual presence of a stray capacitance and also an original enhancement, driving with current the VCCS. Based on the theoretical analysis and experimental measurements, an accurate model of the output impedance is provided, explaining the role of the main constitutive elements of the circuit in the source's output impedance. Using the topologies presented in this work and the proposed model, any electronic designer can easily implement a simple and efficient current source for wideband EBI spectroscopy applications, e.g. in this study, values above 150 kΩ at 1 MHz have been obtained, which to the knowledge of the authors are the largest values experimentally measured and reported for a current source in EBI at this frequency.

  • 50.
    Seoane, Fernando
    et al.
    School of Engineering, University of Borås.
    Marquez, Juan Carlos
    School of Engineering, University of Borås.
    Ferreira, Javier
    School of Engineering, University of Borås.
    Buendia, Ruben
    School of Engineering, University of Borås.
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    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] Anthony N. Laskovski, IN-TECH, 2011Chapter in book (Refereed)
12 1 - 50 of 61
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