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  • 1. Abtahi, F.
    et al.
    Gyllesten, I. C.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Seoane, Fernando
    University of Borås, School of Engineering.
    Software Tool for Analysis of Breathing Related Errors in Transthoracic Electrical Bioimpedance Spectroscopy Measurements2012Conference paper (Refereed)
  • 2. Abtahi, F
    et al.
    Seoane, F
    University of Borås, School of Engineering.
    Lindecrantz, K
    University of Borås, School of Engineering.
    Electrical bioimpedance spectroscopy in time-variant systems: Is undersampling always a problem?2014In: Journal of Electrical Bioimpedance, ISSN 1891-5469, E-ISSN 1891-5469, Vol. 5, no 1, p. 28-33Article in journal (Refereed)
    Abstract [en]

    During the last decades, Electrical Bioimpedance Spectroscopy (EBIS) has been applied mainly by using the frequency-sweep technique, across a range of many different applications. Traditionally, the tissue under study is considered to be time-invariant and dynamic changes of tissue activity are ignored by treating the changes as a noise source. A new trend in EBIS is simultaneous electrical stimulation with several frequencies, through the application of a multi-sine, rectangular or other waveform. This method can provide measurements fast enough to sample dynamic changes of different tissues, such as cardiac muscle. This high sampling rate comes at a price of reduction in SNR and the increase in complexity of devices. Although the frequency-sweep technique is often inadequate for monitoring the dynamic changes in a variant system, it can be used successfully in applications focused on the time-invariant or slowly-variant part of a system. However, in order to successfully use frequency-sweep EBIS for monitoring time-variant systems, it is paramount to consider the effects of aliasing and especially the folding of higher frequencies, on the desired frequency e.g. DC level. This paper discusses sub-Nyquist sampling of thoracic EBIS measurements and its application in the case of monitoring pulmonary oedema. It is concluded that by considering aliasing, and with proper implementation of smoothing filters, as well as by using random sampling, frequency-sweep EBIS can be used for assessing time-invariant or slowly-variant properties of time-variant biological systems, even in the presence of aliasing. In general, undersampling is not always a problem, but does always require proper consideration.

  • 3.
    Abtahi, Farhad
    et al.
    Karolinska Institutet.
    Anund, Anna
    Fors, Carina
    Seoane, Fernando
    University of Borås, Faculty of Textiles, Engineering and Business. University of Borås, Faculty of Caring Science, Work Life and Social Welfare. Karolinska Institutet.
    Lindecrantz, Kaj
    University of Borås, Faculty of Textiles, Engineering and Business. Karolinska Institutet.
    Association of Drivers’ sleepiness with heart rate variability. A Pilot Study with Drivers on Real Road2017Conference paper (Other academic)
  • 4. Abtahi, Farhad
    et al.
    Aslamy, Benjamin
    Boujabir, I
    Seoane, Fernando
    University of Borås, School of Health Science.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    An Affordable ECG and Respiration Monitoring System Based on Raspberry PI and ADAS1000: First Step towards Homecare Applications2014In: 16th Nordic-Baltic Conference on Biomedical Engineering / [ed] Mindedal H., Persson M., Springer International Publishing , 2014, p. 5-8Conference paper (Refereed)
    Abstract [en]

    Homecare is a potential solution for problems associated with an aging population. This may involve several physiological measurements, and hence a flexible but affordable measurement device is needed. In this work, we have designed an ADAS1000-based four-lead electrocardiogram (ECG) and respiration monitoring system. It has been implemented using Raspberry PI as a platform for homecare applications. ADuM chips based on iCoupler technology have been used to achieve electrical isolation as required by IEC 60601 and IEC 60950 for patient safety. The result proved the potential of Raspberry PI for the design of a compact, affordable, and medically safe measurement device. Further work involves developing a more flexible software for collecting measurements from different devices (measuring, e.g., blood pressure, weight, impedance spectroscopy, blood glucose) through Bluetooth or user input and integrating them into a cloud-based homecare system.

  • 5.
    Abtahi, Farhad
    et al.
    University of Borås, School of Health Science.
    Berndtsson, A
    University of Borås, School of Health Science.
    Abtahi, Shirin
    University of Borås, School of Health Science.
    Seoane, Fernando
    University of Borås, School of Health Science.
    Lindecrantz, Kaj
    KTH.
    Development and preliminary evaluation of an Android based heart rate variability biofeedback system2014Conference paper (Refereed)
    Abstract [en]

    The reduced Heart Rate Variability (HRV) is believed to be associated with several diseases such as congestive heart failure, diabetes and chronic kidney diseases (CKD). In these cases, HRV biofeedback may be a potential intervention method to increase HRV which in turn is beneficial to these patients. In this work, a real-time Android biofeedback application based on a Bluetooth enabled ECG and thoracic electrical bioimpedance (respiration) measurement device has been developed. The system performance and usability have been evaluated in a brief study with eight healthy volunteers. The result demonstrates real-time performance of system and positive effects of biofeedback training session by increased HRV and reduced heart rate. Further development of the application and training protocol is ongoing to investigate duration of training session to find an optimum length and interval of biofeedback sessions to use in potential interventions.

  • 6.
    Abtahi, Farhad
    et al.
    KTH-School of Technology and Health.
    Ji, Guangchao
    KTH-School of Technology and Health.
    Lu, Ke
    KTH-School of Technology and Health.
    Rödby, Kristian
    University of Borås, Faculty of Textiles, Engineering and Business.
    Björlin, Anders
    Kiwok AB.
    Östlund, Anders
    Kiwok AB.
    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.
    Textile-Electronic Integration in Wearable Measurement Garments for Pervasive Healthcare Monitoring2015Conference paper (Other academic)
  • 7.
    Abtahi, Farhad
    et al.
    KTH-School of Technology and Health.
    Ji, Guangchao
    KTH-School of Technology and Health.
    Lu, Ke
    KTH-School of Technology and Health.
    Rödby, Kristian
    University of Borås, Faculty of Textiles, Engineering and Business.
    Seoane, Fernando
    University of Borås, Faculty of Caring Science, Work Life and Social Welfare. KTH-School of Technology and Health.
    A knitted garment using intarsia technique for Heart Rate Variability biofeedback: Evaluation of initial prototype2015In: Proceedings of the 2015 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2015, p. 3121-3124Conference paper (Refereed)
  • 8.
    Abtahi, Farhad
    et al.
    KTH-School of Technology and Health.
    Lu, Ke
    KTH-School of Technology and Health.
    Dizon, M
    KTH-School of Technology and Health.
    Johansson, M
    KTH-School of Technology and Health.
    Seoane, Fernando
    University of Borås, Faculty of Caring Science, Work Life and Social Welfare. KTH-School of Technology and Health.
    Lindecrantz, Kaj
    University of Borås, Faculty of Caring Science, Work Life and Social Welfare. KTH-School of Technology and Health.
    Evaluating Atrial Fibrillation Detection Algorithm based on Heart Rate Variability analysis2015In: Medicinteknikdagarna, Uppsala: Svensk förening för medicinsk teknik och fysik , 2015Conference paper (Refereed)
  • 9.
    Abtahi, Farhad
    et al.
    KTH-School of Technology and Health.
    Lu, Ke
    KTH-School of Technology and Health.
    Dizon, M
    KTH-School of Technology and Health.
    Johansson, M
    KTH-School of Technology and Health.
    Seoane, Fernando
    University of Borås, Faculty of Caring Science, Work Life and Social Welfare. KTH-School of Technology and Health.
    Lindecrantz, Kaj
    University of Borås, Faculty of Caring Science, Work Life and Social Welfare. KTH-School of Technology and Health.
    Evaluation of Atrial Fibrillation Detection by using Heart Rate Variability analysis2015Conference paper (Other academic)
  • 10.
    Abtahi, Farhad
    et al.
    KTH-School of Technology and Health.
    Lu, Ke
    KTH-School of Technology and Health.
    Guangchao, Li
    KTH-School of Technology and Health.
    Rödby, Kristian
    University of Borås, Faculty of Textiles, Engineering and Business.
    Seoane, Fernando
    University of Borås, Faculty of Caring Science, Work Life and Social Welfare. KTH-School of Technology and Health.
    A Knitted Garment using Intarsia Technique for Heart Rate Variability Biofeedback: Evaluation of Initial Prototype.2015Conference paper (Other academic)
  • 11. Abtahi, Farhad
    et al.
    Snäll, Jonathan
    Aslamy, Benjamin
    Abtahi, Shirin
    Seoane, Fernando
    University of Borås, Faculty of Caring Science, Work Life and Social Welfare. KTH-School of Technology and Health.
    Lindecrantz, Kaj
    University of Borås, Faculty of Caring Science, Work Life and Social Welfare. KTH-School of Technology and Health.
    Biosignal PI, an Affordable Open-Source ECG and Respiration Measurement System2015In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 15, no 1, p. 93-109Article in journal (Refereed)
    Abstract [en]

    Bioimedical pilot projects e.g., telemedicine, homecare, animal and human trials usually involve several physiological measurements. Technical development of these projects is time consuming and in particular costly. A versatile but affordable biosignal measurement platform can help to reduce time and risk while keeping the focus on the important goal and making an efficient use of resources. In this work, an affordable and open source platform for development of physiological signals is proposed. As a first step an 8–12 leads electrocardiogram (ECG) and respiration monitoring system is developed. Chips based on iCoupler technology have been used to achieve electrical isolation as required by IEC 60601 for patient safety. The result shows the potential of this platform as a base for prototyping compact, affordable, and medically safe measurement systems. Further work involves both hardware and software development to develop modules. These modules may require development of front-ends for other biosignals or just collect data wirelessly from different devices e.g., blood pressure, weight, bioimpedance spectrum, blood glucose, e.g., through Bluetooth. All design and development documents, files and source codes will be available for non-commercial use through project website, BiosignalPI.org.

  • 12. Atefi, S. R.
    et al.
    Seoane, Fernando
    University of Borås, School of Engineering.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Electrical Bioimpedance Cerebral Monitoring.: Preliminary Results from Measurements on Stroke Patients2012Conference 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.

  • 13. Atefi, Seyed Reza
    et al.
    Seoane, Fernando
    University of Borås, School of Health Science.
    The Emergence of Electrical Bioimpedance Monitoring for Prompt Detection of Stroke Damage2014Conference paper (Refereed)
  • 14.
    Atefi, Seyed Reza
    et al.
    Harvard Univsersity.
    Seoane, Fernando
    University of Borås, Faculty of Caring Science, Work Life and Social Welfare. KTH-School of Technology and Health.
    Kamalian, Shervin
    Rosenthal, Eric
    Lev, Michael
    Massachussets University Hospital.
    Bonmassar, Giorgio
    Harvard University.
    Intracranial haemorrhage alters scalp potential distributions in bioimpedance cerebral monitoring applications: preliminary results from FEM simulation on a realistic head model and human subjects2016In: Medical Physics, ISSN 0094-2405, Vol. 43, no 2, p. 675-686Article in journal (Refereed)
    Abstract [en]

    Purpose:

    Current diagnostic neuroimaging for detection of intracranial hemorrhage (ICH) is limited to fixed scanners requiring patient transport and extensive infrastructure support. ICH diagnosis would therefore benefit from a portable diagnostic technology, such as electrical bioimpedance (EBI). Through simulations and patient observation, the authors assessed the influence of unilateral ICH hematomas on quasisymmetric scalp potential distributions in order to establish the feasibility of EBI technology as a potential tool for early diagnosis.

    Methods:

    Finite element method(FEM) simulations and experimental left–right hemispheric scalp potential differences of healthy and damaged brains were compared with respect to the asymmetry caused by ICH lesions on quasisymmetric scalp potential distributions. In numerical simulations, this asymmetry was measured at 25 kHz and visualized on the scalp as the normalized potential difference between the healthy and ICH damaged models. Proof-of-concept simulations were extended in a pilot study of experimental scalp potential measurements recorded between 0 and 50 kHz with the authors’ custom-made bioimpedance spectrometer. Mean left–right scalp potential differences recorded from the frontal, central, and parietal brain regions of ten healthy control and six patients suffering from acute/subacute ICH were compared. The observed differences were measured at the 5% level of significance using the two-sample Welch t-test.

    Results:

    The 3D-anatomically accurate FEM simulations showed that the normalized scalp potential difference between the damaged and healthy brainmodels is zero everywhere on the head surface, except in the vicinity of the lesion, where it can vary up to 5%. The authors’ preliminary experimental results also confirmed that the left–right scalp potential difference in patients with ICH (e.g., 64 mV) is significantly larger than in healthy subjects (e.g., 20.8 mV; P < 0.05).

    Conclusions:

    Realistic, proof-of-concept simulations confirmed that ICH affects quasisymmetric scalp potential distributions. Pilot clinical observations with the authors’ custom-made bioimpedance spectrometer also showed higher left–right potential differences in the presence of ICH, similar to those of their simulations, that may help to distinguish healthy subjects from ICH patients. Although these pilot clinical observations are in agreement with the computer simulations, the small sample size of this study lacks statistical power to exclude the influence of other possible confounders such as age, sex, and electrode positioning. The agreement with previously published simulation-based and clinical results, however, suggests that EBI technology may be potentially useful for ICH detection.

  • 15.
    Atefi, Seyed Reza
    et al.
    Harvard University.
    Seoane, Fernando
    University of Borås, Faculty of Caring Science, Work Life and Social Welfare. KTH-School of Technology and Health.
    Thorlin, Thorleif
    salhgrenska Hospital.
    Lindecrantz, Kaj
    KTH-School of Technology and Health.
    Stroke Damage Detection Using Classification Trees on Electrical Bioimpedance Cerebral Spectroscopy Measurements2013In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 13, no 8, p. 10074-10086Article in journal (Refereed)
  • 16.
    Ayllon, David
    et al.
    Universidad de Alcalá.
    Gil-Pita, Roberto
    Universidad de Alcalá.
    Seoane, Fernando
    University of Borås, Faculty of Textiles, Engineering and Business. KTH-School of Technology and Health.
    Detection and Classification of Measurement Errors in Bioimpedance Spectroscopy2016In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 6, article id e0156522Article in journal (Refereed)
    Abstract [en]

    Bioimpedance spectroscopy (BIS) measurement errors may be caused by parasitic stray capacitance, impedance mismatch, cross-talking or their very likely combination. An accurate detection and identification is of extreme importance for further analysis because in some cases and for some applications, certain measurement artifacts can be corrected, minimized or even avoided. In this paper we present a robust method to detect the presence of measurement artifacts and identify what kind of measurement error is present in BIS measurements. The method is based on supervised machine learning and uses a novel set of generalist features for measurement characterization in different immittance planes. Experimental validation has been carried out using a database of complex spectra BIS measurements obtained from different BIS applications and containing six different types of errors, as well as error-free measurements. The method obtained a low classification error (0.33%) and has shown good generalization. Since both the features and the classification schema are relatively simple, the implementation of this pre-processing task in the current hardware of bioimpedance spectrometers is possible.

  • 17. Ayllón, David
    et al.
    Seoane Martínez, Fernando
    University of Borås, School of Engineering.
    Gil-Pita, Roberto
    Cole Equation and Parameter Estimation from Electrical Bioimpedance Spectroscopy Measurements: A Comparative Study2009Conference paper (Other academic)
    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.

  • 18. Brown, Shannon
    et al.
    Ortiz-Catalan, Max
    Chalmers University of Technology.
    Petersson, Joel
    University of Borås, Faculty of Textiles, Engineering and Business.
    Rödby, Kristian
    University of Borås, Faculty of Textiles, Engineering and Business.
    Seoane, Fernando
    University of Borås, Faculty of Textiles, Engineering and Business. KTH-School of Technology and Health.
    Intarsia-sensorized band and textrodes for real-time myoelectric pattern recognition2016In: Engineering in Medicine and Biology Society (EMBC), 2016 IEEE 38th Annual International Conference of the, Institute of Electrical and Electronics Engineers (IEEE) , 2016, p. 6074-6077Conference paper (Refereed)
    Abstract [en]

    Surface Electromyography (sEMG) has applications in prosthetics, diagnostics and neuromuscular rehabilitation. Self-adhesive Ag/AgCl are the electrodes preferentially used to capture sEMG in short-term studies, however their long-term application is limited. In this study we designed and evaluated a fully integrated smart textile band with electrical connecting tracks knitted with intarsia techniques and knitted textile electrodes. Real-time myoelectric pattern recognition for motor volition and signal-to-noise ratio (SNR) were used to compare its sensing performance versus the conventional Ag-AgCl electrodes. After a comprehending measurement and performance comparison of the sEMG recordings, no significant differences were found between the textile and the Ag-AgCl electrodes in SNR and prediction accuracy obtained from pattern recognition classifiers.

  • 19. Brown, Shannon
    et al.
    Ortiz-Catalan, Max
    Chalmers University of Technology.
    Petersson, Joel
    University of Borås, Faculty of Textiles, Engineering and Business. Högskolan i Borås.
    Rödby, Kristian
    University of Borås, Faculty of Textiles, Engineering and Business.
    Seoane, Fernando
    University of Borås, Faculty of Textiles, Engineering and Business. KTH-School of Technology and Health.
    Intarsia-Sensorized Band and Textrodes for the Acquisition of Myoelectric Signals2016In: The Second International Conference on Smart Portable, Wearable, Implantable and Disability-oriented Devices and Systems, International Academy, Research and Industry Association (IARIA) , 2016, p. 14-19, article id 2_10_80013Conference paper (Refereed)
    Abstract [en]

    Surface Electromyography (sEMG) has applications in prosthetics, diagnostics and neuromuscular rehabilitation, and has been an increasing area of study. This study attempts to use a fully integrated smart textile band with electrical connecting tracks knitted with intarsia techniques to evaluate the quality of sEMG acquired by knitted textile electrodes. Myoelectric pattern recognition for motor volition and signal-to-noise ratio (SNR) were used to compare its sensing performance versus the conventional Ag-AgCl electrodes. Overall no significant differences were found between the textile and the Ag-AgCl electrodes in SNR and prediction accuracy obtained from pattern recognition classifiers. On average the textile electrodes produced a high prediction accuracy, >97% across all movements, which is equivalent to the accuracy obtained with conventional gel electrodes (Ag-AgCl). Furthermore the SNR for the Maximum Voluntary Contraction did not differ considerably between the textile and the Ag-AgCl electrodes.

  • 20.
    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.

  • 21.
    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.

  • 22. Buendia, Ruben
    et al.
    Seoane, Fernando
    University of Borås, School of Engineering.
    Bosaeus, Ingvar
    Gil-Pita, Roberto
    Johannsson, G
    Ellegård, Lars
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Robustness study of the different immittance spectra and frequency ranges in bioimpedance spectroscopy analysis for assessment of total body composition2014In: Physiological Measurement, ISSN 0967-3334, E-ISSN 1361-6579, ISSN 0967-3334, Vol. 35, no 7, p. 1373-Article in journal (Refereed)
    Abstract [en]

    The estimation of body fluids is a useful and common practice for assessment of disease status and therapy outcomes. Electrical bioimpedance spectroscopy (EBIS) methods are noninvasive, inexpensive and efficient alternatives for determination of body fluids. One of the main source of errors in EBIS measurements in the estimation of body fluids is capacitive coupling. In this paper an analysis of capacitive coupling in EBIS measurements was performed and the robustness of the different immittance spectra against it tested. On simulations the conductance (G) spectrum presented the smallest overall error, among all immittance spectra, in the estimation of the impedance parameters used to estimate body fluids. Afterwards the frequency range of 10–500 kHz showed to be the most robust band of the G spectrum. The accuracy of body fluid estimations from the resulting parameters that utilized G spectrum and parameters provided by the measuring device were tested on EBIS clinical measurements from growth hormone replacement therapy patients against estimations performed with dilution methods. Regarding extracellular fluid, the correlation between each EBIS method and dilution was 0.93 with limits of agreement of 1.06 ± 2.95 l for the device, 1.10 ± 2.94 l for G [10–500 kHz] and 1.04 ± 2.94 l for G [5–1000 kHz]. Regarding intracellular fluid, the correlation between dilution and the device was 0.91, same as for G [10–500 kHz] and 0.92 for G [5–1000 kHz]. Limits of agreement were 0.12 ± 4.46 l for the device, 0.09 ± 4.45 for G [10–500 kHz] and 0.04 ± 4.58 for G [5–1000 kHz]. Such close results between the EBIS methods validate the proposed approach of using G spectrum for initial Cole characterization and posterior clinical estimation of body fluids status.

  • 23. Buendia, Ruben
    et al.
    Seoane, Fernando
    University of Borås, School of Engineering.
    Gil-Pita, Roberto
    A Novel Approach for Removing the Hook Effect Artefact from Electrical Bioimpedance Spectroscopy Measurements2009In: Journal of Physics: Conference Series, Institute of Physics Publishing Ltd. , 2009Conference 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 consist on multiplying the obtained spectrum, Zmeas() by a complex exponential in the form of exp[jTd]. 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 real value for Td. First, a real value only modifies the phase of the measured impedance and second, it can only correct the Hook Effect at a single frequency. In addition, the process to select a value for 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 that includes 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.

  • 24.
    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)
  • 25.
    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)
  • 26.
    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.

  • 27.
    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.

  • 28.
    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.

  • 29.
    Chen, Wei
    et al.
    Fudan University.
    Augusto, Juan CarlosMiddlesex University.Seoane, FernandoUniversity of Borås, Faculty of Caring Science, Work Life and Social Welfare. KTH-School of Technology and Health.Ledhocki, FedorSlovak University of Technology.Arends, JohanTechnical University of Technology.Ungureanu, ConstantinHobo Heeze.Wichert, ReinerFraunhofer IGD.
    Recent Advances in Ambient Assisted Living: Bridging Assistive Technologies, e-Health and Personalized Health Care2015Collection (editor) (Refereed)
  • 30.
    Cheng, Jingyuan
    et al.
    German Research Center for Artificial Intelligence (DFKI).
    Zhou, Bo
    German Research Center for Artificial Intelligence (DFKI).
    Lukowicz, Paul
    German Research Center for Artificial Intelligence (DFKI).
    Seoane, Fernando
    University of Borås, Faculty of Textiles, Engineering and Business. University of Borås, Faculty of Caring Science, Work Life and Social Welfare. Karolinska Institutet.
    Varga, Matija
    ETH Zurich.
    Mehmann, Andreas
    ETH Zurich.
    Chabrecek, Peter
    SEFAR AG.
    Gaschler, Werner
    SEFAR AG.
    Goenner, Karl
    ITV Denkendorf.
    Horter, Hansjürgen
    ITV Denkendorf.
    Schneegass, Stefan
    Hassib, Mariam
    University of Stuttgart.
    Schmidt, Albrecht
    University of Stuttgart.
    Freund, Martin
    University of Passau.
    Zhang, Rui
    University of Passau.
    Amft, Oliver
    University of Passau.
    Textile Building Blocks:Toward Simple, Modularized, and Standardized Smart Textile2017In: Smart Textiles: Fundamentals, Design, and Interaction, Springer, Cham , 2017, p. 303-331Chapter in book (Refereed)
    Abstract [en]

    Textiles are pervasive in our life, covering human body and objects, as well as serving in industrial applications. In its everyday use of individuals, smart textile becomes a promising medium for monitoring, information retrieval, and interaction. While there are many applications in sport, health care, and industry, the state-of-the-art smart textile is still found only in niche markets. To gain mass-market capabilities, we see the necessity of generalizing and modularizing smart textile production and application development, which on the one end lowers the production cost and on the other end enables easy deployment. In this chapter, we demonstrate our initial effort in modularization. By devising types of universal sensing fabrics for conductive and non-conductive patches, smart textile construction from basic, reusable components can be made. Using the fabric blocks, we present four types of sensing modalities, including resistive pressure, capacitive, bioimpedance, and biopotential. In addition, we present a multi-channel textile–electronics interface and various applications built on the top of the basic building blocks by ‘cut and sew’ principle.

  • 31.
    Ferreira Gonzalez, Javier
    et al.
    University of Borås, School of Engineering.
    Seoane, Fernando
    University of Borås, School of Engineering.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    AD5933-Based Electrical Bioimpedance Spectrometer. Towards Textile-Enabled Applications.2011Conference paper (Refereed)
  • 32.
    Ferreira, Javier
    et al.
    KTH, Medicinsk teknik.
    Pau, Iván
    Universidad Politecnica de Madrid.
    Lindecrantz, Kaj
    KTH, Medicinsk teknik.
    Seoane, Fernando
    University of Borås, Faculty of Textiles, Engineering and Business. KTH-School of Technology and Health.
    A handheld and textile-enabled bioimpedance system for ubiquitous body composition analysis.: An initial functional validation2016In: IEEE journal of biomedical and health informatics, ISSN 2168-2194, E-ISSN 2168-2208, no 99Article in journal (Refereed)
    Abstract [en]

    In recent years, many efforts have been made to promote a healthcare paradigm shift from the traditional reactive hospital-centered healthcare approach towards a proactive, patient-oriented and self-managed approach that could improve service quality and help reduce costs while contributing to sustainability. Managing and caring for patients with chronic diseases accounts over 75% of healthcare costs in developed countries. One of the most resource demanding diseases is chronic kidney disease (CKD), which often leads to a gradual and irreparable loss of renal function, with up to 12% of the population showing signs of different stages of this disease. Peritoneal dialysis and home haemodialysis are life-saving home-based renal replacement treatments that, compared to conventional in-center hemodialysis, provide similar long-term patient survival, less restrictions of life-style, such as a more flexible diet, and better flexibility in terms of treatment options and locations. Bioimpedance has been largely used clinically for decades in nutrition for assessing body fluid distributions. Moreover, bioimpedance methods are used to assess the overhydratation state of CKD patients, allowing clinicians to estimate the amount of fluid that should be removed by ultrafiltration. In this work, the initial validation of a handheld bioimpedance system for the assessment of body fluid status that could be used to assist the patient in home-based CKD treatments is presented. The body fluid monitoring system comprises a custom-made handheld tetrapolar bioimpedance spectrometer and a textile-based electrode garment for total body fluid assessment. The system performance was evaluated against the same measurements acquired using a commercial bioimpedance spectrometer for medical use on several voluntary subjects. The analysis of the measurement results and the comparison of the fluid estimations indicated that both devices are equivalent from a measurement performance perspective, allowing for its use on ubiquitous e-healthcare dialysis solutions.

  • 33.
    Ferreira, Javier
    et al.
    University of Borås, School of Engineering.
    Seoane, Fernando
    University of Borås, School of Engineering.
    Ansede, Antonio
    Bragos, Ramon
    AD5933-based Spectrometer for Electrical Bioimpedance Applications2010In: Journal of Physics: Conference Series, Institute of Physics Publishing Ltd. , 2010Conference paper (Refereed)
    Abstract [en]

    To build an Electrical Bioimpedance (EBI) spectrometer using the Impedance Measurement System-On-Chip AD5933 together with a 4-Electrode Analog Front End (4E-AFE) has been proven practicable. Such small measurement devices can make possible several new applications of EBI technology, especially when combined with functional textiles, which can enable wearable applications for personal health and home monitoring. After the implementation and functional validation of the 4E-AFE-enabled spectrometer, the next natural step is to validate for which EBI applications the 4E-AFE-enabled system is suitable. To test the applicability of this novel spectrometer on several EBI applications, 2R1C equivalents models have been experimentally obtained and impedance spectroscopy measurements have been performed with the system under study and with the SFB7 EBI spectrometer manufactured by ImpediMed. The 2R1C circuit parameters have been estimated with the BioImp software from the spectra obtained with both EBI spectrometers and the estimated values have been compared with the original values used in each circuit model implementation. The obtained results indicated that the 4E-AFE-enabled system cannot beat the performance of the SFB7 in accuracy but it performs better in preciseness. In any case the overall performance indicates that the 4E-AFE-enabled system can perform spectroscopy measurements in the frequency range from 5 to 100 kHz.

  • 34.
    Garrote Jurado, Ramon
    et al.
    University of Borås, School of Engineering.
    Petersson, Tomas
    Christie, Michael
    Seoane, Fernando
    University of Borås, School of Engineering.
    Sigrén, Peter
    University of Borås, Centrum för lärande och undervisning.
    Training teachers in e-learning without Internet access2010In: Proceedings of EDULEARN10 Conference, 5th-7th July 2010, Barcelona, Spain., International Association of Technology, Education and Development , 2010, p. 6336-6341Conference paper (Refereed)
    Abstract [en]

    In this paper the authors present a solution to the problem of giving practical training in handling information and communication technology (ICT) without depending on internet access. The proposed method is to use an USB-memory to emulate selected educational resources that are otherwise available on the internet or on a local network. How this method can influence pedagogical issues is discussed and, it is asserted that the method offers interesting learning advantages beyond the obvious independence of internet connections. The paper describes the planning and implementation of a course about the use of Learning Management Systems (LMS) in higher education and, in particular, how it was designed to meet the needs of educators in a developing country with slow or unreliable internet connections. The course was a part of the project USo+I: Universidad, Sociedad e Innovación. Mejora de la pertinencia de la educación en las ingenierías de Latinoamérica (University and Society: Improving of the relevance of the education in the engineering of Latinoamerica) this project financed by the European Union, within the ALFA III program. The University of Borås was assigned to design and teach a course about LMS to engineering educators in Latin-America.

  • 35.
    Garrote Jurado, Ramon
    et al.
    University of Borås, School of Engineering.
    Seoane, Fernando
    University of Borås, School of Engineering.
    Christie, Michael
    Las tecnologias de la informacion y communicacion para actualizar education en la Universidad de Borås "Bättrekonceptet"/Information and Communication technologies for education updating at the University of Borås "Bättrekonceptet" (engelska)2009In: La educacion en ciencias e ingenieria. Calidad, innovacion pedagogica y cultura digital / [ed] N Valerias Esteban, E Campo Montalvo, E A Espinoza Montenegro, Universidad de Alcalá. Servicio de Publicaciones, Alcalá,España , 2009Chapter in book (Other academic)
  • 36.
    Hafid, Abdelakram
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business. University of Sciences and Technology Houari Boumediene.
    Benouar, Sara
    University of Borås, Faculty of Textiles, Engineering and Business.
    Kedir-Talha, Malika
    University of Sciences and Technology Houari Boumediene.
    Abtahi, Farhad
    Karolinska Institutet.
    Attari, Mokhtar
    University of Sciences and Technology Houari Boumediene.
    Seoane, Fernando
    University of Borås, Faculty of Textiles, Engineering and Business. University of Borås, Faculty of Caring Science, Work Life and Social Welfare. KTH-School of Technology and Health.
    Full Impedance Cardiography measurement device using Raspberry PI3 and System-on-Chip biomedical Instrumentation Solutions2017In: IEEE journal of biomedical and health informatics, ISSN 2168-2194, E-ISSN 2168-2208Article in journal (Refereed)
    Abstract [en]

    Impedance Cardiography (ICG) is a non-invasive method for monitoring cardiac dynamics using Electrical Bioimpedance (EBI) measurements. Since its appearance more than 40 years ago, ICG has been used for assessing hemodynamic parameters. This paper present a measurement system based on two System on Chip (SoC) solutions and Raspberry PI, implementing both a full 3-lead ECG recorder and an impedance cardiographer, for educational and research development purposes. Raspberry PI is a platform supporting Do-It-Yourself project and education applications across the world. The development is part of Biosignal PI, an open hardware platform focusing in quick prototyping of physiological measurement instrumentation. The SoC used for sensing cardiac biopotential is the ADAS1000, and for the EBI measurement is the AD5933. The recording were wirelessly transmitted through Bluetooth to a PC, where the waveforms were displayed, and hemodynamic parameters such as heart rate, stroke volume, ejection time and cardiac output were extracted from the ICG and ECG recordings. These results show how Raspberry PI can be used for quick prototyping using relatively widely available and affordable components, for supporting developers in research and engineering education. The design and development documents, will be available on www.BiosignalPI.com, for open access under a Non Commercial-Share A like 4.0 International License.

  • 37.
    Jiong, Sun
    et al.
    Högskolan i Skövde.
    Billing, Erik
    Högskolan i Skövde.
    Seoane, Fernando
    University of Borås, Faculty of Textiles, Engineering and Business. University of Borås, Faculty of Caring Science, Work Life and Social Welfare. Karolinska Institutet.
    Zhou, Bo
    DFKI.
    Högberg, Dan
    Högskolan i Skövde.
    Hemeren, Paul
    Högskolan i Skövde.
    Categories of touch: Classifying human touch using a soft tactile sensor2017In: The robotic sense of touch: From sensing to understanding, workshop at the IEEE International Conference on Robotics and Automation (ICRA), 29 May, Singapore., 2017Conference paper (Refereed)
  • 38. Löfhede, J.
    et al.
    Seoane, Fernando
    University of Borås, School of Engineering.
    Thordstein, M.
    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]

    Abstract: 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.

  • 39.
    Löfhede, Johan
    et al.
    University of Borås, School of Engineering.
    Seoane Martínez, Fernando
    University of Borås, School of Engineering.
    Thorstein, M.
    Soft Textile Electrodes for EEG Monitoring2010Conference paper (Refereed)
  • 40. Macias, Raul
    et al.
    Seoane, Fernando
    University of Borås, School of Engineering.
    Bragos, Ramon
    Performance of the Load-in-the-Loop Single Op-Amp Voltage Controlled Current Source from the Op-Amp Parameters2010In: Journal of Physics: Conference Series, Institute of Physics Publishing Ltd. , 2010Conference paper (Refereed)
    Abstract [en]

    In recent years, Electrical Bioimpedance (EBI) methods have gained importance. These methods are often based on obtaining impedance spectrum in the range of β-dispersion, i.e. from a few kHz up to some MHz. To measure EBI a constant current is often injected and the voltage across the tissue under study (TUS) is recorded. Due to the performance of the current source influences the performance of the entire system, in terms of frequency range, several designs have been implemented and studied. In this paper the basic structure of a Voltage-Controlled Current Source (VCCS) based on a single Op-Amp in inverter configuration with a floating load, known as load-in-the-loop current source, is revisited and studied deeply. We focus on the dependence of the output impedance with the circuit parameters, i.e. the feedback resistor and the inverter-input resistor, and the Op-Amp main parameters, i.e. open loop gain, CMRR and input impedance. After obtaining the experimental results and comparing to the theoretical and simulated ones, they confirm the design under study can be a good solution for multi-frequency wideband EBI applications because of higher values of the output impedance than 100kΩ at 1MHz are obtained. Furthermore, an enhancement of the basic design, using a current conveyor as a first stage, is proposed, studied and implemented.

  • 41.
    Malm, Veronica
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Nierstrasz, Vincent
    University of Borås, Faculty of Textiles, Engineering and Business.
    Seoane, Fernando
    University of Borås, Faculty of Textiles, Engineering and Business.
    Electrical resistance characterisations and durability of textile coatings containing metal flake fillers2018Conference paper (Refereed)
  • 42. Malm, Veronica
    et al.
    Seoane, Fernando
    University of Borås, Faculty of Caring Science, Work Life and Social Welfare. University of Borås, Faculty of Textiles, Engineering and Business.
    Nierstrasz, Vincent
    University of Borås, Faculty of Textiles, Engineering and Business.
    Characterisation of Electrical and Stiffness Properties of Conductive Textile Coatings with Metal Flake-shaped FillersIn: Smart materials and structures (Print), ISSN 0964-1726, E-ISSN 1361-665XArticle in journal (Refereed)
    Abstract [en]

    Two conductive formulations containing different types of micron-sized metal flakes (silver-coated copper (Cu) and pure silver (Ag)) were characterised and used to form highly electrically conductive coatings (conductors) on plain and basecoated woven fabrics, the latter in an encapsulated construction. With e-textiles as the intended application, the fabric stiffness, in terms of flexural rigidity and sheet resistance (Rsh), after durability testing (laundering and abrasion) was investigated and related to userfriendliness and long-term performance. Bare and encapsulated conductors with increasing amounts of deposited solids were fabricated by adjusting the knife coating parameters, such as the coating gap height (5, 20, 50 and 200 μm), which reduced the Rsh, as determined by four-point probe (4PP) measurements; however, this improvement was at the expense of increased flexural rigidity of the coated fabrics. The addition of a melamine derivative (MF) as a cross-linker to the Cu formulation and the encapsulation of both conductor types gave the best trade-off between durability andRsh, as confirmed by Fourier transform infrared (FTIR) spectroscopy and 4PP measurements. However, the infrared camera images revealed the formation of hotspots within the bare conductor matrix, although low resistances and no microstructural defects were detected by SEM. These results stress the importance of thorough investigation to assure the design of reliable conductors applied on textiles requiring this type of maintenance.

  • 43.
    Malm, Veronica
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Seoane, Fernando
    University of Borås, Faculty of Textiles, Engineering and Business.
    Nierstrasz, Vincent
    University of Borås, Faculty of Textiles, Engineering and Business.
    Fused deposition modelling – Towards 3D printed electrodes on fabric for surface electromyography (sEMG)2018Conference paper (Other academic)
    Abstract [en]

    Surface electromyography (sEMG) monitoring has promising applications within the field of human robot communication where wearable electrodes are used as the interface. This research investigates the production of flexible 3D printed electrodes using electrically conductive filaments, of thermoplastic polyurethane containing carbon black, and polyester fabric as substrate. Dry 3D printed electrodes of varying thickness, due to increased number of layers, were compared to conventional electrolytic gel electrodes. Initial tests show that the volume resistivity of 3D printed electrodes increased with increased number of layers. This because, with increased number of layers the diffusion between layers deteriorates and hinders conductive particle connections. Additional heat-treatments using hot press plates to improve diffusion between layers were promising as volume resistivity decreased with 200 % for all samples. As a first step to evaluate the 3D printed electrodes, skin-electrode impedance measurements were performed, and compared with measurements of conventional electrodes. Results showed that resistance and reactance versus frequency curves had similar trending slopes, decreasing with increasing frequency. However, this corresponded only between the thinnest (200 μm) 3D-printed dry electrode having a volume resistivity of 6.2 Ω cm and the conventional gel electrode. Future studies regarding the influence of platform and extruder temperature are planned for, focusing on improved diffusion between layers and increased conduction for proper electron transfer. 

  • 44. Malm, Veronica
    et al.
    Seoane, Fernando
    University of Borås, Faculty of Caring Science, Work Life and Social Welfare. University of Borås, Faculty of Textiles, Engineering and Business.
    Nierstrasz, Vincent
    University of Borås, Faculty of Textiles, Engineering and Business.
    Stability of encapsulated electrical interconnections coated on fabric exposed to mechanical strain.In: Composites Part B: Engineering, ISSN 1359-8368, E-ISSN 1879-1069Article in journal (Refereed)
    Abstract [en]

    In this study, two different conductive coating formulation containing silver (Ag) and silver-coated copper (Cu) flakes are studied to evaluate the electromechanical stabilityof encapsulated conductors coated on textiles in a multilayer construction. Consideringe-textiles as a possible application area with integrated conductors functioning as interconnections, the purpose is to obtain a fundamental understanding of the deformation behaviour when subjected to tensile and compressive strains during bending. The results show that an increased Ag conductor thickness with flakes <5 μm was a favourable combination regardless of encapsulation thickness providing samples with minimal stress responses upon bending deformations at angles of -180°, -90°, 90°and 180°, and, sheet resistance (Rsh) values of 0.01 Ω/sq. It was shown that the conductor layer changed shape depending on the bending angle resulting in alternating convex and concave arcs at -180° and a more uniform curvature at 180°. The findings were correlated to lower and larger Rsh ratios, respectively, which are denoted as the thinner encapsulated Ag conductors and the Cu conductors of different thicknesses, respectively. Up to ten repetitive bendings at angles between -180° and 180° did however induce stresses within the material resulting in an increased Rsh by a factor of>10.

  • 45.
    Marquez, J. C.
    et al.
    University of Borås, School of Engineering.
    Seoane Martínez, Fernando
    University of Borås, School of Engineering.
    Välimäki, E.
    University of Borås, Swedish School of Textiles.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    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.

  • 46.
    Marquez, Juan Carlos
    et al.
    University of Borås, School of Engineering.
    Seoane, Fernando
    University of Borås, School of Engineering.
    Välimaki, Elina
    University of Borås, Swedish School of Textiles.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Comparison of Dry-textile Electrodes for Electrical Bioimpedance Spectroscopy Measurements.2010In: Journal of Physics: Conference Series, Institute of Physics Publishing Ltd. , 2010Conference paper (Refereed)
    Abstract [en]

    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

  • 47.
    Marquez Ruiz, Juan Carlos
    et al.
    University of Borås, School of Engineering.
    Seoane, Fernando
    University of Borås, School of Engineering.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Skin-Electrode Contact Area in Electrical Bioimpedance Spectroscopy. Influence in Total Body Composition Assessment.2011Conference paper (Refereed)
    Abstract [en]

    Electrical Bioimpedance Spectroscopy (EBIS) has been widely use 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 skinelectrode area on the estimation of body composition parameters has been study performing experimental EBIS measurement. The results indicate that an increment on the area of the skin-electrode interface did produce noticeable changes in the bioimpedance spectra as well as in the body composition parameters. This influence must be taken into consideration when designing and testing textile-enable EBIS measurement systems.

  • 48.
    Mohino-Herranz, Inma
    et al.
    University of Alcala.
    Gil-Pita, Roberto
    University of Alcala.
    Ferreira, Javier
    University of Borås, Faculty of Caring Science, Work Life and Social Welfare. KTH-School of Technology and Health.
    Rosa-Zurera, Manuel
    University of Alcala.
    Seoane, Fernando
    University of Borås, Faculty of Caring Science, Work Life and Social Welfare. KTH-School of Technology and Health.
    Assessment of Mental, Emotional and Physical Stress through Analysis of Physiological Signals Using Smartphones2015In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 15, no 10, p. 25607-25627Article in journal (Refereed)
  • 49.
    Márquez, J.C.
    et al.
    University of Borås, School of Engineering.
    Seoane Martínez, Fernando
    University of Borås, School of Engineering.
    Välimäki, E.
    University of Borås, School of Engineering.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Textile Electrodes for Electrical Bioimpedance Measurements2009Conference paper (Other academic)
  • 50.
    Márquez, J.C.
    et al.
    University of Borås, School of Engineering.
    Seoane Martínez, Fernando
    University of Borås, School of Engineering.
    Välimäki, E.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Textile Electrodes in Electrical Bioimpedance Measurements: A Comparison with Conventional Ag/AgCl Electrodes2009Conference paper (Other academic)
    Abstract [en]

    Work has been intensified around the integration of textile and measurement technology for physiological measurements in the last years. As a result nowadays it is possible to find available commercial products for cardiovascular personal healthcare monitoring. Most of the efforts have been focused in the acquisition of EKG for cardiovascular monitoring where textile electrodes have shown satisfactory performance. Electrical Bioimpedance is another type of physiological measurement that can be used for personal healthcare monitoring where the integration and the performance of the textile electrodes has not been investigated that thoroughly. In this work, the influence of the textile electrodes on the measurements and on the estimation of the Cole (R-0,R-infinity, f(C) and a) and body composition (TBW, ICW, ECW and FFM) parameters has been especially addressed. Complex Spectroscopy 4-electrode wrist-to-ankle electrical bioimpedance measurements taken with conventional Ag/AgCl and textile-electrodes on customized bracelets have been compared and analyzed in the frequency range 3 to 500 kHz. The obtained results suggest that the use of textile electrodes do not influence remarkably on the complex spectral measurements neither in the estimation of Cole nor body composition parameter. In any case any possible effect introduced by the use of textile is smaller than the effect of preparing the skin by the using abrasive conductive paste.

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