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  • 51.
    Löfgren, N.
    et al.
    School of Engineering, Uiversity of Borås.
    Lindecrantz, Kaj
    School of Engineering, University of Borås.
    Flisberg, A.
    Department of Pediatrics, Queen Silvia Children's Hospital, Sahlgrenska University Hospital-Östra.
    Bågenholm, R.
    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.
    Thordstein, M.
    Department of Clinical Neurophysiology, Institute of Neuroscience and Physiology, Sahlgrenska University Hospital, Göteborg, Sweden.
    Spectral distance for ARMA models applied to electroencephalogram for early detection of hypoxia2006Ingår i: Journal of Neural Engineering, ISSN 1741-2560, Vol. 3, nr 3, s. 227-234Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A novel measure of spectral distance is presented, which is inspired by the prediction residual parameter presented by Itakura in 1975, but derived from frequency domain data and extended to include autoregressive moving average (ARMA) models. This new algorithm is applied to electroencephalogram (EEG) data from newborn piglets exposed to hypoxia for the purpose of early detection of hypoxia. The performance is evaluated using parameters relevant for potential clinical use, and is found to outperform the Itakura distance, which has proved to be useful for this application. Additionally, we compare the performance with various algorithms previously used for the detection of hypoxia from EEG. Our results based on EEG from newborn piglets show that some detector statistics divert significantly from a reference period less than 2 min after the start of general hypoxia. Among these successful detectors, the proposed spectral distance is the only spectral-based parameter. It therefore appears that spectral changes due to hypoxia are best described by use of an ARMA-model-based spectral estimate, but the drawback of the presented method is high computational effort.

  • 52.
    Löfgren, N.
    et al.
    School of Engineering, University of Borås.
    Lindecrantz, Kaj
    School of Engineering, University of Borås.
    Kjellmer, I.
    Department of Pediatrics, Queen Silvia Children's Hospital, Sahlgrenska University Hospital-Östra.
    Flisberg, A.
    Department of Pediatrics, Queen Silvia Children's Hospital, Sahlgrenska University Hospital-Östra.
    Bågenholm, R.
    Department of Pediatrics, Queen Silvia Children's Hospital, Sahlgrenska University Hospital-Östra.
    On evaluation of spectrum estimators for EEG2004Ingår i: Proceedings Of The 26th Annual International Conference Of The  IEEE Engineering In Medicine And Biology Society, IEEE , 2004, Vol. 1, s. 305-309Konferensbidrag (Refereegranskat)
    Abstract [en]

    In the search for how neonatal EEG is affected by asphyxia it is of importance to find reliable estimates of EEG power spectra. Several spectral estimation methods do exist, but since the true spectra are unknown it is hard to tell how well the estimators perform. Therefore a model to generate simulated EEG with known spectrum is proposed and the model is used to evaluate performance of several parametric and Fourier based spectral estimators.

  • 53.
    Löfgren, N.
    et al.
    School of Engineering, University of Borås.
    Lindecrantz, Kaj
    School of Engineering, University of Borås.
    Thordstein, M.
    Department of Clinical Neurophysiology, Institute of Neuroscience and Physiology, Sahlgrenska University Hospital, Göteborg, Sweden.
    Hedström, Anders
    Department of Clinical Neurophysiology, Institute of Neuroscience and Physiology, Sahlgrenska University Hospital, Göteborg, Sweden.
    Wallin, B Gunnar
    Department of Clinical Neurophysiology, Institute of Neuroscience and Physiology, Sahlgrenska University Hospital, Göteborg, Sweden.
    Andreasson, Svenerik
    Flisberg, Anders
    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.
    Remote sessions and frequency analysis for improved insight into cerebral function during pediatric and neonatal intensive care.2003Ingår i: IEEE transactions on information technology in biomedicine, ISSN 1089-7771, E-ISSN 1558-0032, Vol. 7, nr 4, s. 283-90Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A project involving recording and analysing EEG together with cardiovascular signals and temperature has been initiated. The aim of this project is to establish difficulties and possibilities involved with implementing a system for remote sessions and analysing EEG in correlation with other physiological signals. One objective is to find indicators of cerebral function during postasphyxia neonatal intensive care and pediatric cardiopulmonary bypass surgery with hypothermia. Remote sessions for joint interpretation have been carried out between pediatricians and clinical neurophysiologists, and EEG has been analyzed using frequency analyzing tools. One result is the discovery of reversible spectral changes coinciding with blood pressure falls, which may indicate loss of autoregulation function. This finding is one outcome from initial use of a system, developed during the project to facilitate communication about, and analysis of the recorded signals. Thus, already from a limited number of remote sessions and the use of basic signal processing techniques, important results have been achieved and better insight has been gained of how cerebral function is affected by cardiopulmonary bypass surgery. In this paper, we present our experiences from introducing a system for remote consultations, and evaluate the use for such a system in the current applications.

  • 54.
    Löfhede, J.
    et al.
    University of Borås.
    Degerman, J.
    Chalmers University of Technology.
    Löfgren, N.
    Neoventa AB.
    Thordstein, M.
    Department of Clinical Neurophysiology, Institute of Neuroscience and Physiology, Sahlgrenska University Hospital, Göteborg, Sweden.
    Flisberg, Anders
    Sahlgrenska Akademin, Göteborg universitet.
    Kjellmer, I.
    Department of Pediatrics, Queen Silvia Children's Hospital, Sahlgrenska University Hospital-Östra.
    Lindecrantz, Kaj
    University College of Borås.
    Comparing a supervised and an unsupervised classification method for burst detection in neonatal EEG2008Ingår i: Proceedings of the 30th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS'08 - "Personalized Healthcare through Technology", IEEE , 2008, Vol. 2008, s. 3836-3839Konferensbidrag (Refereegranskat)
    Abstract [en]

    Hidden Markov Models (HMM) and Support Vector Machines (SVM) using unsupervised and supervised training, respectively, were compared with respect to their ability to correctly classify burst and suppression in neonatal EEG. Each classifier was fed five feature signals extracted from EEG signals from six full term infants who had suffered from perinatal asphyxia. Visual inspection of the EEG by an experienced electroencephalographer was used as the gold standard when training the SVM, and for evaluating the performance of both methods. The results are presented as receiver operating characteristic (ROC) curves and quantified by the area under the curve (AUC). Our study show that the SVM and the HMM exhibit similar performance, despite their fundamental differences.

  • 55.
    Löfhede, J.
    et al.
    School of Engineering, University of Borås.
    Löfgren, N.
    School of Engineering, University of Borås.
    Thordstein, M.
    Department of Clinical Neurophysiology, Institute of Neuroscience and Physiology, Sahlgrenska University Hospital, Göteborg, Sweden.
    Flisberg, A.
    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.
    Lindecrantz, Kaj
    School of Engineering, University of Borås.
    Classifying burst and suppression in the EEG of post asphyctic newborns using a support vector machine2007Ingår i: Proceedings of the 3rd International IEEE EMBS Conference on Neural Engineering, IEEE , 2007, s. 630-633Konferensbidrag (Refereegranskat)
    Abstract [en]

    A Support Vector Machine (SVM) was trained to distinguish bursts from suppression in burst-suppression EEG, using Ave features inherent in the electro-encephalogram (EEG) as input. The study was based on data from six full term infants who had suffered from perinatal asphyxia, and the machine was trained with reference classifications made by an experienced electroencephalographer. The results show that the method may be useful, but that differences between patients in the data set makes optimization of the system difficult.

  • 56.
    Löfhede, J.
    et al.
    School of Engineering, University of Borås.
    Löfgren, N.
    Neoventa Medical AB, Göteborg.
    Thordstein, M.
    Department of Clinical Neurophysiology, Institute of Neuroscience and Physiology, Sahlgrenska University Hospital, Göteborg, Sweden.
    Flisberg, A.
    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.
    Lindecrantz, Kaj
    School of Engineering, University College of Borås.
    Comparison of three methods for classifying burst and suppression in the EEG of post asphyctic newborns2007Ingår i: 2007 ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY, VOLS 1-16, IEEE , 2007, Vol. 2007, s. 5136-5139Konferensbidrag (Refereegranskat)
    Abstract [en]

    Fisher's linear discriminant, a feed-forward neural network (NN) and a support vector machine (SVM) are compared with respect to their ability to distinguish bursts from suppression in burst-suppression electroencephalogram (EEG) signals using five features inherent in the EEG as input. The study is based on EEG signals from six full term infants who have suffered from perinatal asphyxia, and the methods have been trained with reference data classified by an experienced electroencephalographer. The results are summarized as area under the curve (AUC) values derived from receiver operating characteristic (ROC) curves for the three methods, and show that the SVM is slightly better than the others, at the cost of a higher computational complexity.

  • 57.
    Löfhede, J.
    et al.
    School of Engineering, University of Borås.
    Löfgren, N.
    School of Engineering, University of Borås.
    Thordstein, M.
    Department of Clinical Neurophysiology, Institute of Neuroscience and Physiology, Sahlgrenska University Hospital, Göteborg, Sweden.
    Flisberg, A.
    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.
    Lindecrantz, Kaj
    School of Engineering, University of Borås.
    Detection of bursts in the EEG of post asphyctic newborns2006Ingår i: 2006 28th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2006, Vol. 1, s. 2179-2182Konferensbidrag (Refereegranskat)
    Abstract [en]

    Eight features inherent in the electroencephalogram (EEG) have been extracted and evaluated with respect to their ability to distinguish bursts from suppression in burst-suppression EEG. The study is based on EEG from six full term infants who had suffered from lack of oxygen during birth. The features were used as input in a neural network, which was trained on reference data segmented by an experienced electroencephalographer. The performance was then evaluated on validation data for each feature separately and in combinations. The results show that there are significant variations in the type of activity found in burst-suppression EEG from different subjects, and that while one or a few features seem to be sufficient for most patients in this group, some cases require specific combinations of features for good detection to be possible.

  • 58.
    Löfhede, J.
    et al.
    School of Engineering, University of Borås.
    Löfgren, N.
    Neoventa Medical AB, Göteborg.
    Thordstein, M.
    Department of Clinical Neurophysiology, Institute of Neuroscience and Physiology, Sahlgrenska University Hospital, Göteborg, Sweden.
    Kjellmer, I.
    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.
    Lindecrantz, Kaj
    School of Engineering, University of Borås.
    Classification of burst and suppression in the neonatal electroencephalogram2008Ingår i: Journal of Neural Engineering, ISSN 1741-2560, Vol. 5, nr 4, s. 402-410Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fisher's linear discriminant (FLD), a feed-forward artificial neural network (ANN) and a support vector machine (SVM) were compared with respect to their ability to distinguish bursts from suppressions in electroencephalograms (EEG) displaying a burst-suppression pattern. Five features extracted from the EEG were used as inputs. The study was based on EEG signals from six full-term infants who had suffered from perinatal asphyxia, and the methods have been trained with reference data classified by an experienced electroencephalographer. The results are summarized as the area under the curve (AUC), derived from receiver operating characteristic (ROC) curves for the three methods. Based on this, the SVM performs slightly better than the others. Testing the three methods with combinations of increasing numbers of the five features shows that the SVM handles the increasing amount of information better than the other methods.

  • 59.
    Löfhede, Johan
    et al.
    Högskolan i Borås.
    Thordstein, Magnus
    Sahlgrenska Akademin, Göteborg universitet.
    Löfgren, Nils
    Högskolan i Borås.
    Flisberg, Anders
    Sahlgrenska Akademin, Göteborg universitet.
    Rosa-Zurera, Manuel
    Universidad de Alcalá.
    Kjellmer, Ingemar
    Sahlgrenska Akademin, Göteborg universitet.
    Lindecrantz, Kaj
    Högskolan i Borås.
    Automatic classification of background EEG activity in healthy and sick neonates2010Ingår i: Journal of Neural Engineering, ISSN 1741-2560, Vol. 7, nr 1, s. 016007-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The overall aim of our research is to develop methods for a monitoring system to be used at neonatal intensive care units. When monitoring a baby, a range of different types of background activity needs to be considered. In this work, we have developed a scheme for automatic classification of background EEG activity in newborn babies. EEG from six full-term babies who were displaying a burst suppression pattern while suffering from the after-effects of asphyxia during birth was included along with EEG from 20 full-term healthy newborn babies. The signals from the healthy babies were divided into four behavioural states: active awake, quiet awake, active sleep and quiet sleep. By using a number of features extracted from the EEG together with Fisher's linear discriminant classifier we have managed to achieve 100% correct classification when separating burst suppression EEG from all four healthy EEG types and 93% true positive classification when separating quiet sleep from the other types. The other three sleep stages could not be classified. When the pathological burst suppression pattern was detected, the analysis was taken one step further and the signal was segmented into burst and suppression, allowing clinically relevant parameters such as suppression length and burst suppression ratio to be calculated. The segmentation of the burst suppression EEG works well, with a probability of error around 4%.

  • 60.
    Marquez, Juan Carlos
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS).
    Ferreira, Javier
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS).
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS).
    Buendia, Ruben
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS).
    Textile electrode straps for wrist-to-ankle bioimpedance measurements for Body Composition Analysis: Initial validation & experimental results2010Ingår i: 2010 ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY (EMBC), IEEE Engineering in Medicine and Biology Society , 2010, s. 6385-6388Konferensbidrag (Refereegranskat)
    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.

  • 61.
    Marquez, Juan Carlos
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS).
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS).
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS).
    Skin-electrode contact area in electrical bioimpedance spectroscopy. Influence in total body composition assessment2011Ingår i: 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, s. 1867-1870Konferensbidrag (Refereegranskat)
    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.

  • 62.
    Marquez, Juan Carlos
    et al.
    Univerisity of Borås.
    Seoane, Fernando
    University of Borås.
    Välimäki, E.
    Lindecrantz, Kaj
    University of Borås.
    Textile electrodes in Electrical Bioimpedance measurements - a comparison with conventional Ag/AgCl electrodes2009Ingår i: EMBC: 2009 ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY, VOLS 1-20, IEEE , 2009, Vol. 2009, s. 4816-4819Konferensbidrag (Refereegranskat)
    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 alpha) 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.

  • 63. Marquez, Juan Carlos
    et al.
    Seoane, Fernando
    Välimäki, Elina
    University of Borås.
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS).
    Comparison of dry-textile electrodes for electrical bioimpedance spectroscopy measurements2010Konferensbidrag (Refereegranskat)
    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.

  • 64.
    Marquez Ruiz, Juan Carlos
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS) (Stängd 20130701). University of Borås, Sweden.
    Rempfler, Markus
    University of Borås, Sweden.
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS) (Stängd 20130701). University of Borås, Sweden.
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS) (Stängd 20130701). Karolinska Institutet, Sweden.
    Textrode-enabled transthoracic electrical bioimpedance measurements: towards wearable applications of impedance cardiography2013Ingår i: Journal of Electrical Bioimpedance, ISSN 1891-5469, E-ISSN 1891-5469, Vol. 4, s. 45-50Artikel i tidskrift (Refereegranskat)
    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.

  • 65.
    Marquez Ruiz, Juan Carlos
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS).
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS).
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS).
    Textrode functional straps for bioimpedance measurements-experimental results for body composition analysis2013Ingår i: European Journal of Clinical Nutrition, ISSN 0954-3007, E-ISSN 1476-5640, Vol. 67, nr SUPPL. 1, s. S22-S27Artikel i tidskrift (Refereegranskat)
    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.

  • 66.
    Pau, Ivan
    et al.
    Universidad Politecnica de Madrid.
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS) (Stängd 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.2009Ingår i: EMBC: 2009 ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY, VOLS 1-20, 2009, Vol. 2009, s. 6171-6174Konferensbidrag (Refereegranskat)
    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.

  • 67.
    Sandsjö, L.
    et al.
    National Institute of Working Life, Gothenburg.
    Berglin, L.
    School of Textiles, University of Borås.
    Wiklund, U.
    Engineering and Informatics, Univeristy Hospital of Umeå.
    Karlsson, M.
    Engineering and Informatics, Univeristy Hospital of Umeå.
    Östlund, N.
    Engineering and Informatics, Univeristy Hospital of Umeå.
    Bäcklund, T.
    Engineering and Informatics, Univeristy Hospital of Umeå.
    Lindecrantz, Kaj
    School of Engineering, University of Borås.
    Karlsson, S.
    Engineering and Informatics, Univeristy Hospital of Umeå.
    Self-Administered Longterm Ambulatory Monitoring of Electrophysiological Signals Based on Smart Textiles2006Konferensbidrag (Refereegranskat)
  • 68.
    Seoane, Fernando
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system. University of Borås, Sweden.
    Atefi, seyed Reza
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Jens, Tomner
    Karolinska Hospital.
    Kostulas, Konstantinos
    Karolinska Institute, Department of Neurology.
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Electrical Bioimpedance Spectroscopy on Acute Unilateral Stroke Patients: Initial Observations regarding Differences between Sides2015Ingår i: BioMed Research International, ISSN 2314-6133, E-ISSN 2314-6141, Vol. 2015, artikel-id 613247Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose. Electrical Bioimpedance Cerebral Monitoring is assessment in real time of health of brain tissue through study of passive dielectric properties of brain. During the last two decades theory and technology have been developed in parallel with animal experiments aiming to confirm feasibility of using bioimpedance-based technology for prompt detection of brain damage. Here, for the first time, we show that electrical bioimpedance measurements for left and right hemispheres are significantly different in acute cases of unilateral stroke within 24 hours from onset. Methods. Electrical BIS measurements have been taken in healthy volunteers and patients suffering from acute stroke within 24 hours of onset. BIS measurements have been obtained using SFB7 bioimpedance spectrometer manufactured by Impedimed ltd. and 4-electrode method. Measurement electrodes, current, and voltage have been placed according to 10–20 EEG system obtaining mutual BIS measurements from 4 different channels situated in pairs symmetrically from the midsagittal line. Obtained BIS data has been analyzed, assessing for symmetries and differences regarding healthy control data.Results. 7 out of 10 patients for Side-2-Side comparisons and 8 out 10 for central/lateral comparison presented values outside the range defined by healthy control group. When combined only 1 of 10 patients exhibited values within the healthy range. Conclusions. If these initial observations are confirmed with more patients, we can foresee emerging of noninvasive monitoring technology for brain damage with the potential to lead to paradigm shift in treatment of brain stroke and traumatic brain damage.

  • 69.
    Seoane, Fernando
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (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 NICU2012Ingår i: Neonatal Monitoring Technologies: : Design for Integrated Solutions / [ed] W. Chen, S. Oetomo, & L. Feijs, IGI Global, 2012, s. -55Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 70.
    Seoane, Fernando
    et al.
    School of Engineering, University College of Borås.
    Bragós, Ramon
    Department of Electronic Engineering, Technical University of Catalonia.
    Lindecrantz, Kaj
    School of Engineering, University College of Borås.
    Current Source for Multifrequency Broadband Electrical Bioimpedance Spectroscopy Systems: A Novel Approach2006Ingår i: 2006 28th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, Vols 1-15, 2006, s. 5121-5125Konferensbidrag (Refereegranskat)
    Abstract [en]

    New research and clinical applications of broadband electrical bioimpedance spectroscopy arise; increasing the upper limit frequency used in the measurement systems. The current source, an essential block of an electrical bioimpedance impedance analyzer, must have a large-enough output impedance at any frequency of operation to keep the output current constant regardless of the value of working load. In this paper a novel approach to increase the output impedance of a common voltage controlled current source is proposed. The circuit is analyzed, implemented and tested. The results, remarking the significant effect of the circuit parasitic capacitances, show a clear increment of the output impedance, but smaller than the originally expected

  • 71.
    Seoane, Fernando
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS) (Stängd 20130701).
    Bragós, Ramon
    Technical University of Catalonia.
    Lindecrantz, Kaj
    Current Source for Wideband Electrical Bioimpedance Spectroscopy Based on a Single Operational Amplifier2006Ingår i: WORLD CONGRESS ON MEDICAL PHYSICS AND BIOMEDICAL ENGINEERING 2006, VOL 14, PTS 1-6 / [ed] Kim, SI; Suh, TS, 2006, s. 707-710Konferensbidrag (Refereegranskat)
    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.

  • 72. Seoane, Fernando
    et al.
    Bragós, Ramon
    Technical University of Catalonia.
    Lindecrantz, Kaj
    Högskolan i Borås.
    Riu, Pere
    Technical University of Catalonia.
    Current Source Design for Electrical Bioimpedance Spectroscopy2008Ingår i: Encyclopedia of Healthcare Information Systems / [ed] N. Wickramasinghe, & E. Geisler, IGI Global, 2008, s. 359-367Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    The passive electrical properties of biological tissue have been studied since the 1920s, and with time, the use of Electrical Bioimpedance (EBI) in medicine has successfully spread (Schwan, 1999). Since the electrical properties of tissue are frequency-dependent (Schwan, 1957), observations of the bioimpedance spectrum have created the discipline of Electrical Impedance Spectroscopy (EIS), a discipline that has experienced a development closely related to the progress of electronic instrumentation and the dissemination of EBI technology through medicine.

  • 73.
    Seoane, Fernando
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS).
    Ferreira, Javier
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS).
    Buendia, Ruben
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS).
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS).
    Adaptive frequency distribution for Electrical Bioimpedance Spectroscopy measurements2012Ingår i: Engineering in Medicine and Biology Society (EMBC), 2012 Annual International Conference of the IEEE, IEEE , 2012, s. 562-565Konferensbidrag (Refereegranskat)
    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.

  • 74.
    Seoane, Fernando
    et al.
    Högskolan i Borås.
    Lindecrantz, Kaj
    Högskolan i Borås.
    A Novel Approach for Estimation of Electrical Bioimpedance: Total Least Square2007Ingår i: 13TH INTERNATIONAL CONFERENCE ON ELECTRICAL BIOIMPEDANCE AND THE 8TH CONFERENCE ON ELECTRICAL IMPEDANCE TOMOGRAPHY 2007, 2007, s. 190-193Konferensbidrag (Refereegranskat)
    Abstract [en]

    There are several methods used for AC-impedance estimation in Electrical Bioimpedance measurements. In this paper we propose a novel method for digital estimation of electrical impedance based in the Total Least Square (TLS) technique and we carry out a performance comparison between the proposed method and the typical Digital Sine Correlation (DSC) method. The TLS method has been implemented using the Singular Value Decomposition approach and the performance of both methods have been compared in terms of robustness against noise and size of the data set. The results indicate that the TLS method shows a better performance for impedance estimation than the DSC with reduced set of measurement samples and high SNR levels, while its performance worsen for increasing number of samples and decreasing SNR. The DSC method exhibits a better robustness against noise, especially for increasing the number of data samples. The main observed advantage of the TLS method is that it suffers from less mathematical constrains than the DSC method, and since the noise levels in bioimpedance applications are not expected to be very high we conclude that the TLS method is a good choice as impedance estimator.

  • 75.
    Seoane, Fernando
    et al.
    Högskolan i Borås.
    Lindecrantz, Kaj
    Högskolan i Borås.
    Electrical Bioimpedance Cerebral Monitoring2008Ingår i: Encyclopedia of Healthcare Information Systems / [ed] N. Wickramasinghe, & E. Geisler, IGI Global, 2008, s. 480-486Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Electrical Bioimpedance (EBI) is now a mature technology in medicine, with applications in clinical investigations, physiological research, and medical diagnosis (Schwan, 1999). The first monitoring application of bioimpedance techniques, impedance cardiography, date back to 1940. Since then, bioimpedance measurements have been used in several medical applications, from lung function monitoring and body composition, to skin cancer detection. A complete historical review is available in Malmivuo and Plonsey (1995). A medical imaging modality based on bioimpedance, Electrical Impedance Tomography (EIT) has also been developed. EBI has been used to study the effect in the brain of spreading depression, seizure activity, asphyxia and cardiac arrest since 1950s and 1960s (Ochs & Van Harreveld, 1956), but the most important activities in electrical cerebral bioimpedance research has been during the last 20 years (Holder, 1987; Holder & Gardner-Medwin, 1988).

  • 76.
    Seoane, Fernando
    et al.
    Chalmers University of Technology.
    Lindecrantz, Kaj
    Chalmers University of Technology.
    Enhancement of a Voltage Controlled Current Source for Wideband Electrical Bioimpedance Spectroscopy2006Ingår i: Proceedings of Medicinteknikdagarna 2006, 2006, s. 40-41Konferensbidrag (Övrigt vetenskapligt)
  • 77.
    Seoane, Fernando
    et al.
    Chalmers University of Technology.
    Lindecrantz, Kaj
    Chalmers University of Technology.
    Extraction of Structural Information from Impedance Spectrum Data: A Step towards the Identification of Cellular Oedema2006Ingår i: Analysis of Biomedical Signals and Images: 18th EURASIP Conference Biosignal 2006 Proceedings, Brno: VUTIUM press , 2006, s. 90-93Konferensbidrag (Refereegranskat)
  • 78.
    Seoane, Fernando
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS) (Stängd 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 Edema2005Ingår i: IFMBE proceedings of the 12th International Conference on Biomedical Engineering, Singapore: Springer , 2005Konferensbidrag (Refereegranskat)
  • 79.
    Seoane, Fernando
    et al.
    Chalmers University, Sweden.
    Lindecrantz, Kaj
    The effect of the scalp and the skull bone in the total impedivity of the neonatal head and its implications in the detection of brain cellular edema2005Ingår i: The 3rd European Medical and Biological Engineering Conference EMBEC´05. IFBME European Conference on BME, Prague: IFMBE , 2005Konferensbidrag (Refereegranskat)
    Abstract [en]

    Hypoxic-ischemic encephalopathy (HIE) affects severely and frequently on newborns and yet not an efficient detection method has been implemented to assist the early initiation of a saving therapy. Invasive measurements of electrical bioimpedance can be used to detect the changes in the electrical properties of brain tissue as a consequence of the hypoxic cellular edema. In the case of non-invasive measurement the skull and the scalp will modified the measurements in a certain way. In this work, using numerical calculations on a four-concentric spheres model, we study the contribution of the scalp and the skull bone to the total equivalent impedivity, complex resistivity, of the neonatal head and its effect on the non-invasive detection of brain cellular edema. The results confirm the importance of the reactive part of the impedivity on the electrical bioimpedance monitoring of hypoxic brain damage.

  • 80.
    Seoane, Fernando
    et al.
    University of Borås.
    Lindecrantz, Kaj
    University of Borås.
    The Transcephalic Electrical Impedance Method: Principles for Brain Tissue State Monitoring2005Ingår i: EU-Biopattern Brain Workshop / [ed] Emmanuel Ifeachor & Kaj Lindecrantz, 2005, s. 11-12Konferensbidrag (Övrigt vetenskapligt)
  • 81. Seoane, Fernando
    et al.
    Lindecrantz, Kaj
    Olsson, T
    Kjellmer, I
    Flisberg, A
    Bagenholm, R
    Brain electrical impedance at various frequencies: the effect of hypoxia2004Ingår i: Proceedings of the 26th Annual International Conference of the IEEE EMBS, San Francisco, CA, USA • September 1-5, 2004, IEEE Engineering in Medicine and Biology Society , 2004, Vol. 3, s. 2322-2325Konferensbidrag (Refereegranskat)
    Abstract [en]

    Non-invasive multi-frequency measurements of transcephalic impedance, both reactance and resistance, can efficiently detect cell swelling of brain tissue and can be used for early detection of threatening brain damage. We have performed experiments on piglets to monitor transcephalic impedance during hypoxia. The obtained results have confirmed the hypothesis that changes in the size of cells modify the tissue impedance. During tissue inflammation after induced hypoxia, cerebral tissue exhibits changes in both reactance and resistance. Those changes are remarkably high, up to 71% over the baseline, and easy to measure especially at certain frequencies. A better understanding of the electrical behaviour of cerebral tissue during cell swelling would lead us to develop effective non-invasive clinical tools and methods for early diagnosis of cerebral edema and brain damage prevention.

  • 82.
    Seoane, Fernando
    et al.
    School of Engineering, University College of Borås, SE-50190 Borås.
    Lindecrantz, Kaj
    School of Engineering, University College of Borås, SE-50190 Borås.
    Olsson, Torsten
    bDepartment of Signal and Systems, Chalmers University of Technology, SE-41296 Gothenburg.
    Kjellmer, Ingemar
    cDepartment of Pediatrics, Göteborg University, The Queen Silvia Children's Hospital, SE-41685 Gothenburg.
    Bioelectrical Impedance During Hypoxic Cell Swelling: Modeling of Tissue as a Suspension of Cells2004Konferensbidrag (Refereegranskat)
    Abstract [en]

    Non-invasive multi-frequency measurements of transcephalic impedance, both reactance and resistance, can efficiently detect cytotoxic edema in brain tissue and can be used for early detection of threatening brain damage. The model of biological tissue as a suspension of cells can be used as a valuable guide to identify the optimum range of frequencies for electrical impedance monitoring to detect cell swelling efficiently. We have performed experiments on piglets to monitor transcephalic impedance during hypoxia. The obtained results have confirmed the hypothesis that changes in the size of cells modify the tissue impedance. During tissue inflammation after induced hypoxia, cerebral tissue exhibits changes in both reactance and resistance. Those changes in impedance exhibit certain dependency of frequency in concordance with the suspension of cells model. The experimentally observed changes are remarkably high, up to 71% over the baseline, and easy to measure especially at certain frequencies. A better understanding of the electrical behaviour of cerebral tissue during cell swelling may lead the development effective non-invasive clinical tools and methods for early diagnosis of cerebral edema and brain damage prevention.

  • 83. Seoane, Fernando
    et al.
    Lindecrantz, Kaj
    Olsson, Torsten
    Kjellmer, Ingemar
    Fliesberg, Anders
    Bågenholm, Ralph
    Electrical Bioimpedance Cerebral Monitoring2005Ingår i: Medicinteknikdagarna, 2005Konferensbidrag (Övrigt vetenskapligt)
  • 84. Seoane, Fernando
    et al.
    Lindecrantz, Kaj
    Olsson, Torsten
    Kjellmer, Ingemar
    Flisberg, Anders
    Bågenholm, Ralph
    Spectroscopy study of the dynamics of the transencephalic electrical impedance in the perinatal brain during hypoxia2005Ingår i: Physiological Measurement, ISSN 0967-3334, E-ISSN 1361-6579, Vol. 26, nr 5, s. 849-863Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hypoxia/ischaemia is the most common cause of brain damage in neonates. Thousands of newborn children suffer from perinatal asphyxia every year. The cells go through a response mechanism during hypoxia/ischaemia, to maintain the cellular viability and, as a response to the hypoxic/ischaemic insult, the composition and the structure of the cellular environment are altered. The alterations in the ionic concentration of the intra- and extracellular and the consequent cytotoxic oedema, cell swelling, modify the electrical properties of the constituted tissue. The changes produced can be easily measured using electrical impedance instrumentation. In this paper, we report the results from an impedance spectroscopy study on the effects of the hypoxia on the perinatal brain. The transencephalic impedance, both resistance and reactance, was measured in newborn piglets using the four-electrode method in the frequency range from 20 kHz to 750 kHz and the experimental results were compared with numerical results from a simulation of a suspension of cells during cell swelling. The experimental results make clear the frequency dependence of the bioelectrical impedance, confirm that the variation of resistance is more sensitive at low than at high frequencies and show that the reactance changes substantially during hypoxia. The resemblance between the experimental and numerical results proves the validity of modelling tissue as a suspension of cells and confirms the importance of the cellular oedema process in the alterations of the electrical properties of biological tissue. The study of the effects of hypoxia/ischaemia in the bioelectrical properties of tissue may lead to the development of useful clinical tools based on the application of bioelectrical impedance technology.

  • 85.
    Seoane, Fernando
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS) (Stängd 20130701).
    Lindecrantz, Kaj
    Olsson, Torsten
    Kjellmer, Ingemar
    Mallard, Carina
    Evolution of Cerebral Bioelectrical Resistance at Various Frequencies During Hypoxia in Fetal Sheep2004Ingår i: Australasian Physical & Engineering Sciences in Medicine, ISSN 0158-9938, Vol. 27, nr 4Artikel i tidskrift (Refereegranskat)
  • 86. Seoane, Fernando
    et al.
    Lu, Mai
    Persson, Mikael
    Lindecrantz, Kaj
    Electrical Bioimpedance Cerebral Monitoring: A Study of the Current Density Distribution and Impedance Sensitivity Maps on a 3D Realistic Head Model2007Konferensbidrag (Refereegranskat)
    Abstract [en]

    There have been several studies of the application of electrical bioimpedance technology for brain monitoring in the past years. They have targeted a variety of events and injuries e.g. epilepsy or stroke. The current density distribution and the voltage lead field associated with an impedance measurement setup is of critical importance for the proper analysis of any dynamics in the impedance measurement or for an accurate reconstruction of an EIT image, specially a dynamic type. In this work for the first time, the current density distribution is calculated in a human head with anatomical accuracy and resolution down to 1 mm, containing up to 24 tissues and considering the frequency dependency of the conductivity of each tissue. The obtained current densities and the subsequent sensitivity maps are analyzed with a special focus on the dependency of the electrode arrangement and also the measurement frequency. The obtained results provide us with interesting and relevant information to consider in the design of any tool for electrical bioimpedance cerebral monitoring.

  • 87.
    Seoane, Fernando
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS).
    Macias, Raul
    Technical University of Catalonia.
    Bragós, Ramon
    Technical University of Catalonia.
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS).
    Simple voltage-controlled current source for wideband electrical bioimpedance spectroscopy: circuit dependences and limitations2011Ingår i: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 22, nr 11Artikel i tidskrift (Refereegranskat)
    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.

  • 88.
    Seoane, Fernando
    et al.
    University College of Borås.
    Mai, Lu
    Persson, Mikael
    Lindecrantz, Kaj
    University College of Borås.
    The Role of the Cerebrospinal Fluid in the Distribution of Electrical Current within the Brain and its Implications for Electrical Bioimpedance Cerebral Monitoring2007Ingår i: Medicinteknikdagarna, 2007, Vol. 1Konferensbidrag (Övrigt vetenskapligt)
  • 89.
    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, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS).
    The Challenge of the Skin-Electrode Contact in Textile-enabled Electrical Bioimpedance, Measurements for Personalized Healthcare Monitoring Applications2011Ingår i: Biomedical Engineering, Trends in Materials Science / [ed] Anthony N. Laskovski, IN-TECH, 2011Kapitel i bok, del av antologi (Refereegranskat)
  • 90.
    Seoane, Fernando
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS).
    Rempfer, Markus
    University of Borås.
    Marquez, Juan Carlos
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS).
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS).
    Textile-enabled Instrumentation for Impedance Cardiographic Signals2011Konferensbidrag (Övrigt vetenskapligt)
  • 91.
    Seoane, Fernando
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS).
    Ward, L. C.
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS).
    Lingwood, B. E.
    Automated criterion-based analysis for Cole parameters assessment from cerebral neonatal electrical bioimpedance spectroscopy measurements2012Ingår i: Physiological Measurement, ISSN 0967-3334, E-ISSN 1361-6579, Vol. 33, nr 8, s. 1363-1377Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hypothermia has been proven as an effective rescue therapy for infants with moderate or severe neonatal hypoxic ischemic encephalopathy. Hypoxiaischemia alters the electrical impedance characteristics of the brain in neonates; therefore, spectroscopic analysis of the cerebral bioimpedance of the neonate may be useful for the detection of candidate neonates eligible for hypothermia treatment. Currently, in addition to the lack of reference bioimpedance data obtained from healthy neonates, there is no standardized approach established for bioimpedance spectroscopy data analysis. In this work, cerebral bioimpedance measurements (12 h postpartum) in a cross-section of 84 term and near-term healthy neonates were performed at the bedside in the post-natal ward. To characterize the impedance spectra, Cole parameters (R-0, R-infinity, f(C) and alpha) were extracted from the obtained measurements using an analysis process based on a best measurement and highest likelihood selection process. The results obtained in this study complement previously reported work and provide a standardized criterion-based method for data analysis. The availability of electrical bioimpedance spectroscopy reference data and the automatic criterion-based analysis method might support the development of a non-invasive method for prompt selection of neonates eligible for cerebral hypothermic rescue therapy.

  • 92. Thordstein, M.
    et al.
    Flisberg, A.
    Löfgren, N.
    Bågenholm, R.
    Lindecrantz, Kaj
    School of Engineering, University of Borås.
    Kjellmer, I.
    The difficulty of appreciating slowness2006Ingår i: Clinical Neurophysiology, ISSN 1388-2457, E-ISSN 1872-8952, ISSN 1388-2457, Vol. 117, nr 4, s. 929-930Artikel i tidskrift (Refereegranskat)
  • 93.
    Thordstein, M.
    et al.
    Department of Clinical Neurophysiology, Institute of Neuroscience and Physiology, Sahlgrenska University Hospital, Göteborg, Sweden.
    Kjellmer, I.
    Department of Pediatrics, Queen Silvia Children's Hospital, Sahlgrenska University Hospital-Östra.
    Löfgren, N.
    School of Engineering, University of Borås.
    Löfhede, J.
    School of Engineering, University of Borås.
    Lindecrantz, Kaj
    School of Engineering, University of Borås.
    Mallard, C.
    Dean, J.
    Effects of Inflammation on Cerebral Electrical Activity in Fetal Sheep2008Konferensbidrag (Refereegranskat)
  • 94.
    Thordstein, M.
    et al.
    Department of Clinical Neurophysiology, Institute of Neuroscience and Physiology, Sahlgrenska University Hospital, Göteborg, Sweden.
    Löfgren, N.
    School of Engineering, University of Borås.
    Bågenholm, R
    Department of Pediatrics, Queen Silvia Children's Hospital, Sahlgrenska University Hospital-Östra.
    Lindecrantz, Kaj
    School of Engineering, University of Borås.
    Wallin, B. G.
    Department of Clinical Neurophysiology, Institute of Neuroscience and Physiology, Sahlgrenska University Hospital, Göteborg, Sweden.
    Kjellmer, I.
    Department of Pediatrics, Queen Silvia Children's Hospital, Sahlgrenska University Hospital-Östra.
    Spectral analysis of burst periods in EEG from healthy and post-asphyctic full-term neonates2004Ingår i: Clinical Neurophysiology, ISSN 1388-2457, E-ISSN 1872-8952, Vol. 115, nr 11, s. 2461-2466Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    OBJECTIVE: To investigate whether the periodic EEG patterns seen in healthy and sick full term neonates (trace alternant and burst suppression, respectively) have different frequency characteristics.

    METHODS: Burst episodes were selected from the EEGs of 9 healthy and 9 post-asphyctic full-term neonates and subjected to power spectrum analysis. Powers in two bands were estimated; 0-4 and 4-30 Hz, designated low- and high-frequency activity, respectively (LFA, HFA). The spectral edge frequency (SEF) was also assessed.

    RESULTS: In bursts, the LFA power was lower in periods of burst suppression as compared to those of trace alternant. The parameter that best discriminated between the groups was the relative amount of low- and high-frequency activity. The SEF parameter had a low sensitivity to the group differences. In healthy neonates, the LFA power was higher over the posterior right as compared to the posterior left region.

    CONCLUSIONS: Spectral power of low frequencies differs significantly between the burst episodes of healthy and sick neonates.

    SIGNIFICANCE: These results can be used when monitoring cerebral function in neonates.

  • 95.
    Thordstein, M.
    et al.
    Department of Clinical Neurophysiology, Institute of Neuroscience and Physiology, Sahlgrenska University Hospital, Göteborg, Sweden.
    Löfgren, N.
    School of Engineering, University of Borås.
    Flisberg, Anders
    Department of Pediatrics, Queen Silvia Children's Hospital, Sahlgrenska University Hospital-Östra.
    Bågenholm, R
    Department of Pediatrics, Queen Silvia Children's Hospital, Sahlgrenska University Hospital-Östra.
    Lindecrantz, Kaj
    School of Engineering, University of Borås.
    Kjellmer, I.
    Department of Pediatrics, Queen Silvia Children's Hospital, Sahlgrenska University Hospital-Östra.
    Infraslow EEG activity in burst periods from post asphyctic full term neonates2005Ingår i: Clinical Neurophysiology, ISSN 1388-2457, E-ISSN 1872-8952, Vol. 116, nr 7, s. 1501-1506Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    OBJECTIVE: To investigate whether very low EEG frequency activity can be recorded from post asphyctic full term neonates using EEG equipment where the high pass filter level was lowered to 0.05 Hz.

    METHODS: The time constant of the amplifier hardware was set to 3.2 s in order to enable recordings that equal to a high pass filter cut off at 0.05 Hz. Burst episodes were selected from the EEGs of 5 post asphyctic full term neonates. The episodes were analysed visually using different montages and subjected to power spectrum analysis. Powers in two bands were estimated; 0-1 and 1-4 Hz, designated very low- and low-frequency activity, respectively (VLFA, LFA).

    RESULTS: In all infants, VLFA coinciding with the burst episodes could be detected. The duration of the VLFA was about the same as that of the burst episode i.e. around 4s. The activity was most prominent over the posterior regions. In this small material, a large amount of VLFA neonatally seemed to possibly be related to a more favourable prognosis.

    CONCLUSIONS: VLFA can be recorded from post asphyctic full term neonates using EEG equipment with lowered cut off frequency for the high pass filter.

    SIGNIFICANCE: VLFA normally disregarded due to filtering, is present in the EEG of sick neonates and may carry important clinical information.

  • 96.
    Thordstein, M.
    et al.
    Department of Clinical Neurophysiology, Institute of Neuroscience and Physiology, Sahlgrenska University Hospital, Göteborg, Sweden.
    Löfgren, N.
    School of Engineering, Uiversity of Borås.
    Flisberg, Anders
    Department of Pediatrics, Queen Silvia Children's Hospital, Sahlgrenska University Hospital-Östra.
    Lindecrantz, Kaj
    School of Engineering, University of Borås.
    Kjellmer, I.
    Department of Pediatrics, Queen Silvia Children's Hospital, Sahlgrenska University Hospital-Östra.
    Sex differences in electrocortical activity in human neonates2006Ingår i: NeuroReport, ISSN 0959-4965, E-ISSN 1473-558X, Vol. 17, nr 11, s. 1165-1168Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cerebral cortical activity in healthy, full-term human neonates (10 boys and 10 girls) was evaluated using spectral estimation of electroencephalogram frequency content with new equipment and analysis technique allowing the assessment of the lowest frequencies (i.e. infraslow waves). The activity was analysed under quiet sleep and active wakefulness taking sex into consideration. During sleep, the mean amount of infraslow activity was 27% larger in boys, whereas during wakefulness the average amount of higher frequencies was 17% larger in girls. Both these differences indicate an earlier maturation of cortical function in girls than in boys.

  • 97.
    Thordstein, M.
    et al.
    Department of Clinical Neurophysiology, Institute of Neuroscience and Physiology, Sahlgrenska University Hospital, Göteborg, Sweden.
    Sultan, Bo L
    Wennergren, Margareta M
    Törnqvist, Eva
    Department of Signals and Systems, Chalmers.
    Lindecrantz, Kaj
    School of Engineering, University of Borås.
    Kjellmer, I.
    Department of Pediatrics, Queen Silvia Children's Hospital, Sahlgrenska University Hospital-Östra.
    Visual evoked potentials in disproportionately growth-retarded human neonates2004Ingår i: Pediatric Neurology, ISSN 0887-8994, E-ISSN 1873-5150, Vol. 30, nr 4, s. 262-270Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To study brain function in the neonatal period, disproportionately growth-retarded (n = 33) and appropriately grown (n = 21) infants were examined using Doppler flow velocities prenatally and visual evoked potentials postnatally. Visual evoked potentials recordings were made at gestation of 40 and 46 weeks. The group of growth-retarded infants had significantly prolonged latencies to both of the two major peaks (designated P and N), most pronounced for the P peak. This result was observed at both ages investigated and corresponds to a developmental delay of 3 weeks. For individuals, the increase in P latency correlated to prenatal flow indices and to neonatal anthropometric parameters indicative of growth retardation. We conclude that in utero growth retardation affects brain development as assessed by visual evoked potentials in the neonatal period. This developmental delay may be produced by intracerebral factors during the process of growth retardation, and these alterations may have a prognostic value.

  • 98.
    Wiklund, Urban
    et al.
    Department of Biomedcal Engineering and Informatics, Univeristy Hospital of Umeå.
    Karlsson, Marcus
    Department of Biomedcal Engineering and Informatics, Univeristy Hospital of Umeå.
    Ostlund, Nils
    Department of Biomedcal Engineering and Informatics, Univeristy Hospital of Umeå.
    Berglin, Lena
    School of Textiles, University of Borås.
    Lindecrantz, Kaj
    School of Engineering, University of Borås.
    Karlsson, Stefan
    Engineering and Informatics, Univeristy Hospital of Umeå.
    Sandsjö, Leif
    National Institute of Working Life, Gothenburg.
    Adaptive spatio-temporal filtering of disturbed ECGs: a multi-channel approach to heartbeat detection in smart clothing2007Ingår i: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 45, nr 6, s. 515-523Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Intermittent disturbances are common in ECG signals recorded with smart clothing: this is mainly because of displacement of the electrodes over the skin. We evaluated a novel adaptive method for spatio-temporal filtering for heartbeat detection in noisy multi-channel ECGs including short signal interruptions in single channels. Using multi-channel database recordings (12-channel ECGs from 10 healthy subjects), the results showed that multi-channel spatio-temporal filtering outperformed regular independent component analysis. We also recorded seven channels of ECG using a T-shirt with textile electrodes. Ten healthy subjects performed different sequences during a 10-min recording: resting, standing, flexing breast muscles, walking and pushups. Using adaptive multi-channel filtering, the sensitivity and precision was above 97% in nine subjects. Adaptive multi-channel spatio-temporal filtering can be used to detect heartbeats in ECGs with high noise levels. One application is heartbeat detection in noisy ECG recordings obtained by integrated textile electrodes in smart clothing.

  • 99. Wollmann, Thomas
    et al.
    Abtahi, Farhad
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Eghdam, Abouzar
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik.
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik.
    Haag, Martin
    Koch, Sabine
    User-Centred Design and Usability Evaluation of a Heart Rate Variability Biofeedback Game2016Ingår i: IEEE Access, E-ISSN 2169-3536, Vol. 4, s. 5531-5539Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background and objective: Reduced heart rate variability (HRV) is an indicatorof a malfunctioning autonomic nervous system. Resonant frequencybreathing is a potential non-invasive means of intervention for improvingthe balance of the autonomic nervous system and increasing HRV. However,such breathing exercises are regarded as boring and monotonous tasks.The use of gaming elements (gamification) or a full gaming experience is awell-recognised method for achieving higher motivation and engagement invarious tasks. However, there is limited documented knowledge on how todesign a game for breathing exercises. In particular, the influence of additionalinteractive elements on the main course of training has not yet beenexplored. In this study, we evaluated the satisfaction levels achieved usingdifferent game elements and how disruptive they were to the main task, i.e.,paced breathing training.

    Methods: An Android flight game was developed with three game modes thatdiffer in the degrees of multitasking they require. Design, development and evaluation were conducted using a user-centred approach, including contextanalysis, the design of game principle mock-ups, the selection of game principlesthrough a survey, the design of the game mechanics and GUI mock-up,icon testing and the performance of a summative study through user questionnairesand interviews. A summative evaluation of the developed gamewas performed with 11 healthy participants (ages 40-67) in a controlled setting.Results: The results confirm the potential of video games for motivatingplayers to engage in HRV biofeedback training. The highest training performanceon the first try was achieved through pure visualisation rather thanin a multitasking mode. Players had higher motivation to play the morechallenging game and were more interested in long-term engagement.Conclusion: A framework for gamified HRV biofeedback research is presented.It has been shown that multitasking has considerable influence onHRV biofeedback and should be used with an adaptive challenge level.

  • 100.
    Yang, Liyun
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Ergonomi.
    Abtahi, Farhad
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Ergonomi.
    Eklund, Jörgen
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Ergonomi.
    Hanson, Lars
    School of Engineering Science, University of Skövde.
    Lindecrantz, Kaj
    KTH.
    Forsman, Mikael
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Ergonomi.
    Carl, Lind
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Ergonomi.
    Smart workwear system with real-time vibrotactile feedback for improving postural behaviour in industry2019Ingår i: From research to evidence based sustainable interventions and practices: Book of Abstracts, Bologna, Italy, 2019, s. 160-Konferensbidrag (Refereegranskat)
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