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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.
    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)
  • 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.
    Evaluation of Atrial Fibrillation Detection by using Heart Rate Variability analysis2015Conference paper (Other academic)
  • 9. 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.

  • 10. 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.

  • 11.
    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)
  • 12.
    Björk, Hans
    et al.
    University of Borås, School of Engineering.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Ericsson, Dag
    University of Borås, School of Engineering.
    Sarv, Hans
    University of Borås, School of Engineering.
    Bolton, Kim
    University of Borås, School of Engineering.
    Börjesson, Anders
    University of Borås, School of Engineering.
    Bazooyar, Faranak
    University of Borås, School of Engineering.
    Ahlström, Peter
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad
    University of Borås, School of Engineering.
    Andersson, Bengt-Åke
    University of Borås, School of Engineering.
    Johansson, Andreas
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    20 år med Institutionen Ingenjörshögskolan: historik, nuläge och framtid2009Report (Other academic)
  • 13.
    Brorström, Björn
    et al.
    University of Borås, School of Business and IT.
    Forsgren, Olov
    University of Borås, School of Business and IT.
    Hallnäs, Lars
    University of Borås, Swedish School of Textiles.
    Höglund, Lars
    University of Borås, Swedish School of Library and Information Science.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Nyström, Maria
    University of Borås, School of Health Science.
    Ordell Björkdahl, Susanne
    University of Borås, School of Education and Behavioural Science.
    Forskning vid Högskolan i Borås2007Report (Other academic)
  • 14. 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.

  • 15.
    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)
  • 16.
    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)
  • 17.
    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.

  • 18. Flisberg, A
    et al.
    Kjellmer, I
    Bågenholm, R
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Löfgren, N
    Trondstein, M
    EEG and spectral edge frequency: analysis in posthypoxic newborn piglets2010In: Neuro - endocrinology letters, ISSN 0172-780X, Vol. 31, no 2, p. 181-186Article in journal (Refereed)
    Abstract [en]

    OBJECTIVE: To evaluate the frequency content of the electroencephalogram (EEG) during recovery after a severe hypoxic insult in newborn piglets. METHODS: EEG was continuously monitored in nine newborn piglets exposed to a severe hypoxic period. Power spectra in five frequency bands were calculated using Fourier transformation. Spectral edge frequency 90 (SEF90) was defined as the frequency below which 90% of the power in the EEG was located. The piglets were divided into two groups; Group 1 represented piglets with some EEG recovery and Group 2 represented piglets without any EEG recovery. RESULTS: The recovery of the EEG in Group 1 had the same time course in all frequency bands. SEF90 indicates recovery earlier than the value of total power. But SEF90 also signals activity in the EEGs that were almost completely suppressed. When SEF90 was calculated during periods of periodic EEG activity during the very early phase of recovery, the values fell within the same range as during the control period. CONCLUSION: Spectral analysis of continuous EEG in newborn piglets exposed to very severe hypoxia showed that no specific frequency band of the EEG preceded the other ones during recovery. The results of the SEF90 measure, demonstrates the need for critical analysis of the raw EEG before any reliable estimation of cerebral function can be made.

  • 19. Flisberg, A
    et al.
    Kjellmer, I
    Löfhede, J
    University of Borås, School of Engineering.
    Lindecrantz, K
    University of Borås, School of Engineering.
    Thordstein, M
    Prognostic capacity of automated quantification of suppression time in the EEG of post-asphyctic full-term neonates2011In: Acta Paediatrica, ISSN 0803-5253, E-ISSN 1651-2227, Vol. 100, no 10, p. 1338-1343Article in journal (Refereed)
    Abstract [en]

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

  • 20. Flisberg, Anders
    et al.
    Kjellmer, I
    Löfhede, Johan
    University of Borås, School of Engineering.
    Löfgren, N
    Rosa-Zurera, M
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Thordstein, M
    Does indomethacin for closure of patent ductus arteriosus affect cerebral function?2010In: Acta Paediatrica, ISSN 0803-5253, E-ISSN 1651-2227, Vol. 99, no 10, p. 1493-1497Article in journal (Refereed)
    Abstract [en]

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

  • 21. Gund, A.
    et al.
    Ekman, I.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Sjöqvist, B. A.
    Staaf, E. L.
    Thornesköld, N.
    Design Evaluation of a Home-Based Telecare System for Chronic Heart Failure Patients2008Conference paper (Refereed)
  • 22. Gund, Ann
    et al.
    Sjöqvist, Bengt Arne
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Ekman, Inger
    Care@Distance: Disease Mangement för hjärtsviktspatienter i hemmet2007Conference paper (Refereed)
    Abstract [sv]

    Antalet äldre i samhället ökar, och med det kostnaderna p.g.a. kroniska åldersrelaterade sjukdomstillstånd. Ett sådant tillstånd är hjärtsvikt vilket drabbar ca 2 % av västvärldens befolkning. Forskning har visat att IT-baserad hemvård för s.k. Disease Management kan resultera i minskade kostnader så väl som ökad livskvalitet hos patienterna. Inom projektet Care@Distance är avsikten att utforma ett sådant system där tyngden ligger dels på regelbundna dagliga enkla mätningar av fysiologiskt relaterade parametrar såsom vikt och blodtryck, och dels på formulär där patienten svarar på några enkla frågor om det upplevda tillståndet. Syftet är att få med både objektiv och subjektiv information som sedan kan ligga till grund för en förbättrad vård av den enskilde patienten. Systemet utformas främst för att skapa underlag för en bättre långsiktig behandling, terapi och för uppföljning av Treatment Compliance, men även för att hantera akuta situationer genom t.ex. larm till vårdgivaren. Under projektets tid har ett samarbete med DAGA-kliniken på Östra sjukhuset upprättats, genom bl.a. diskussioner om frågeformulärets utformning. Under våren 2007 har även två förstudier genomförts på kliniken, den första med inriktning mot patientdelen av systemet, och den andra mot vårdgivarsidan. Studien visar att patientdelen är lätthanterad ur patientsynpunkt samt att intresse för systemet finns. Även på vårdgivarsidan är resultaten positiva när det gäller design, funktioner och intresse, men utrymme för förbättringar finns. Fortsatta studier i form av ett längre försök i hemmet hos patienter är planerat under sommaren och hösten 2007. Under sommaren kommer även patientdelen att vidareutvecklas med ny programvara. Ett framtida projekt innefattar att utveckla en metod för att utnyttja EBI (Elektrisk Bio-Impedans). Med relativt enkla och robusta mätningar förväntas mycket användbar och relevant information om sjukdomstillståndet kunna erhållas med denna metod, men detta kräver att ny sensorteknik utvecklas för hemmiljön.

  • 23.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Care@Distance: Hemövervakning av hjärtsviktpatienter2007Conference paper (Other academic)
  • 24.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Från projekt till klinisk rutin: när blir det så?2007Other (Other academic)
  • 25.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Välrenommerad medicinteknik från Borås2009In: Vetenskap för profession, ISSN 1654-6520, p. 27-35Article in journal (Other academic)
  • 26. Löfgren, N.
    et al.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Flisberg, A.
    Bågenholm, R.
    Kjellmer, I.
    Thordstein, M.
    Spectral Distance for ARMA Models Applied to Electroencephalogram for Early Detection of Hypoxia.2006In: Journal of Neural Engineering, ISSN 1741-2560, E-ISSN 1741-2552, Vol. 3, no 3, p. 227-234Article in journal (Refereed)
  • 27. Löfgren, Nils
    et al.
    Thordstein, Magnus
    Löfhede, Johan
    University of Borås, School of Engineering.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Kjellmer, Ingemar
    Dean, Justin
    Mallard, Carina
    Slowly Altering Electrical Potentials over the Head During Hypoxia and LPS Exposure2007Conference paper (Refereed)
  • 28.
    Löfhede, Johan
    et al.
    University of Borås, School of Engineering.
    Degerman, Johan
    Löfgren, Nils
    Thordstein, Magnus
    Flisberg, Anders
    Kjellmer, Ingemar
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Comparing a Supervised and an Unsupervised Classification Method for Burst Detection in Neonatal EEG2008In: Proceedings of Engineering in Medicine and Biology Society, EMBS 2008. 30th Annual International Conference of the IEEE, 20-24 August, 2008, IEEE , 2008, p. 3836-3839Conference paper (Refereed)
    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.

  • 29.
    Löfhede, Johan
    et al.
    University of Borås, School of Engineering.
    Löfgren, N.
    Thordstein, M.
    Flisberg, A.
    Kjellmer, I.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Classifying Neonatal EEG2007Conference paper (Refereed)
  • 30.
    Löfhede, Johan
    et al.
    University of Borås, School of Engineering.
    Löfgren, N.
    Thordstein, M.
    Flisberg, A.
    Kjellmer, I.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Comparison of Three Methods for Classifying Burst and Suppression in the EEG of Post Asphyctic Newborns2007In: Proceedings of the 29th Annual International Conference of the IEEE EMBS, Cité Internationale, Lyon, France, August 23-26, 2007, IEEE , 2007Conference paper (Refereed)
  • 31.
    Löfhede, Johan
    et al.
    University of Borås, School of Engineering.
    Löfgren, N
    Thordstein, M
    Flisberg, A
    Kjellmer, I
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Detection of bursts in the EEG of post asphyctic newborns2006Conference paper (Refereed)
  • 32.
    Löfhede, Johan
    et al.
    University of Borås, School of Engineering.
    Löfgren, N.
    Thordstein, M.
    Flisberg, I.
    Kjellmer, I.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Classifying Burst and Suppression in the EEG of Post Asphyctic Newborns Using a Support Vector Machine2007In: Proceedings of the 3rd International IEEE EMBS Conference on Neural Engineering, Kohala Coast, Hawaii, USA, May 2-5, 2007, IEEE , 2007Conference paper (Refereed)
  • 33.
    Löfhede, Johan
    et al.
    University of Borås, School of Engineering.
    Löfgren, Nils
    Thordstein, Magnus
    Flisberg, Anders
    Kjellmer, Ingemar
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Classification of burst and suppression in the neonatal electroencephalogram2008In: Journal of Neural Engineering, ISSN 1741-2560, E-ISSN 1741-2552, Vol. 5, no 4, p. 402-410Article in journal (Refereed)
    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.

  • 34.
    Löfhede, Johan
    et al.
    University of Borås, School of Engineering.
    Löfgren, Nils
    Thordstein, Magnus
    Flisberg, Anders
    Kjellmer, Ingmar
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Classification of Burst Suppression and Tracé Alternant in Neonatal EEG2008In: Proceedings of Medicinteknikdagarna 2008. Annual conference of Svensk Förening för Medicinsk Teknik och Fysik, Göteborg, Oct., 2008, 2008Conference paper (Refereed)
  • 35.
    Löfhede, Johan
    et al.
    University of Borås, School of Engineering.
    Thordstein, Magnus
    Löfgren, Nils
    Flisberg, Anders
    Rosa-Zurera, Manuel
    Kjellmer, Ingemar
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Automatic classification of background EEG activity in healthy and sick neonates2010In: Journal of Neural Engineering, ISSN 1741-2560, E-ISSN 1741-2552, Vol. 7, no 1Article in journal (Refereed)
    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%.

  • 36.
    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.

  • 37.
    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

  • 38.
    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.

  • 39.
    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)
  • 40.
    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.

  • 41.
    Márquez, 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.
    Textrode functional straps for bioimpedance measurements-experimental results for body composition analysis2013In: European Journal of Clinical Nutrition, ISSN 0954-3007, E-ISSN 1476-5640, Vol. 67, no Suppl 1, p. 22-27Article in journal (Refereed)
    Abstract [en]

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

  • 42. Pau, I.
    et al.
    Seoane Martínez, Fernando
    University of Borås, School of Engineering.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Valero, M.A.
    Carracedo, J.
    Home e-health system integration in the Smart Home through a common media server2009Conference paper (Other academic)
  • 43. Reza Atefi, Seyed
    et al.
    Seoane, Fernando
    University of Borås, School of Engineering.
    Buendia, Ruben
    University of Borås, School of Engineering.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Cole Function and Conductance-Based Parasitic Capacitance Compensation for Cerebral Electrical Bioimpedance Measurements2012Conference paper (Refereed)
    Abstract [en]

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

  • 44.
    Seoane, Fernando
    et al.
    University of Borås, Faculty of Caring Science, Work Life and Social Welfare. KTH-School of Technology and Health.
    Atefi, Seyed Reza
    Harvard Univsersity.
    Tomner, Jens
    Karolinska Hospital.
    Kostulas, Konstantinos
    Karolinska Hospital.
    Lindecrantz, Kaj
    KTH-School of Technology and Health.
    Electrical Bioimpedance Spectroscopy on Acute Unilateral Stroke Patients: Initial Observations regarding Differences between Sides2015In: BioMed research international, Vol. 2015Article in journal (Refereed)
  • 45.
    Seoane, Fernando
    et al.
    University of Borås, School of Engineering.
    Bragós, Ramon
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Current Source for Wideband Multifrequency Electrical Bioimpedance Measurements2006In: IEEE Transactions on Biomedical Circuits and Systems, ISSN 1932-4545, E-ISSN 1940-9990, p. 5121-5125Article in journal (Other academic)
  • 46.
    Seoane, Fernando
    et al.
    University of Borås, School of Engineering.
    Bragós, Ramon
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Riu, Pere J.
    Current Source Design for Electrical Bioimpedance Spectroscopy2008In: Encyclopaedia of Healthcare Information Systems, Encyclopaedia of Healthcare Information Systems , 2008Chapter in book (Other academic)
  • 47.
    Seoane, Fernando
    et al.
    University of Borås, School of Engineering.
    Bragós, Ramón
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Current Source for Wideband Electrical Bioimpedance Spectroscopy Based on a Single Operational Amplifier.2006Conference paper (Refereed)
    Abstract [en]

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

  • 48.
    Seoane, Fernando
    et al.
    University of Borås, School of Engineering.
    Ferreira, Javier
    University of Borås, School of Engineering.
    Buendia, Ruben
    University of Borås, School of Engineering.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Adaptive Frequency Distribution for Electrical Bioimpedance Spectroscopy Measurements2012Conference paper (Refereed)
    Abstract [en]

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

  • 49.
    Seoane, Fernando
    et al.
    University of Borås, School of Engineering.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    A Novel Approach for Estimation of Electrical Bioimpedance: Total Least Square.2007Conference paper (Other academic)
  • 50.
    Seoane, Fernando
    et al.
    University of Borås, School of Engineering.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Electrial Bioimpedance Cerebral Monitoring2008In: Encyclopaedia of Healthcare Information Systems, Encyclopaedia of Healthcare Information Systems. , 2008Chapter in book (Other academic)
12 1 - 50 of 66
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