Biomedical Signals and Sensors III
Description
Readers will learn how these electric, magnetic and electromagnetic fields propagate and interact with biological tissues, are influenced by inhomogeneity effects, cause neuromuscular stimulation and thermal effects, and finally pass the electrode/tissue boundary to be recorded. As such, the book helps them manage the challenges posed by the highly interdisciplinary nature of biosignals and biomedical sensors by presenting the basics of electrical engineering, physics, biology and physiology that are needed to understand the relevant phenomena.
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Prof. Eugenijus Kaniusas graduated from the Faculty of Electrical Engineering and Information Technology of the Vienna University of Technology (VUT) in 1997. In 2001 he got the degree Dr. techn. He habilitated (venia docendi) in the field of bioelectrical engineering in 2006. Since 1997 he has been with the Institute of Fundamentals and Theory of Electrical Engineering, VUT, since 2007 as associate professor. He gives numerous mandatory lectures at VUT, concerning Biophysics, Biomedical Sensors and Signals, Biomedical Instrumentation. Since 2011 he is the chairman of the advisory board of study affairs of Biomedical Engineering at VUT. Currently he is the head of the research group Biomedical Sensing / Theranostics within the Institute of Electrodynamics, Microwave and Circuit Engineering, VUT.
He has (co)authored more than 160 publications, two volumes books, 2 patents, and various invited book chapters. Since 1999 he has contributed to 19 national and international (including EU) projects, funded by public and industry, 10 of them being coordinated by him. He is engaged as reviewer for 20 international journals and for diverse research councils (e.g., ERC grants). He is organiser of special IEEE sessions and COST workshops and co-organiser of diverse international symposia.
His research areas include diagnostic and therapeutic approaches and their closed-loop combination in portable Health Care Engineering. Electric, acoustic, optic, and magneto-elastic sensors for biomedical applications are developed, e.g., for sleep, anaesthesia and fitness monitoring as well as for apneas detection and heart rate variability monitoring. Electrical Impedance Tomography - enhanced by computer tomography - is developed for a novel individual setting of lung ventilators. Modelling of physiological signals and systems is performed for the voluntary breath holding (apnea diving) and the associated fitness assessment. Electric auricular vagus nerve stimulation is developed to realise individualised Point-of-Care therapy in pain and arterial disease therapy, and in triggering healing of diabetic chronic wounds. Extensive expertise is available in adaptive, multiparametric, clinically-relevant processing of hybrid biomedical signals in the time, spectral, and space domains, and in wearable hardware/software concepts for diagnostic/therapeutic biomedical devices.He is Chief Technology Officer (CTO) in SzeleStim GmbH, a spin-off developing auricular vagus nerve stimulators for personalized treatment of pain and perfusion problems. Since 2018 he is the head of the Institute of Electrodynamics, Microwave and Circuit Engineering, VUT.
Content
PREFACE
ACKNOWLEDGEMENTS
SYMBOLS AND ABBREVIATIONS
SYMBOLS OF BIOSIGNALS
6 SENSING BY ELECTRIC BIOSIGNALS
6.1 Formation aspects
6.1.1 Permanent biosignals
6.1.2 Induced biosignals
6.1.3 Transmission of electric signals
6.1.3.1 Propagation of electric signals
6.1.3.1.1 Lossless medium
6.1.3.1.2 Lossy medium
6.1.3.2 Effects on electric signals
6.1.3.2.1 Volume effects
6.1.3.2.1.1 General issues6.1.3.2.1.1.1 Electric and magnetic fields
6.1.3.2.1.1.2 Current density and current
6.1.3.2.1.1.3 Electric field and voltage
6.1.3.2.1.1.4 Electrical impedance
6.1.3.2.1.1.5 Simple tissue model
6.1.3.2.1.1.6 Mutual field coupling and quasi-electrostatic situation
6.1.3.2.1.2 Incident electric fields
6.1.3.2.1.2.1 Conductive phenomena
6.1.3.2.1.2.2 Polarization phenomena
6.1.3.2.1.2.3 Conductive versus polarization behaviour
6.1.3.2.1.2.4 Conductivity and polarization with relaxation and dispersion
6.1.3.2.1.2.5 Charge and current induction
6.1.3.2.1.3 Incident magnetic fields
6.1.3.2.1.4 Incident electromagnetic fields
6.1.3.2.2 Inhomogeneity effects
6.1.3.2.2.1 Boundary conditions
6.1.3.2.2.1.1 Conductive phenomena
6.1.3.2.2.1.2 Displacement phenomena
6.1.3.2.2.1.3 Conductive and displacement phenomena
6.1.3.2.2.1.4 Inhomogeneous structures and varying frequency
6.1.3.2.2.2 Diffraction
6.1.3.2.2.3 Reflection and refraction
6.1.3.2.3 Volume and inhomogeneity effects - a quantitative approach
6.1.3.2.3.1 Incindent electric field
6.1.3.2.3.1 Incident contact current
6.1.3.2.3.1 Incident magnetic field
6.1.3.2.4 Physiological effects
6.1.3.2.4.1 Stimulation effects
6.1.3.2.4.1.1 Current density versus electric field6.1.3.2.4.1.2 Charge transfer during stimulation
6.1.3.2.4.1.3 Stimulation pattern
6.1.3.2.4.1.3.1 Single monophasic stimulus
6.1.3.2.4.1.3.2 Single biphasic stimulus
6.1.3.2.4.1.3.3 Periodic stimulus
6.1.3.2.4.1.4 Strength-duration curve
6.1.3.2.4.1.5 Activating function
6.1.3.2.4.1.6 Cathodic and anodic stimulation
6.1.3.2.4.1.6.1 Cathodic block and stimulation upper threshold
6.1.3.2.4.1.6.2 Current-distance relationship
6.1.3.2.4.1.6.3 Numerical simulation - a quantitative approach
6.1.3.2.4.1.7 Axon thickness and its distance to electrode
6.1.3.2.4.1.8 Monopolar, bipolar, and tripolar modes
6.1.3.2.4.2 Thermal effects
6.1.3.2.5 Adverse health effects and exposure limits
6.1.3.2.5.1 Heart current factor
6.1.3.2.5.2 Neural stimulation
6.1.3.2.5.3 Effects of the direct current on tissue
6.2 Sensing and coupling of electric signals
6.2.1 Electrodes
6.2.1.1 Tissue, skin, and electrode effects
6.2.1.1.1 Tissue impedance
6.2.1.1.2 Skin impedance
6.2.1.1.3 Electrode polarization and impedance
6.2.1.1.3.1 Metal ion electrode and its double layer
6.2.1.1.3.1.1 Electrical double layer
6.2.1.1.3.1.2 Specific adsorption
6.2.1.1.3.1.3 Water relevance
6.2.1.1.3.1.4 Mass transfer
6.2.1.1.3.1.5 Electric potential and Debye length
6.2.1.1.3.1.6 Half-cell voltage
6.2.1.1.3.2 Redox electrode and its double layer
6.2.1.1.3.3 Reference Ag/AgCl electrode
6.2.1.1.3.4 Active current or voltage application between electrodes
6.2.1.1.3.4.1 Charge transfer and activation overvoltage
6.2.1.1.3.4.2 Diffusion and diffusion overvoltage
6.2.1.1.3.4.3 Coupled reactions and reaction overvoltage
6.2.1.1.3.4.4 Dynamics of electro-kinetic processes
6.2.1.1.3.4.5 Polarization of the electrode/tissue boundary
6.2.1.1.3.4.6 Direct voltage application
6.2.1.1.3.4.7 Alternating voltage application
6.2.1.1.3.4.7.1 High field frequency
6.2.1.1.3.4.7.2 Low field frequency
6.2.1.1.3.4.7.3 Medium field frequency
6.2.1.1.3.4.8 Ag/AgCl and Pt electrodes
6.2.1.1.3.4.8.1 Ag/AgCl electrodes
6.2.1.1.3.4.8.2 Pt electrodes
6.2.1.1.3.4.8.3 Recording versus stimulation
6.2.1.1.3.5 Electrode impedance model
6.2.1.1.3.5.1 Polarizable electrode
6.2.1.1.3.5.2 Non-polarizable electrode
6.2.1.1.3.5.3 Polarizable versus non-polarizable electrodes
6.2.1.1.3.6 Experimental issues
6.2.1.1.3.6.1 Measurement of tissue impedance
6.2.1.1.3.6.2 Tissue conductivity
6.2.1.1.3.6.3 Movement artefacts
6.2.1.1.3.6.4 Charge and discharge of monitoring electrodes
6.2.1.1.4 Whole-body impedance
6.2.1.2 Signal coupling in diagnosis and therapy
6.2.1.2.1 Diagnosis
6.2.1.2.2 Therapy
6.2.1.2.3 Non-contact diagnosis
6.2.2 Biosignal and interference coupling
6.2.2.1 Capacitive coupling of interference
6.2.2.2 Inductive coupling of interference
6.2.2.3 Biosignal coupling - voltage divider
6.2.2.4 Common-mode interference
6.2.2.5 Differential-mode interference
6.2.2.6 Inner body resistance
6.2.2.7 Electrode area
6.2.2.8 Countermeasures against interference
6.2.2.8.1 Shielding
6.2.2.8.2 Driven-right-leg circuit
6.2.2.8.3 Notch filter
6.2.2.8.4 Preamplifier
6.2.2.8.5 Length of electrode leads
6.2.2.9 Triboelectricity
6.2.3 Body area networks
References