Basic Introduction to Bioelectromagnetics / Edition 2

by Cynthia Furse, Douglas A. Christensen, Carl H. Durney

Overview

Although classical electromagnetic (EM) field theory is typically embedded in vector calculus and differential equations, many of the basic concepts and characteristics can be understood with precursory mathematical knowledge. Completely revised and updated, Basic Introduction to Bioelectromagnetics, Second Edition facilitates the process of interdisciplinary research by introducing life scientists to the basic concepts of EM fields.

This new edition outlines elements of EM that are helpful to life scientists working with physicists and electrical engineers. Each concept is presented with an associated application and discussion. Example applications include hyperthermia, neural stimulation, MRI, NMR, ultrasound, and cardiac pacing/defibrillation. With the liberal use of diagrams and graphs, this qualitative and illustrative point of access:

• Covers the entire frequency spectrum from direct current (DC) up through optical frequencies











• Includes more than 200 illustrations with 40 medical applications











• Incorporates examples from real applications to explain concepts











• Concentrates on the qualitative explanation of the key concepts, fundamental principles, and characteristic behaviors of EM fields, without mathematical rigor











• Offers practical rules of thumb to understand real situations











• Requires only an algebra background, in contrast to typical EM books that require vector calculus and partial differential equations

Offering a simplified view of a very complex subject, this second edition provides an accessible introduction for life scientists and medical technologists on how EM fields work, what controls them, and the factors important to experimental setups.

Product Details

ISBN-13:	9780367385927
Publisher:	Taylor & Francis
Publication date:	10/18/2019
Edition description:	2nd ed.
Pages:	290
Product dimensions:	7.00(w) x 10.00(h) x (d)

About the Author

Furse, Cynthia; Christensen, Douglas A.; Durney, Carl H.

Table of Contents

Preface xi

Authors xiii

1 Electric and Magnetic Fields: Basic Concepts 1

1.1 Introduction 1

1.2 Electric Field Concepts 1

1.3 Magnetic Field Concepts 5

1.4 Sources of Electric Fields (Maxwell's Equations) 8

1.5 Sources of Magnetic Fields (Maxwell's Equations) 12

1.6 Electric and Magnetic Field Interactions with Materials 14

1.7 Other Electromagnetic Field Definitions 17

1.8 Waveforms Used in Electromagnetics 17

1.9 Sinusoidal EM Functions 19

1.10 Root Mean Square or Effective Values 21

1.11 Wave Properties in Lossless Materials 22

1.12 Boundary Conditions for Lossless Materials 25

1.13 Complex Numbers in Electromagnetics (the Phasor Transform) 28

1.14 Wave Properties in Lossy Materials 30

1.15 Boundary Conditions for Lossy Materials 34

1.16 Energy Absorption 35

1.17 Electromagnetic Behavior as a Function of Size and Wavelength 36

1.18 Electromagnetic Dosimetry 40

2 EM Behavior When the Wavelength Is Large Compared to the Object Size 45

2.1 Introduction 45

2.2 Low-Frequency Approximations 46

2.3 Fields Induced in Objects by Incident E Fields in Free Space 47

2.4 E Field Patterns for Electrode Configurations 52

2.4.1 Capacitor-Plate Electrodes 52

2.4.2 Displacement Current 55

2.4.3 In Vitro Electrode Configurations 57

2.5 Electrodes for Reception and Stimulation in the Body 61

2.5.1 Electrodes for Reception 64

2.5.1.1 Electrophysiological Assessment 64

2.5.1.2 Intracellular Recording: Receiving Signals from Brain and Nerves 65

2.5.1.3 Impedance Imaging 65

2.5.1.4 Impedance Monitoring for Lung Water Content and Percent Body Fat 66

2.5.2 Electrodes for Stimulation 68

2.5.2.1 Cardiac Pacemakers and Defibrillators 68

2.5.2.2 Pulsed Electromagnetic Fields 69

2.5.2.3 Direct Nerve Stimulation 70

2.5.2.4 Ablation 70

2.6 Fields Induced in Objects by Incident B Fields in Free Space 71

2.7 E Field Patterns for In Vitro Applied B Fields 75

2.8 Measurement of Low-Frequency Electric and Magnetic Fields 83

2.9 Summary 90

3 EM Behavior When the Wavelength Is About the Same Size as the Object 95

3.1 Introduction 95

3.2 Waves in Lossless Media 96

3.2.1 Spherical Waves 96

3.2.2 Planewaves 99

3.3 Wave Reflection and Refraction 101

3.3.1 Planewave Reflection at Metallic Interfaces 101

3.3.2 Planewave Reflection and Refraction at Dielectric Interfaces 109

3.4 Waves in Lossy Media 116

3.4.1 Waves in Metals 116

3.4.2 Waves in Lossy Dielectrics 117

3.4.3 Energy Absorption in Lossy Media 117

3.5 Transmission Lines and Waveguides 120

3.5.1 TEM Systems 120

3.5.2 TEM Systems for Exposing Biological Samples 125

3.5.3 Waveguides 128

3.5.3.1 TE and TM Mode Patterns in Rectangular Waveguides 128

3.5.3.2 Mode Excitation and Cutoff Frequencies 131

3.5.3.3 Waveguide Systems for Exposing Biological Samples 134

3.6 Resonant Systems 135

3.7 Antennas 138

3.8 Diffraction 150

3.8.1 Diffraction from Apertures 150

3.8.2 Diffraction from Periodic Structures 152

3.9 Measurement of Mid-Frequency Electric and Magnetic Fields 154

3.10 Summary 160

4 EM Behavior When the Wavelength Is Much Smaller Than the Object 161

4.1 Introduction 161

4.2 Ray Propagation Effects 163

4.2.1 Refraction at Dielectric Interfaces 163

4.2.2 Optical Polarization and Reflection from Dielectric Interfaces 165

4.2.3 Ray Tracing with Mirrors and Lenses 168

4.2.4 Imaging with Lenses 170

4.2.5 Graded-Index Lenses 173

4.3 Total Internal Reflection and Fiber Optic Waveguides 173

4.3.1 Multimode Optical Fibers 175

4.3.2 Single-Mode Optical Fibers 176

4.4 Propagation of Laser Beams 177

4.4.1 Linewidths of Laser Beams 177

4.4.2 The Gaussian Spherical Profile 178

4.4.3 Propagation Characteristics of a Gaussian Beam 179

4.4.4 Focusing a Gaussian Beam with a Lens 181

4.4.5 Applying the Gaussian Beam Equations 182

4.5 Scattering from Particles 183

4.5.1 Rayleigh Scattering 184

4.5.2 Mie Scattering 185

4.6 Photon Interactions with Tissues 187

4.6.1 Light Scattering in Tissues and Photon Migration 188

4.6.2 Tissue Absorption and Spectroscopy 189

4.7 X-Rays 191

4.8 Measurement of High-Frequency Electric and Magnetic Fields (Light) 191

4.9 Summary 193

5 Bioelectromagnetic Dosimetry 195

5.1 Introduction 195

5.2 Polarization 197

5.3 Electrical Properties of the Human Body 200

5.4 Human Models 200

5.5 Energy Absorption (SAR) 202

5.5.1 SARs at Low Frequencies 203

5.5.2 SAR as a Function of Frequency 204

5.5.3 Effects of Polarization on SAR 205

5.5.4 Effects of Object Size on SAR 207

5.6 Extrapolating from Experimental Animal Results to Those Expected in Humans 208

5.7 Numerical Methods for Bioelectromagnetic Stimulation 210

5.7.1 The Finite-Difference Time-Domain (FDTD) Method 211

5.7.1.1 Computation of Fields in a Human under a 60-Hz Power Line 213

5.7.1.2 Computation of SAR from Cellular Telephones 213

5.7.2 The Impedance Method 215

5.7.2.1 Calculation of the E Fields Induced Near Implants During MRI 216

5.7.2.2 Modeling an Implant in the Human Body 217

5.7.2.3 Results of the Numerical Calculations 218

5.8 Electromagnetic Regulations 222

5.8.1 Allowable Frequencies 222

5.8.2 Limits on Absorbed Power 222

5.8.3 Localized Exposure Limits 224

5.8.4 Induced Current and Shock Guidelines 224

5.8.5 Power-Line and Static Field Limits 225

5.9 Conclusion and Summary 226

References 227

6 Electromagnetics in Medicine: Today and Tomorrow 229

6.1 Introduction 229

6.2 Fundamental Potential and Challenges 229

6.3 Hyperthermia for Cancer Therapy 232

6.3.1 Types of Hyperthermia Applicators 233

6.3.1.1 Capacitive Applicators 234

6.3.1.2 Inductive Applicators 235

6.3.1.3 Radiative Applicators 237

6.3.1.4 Invasive Applicators 240

6.3.2 Engineering Problems Remaining in Hyperthermia 241

6.4 Magnetic Effects 242

6.4.1 Magnetic Resonance Imaging (MRI) 242

6.4.2 Nuclear Magnetic Resonance (NMR) Spectroscopy 245

6.5 Proposed Bioelectromagnetic Effects 246

6.5.1 Soliton Mechanisms 247

6.5.2 Spatial/Temporal Cellular Integration 247

6.5.3 Stochastic Resonance 247

6.5.4 Temperature-Mediated Alteration of Membrane Ionic Transport 247

6.5.5 Plasmon Resonance Mechanisms 247

6.5.6 Radon Decay Product Attractors 247

6.5.7 Rectification by Cellular Membranes 248

6.5.8 Ion Resonance 248

6.5.9 Ca++ Oscillations 248

6.5.10 Magnetite Interactions 248

6.6 Emerging Bioelectromagnetic Applications 248

6.6.1 Low-Frequency Applications 249

6.6.2 Medium-Frequency Applications 249

6.6.3 High-Frequency Applications 250

6.7 Conclusion 251

Appendix A Electrical Properties of the Human Body 253

Appendix B Definition of Variables 257

Appendix C Decibels 263

Index 265