Omnidirectional Inductive Powering for Biomedical Implants

by Lenaerts, Bert; Puers, Robert

• ISBN13: 9781402090745
• ISBN10: 1402090749
• Format: Hardcover
• Copyright: 2008-12-01
• Publisher: Springer Verlag

Summary

"Omnidirectional Inductive Powering for Biomedical Implants investigates the feasibility of inductive powering for capsule endoscopy and freely moving systems in general. Before elaborating on different approaches towards omnidirectional powering, the design and optimisation of a general inductive power link is discussed in all its aspects. Useful rectifier and inverter topologies are presented, including a class E driver that copes with coil deformations. Special attention is paid to the interaction of the inductive power link with the patient's body. Putting theory into practice, the implementation of an inductive power link for a capsule endoscope is included in a separate chapter."--BOOK JACKET.

Table of Contents

Abstract	p. v
List of Abbreviations	p. vii
List of Symbols	p. ix
Contents	p. xiii
Introduction	p. 1
Wireless Power Transmission	p. 1
Types of Wireless Power Transmission	p. 2
Radiative	p. 2
Conductive	p. 3
Capacitive	p. 4
Inductive	p. 5
A Biomedical Perspective	p. 6
Instrumentated Implants	p. 6
Transcutaneous Powering	p. 7
Inductive Links	p. 9
Powering System	p. 9
Data Communication	p. 10
Conclusions	p. 11
What to Expect	p. 12
Magnetic Induction	p. 13
Maxwell's Equations	p. 13
Time-Domain, Integral Form	p. 13
Time-Harmonic, Differential Form	p. 14
Constitutive Relations and Ohm's Law	p. 14
Magnetic and Electric Potential	p. 15
Current and Flux	p. 16
Conductive Wire	p. 17
Inductance	p. 18
Inductor Models	p. 21
Finite Element Modelling	p. 24
Axisymmetric Geometries	p. 25
2-D Wire Models	p. 32
3-D Models	p. 33
Mutual Inductance	p. 36
Conclusions	p. 36
Inductive Link Design	p. 39
Link Equations	p. 39
Important Quantities	p. 39
Equivalent Two-Port Representations	p. 42
Secondary Resonance	p. 43
Transmitted Power	p. 45
Link Efficiency	p. 46
Link Gain and Critical Coupling	p. 48
Parallel vs. Series Resonance	p. 50
Summary	p. 53
Loose-Coupling Approximation	p. 53
Tertiary Circuits	p. 55
Conductive Objects	p. 56
Coupled Resonators	p. 61
Link Optimisation	p. 65
Operating Frequency: ¿	p. 65
Magnetic Design: M0	p. 66
Winding Losses: R10 and R20	p. 68
Secondary Coil Optimisation: N2	p. 71
Secondary Coil and Capacitance Tapping	p. 75
Advanced Gain Stabilisation	p. 77
Misconceptions About k and Q	p. 78
Conclusions	p. 80
Power Converters and Voltage Regulators	p. 83
Rectifiers	p. 83
Diodes	p. 84
Peak Rectifiers	p. 85
Class D Rectifiers	p. 88
Class E Rectifiers	p. 91
To Conclude	p. 91
Inverters	p. 92
Semiconductor Switches	p. 93
Saturating Class C Inverter	p. 94
Class D Inverters	p. 96
Class E Inverters	p. 97
Alternative Load Networks	p. 102
Design of an Inductive Link Driver	p. 104
Voltage Regulators	p. 112
Linear Regulators	p. 113
Switching Regulators	p. 115
Conclusions	p. 116
Omnidirectional Coupling	p. 119
Problem Definition	p. 119
Multiple Primary Coils	p. 120
System Concept	p. 120
Worst-Coupling Map	p. 121
Capsule Endoscope with One Secondary Coil	p. 123
Multiple Secondary Coils	p. 127
Power-Combining Rectifiers	p. 127
Worst-Case Conditions	p. 129
Capsule Endoscope with Three Secondary Coils	p. 134
Conclusions	p. 137
Biological Tissue Interaction	p. 139
Electromagnetic Fields in Biological Tissue	p. 139
Near Field	p. 139
Far Field	p. 142
Health Effects of Electromagnetic Fields	p. 143
Directly Observable Effects	p. 143
Other Biological Effects	p. 145
Exposure Limits and Regulations	p. 145
Examples from Biomedical Engineering Practice	p. 148
Conclusions	p. 150
An Inductive Power Link for a Capsule Endoscope	p. 151
Wireless Endoscopy	p. 151
Design: Choices and Motivation	p. 152
Specifications	p. 152
Operating Frequency	p. 152
Coil Configuration	p. 153
Voltage Regulator and Rectifier	p. 153
Power Optimisation	p. 154
Verification	p. 155
Fabrication	p. 156
Measurement	p. 160
Biological Tissue Interaction	p. 163
ICNIRP Compliance	p. 165
Link Efficiency	p. 169
Class E Tuning	p. 170
Secondary Resonance Tuning	p. 172
Conclusions	p. 172
A Class E Driver for Deformable Coils	p. 175
Class E ZVS Inverter with Transductor	p. 175
Control Loop	p. 179
Measurement Results	p. 183
Deforming the Primary Coil	p. 184
Varying the Frequency	p. 186
Conclusions	p. 187
Conclusions	p. 191
Comprehensive Summary	p. 191
Main Contributions and Achievements	p. 193
Further Research	p. 194
Appendix: Coil Measurements	p. 197
Single Coil Characterisation	p. 197
General Considerations	p. 197
One-Port S11 Measurement	p. 199
Two-Port Q' Measurement	p. 200
Impedance Analysers and LCR Meters	p. 203
Coupling Characterisation	p. 204
References	p. 211
Index	p. 219
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