Antennas and Wireless Power Transfer Methods for Biomedical Applications

Yongxin Guo is a Full Professor at National University of Singapore. He is a Fellow of IEEE and Singapore Academy of Engineering. He is serving as Editor-in-Chief, IEEE Journal of Electromagnetics, RF and Microwave in Medicine and Biology. He is a Distinguished Lecturer for IEEE Antennas and Propagation Society and his current research interests include wireless power transfer, antennas, oxford, electromagnetic sensing and MMIC modelling and design for biomedicine, internet of things and wireless communications. Yuan Feng is a Research Fellow of National University of Singapore and an Adjunct Associate Investigator of NUS Suzhou Research Institute. Dr. Feng serves as a Reviewer for the IEEE Transactions on Antennas and Propagation and he received his PhD. from Tsinghua University, China, in 2020. His research interests include neuromodulation technology, implantable and wearable antennas for biomedical and healthcare applications, RF energy harvesting, and wireless power. Changrong Liu is an Associate Professor at Soochow University, China, and is a member of the IEEE. He received his PhD in radio physics from the University of Electronic Science and Technology of China in 2015 and his research interests include LTCC-based millimeter-wave antenna array design, circularly polarized beam-steering antenna array, and implantable antennas for biomedical applications, including wireless data telemetry, and power transfer.

• Foreword xiPreface xiiiAcknowledgment xv1 Introduction: Toward Biomedical Applications 11.1 Biomedical Devices for Healthcare 11.1.1 Wearable Devices 31.1.2 Implantable Devices 61.2 Wireless Date Telemetry and Powering for Biomedical Devices 81.2.1 Wireless Data Telemetry for Biomedical Devices 81.2.2 Wireless Power Transmission for Biomedical Devices 121.3 Overview of Book 132 Miniaturized Wideband and Multiband Implantable Antennas 172.1 Introduction 172.2 Miniaturization Methods for Implantable Antenna Design 182.2.1 Use of High-permittivity Dielectric Substrate/Superstrate 182.2.2 Use of Planar Inverted-F Antenna Structure 202.2.3 Lengthening the Current Path of the Radiator 222.2.4 Loading Technique for Impedance Matching 242.2.5 Choosing Higher Operating Frequency 262.3 Wideband Miniaturized Implantable Antenna 282.3.1 Introducing Adjacent Resonant Frequency Points 282.3.1.1 Linear Wire Antenna 282.3.1.2 Slot Antenna 322.3.1.3 Loop Antenna 342.3.1.4 Microstrip Patch Antenna 342.3.2 Multiple Resonance and Wideband Impedance Matching 352.3.3 Advanced Technology for Detuning Problem 492.4 Multiband Miniaturized Implantable Antennas 502.4.1 Compact PIFAWith Multi-current Patch 502.4.2 Open-end Slots on Ground 542.4.3 Single-layer Design 552.5 Conclusions 613 Polarization Design for Implantable Antennas 673.1 Introduction 673.2 Compact Microstrip Patch Antenna for CP-implantable Antenna Design 683.2.1 Capacitively-loaded CP-implantable Patch Antenna 683.2.1.1 An Implantable Microstrip Patch Antenna with a Center Square Slot 683.2.1.2 Compact-implantable CP Patch Antenna with Capacitive Loading 713.2.1.3 Communication Link Study of the CP-implantable Patch Antenna 733.2.1.4 Sensitivity Evaluation of the Implantable CP Patch Antenna 753.2.2 Miniaturized Circularly Polarized-implantable Annular-ring Antenna 793.3 Wide AR Bandwidth-implantable Antenna 833.3.1 Miniaturized CP-implantable Loop Antenna 833.3.1.1 Configuration of the CP-implantable Loop Antenna 833.3.1.2 Principle of the CP-implantable Loop Antenna 863.3.1.3 Antenna Measurement and Discussions 883.3.1.4 Communication Link of the Implantable CP Loop Antennas 903.3.2 Ground Radiation CP-implantable Antenna 913.4 Application Base Design of CP-implantable Antenna -- Capsule Endoscopy 973.4.1 Axial-mode Multilayer Helical Antenna 973.4.1.1 Antenna Structure 993.4.1.2 Conformal Capsule Antenna Design Including Biocompatibility Shell Consideration 1013.4.1.3 Wireless Capsule Endoscope System in a Human Body 1033.4.1.4 In Vitro Testing and Discussions 1083.4.2 Conformal CP Antenna for Wireless Capsule Endoscope Systems 1123.4.2.1 Antenna Layout and Simulation Phantom 1123.4.2.2 Mechanism of CP Operation 1143.4.2.3 Results and Discussion 1153.5 In Vivo Testing of Circularly Polarized-implantable Antennas 1183.5.1 In Vivo Testing Configuration 1183.5.2 Measured Reflection Coefficient 1193.5.3 Analysis of the Results and Discussions 1203.6 Conclusions 1224 Differential-fed Implantable Antennas 1294.1 Introduction 1294.2 Dual-band Implantable Antenna for Neural Recording 1304.2.1 Differential Reflection Coefficient Characterization 1304.2.2 Antenna Design and Operating Principle 1314.2.3 Measurement and Discussions 1344.2.4 Communication Link Study 1364.3 Integrated On-chip Antenna in 0.18μm CMOS Technology 1374.3.1 System Requirement and Antenna Design 1394.3.2 Chip-to-SMA Transition Design and Measurement 1424.4 Dual-band Implantable Antenna for Capsule Systems 1464.4.1 Planar-implantable Antenna Design 1464.4.2 Conformal Capsule Design 1494.4.3 Coating and In Vitro Measurement 1534.5 Miniaturized Differentially Fed Dual-band Implantable Antenna 1544.5.1 Miniaturized Dual-band Antenna Design 1554.5.2 Parametric Analysis and Measurement 1584.5.2.1 The Effect of the Shorting Strip 1584.5.2.2 The Effect of the Length of L-shaped Arms 1584.5.2.3 Measurement 1594.6 Differentially Fed Antenna With Complex Input Impedance for Capsule Systems 1604.6.1 Antenna Geometry 1614.6.2 Operating Principle 1624.6.2.1 Equivalent Circuit 1634.6.2.2 Parametric Study 1644.6.2.3 Comparison With T-Match 1664.6.3 Experiment 1694.7 Conclusions 1725 Wearable Antennas for On-/Off-Body Communications 1775.1 Introduction 1775.2 ExploringWearable Antennas: Design and Fabrication Techniques 1795.2.1 Typical Designs ofWearable Antennas 1795.2.2 Variation of Antenna Characteristics and Design Considerations 1815.2.3 AMC-Backed Near-EndfireWearable Antenna 1825.3 Latex Substrate and Screen-Printing forWearable Antennas Fabrication 1835.4 AMC-backed Endfire Antenna 1845.4.1 Bidirectional Yagi Antenna for Endfire Radiation 1845.4.2 Near-Endfire Yagi Antenna Backed by SAMC 1845.4.3 Near-Endfire Yagi Antenna Backed by DAMC 1875.5 Simulations of the Antennas in Free Space 1895.5.1 Return Loss 1895.5.2 Radiation Patterns 1895.5.3 Gain 1905.6 Simulations of the Antennas on Human Body 1915.6.1 Frequency Detuning 1915.6.2 SAR and Antenna Efficiency 1925.6.3 Radiation Patterns on A Human Body 1945.7 Antenna Performance Under Deformation 1955.8 Experiment 1985.8.1 Return Loss 1985.8.2 Radiation Pattern Measurement 1985.8.3 Gain Measurement 2015.9 Conclusion 2016 Investigation and Modeling of Capacitive Human Body Communication 2056.1 Introduction 2056.2 Galvanic and Capacitive Coupling HBC 2066.3 Capacitive HBC 2076.3.1 Experimental Characterizations 2076.3.2 Numerical Models 2116.3.3 Circuit Models of Capacitive HBC 2126.3.4 Theoretical Analysis 2126.4 Investigation and Modeling of Capacitive HBC 2146.4.1 Measurement Setup and Results 2146.4.2 Simulation Setup and Results 2206.4.3 Equivalent Circuit Model 2266.5 Conclusions: Other Design Considerations of HBC Systems 2306.5.1 Channel Characteristics 2316.5.2 Modulation and Communication Performance 2326.5.3 Systems and Application Examples 2327 Near-field Wireless Power Transfer for Biomedical Applications 2377.1 Introduction 2377.2 Resonant InductiveWireless Power Transfer (IWPT) and IWPT Topologies 2387.2.1 Resonances in IWPT 2387.2.2 Resonant IWPT Topologies 2427.2.3 Power Transfer Efficiency 2427.2.4 Experimental Verification 2447.2.5 Limitations of the Resonance Tuning 2457.3 IWPT Topology Selection Strategies 2477.3.1 For Applications With a Fixed Load 2477.3.2 For Applications With a Variable Load 2497.3.3 Optimal Operating Frequency 2517.3.4 Upper Limit on Power Transfer Efficiency 2527.4 CapacitiveWireless Power Transfer (CWPT) 2547.4.1 NCC Link Modeling 2567.4.1.1 Tissue Model 2577.4.1.2 Tissue Loss 2587.4.1.3 Conductor Loss (RC) 2607.4.1.4 Self-inductance 2607.4.1.5 Equivalent Capacitance 2607.4.1.6 Return Loss 2617.4.1.7 Power Transfer Efficiency 2617.4.1.8 Power Transfer Limit 2627.4.2 Full-wave Simulation 2647.4.3 Optimal Link Design 2667.5 CWPT: Experiments in Nonhuman Primate Cadaver 2677.5.1 Study on Power Transfer Efficiency 2677.5.2 Flexion Study 2697.6 Summary 2708 Far-field Wireless Power Transmission for Biomedical Application 2758.1 Introduction 2758.2 Far-Field EM Coupling 2758.2.1 Power Transfer Efficiency 2778.2.2 Link Design 2788.2.3 Challenges and Solutions 2798.3 Enhanced Far-field WPT Link for Implants 2808.3.1 Safety Considerations for Far-field Wireless Power Transmission 2808.3.2 Implantable Rectenna Design 2818.3.2.1 Implantable Antenna Configuration 2818.3.2.2 Wireless Power Link Study 2848.3.2.3 Safety Concerns 2858.3.2.4 Method to Enhance the Received Power 2878.3.2.5 Wireless Power Link With the Parasitic Patch 2888.3.3 Measurement and Discussion 2908.3.3.1 Rectifier Circuit Design 2918.3.3.2 Integration Solution of the Implantable Rectenna 2948.3.3.3 Measurement Setup 2958.4 WPT Antenna Misalignment: An Antenna Alignment Method Using Intermodulation 2978.4.1 Operation Mechanism 2988.4.1.1 PCE Enhancement and Intermodulation Generation 2988.4.1.2 Relation Between Intermodulation and Misalignments 3008.4.2 Miniaturized IMD Rectenna Design With NRIC Link 3008.4.2.1 Miniaturized Rectifier With Intermodulation Readout 3008.4.2.2 IMD Antenna CodesignedWith Rectifier Circuit 3028.4.2.3 NRIC Link Establishment 3048.4.3 Experimental Validation 3068.4.3.1 Experimental Setup 3068.4.3.2 Results and Discussion 3088.5 Summary 3099 System Design Examples: Peripheral Nerve Implants and Neurostimulators 3139.1 Introduction 3139.2 Wireless Powering and Telemetry for Peripheral Nerve Implants 3149.2.1 Peripheral Nerve Prostheses 3149.2.1.1 Stimulator Implant 3149.2.1.2 Neural Recording 3149.2.1.3 Wireless Power Delivery and Telemetry Requirements 3169.2.2 Wireless Platform for Peripheral Nerve Implants 3179.2.2.1 Wireless Platform for Stimulator Implant 3179.2.2.2 Wireless Platform for Recording Implant 3199.2.3 Design and Experiments 3199.2.3.1 Power Transfer Characteristics in Tissue Environments 3209.2.3.2 Power Transfer Link for Peripheral Nerve Implants 3239.2.3.3 Stimulator Implant Experiment 3249.2.4 Safety 3289.2.4.1 Biosafety 3289.2.4.2 Electrical Safety 3289.2.5 Near-field Resonant Inductive-coupling Link (NRIC) Versus Near-field Capacitive-coupling Link (NCC) 3289.3 Co-matching Solution for Neurostimulator Narrow Band Antenna 3309.3.1 Co-matching Antenna Operating Mode 3329.3.2 Antenna Property in Body Phantom 3349.3.3 Co-matching Circuit Design 3369.3.4 Fabrication Processing of the Proposed Antenna 3389.3.5 Reflection Coefficient and Impedance Measurement 3399.3.6 Radiation Performance 3409.4 Reconfigurable Antenna for Neurostimulator 3439.4.1 Tuning Principle 3449.4.2 Antenna Configuration and Design Procedures 3449.4.3 Antenna Manufacturing and Measurement Setup 3479.4.4 System Design 3489.4.5 Antenna Tuning and Optimized RF Link 3499.5 Summary 352References 352Index 357

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