Zhou / Greenbaum Implantable Neural Prostheses 2

Techniques and Engineering Approaches
1. Auflage 2010
ISBN: 978-0-387-98120-8
Verlag: Springer
Format: PDF
Kopierschutz: 1 - PDF Watermark

E-Book, Englisch, 371 Seiten

Reihe: Biological and Medical Physics, Biomedical Engineering

Signi?cant progress has been made in the development of neural prostheses for restoration of human functions and improvement of the quality of life. Biomedical engineers and neuroscientists around the world are working to improve the design and performance of existing devices and to develop novel devices for arti?cial vision, arti?cial limbs, and brain-machine interfaces. This book, Implantable Neural Prostheses 2: Techniques and Engineering Approaches, is part two of a two-volume sequence that describes state-of-the-art advances in techniques associated with implantable neural prosthetic devices. The techniques covered include biocompatibility and biostability, hermetic packaging, electrochemical techniques for neural stimulation applications, novel electrode materials and testing, thin-?lm ?exible microelectrode arrays, in situ char- terization of microelectrode arrays, chip-size thin-?lm device encapsulation, microchip-embedded capacitors and microelectronics for recording, stimulation, and wireless telemetry. The design process in the development of medical devices is also discussed. Advances in biomedical engineering, microfabrication technology, and neu- science have led to improved medical-device designs and novel functions. However, many challenges remain. This book focuses on the engineering approaches, R&D advances, and technical challenges of medical implants from an engineering p- spective. We are grateful to leading researchers from academic institutes, national laboratories, as well as design engineers and professionals from the medical device industry who have contributed to the book. Part one of this series covers designs of implantable neural prosthetic devices and their clinical applications.

Autoren/Hrsg.

Zhou, David

Greenbaum, Elias

Inhaltsverzeichnis

1;Preface;6
2;Contents;7
3;Contributors;9
4;Acronyms;11
5;The Biocompatibility and Biostability of New Cardiovascular Materials and Devices;15
5.1;1 Introduction;16
5.2;2 Background;17
5.2.1;2.1 Learning from the Past;17
5.2.2;2.2 Environmental Stress Cracking (ESC);18
5.2.3;2.3 Metal Ion Oxidation (MIO);20
5.2.4;2.4 Subclavian Crush;22
5.2.5;2.5 Why Were These Mechanisms Not Discovered Before Market Release?;23
5.2.6;2.6 Chronic Removability of Transvenous Cardiac Leads;24
5.3;3 Risk Assessment;26
5.4;4 Material Biocompatibility Testing;26
5.4.1;4.1 Substantially Equivalent Materials;26
5.4.2;4.2 New Materials;26
5.4.3;4.3 Phase 1 Tests (ISO 10993-1);27
5.4.3.1;4.3.1 Phase 2 Tests;28
5.5;5 Potential for Biodegradation;29
5.6;6 New Material Stability Testing In Vitro;29
5.6.1;6.1 Metals;30
5.6.2;6.2 Polymers;30
5.7;7 In Vivo Materials Testing;32
5.8;8 Device Implants in Animal Models;33
5.9;9 Human Clinical Implants;34
5.10;10 Market Release and Postmarket Surveillance;34
5.10.1;10.1 Returned Products Analysis;34
5.10.2;10.2 Postmarket Clinical Studies;35
5.11;11 Summary and Conclusions;38
5.12;References;38
6;Technology Advances and Challenges in Hermetic Packaging for Implantable Medical Devices;41
6.1;1 Introduction;42
6.1.1;1.1 Hermetic Packaging Technology Advances;42
6.1.2;1.2 Significance of Hermetic Packaging for Implantable Medical Devices;45
6.2;2 General Packaging Considerations for Implantable Medical Devices;45
6.2.1;2.1 Biocompatibility;45
6.2.2;2.2 Hermeticity Requirement;46
6.2.3;2.3 Outgassing of Internal Materials;46
6.2.4;2.4 Wireless Communication;47
6.2.5;2.5 Package Heating;47
6.2.6;2.6 Coefficient of Thermal Expansion Compatibility;47
6.3;3 Types of Hermetic Sealing and Their Applications;48
6.3.1;3.1 Polymer Encapsulation;48
6.3.2;3.2 Glass-to-Metal Seal;48
6.3.3;3.3 Ceramic-to-Metal Feedthrough;49
6.3.4;3.4 Ceramic-to-Metal Seal;51
6.3.4.1;3.4.1 Active Brazing;51
6.3.4.2;3.4.2 Nonactive Brazing;52
6.3.4.3;3.4.3 Diffusion Bonding of Ceramic-to-Metal;52
6.3.5;3.5 Hermetic Seal with Fusion Welding;53
6.3.6;3.6 Conductive Vias on Ceramic Substrate;54
6.4;4 Testing Methods for Hermetic Sealing of Implantable Medical Devices;55
6.4.1;4.1 Mechanical and Environmental Tests;55
6.4.2;4.2 Hermeticity Testing Methods and Their Limitations;56
6.4.3;4.3 Biocompatibility Tests;59
6.4.4;4.4 Corrosion Tests;60
6.4.5;4.5 Morphological and Microstructural Characterization;61
6.4.6;4.6 Accelerated Life Test;62
6.4.7;4.7 X-Ray Microscopy;63
6.4.8;4.8 Acoustic Microscopy;65
6.5;5 Challenges of Hermetic Packaging for Implantable Medical Devices;65
6.5.1;5.1 Long-Term Stability of Ceramic Materials;65
6.5.2;5.2 Metals and Alloys Corrosion;66
6.5.3;5.3 Challenges in Accelerated Life Test;67
6.5.4;5.4 Hermeticity Test Reliability for Miniature Devices;68
6.5.5;5.5 Design challenges for Miniature Devices;69
6.5.6;5.6 Hermetic Packaging of MEMS for Implantable Medical Devices;69
6.6;6 Conclusions;70
6.7;References;70
7;Science and Technology of Bio-Inert Thin Films as Hermetic-Encapsulating Coatings for Implantable Biomedical Devices: Application to Implantable Microchip in the Eye for the Artificial Retina;77
7.1;1 Scientific and Technological State-of-the-Art of Bio-inert Coatings for Encapsulation of Implantable Microchips;78
7.2;2 Process and Design Considerations for Hermetic Bio-inert Coatings for Implantable Artificial Retina;80
7.2.1;2.1 Materials for Hermetic-Encapsulating Coatings;80
7.2.2;2.2 Carbon-Based Ultrananocrystalline Diamond (UNCD) Coatings and Film;81
7.2.3;2.3 Oxide Films Alone or as Component of Hybrid UNCD/Oxide for Hermetic-Encapsulating Coatings;85
7.3;3 Characterization of Bio-inert Hermetic-Encapsulating Coatings;86
7.3.1;3.1 Characterization of Chemical, Microstructural, and Morphological Properties of UNCD Coatings;86
7.3.2;3.2 Characterization of Microstructural and Morphological Properties of Oxide Films for Hybrid Hermetic-Encapsulating Coatings;91
7.3.3;3.3 Characterization of Electrochemical Performance in Saline Solution for Hermetic UNCD Coatings;91
7.3.4;3.4 Characterization of Electrochemical Performance in Saline Solution for Hermetic Oxide Films;92
7.3.5;3.5 Characterization of UNCD/CMOS Integration;93
7.3.6;3.6 In Vivo Animal Tests of Hermetic-Encapsulating Coatings for Artificial Retina;94
7.4;4 Challenges for Bio-inert Microchip Encapsulation Hermetic Coatings;95
7.5;5 Conclusions and a Future Outlook;96
7.6;References;97
8;The Electrochemistry of Charge Injection at the Electrode/Tissue Interface;99
8.1;1 Physical Basis of the Electrode/Electrolyte Interface;100
8.1.1;1.1 Capacitive/Non-Faradaic Charge Transfer;101
8.1.2;1.2 Faradaic Charge Transfer and the Electrical Model of the Electrode/Electrolyte Interface;102
8.1.3;1.3 Reversible and Irreversible Faradaic Reactions;104
8.1.4;1.4 The Origin of Electrode Potentials and the Three-Electrode Electrical Model;106
8.1.5;1.5 Faradaic Processes: Quantitative Description;110
8.1.6;1.6 Ideally Polarizable Electrodes and Ideally Nonpolarizable Electrodes;115
8.2;2 Charge Injection Across the Electrode/Electrolyte Interface During Electrical Stimulation;117
8.2.1;2.1 Charge Injection During Pulsing: Interaction of Capacitive and Faradaic Mechanisms;117
8.2.2;2.2 Methods of Controlling Charge Delivery During Pulsing;119
8.2.3;2.3 Charge Delivery by Current Control;120
8.2.4;2.4 Pulse train response during current control;121
8.2.5;2.5 Electrochemical reversal;124
8.2.6;2.6 Charge delivery by a voltage source between the working electrode and counter electrode;126
8.3;3 Materials Used as Electrodes for Charge Injection and Reversible Charge Storage Capacity;128
8.4;4 Charge Injection for Extracellular Stimulation of Excitable Tissue;133
8.5;5 Mechanisms of Damage;137
8.6;6 Design Compromises for Efficacious and Safe Electrical Stimulation;141
8.7;References;145
9;In Situ Characterization of Stimulating Microelectrode Arrays: Study of an Idealized Structure Based on Argus II Retinal implants;153
9.1;1 Introduction;154
9.2;2 Physical Analysis of Argus II Electrode Array and Representative Analogs;154
9.2.1;2.1 The Argus II Electrode Array;154
9.2.2;2.2 Electrical Properties of the Vitreous;155
9.2.2.1;2.2.1 Stimulation Waveforms;156
9.2.2.2;2.2.2 AC and DC Impedance;156
9.2.2.3;2.2.3 Retinal Tissues;156
9.2.3;2.3 Electrical Stimulation, Electrodes, and Systems;157
9.2.3.1;2.3.1 Electrode Configuration;157
9.2.3.2;2.3.2 Electrode Size and Spacing;157
9.2.3.3;2.3.3 Materials and Stability;157
9.2.4;2.4 Return Electrode;158
9.2.4.1;2.4.1 Functions;158
9.2.4.2;2.4.2 Design;158
9.3;3 Characterization of Simplified Argus II Analogs;159
9.3.1;3.1 Single Electrode;159
9.3.1.1;3.1.1 Design and Material;159
9.3.2;3.2 9-Electrode Array Structure;159
9.4;4 Numerical Simulation of Argus II Simplified Model;166
9.4.1;4.1 Numerical Simulation;166
9.4.2;4.2 Single Electrode;166
9.4.3;4.3 60-Electrode Array Cross-Talk Modeling;168
9.5;5 Conclusions;169
9.6;References;169
10;Thin-Film Microelectrode Arrays for Biomedical Applications;171
10.1;1 Introduction;172
10.2;2 Microfabrication Methods and Materials;173
10.2.1;2.1 Micromachining;173
10.2.2;2.2 Microfabricated Microelectrodes;174
10.2.3;2.3 Silicon-Based Thin-Film Electrodes;175
10.2.3.1;2.3.1 Planar Silicon-Based Electrodes;176
10.2.3.2;2.3.2 Three-Dimensional Silicon-Based Electrodes;178
10.2.3.3;2.3.3 Sieve Electrodes;179
10.2.4;2.4 Metal-Based Thin-Film Electrodes;180
10.2.5;2.5 Ceramic-Based Thin-Film Electrodes;181
10.2.6;2.6 Polymer-Based Thin-Film Electrodes;182
10.2.6.1;2.6.1 Polyimide;182
10.2.6.2;2.6.2 Other Polymer-Based Microelectrodes;185
10.2.7;2.7 Nanostructured Electrodes;188
10.2.7.1;2.7.1 Carbon Nanotube Coatings;189
10.2.7.2;2.7.2 Conductive Polymer Nanotubes;190
10.3;3 Central Nervous System Response to Implanted Devices;191
10.3.1;3.1 Reactive Gliosis;192
10.3.2;3.2 Histology;192
10.3.3;3.3 Glial Scar and Tissue Impedance;193
10.4;4 Implant Biocompatibility;194
10.4.1;4.1 Microelectrode Structure;195
10.4.2;4.2 Pharmacology;195
10.4.3;4.3 Hybrid Structures;196
10.5;5 Conclusion;197
10.6;References;197
11;Stimulation Electrode Materials and Electrochemical TestingMethods;205
11.1;1 Introduction;206
11.2;2 Electrode Reactions;207
11.2.1;2.1 Electrode Interface;207
11.2.2;2.2 Electrical Double Layer;208
11.2.3;2.3 Reversible Metal Oxidation/Reduction;208
11.2.4;2.4 Irreversible Chemical Reaction;209
11.2.5;2.5 Electrolyte Resistance;210
11.3;3 Common Electrochemical Tests and Electrode Materials;210
11.3.1;3.1 Cyclic Voltammetry;210
11.3.2;3.2 Platinum;212
11.3.3;3.3 Titanium;213
11.3.4;3.4 Iridium;213
11.3.5;3.5 Effect of Protein;215
11.3.6;3.6 Impedance Measurement;215
11.4;4 Neural Stimulation Settings Which Affect Charge Injections;216
11.4.1;4.1 Basis of Neural Stimulation;216
11.4.2;4.2 Components of a Neural Stimulation System;217
11.4.3;4.3 Monophasic Voltage Stimulation;217
11.4.4;4.4 Constant Voltage vs. Constant Current;217
11.4.5;4.5 Analysis of Constant-Current Electrode-Voltage Waveform;218
11.4.6;4.6 Current Control with Passive Recharge;219
11.4.7;4.7 Active Recharge;220
11.4.8;4.8 Cathodic Bias;221
11.4.9;4.9 Bipolar vs. Monopolar Stimulation;221
11.5;5 Other Measurement Techniques;221
11.5.1;5.1 Electrode-Potential Measurement;222
11.5.2;5.2 Pulse Cl223
11.5.3;5.3 Computer Simulation;224
11.5.4;5.4 Dissolution Testing;227
11.5.5;5.5 Inductively Coupled Plasma (ICP);228
11.6;6 Summary;228
11.7;References;228
12;Conducting Polymers in Neural Stimulation Applications;231
12.1;1 Introduction;232
12.2;2 Neural Stimulation and Electrode Materials;233
12.2.1;2.1 Charge Transfer Processes During Stimulation;233
12.2.2;2.2 Electrodes for Neural Stimulation Implants;234
12.3;3 Conducting Polymers;236
12.3.1;3.1 Various Conducting Polymers;236
12.3.1.1;3.1.1 Polypyrrole;236
12.3.1.2;3.1.2 Polyaniline;237
12.3.1.3;3.1.3 PEDOT;237
12.3.2;3.2 Methods of Preparing Conducting Polymers;239
12.3.3;3.3 Biomedical Applications of Conducting Polymers;244
12.4;4 Challenges of Conducting Polymers for Chronic Neural Stimulation;246
12.4.1;4.1 Electrode Impedance;246
12.4.2;4.2 Polymer Volume Changes Under Electrical Stimulation;251
12.4.3;4.3 Charge Injection Capability;253
12.4.4;4.4 Biocompatibility;255
12.4.5;4.5 Long-Term Stability;257
12.5;5 Conclusions;260
12.6;References;261
13;Microelectronics of Recording, Stimulation, and Wireless Telemetry for Neuroprosthetics: Design and Optimization;267
13.1;1 Introduction;268
13.2;2 Basic Building Blocks;269
13.2.1;2.1 Amplifier;269
13.2.1.1;2.1.1 Negative-Feedback Amplifier;271
13.2.1.2;2.1.2 Chopper Amplifier;275
13.2.2;2.2 Filter;276
13.2.2.1;2.2.1 Passive R-C Filter;276
13.2.2.2;2.2.2 Active Filter;277
13.2.2.3;2.2.3 Switched-Capacitor Filter;278
13.2.3;2.3 ADC;279
13.3;3 Subsystem Design;280
13.3.1;3.1 Front-End Blocks for Neural Recording;280
13.3.1.1;3.1.1 System Architecture and Circuit Modeling;280
13.3.1.2;3.1.2 System Resolution;285
13.3.1.3;3.1.3 Trade-Off Between System Power and Chip Area;287
13.3.2;3.2 Neural-Signal Processing Unit;291
13.3.2.1;3.2.1 Theory;291
13.3.2.2;3.2.2 Spike Sorting Methods and Results;296
13.3.3;3.3 Neuromuscular Current Stimulator with High-Compliance Voltage;302
13.3.4;3.4 Wireless Telemetry;303
13.3.4.1;3.4.1 Power Telemetry;305
13.3.4.2;3.4.2 Data Telemetry;312
13.4;4 System Design Examples;321
13.4.1;4.1 Recording: 128-Channel Wireless Neural-Recording System;321
13.4.1.1;4.1.1 Chip Architecture;323
13.4.1.2;4.1.2 Front-End Block Design;324
13.4.1.3;4.1.3 Neural-Signal Processing Engine;327
13.4.1.4;4.1.4 UWB Telemetry;328
13.4.1.5;4.1.5 Test Results;330
13.4.1.6;4.1.6 60-Hz Power Interference Issue;331
13.4.2;4.2 Stimulation: 256-Channel Retinal Prosthesis Chip;333
13.4.2.1;4.2.1 System Architecture;333
13.4.2.2;4.2.2 Stimulator Pixel Design;334
13.4.2.3;4.2.3 Dual-Band Power and Data Telemetry Design;335
13.5;5 Summary;335
13.6;References;336
14;Microchip-Embedded Capacitors for Implantable NeuralStimulators;345
14.1;1 Introduction;346
14.2;2 Design and Process Considerations for Oxide Films for Microchip-Embedded Capacitors;346
14.2.1;2.1 Materials for High-Dielectric Constant (K) Layers;346
14.2.2;2.2 TiAlOx or TiO2/Al2O3Superlattice Oxide Layers;348
14.2.3;2.3 Synthesis and Deposition Techniques of Oxide Films for Embedded Capacitors;350
14.2.3.1;2.3.1 Sputter-Deposition;350
14.2.3.2;2.3.2 Atomic Layer Deposition (ALD);350
14.3;3 Characterization of Oxide Films for Microchip Embedded Capacitors;352
14.3.1;3.1 Characterization of Oxide/Silicon Interface and Structure;352
14.3.2;3.2 Electrical Performance of High-K Dielectric Oxide;352
14.4;4 Challenges for Oxide Films as High-K Dielectric Films for Microchip-Embedded Capacitors;355
14.5;5 Conclusions;356
14.6;References;356
15;An Effective Design Process for the Successful Developmentof Medical Devices;359
15.1;1 Introduction;360
15.2;2 The Design Control Process for the Development of Medical Devices ;360
15.2.1;2.1 Overview of the Design Control Process;360
15.2.2;2.2 Research and Development Phase;361
15.2.3;2.3 General Design Control Philosophy;363
15.2.4;2.4 Design and Development Planning;364
15.2.5;2.5 Design Input;365
15.2.5.1;2.5.1 Case Studies of Design Input Requirements;367
15.2.6;2.6 Design Output;367
15.2.7;2.7 Design Review;368
15.2.8;2.8 Design Verification;368
15.2.9;2.9 Design Validation;369
15.2.9.1;2.9.1 Case Studies of Design Verification and Validation;370
15.2.10;2.10 Design Transfer;370
15.2.11;2.11 Design Changes;371
15.2.11.1;2.11.1 Case Studies of the Design Changes Process;371
15.2.12;2.12 Risk and Hazard Analysis;371
15.2.13;2.13 Design History File;372
15.3;3 Conclusion;372
15.4;References;373
16;Subject Index;375