Soft Actuators (eBook)

Preface 6
Contents 8
Part I: Introduction 12
Chapter 1: Progress and Current Status of Materials and Properties of Soft Actuators 13
1.1 Introduction 13
1.2 Gel Actuators 15
1.2.1 pH-Responsive Gels 15
1.2.2 Salt-Responsive Gels 15
1.2.3 Solvent-Responsive Gels 15
1.2.4 Thermo-Responsive Gels 16
1.2.5 Electro-Responsive Gels 16
1.2.6 Photo-Responsive Gels 19
1.2.7 Magneto-Responsive Gels 20
1.3 Conductive Polymer Actuators 20
1.3.1 Electro-Responsive Conductive Polymers 20
1.3.2 Humidity-Responsive Conductive Polymers 21
1.4 Elastomer Actuators 22
1.4.1 Electro-Responsive Elastomers 22
1.4.2 Photo-Responsive Elastomers 23
1.5 Carbon Nanotube Actuators 23
1.6 Bio-Actuators 24
References 24
Chapter 2: Current Status of Applications and Markets of Soft Actuators 29
2.1 Introduction 29
2.2 Current Status of Applications of Soft Actuators 30
2.2.1 Groundbreaking Studies 30
2.2.2 Current Status of Technology of EAP Actuators for Applications 31
2.2.3 Consumer Electronics 31
2.2.4 Biomedical Devices 33
2.2.5 Robotics 34
2.2.6 Other Applications of Soft Actuators 35
2.2.7 Energy Harvesting and Sensor 35
2.3 Current and Expected Markets for Soft Actuators 37
2.4 Conclusion 40
References 40
Part II: Materials of Soft Actuators: Thermo-Driven Soft Actuators 41
Chapter 3: Electromagnetic Heating 42
3.1 Introduction 42
3.2 Surface Modification of CMCs 44
3.3 Preparation of Composite Gels 45
3.4 Sensitivity of Composite Gels Against Electromagnetic Wave 47
3.5 Conclusions 49
References 50
Chapter 4: Thermo-Responsive Nanofiber Mats Fabricated by Electrospinning 51
4.1 Introduction 51
4.2 Experimental 52
4.3 Results and Discussion 54
4.3.1 Synthesis and Characterization of PNIPA and PNIPA-SAX 54
4.3.2 Electrospinning and Morphology of PNIPA and PNIPA-SAX 55
4.3.3 Thermo-Response of Nanofiber Mats 57
4.4 Conclusions 61
References 61
Chapter 5: Self-Oscillating Gels 63
5.1 Introduction 63
5.2 Design of Self-Oscillating Polymer Gel 64
5.2.1 Oscillating Chemical Reaction: The Belousov-Zhabotinsky Reaction 64
5.2.2 Mechanism of Self-Oscillation 65
5.2.3 Self-Oscillating Behavior on Several Scales 65
5.3 Control of Self-Oscillating Chemomechanical Behaviors 68
5.3.1 Concentration and Temperature Dependence of Oscillation 68
5.3.2 On-Off Regulation of Self-Oscillation by External Stimuli 68
5.3.3 Control of Self-Oscillating Behaviors by Designing Chemical Structure of Gel 69
5.3.4 Remarkable Swelling-Deswelling Changes by Assembled Self-Oscillating Microgels 70
5.3.5 Comb-Type Self-Oscillating Gel 70
5.4 Design of Biomimetic Soft-Actuators 71
5.4.1 Ciliary Motion Actuator Using Self-Oscillating Gel (Artificial Cilia) 71
5.4.2 Self-Walking Gel 72
5.4.3 Self-Propelled Motion 75
5.4.4 Theoretical Simulation of the Self-Oscillaiting Gel 76
5.5 Design of Autonomous Mass Transport Systems 76
5.5.1 Self-Driven gel Conveyer: Autonomous Transportation on the Self-Oscillating Gel Surface by Peristaltic Motion 76
5.5.2 Autonomous Intestine-Like Motion of Tubular Self-Oscillating Gel 78
5.5.3 Self-Oscillating Polymer Brushes 79
5.6 Self-Oscillating Fluids 80
5.6.1 Transmittance and Viscosity Oscillation of Polymer Solution and Microgel Dispersion 80
5.6.2 Autonomous Viscosity Oscillation by Reversible Complex Formation of Terpyridine-Terminated PEG in the BZ Reaction 82
5.6.3 Self-Oscillating Micelles 83
5.6.4 BZ Reaction in Protic Ionic Liquids 84
5.7 Future Prospects 84
References 84
Part III: Materials of Soft Actuators: Electro-Driven Soft Actuators 87
Chapter 6: Ionic Conductive Polymers 88
6.1 Introduction 88
6.2 Fabrication Methods 90
6.2.1 Ionic Polymers 90
6.2.2 Plating Methods 91
6.3 Evaluation Techniques of IPMC 91
6.4 Recent Developments 93
6.4.1 IPMC Containing Ionic Liquids 93
6.4.2 Fabrication Techniques for Miniaturized IPMCs 95
6.4.3 Materials 97
6.5 Conclusion 97
References 97
Chapter 7: Conducting Polymers 101
7.1 Introduction 101
7.2 Mechanism of Actuation 103
7.2.1 Electrochemomechanical Actuation 104
7.2.2 Water Vapor Sorption Based Actuation 105
7.3 Measurement of Actuation 105
7.4 Characteristics and Performance 106
7.4.1 Basic Characteristics in Conducting Polymer Actuators 106
7.4.2 Polypyrrole Actuator 108
7.4.3 Polyaniline Actuator 108
7.4.4 Polyalkylthiphene and PEDOT Actuators 110
7.4.5 Ionic Liquids 110
7.5 Creep and Related Phenomena 111
7.6 Conclusion 112
References 113
Chapter 8: Humidity-Sensitive Conducting Polymer Actuators 116
8.1 Introduction 116
8.2 Experimental 117
8.3 Results and Discussion 118
8.3.1 Specific Surface Area 118
8.3.2 Water Vapor Sorption 119
8.3.3 Contraction Under Electric Field 121
8.3.4 Stress Generation and Modulus Change 124
8.3.5 Work Capacity and Energy Efficiency 126
8.3.6 Applications to Linear Actuators 126
8.4 Conclusions 129
References 129
Chapter 9: Carbon Nanotube/Ionic Liquid Composites 132
9.1 Introduction 132
9.2 Fabrication of Bucky Gel Actuator and the Actuation Mechanism 133
9.3 Measurements 134
9.4 Influence of ILs 135
9.5 Nano-Carbon Materials 138
9.6 Improving the Actuation Properties by Using Additives 139
9.7 Application 142
9.8 Conclusions 143
References 143
Chapter 10: Ion Gels for Ionic Polymer Actuators 145
10.1 Introduction 145
10.2 Materials for Ionic Polymer Actuators Using Ionic Liquids 147
10.3 Polymer Actuator Prepared by Self-Assembly of an ABA-Triblock Copolymer 148
10.4 Ionic Polymer Actuator Based on a Multi-Block Copolymer and Its Driving Mechanism 150
10.5 Sulfonated Polyimide for a High-Performance Ionic Polymer Actuator 154
References 157
Chapter 11: Ionic Liquid/Polyurethane/PEDOT:PSS Composite Actuators 161
11.1 Introduction 161
11.2 Experimental 162
11.3 Results and Discussion 163
11.3.1 Mechanical Properties of IL/PU Gels 163
11.3.2 Electrical Properties of IL/PU Gels 164
11.3.3 EAP Actuating Behavior of IL/PU/PEDOT:PSS Composites 166
11.4 Conclusions 170
References 171
Chapter 12: Dielectric Gels 172
12.1 General Background 173
12.2 Electroactive Dielectric Actuators 174
12.2.1 Gels Swollen with Dielectric Solvent 174
12.2.1.1 Behavior of Dielectric Solvent Under dc Electric Field 174
12.2.1.2 Highly Swollen Chemically Crosslinked Dielectric Gel 175
12.2.2 Possibility of Elastomers as Electroactive Dielectric Actuator 176
12.2.3 Plasticized Polymer (PVC Gel) 177
12.2.4 Solid Crystalline Polymer Film 179
12.3 Electro-Optical Functions 180
12.4 Mechano-Electric Functions 181
12.5 Concluding Remarks 182
References 183
Chapter 13: Dielectric Elastomers 186
13.1 Introduction 186
13.2 Background on DE Artificial Muscles 187
13.3 Principle of Operation of DEs 188
13.4 Materials, Fabrication, Performance and Operating Considerations of DE Actuators 190
13.5 Application of DE Actuators 191
13.6 Principle of DE Generators 192
13.7 Innovative DC Generation System by DE Generators 194
13.8 Future of DE System 196
13.8.1 Toward the Future 196
13.8.1.1 Super Artificial Muscle 196
13.8.1.2 Carbon Management 196
References 197
Chapter 14: Development of Actuators Using Slide Ring Materials and Their Various Applications 199
14.1 Introduction 199
14.2 Development of Dielectric Elastomer Actuator 200
14.3 Application Development 201
14.3.1 Application as Artificial Muscle 201
14.3.2 Application to General Machinery 203
14.4 For the Future 204
References 204
Chapter 15: Piezoelectric Polymers 205
15.1 Introduction 205
15.2 Macroscopic Piezoelectricity of Polymers 206
15.3 Typical Piezoelectric Polymers in Practical Use 208
15.3.1 Polyvinylidene Fluoride (PVDF) 208
15.3.2 Poly-l-Lactic Acid (PLLA) 210
15.3.2.1 Improving the Piezoelectricity of PLLA Films 211
15.3.2.2 PLLA Fiber Actuator 213
15.3.3 Cellular and Porous Electrets 214
15.4 Polymeric Composite Systems 215
15.5 Summary 216
References 216
Part IV: Materials of Soft Actuators: Light-Driven Soft Actuators 218
Chapter 16: Spiropyran-Functionalized Hydrogels 219
16.1 Introduction 219
16.2 Past Researches on Photoresponsive Hydrogels 220
16.3 Spiropyran-Functionalized Hydrogel Actuators 220
16.3.1 Mechanism and Characteristics 220
16.3.2 Bending of Rod Actuator 222
16.3.3 Surface Profile Modulation of Sheet Actuator 224
16.3.4 On-demand Formation of Arbitrary Microchannel 225
16.3.5 Individual Control of Microvalve Array 226
16.4 Conclusions and Future Outlook 227
References 228
Chapter 17: Photomechanical Energy Conversion with Cross-Linked Liquid-Crystalline Polymers 230
17.1 Introduction 230
17.2 Light-Driven Polymer Actuators 231
17.2.1 Photochromism 231
17.2.2 Photochemical Reaction 232
17.2.3 Photothermal Effect 234
17.3 Photomechanical Property of Cross-Linked Liquid-Crystalline Polymers 234
17.3.1 Fabrication of Cross-Linked LC Polymers 234
17.3.2 Photoinduced Deformation of LC Polymers 235
17.3.3 Light-Driven Polymer Actuators Based on Cross-Linked LC Polymers 236
17.4 Conclusion 240
References 240
Chapter 18: Photoredox Reaction 243
18.1 Introduction 243
18.2 Electrochemical Swelling and Shrinking of the Gel 244
18.3 UV-Induced Swelling of the Gel and Shrinking in the Dark 245
18.4 Partial Changes of the Gel Morphology 247
18.5 Application of the Plasmonic Photoelectrochemicstry to Actuators 247
18.6 UV-Induced Swelling and Visible Light-Induced Shrinking of the Gel 249
18.7 Conclusions 250
References 250
Part V: Materials of Soft Actuators: Magneto-Driven Soft Actuators 251
Chapter 19: Magnetic Fluid Composite Gels 252
19.1 Introduction 252
19.2 Magnetic Fluid 253
19.2.1 Various Hydrodynamic Characteristics and Behavior 253
19.2.2 Deformation of Magnetic Fluid by Magnetic Field 254
19.2.2.1 Conical Meniscus 254
19.2.2.2 Swelling of the Interface by the Magnetic Field 254
19.2.2.3 Magnetic Levitation 254
19.2.2.4 Application of Magnetic Fluid 255
19.3 Magnetic Fluid Composite Gels 256
19.3.1 Magnetostriction of Magnetic Fluid Immobilized Gel 256
19.3.1.1 Immobilization Magnetic Fluid in the Gels 256
19.3.1.2 Morphology of the Magnetic Fluid Gels 256
19.3.1.3 Magneto-Striction of Magnetic Fluid Immobilized Gel 257
19.3.2 Structural Change of Magnetic Fluid Gels Induced by Magnetic Field [19] 258
19.4 The Applications of Magnetic Fluid Composite Gels 262
19.4.1 Magnetite Immobilization in the Gel by Complexation Reaction 262
19.4.2 Release Control by Magnetic Field 264
19.4.3 Encapsulation of Magnetic Fluid for Display Device 265
19.5 Conclusion 266
References 267
Chapter 20: Magnetic Particle Composite Gels 268
20.1 Introduction 268
20.2 Magnetically Driven Actuators Made of Soft Materials 269
20.2.1 Magnetic Gel Pumps 269
20.2.2 Rotational Motion of Magnetic Gel Beads 270
20.2.3 Magnetic Gel Valves 271
20.3 Magnetic Soft Materials with Variable Viscoelasticity 272
20.4 Conclusion 279
References 280
Part VI: Modeling 282
Chapter 21: Molecular Mechanism of Electrically Induced Volume Change of Porous Electrodes 283
21.1 Introduction 283
21.2 Model 284
21.3 The Monte Carlo Simulation 285
21.4 Thermodynamic Behaviors of Ions in Porous Electrodes 286
21.4.1 Effects of Porosity 286
21.4.2 Some Simulation Results and Their Implications 287
21.4.3 Comparison with Experimentally Proposed Theories 290
21.5 Conclusions 292
References 292
Chapter 22: Material Modeling 294
22.1 Ionic Conducting Polymer Actuators 294
22.2 Computational Modeling of Electrochemical Response of Ionic Conducting Polymer Actuators 295
22.2.1 Forward Motion 296
22.2.2 Backward Motion 297
22.3 Three-Dimensional Mechanical Response Analysis of Nafion Actuators 298
22.4 Conducting Polymer Actuators 300
22.5 Computational Modeling of Electrochemical-Poroelastic Response of Conducting Polymer Actuators 301
22.5.1 Stiffness Equation of Poroelastic Solid 301
22.5.2 Poisson´s Equation for Pressure 302
22.5.3 Evolution Equation for Volumetric Strain Rate 303
22.5.4 Ionic Transport Equation 304
22.5.5 Computational Procedure 304
22.6 Electrochemical-Poroelastic Response Analysis of Polypyrrole Actuators with Solid Electrolyte 304
References 306
Chapter 23: Distributed Parameter System Modeling 308
23.1 Introduction 308
23.2 Physics of Ionic Polymer-Metal Composite 309
23.2.1 Electrical Model 309
23.2.2 Electro-Mechanical Coupling Model: Electro-Stress Diffusion Coupling Model (Yamaue´s Model) 310
23.2.3 Mechanical Model 311
23.3 The Simplest Approximation: Linear Time Invariant State Space Equation 311
23.3.1 General Description of State Space Model and Method of Numerical Simulation 311
23.3.2 Approximation of Partial Differential Equations: Separation of Variables and Derivation of the State Space Model 312
23.3.2.1 Electrical System 312
23.3.2.2 Electro-Mechanical Coupling System 312
23.3.2.3 Mechanical System 315
23.3.2.4 Interconnection of Sub-Systems 316
23.3.3 Simulation 317
23.4 Conclusion 318
References 319
Chapter 24: Modeling and Feedback Control of Electro-Active Polymer Actuators 321
24.1 Introduction 321
24.2 Modeling and Actuation Methods for Electro-Active Polymer Actuators 322
24.2.1 Modeling Methods 322
24.2.2 Actuation Method 323
24.2.3 Control Research for Ionic Polymer Actuators 324
24.3 Deformation Control 324
24.3.1 PID Control 324
24.3.2 2DOF Control Based on the Identified Model 325
24.3.3 Servo Control 327
24.4 Force Control 328
24.4.1 Modeling Method for Force Control 328
24.4.2 Robust PID Force Control [34] 331
24.5 Conclusion 333
References 333
Chapter 25: Motion Design-A Gel Robot Approach 336
25.1 Gel Robot Approach 336
25.2 Agent Model of Electroactive Polymers 337
25.3 Control System Design based on the Agent Model 338
25.4 Turning Over Motion Design 338
25.4.1 Simulation of Deformation of the Electroactive Polymer Gel in Applied Electric Field 338
25.4.1.1 Migration of Surfactant Molecules Driven by the Electric Field 339
25.4.1.2 Adsorption of Surfactant Molecules to the Polymers 339
25.4.1.3 Gel Deformation Caused by Adsorption of Surfactant Molecules 340
25.4.1.4 Summary 340
25.4.2 Definition of Utility Function for Achieving Turning Over Motion 341
25.4.2.1 Abstraction of the Objective Motion 341
25.4.2.2 Spatially Varying Electric Field to Move the Center of the Gel 342
25.4.2.3 Selection of a Set of Operators 342
25.4.2.4 Phase Diagram for Switching of Operators 343
25.4.3 Application of Condition Action Rules 345
25.5 Discussion 347
References 347
Chapter 26: Motion Control 348
26.1 Introduction 348
26.2 Contraction Type PVC Gel Actuator 349
26.2.1 Configuration of a Contraction Type Actuator 349
26.2.2 Characteristics of the PVC Gel Actuator 350
26.3 Modeling and Motion Control 353
26.3.1 Modeling of the PVC Gel Actuator 353
26.3.1.1 Modeling by the Electric Impedance Measurement 353
26.3.2 Relationship Between the Current and Contraction Stress 355
26.3.3 Relationship Between the Contraction Stress and Strain 356
26.3.3.1 Modeling the Whole System of the PVC Gel Actuator 356
26.3.4 Control of the PVC Gel Actuator 357
26.3.4.1 Control Law 357
26.3.4.2 Determination of Gains 357
26.3.4.3 Feedback Control 358
26.4 Conclusions 359
References 360
Part VII: Applications 362
Chapter 27: Application of Nano-Carbon Actuator to Braille Display 363
27.1 Introduction 363
27.2 Ionic Electro-Active Polymer (EAP) Actuators Based on Nano-Carbon Electrodes 364
27.3 Goal of Braille Display Development 365
27.3.1 Specification of Braille Dots 365
27.3.2 Specifications of Braille Size 365
27.4 Development of Direct Drive Type of Braille Display [4] 365
27.4.1 Layout and Shape of Actuators 365
27.4.2 Support and Wiring of Actuators 366
27.4.3 Actuator Drive Circuit 368
27.4.4 Braille Display Controller 368
27.4.5 Direct Drive Type of Braille Display 370
27.5 Development of Braille Display with Latching Mechanism [5] 370
27.5.1 Policy of Developing Latching Mechanism 371
27.5.2 Study and Decision on the Latching Mechanism 371
27.5.3 Braille Display with Latching Mechanism 372
27.6 Latest Status on Actuator Development [42] 373
27.7 Ethical and Safety Issues in Test Environment 374
27.8 Conclusions 374
27.9 Other Examples of Actuator Application to Products 375
References 375
Chapter 28: Underwater Soft Robots 377
28.1 Introduction 378
28.2 Autonomous Ray-Like Robot 379
28.2.1 Development of the Ray-Like Robot 379
28.2.1.1 Design of the Fin Using IPMC 379
28.2.1.2 Electrical Devices for Autonomous Operation 380
28.2.2 Design of the Control Input 380
28.2.2.1 Traveling Wave of the Fin 380
28.2.2.2 Design of the Voltage Input to the Actuators 381
28.2.3 Experiments 381
28.2.3.1 Measurement of the Propulsion Speed 382
28.2.3.2 Measurement of the Amplitude of the Traveling Wave 382
28.2.3.3 Discussions 383
28.3 Quadruped Robot with Fully Polymer Body 384
28.3.1 Development of the Quadruped Robot 384
28.3.2 Design of the Control Input 386
28.3.2.1 Design of the Walking Pattern, Gait 386
28.3.2.2 Feedforward Controller for Smoothing the Voltage Input 387
28.3.3 Experiment 387
28.3.3.1 Method 387
28.3.3.2 Results and Discussions 388
28.4 Conclusion 389
References 390
Chapter 29: IPMC Actuator-Based Multifunctional Underwater Microrobots 392
29.1 Introduction 393
29.2 Biomimetic Locomotion 395
29.2.1 IPMC Actuators 395
29.2.2 Bio-Inspired Locomotion 396
29.2.2.1 Stick Insect-Inspired Walking Locomotion 396
29.2.2.2 Jellyfish-Like Floating Locomotion 397
29.2.2.3 Butterfly-Inspired Swimming Locomotion 397
29.2.2.4 Inchworm-Inspired Crawling Locomotion 398
29.3 Developed Microrobots 398
29.4 Proposed Multifunctional Lobster-Like Microrobot 400
29.4.1 Actual Lobsters 400
29.4.2 Proposed Lobster-Like Microrobot 401
29.4.3 Crawling and Rotating Mechanism 401
29.4.4 Floating Mechanism 402
29.4.5 Grasping Mechanism 403
29.4.6 Control System 403
29.5 Prototype Microrobot and Experiments 403
29.5.1 Prototype of the Lobster-Like Microrobot 403
29.5.2 Walking Experiments 404
29.5.3 Rotating Experiments 404
29.5.4 Floating Experiments 405
29.5.5 Walking, Rotating and Hand Manipulation Experiments 406
29.5.6 Obstacle-Avoidance Experiments 406
29.6 Discussion 408
29.7 Conclusion 409
References 410
Chapter 30: Medical Applications 413
30.1 Medical Applications of Soft Actuators 413
30.2 Polymer Film/Resin Actuators 414
30.3 Elastomer Actuators 418
30.4 Gel Actuators 419
30.5 Biocompatibility 420
30.6 Conclusion 421
References 421
Chapter 31: Micro Pump Driven by a Pair of Conducting Polymer Soft Actuators 424
31.1 Introduction 424
31.2 Experimental 425
31.2.1 Preparation for Conducting Polymer Soft Actuator 425
31.3 Results and Discussions 427
31.3.1 Opening and Closing Movement of the Soft Actuator 427
31.3.2 Micro Pump Driven by Two Conducting Polymer Soft Actuators 427
31.3.3 Unidirectional Fluid Transport of the Micro Pump 428
31.3.4 Transport Mechanism of the Micro Pump 430
31.3.5 Pressure and Flow Rate Characteristics of the Micro Pump 432
31.3.6 Energy Consumption Rate of the Micro Pump 433
31.4 Conclusion 434
References 434
Chapter 32: Elastomer Transducers 436
32.1 Introduction 436
32.2 Background on DE Transducers 437
32.3 DE Actuators and DE Sensors 437
32.3.1 Application of Robots (Include Care and Rehabilitation Purpose) and Sensors 438
32.3.2 Application to Audio Equipment 439
32.3.3 Other Applications 441
32.4 Application of DE Generation Devices 442
32.4.1 DE Wave Generation 443
32.4.2 DE Water Mill Generators 445
32.4.3 Portable DE Generators 446
32.4.4 Wearable Generators 446
32.4.5 Production of Hydrogen 447
32.5 Future of DE 448
References 448
Part VIII: Next-Generation Bio-Actuators 450
Chapter 33: Tissue Engineering Approach to Making Soft Actuators 451
33.1 Tissue Engineering 451
33.2 Actuator Made of Muscle Cells 453
33.3 Our Tissue-Engineered Bio-Actuator 454
33.4 Contractile Force Measurement of Bio-Actuator and Its Drive of Micro-Object 456
33.5 Further Study of Bio-Actuator 458
References 460
Chapter 34: ATP-Driven Bio-machine 462
34.1 Biomolecular Motors 462
34.1.1 Active Self-Organization of Biomolecular Motors 463
34.1.2 Controlling the Direction of Rotational Motion of the Ring-Shaped Microtubule Assemblies 465
34.2 Prolonged In Vitro Lifetime of Biomolecular Motor in a Reactive Oxygen Species Free Inert Atmosphere 467
34.2.1 Growth of Ring-Shaped Microtubule Assemblies Through Stepwise Active Self-Organization in an Inert Atmosphere 468
34.3 Spatiotemporal Control of Active Self-Organization of Biomolecular Motors 469
34.3.1 Formation of Well-Oriented Microtubules with Preferential Polarity Under a Temperature Gradient 469
34.3.2 Formation of Ring-Shaped Assembly of Microtubules with a Narrow Size Distribution at an Air-Buffer Interface 470
34.4 Conclusion 472
References 472
Chapter 35: Employing Cytoskeletal Treadmilling in Bio-Actuator 475
35.1 Introduction 475
35.2 What Is Treadmilling? 477
35.3 Studies of Treadmilling Systems 479
35.4 Supra-Macromolecular Hierarchical Cytoskeletal Protein Hydrogels 480
35.5 Conclusions 482
References 482
Index 484