Biomimetics (eBook)

Dr. Bharat Bhushan is an Ohio Eminent Scholar and The Howard D. Winbigler Professor in the College of Engineering, and the Director of the Nanoprobe Laboratory for Bio- & Nanotechnology and Biomimetics (NLB2) and affiliated faculty in John Glenn College of Public Affairs at the Ohio State University, Columbus, Ohio. In 2013-14, he served as an ASME/AAAS Science & Technology Policy Fellow, House Committee on Science, Space & Technology, United States Congress, Washington, DC. He holds two M.S., a Ph.D. in mechanical engineering/mechanics, an MBA, and two honorary and two semi-honorary doctorates. His research interests include fundamental studies with a focus on scanning probe techniques in the interdisciplinary areas of bio/nanotribology, bio/nanomechanics and bio/nanomaterials characterization and applications to bio/nanotechnology, and biomimetics. He has authored 8 scientific books, 90+ handbook chapters,  800+ scientific papers (h index–76+; ISI Highly Cited Researcher in Materials Science since 2007 and in Biology and Biochemistry since 2013; ISI Top 5% Cited Authors for Journals in Chemistry since 2011), and 60+ scientific reports. He has also edited 50+ books and holds 20 U.S. and foreign patents. He is co-editor of Springer NanoScience and Technology Series and Microsystem Technologies, and member of editorial board of PNAS. He has organized various international conferences and workshops.  He is the recipient of numerous prestigious awards and international fellowships including the Alexander von Humboldt Research Prize for Senior Scientists, Max Planck Foundation Research Award for Outstanding Foreign Scientists, Fulbright Senior Scholar Award, Life Achievement Tribology Award, and Institution of Chemical Engineers (UK) Global Award.  His research was listed as the top ten science stories of 2015. He is a member of various professional societies, including the International Academy of Engineering (Russia). He has previously worked for various research labs including IBM Almaden Research Center, San Jose, CA. He has held visiting professorship at University of California at Berkeley, University of Cambridge, UK, Technical University Vienna, Austria, University of Paris, Orsay, ETH Zurich, EPFL Lausanne, Univ. of Southampton, UK, Univ. of Kragujevac, Serbia, Tsinghua Univ., China, Harbin Inst., China, and KFUPM, Saudi Arabia.   

Foreword 8
Preface to the Third Edition 10
Preface to the First Edition 12
Contents 14
About the Author 27
1 Introduction 30
1.1 Biomimetics and Green Science and Technology 30
1.1.1 Climate Change and Lack of Recycling Impact on Sustainable Environment 32
1.1.2 Green Science and Technology 32
1.2 Biodiversity 33
1.3 Lessons from Living Nature 33
1.3.1 Bacteria 35
1.3.2 Plants 35
1.3.3 Insects, Spiders, Lizards, and Frogs 37
1.3.4 Aquatic Animals 38
1.3.5 Birds 39
1.3.6 Seashells, Bones, and Teeth 39
1.3.7 Spider Web 40
1.3.8 Insect Piercing 40
1.3.9 Eyes 40
1.3.10 Fur and Skin of Polar Bear 41
1.3.11 Anti-freeze Proteins (AFPs) 41
1.3.12 Biological Systems 41
1.4 Locomotion in Living Nature 42
1.4.1 Walking 42
1.4.2 Gear Systems for Precise Movement 43
1.5 Golden Ratio and Fibonacci Numbers 45
1.6 Biomimetics and Bioinspiration in Art and Architecture—Bioarchitecture 49
1.6.1 Biomimetics in Arts and Architecture 50
1.6.2 Bioinspiration in Arts and Architecture 52
1.7 Industrial Applications 58
1.8 Economic Impact 61
1.9 Research Objective and Approach 62
1.10 Organization of the Book 63
References 63
2 Roughness-Induced Superliquiphilic/Phobic Surfaces: Wetting States and Lessons from Living Nature 68
2.1 Introduction 68
2.2 Wetting States 68
2.3 Applications 70
2.4 Natural Superhydrophobic, Self-cleaning, Low Adhesion/Drag Reduction Surfaces with Antifouling 72
2.5 Natural Superhydrophobic and High Adhesion Surfaces 74
2.6 Natural Superoleophobic Self-cleaning and Low Drag Surfaces with Antifouling 74
2.7 Closure 75
References 76
3 Modeling of Contact Angle for a Liquid in Contact with a Rough Surface for Various Wetting Regimes 79
3.1 Introduction 79
3.2 Contact Angle Definition 79
3.3 Homogeneous and Heterogeneous Interfaces and the Wenzel, Cassie-Baxter and Cassie Equations 81
3.3.1 Limitations of the Wenzel and Cassie-Baxter Equations 87
3.3.2 Range of Applicability of the Wenzel and Cassie-Baxter Equations 88
3.4 Contact Angle Hysteresis, Tilt Angle, and Energy Dissipation 92
3.5 Stability of a Composite Interface and Role of Hierarchical Structure with Convex Surfaces 96
3.6 The Cassie-Baxter and Wenzel Wetting Regime Transition 100
3.7 Closure 104
References 105
4 Plant Leaf Surfaces in Living Nature 109
4.1 Introduction 109
4.2 Plant Leaves 113
4.3 Characterization of Superhydrophobic and Hydrophilic Leaf Surfaces 116
4.3.1 Experimental Techniques 116
4.3.2 SEM Micrographs 117
4.3.3 Contact Angle Measurements 119
4.3.4 Surface Characterization Using an Optical Profiler 120
4.3.5 Surface Characterization, Adhesion, and Friction Using an AFM 122
4.3.5.1 Comparison of Two AFM Measurement Techniques 122
4.3.5.2 Surface Characterization 124
4.3.5.3 Adhesive Force and Friction 124
4.3.6 Role of the Hierarchical Roughness 128
4.3.7 Summary 130
4.4 Various Self-cleaning Approaches 130
4.4.1 Comparison Between Superhydrophobic and Superhydrophilic Surface Approaches for Self-cleaning 130
4.4.2 Summary 133
4.5 Closure 134
References 134
5 Nanofabrication Techniques Used for Superhydrophobic Surfaces 136
5.1 Introduction 136
5.2 Roughening to Create One-Level Structure 137
5.3 Coatings to Create One-Level Structures 141
5.4 Methods to Create Two-Level (Hierarchical) Structures 142
5.5 Closure 143
References 143
6 Strategies for Micropatterned, Nanopatterned, and Hierarchically Structured Lotus-like Surfaces 147
6.1 Introduction 147
6.2 Experimental Techniques 149
6.2.1 Contact Angle, Surface Roughness, and Adhesion 149
6.2.2 Droplet Evaporation Studies 149
6.2.3 Bouncing Droplet Studies 150
6.2.4 Vibrating Droplet Studies 150
6.2.5 Microdroplet Condensation and Evaporation Studies Using ESEM 150
6.2.6 Generation of Submicron Droplets 151
6.2.7 Self-cleaning Studies 154
6.3 Micro- and Nanopatterned Polymers 155
6.3.1 Contact Angle 156
6.3.2 Effect of Submicron Droplet on Contact Angle 158
6.3.3 Adhesive Force 159
6.3.4 Summary 160
6.4 Micropatterned Si Surfaces 161
6.4.1 Cassie-Baxter and Wenzel Transition Criteria 163
6.4.2 Effect of Pitch Value on the Transition 166
6.4.3 Observation of Transition During the Droplet Evaporation 167
6.4.4 Another Cassie-Baxter and Wenzel Transition for Different Series 171
6.4.5 Contact Angle Hysteresis and Wetting/Dewetting Asymmetry 173
6.4.6 Contact Angle Measurements During Condensation and Evaporation of Microdroplets on Micropatterned Surfaces 176
6.4.7 Observation of Transition During the Bouncing Droplet 179
6.4.8 Summary 184
6.5 Ideal Surfaces with Hierarchical Structure 185
6.6 Hierarchically Structured Surfaces with Wax Platelets and Tubules Using Nature’s Route 186
6.6.1 Effect of Nanostructures with Various Wax Platelet Crystal Densities on Superhydrophobicity 191
6.6.2 Effect of Hierarchical Structure with Wax Platelets on the Superhydrophobicity 195
6.6.3 Effect of Hierarchical Structure with Wax Tubules on Superhydrophobicity 199
6.6.3.1 T. Majus Tubules 199
6.6.3.2 Lotus Tubules 202
6.6.4 Self-cleaning Efficiency of Hierarchically Structured Surfaces 206
6.6.5 Observation of Transition During the Bouncing Droplet 208
6.6.6 Observation of Transition During the Vibrating Droplet 212
6.6.6.1 Model for the Adhesion and Inertia Forces of the Vibrating Droplet 212
6.6.6.2 Vibration Study Results 213
6.6.7 Measurement of Fluid Drag Reduction 218
6.6.8 Summary 218
6.7 Closure 219
References 220
7 Fabrication and Characterization of Mechanically Durable Superhydrophobic Surfaces 224
7.1 Introduction 224
7.2 Characterization Techniques 225
7.2.1 Mechanical Durability 225
7.2.2 Waterfall/Jet Tests 226
7.2.3 Optical Transmittance Measurements 227
7.3 Superhydrophobic Surfaces Using CNT Composites 227
7.3.1 Fabrication Details 227
7.3.2 Contact Angle 229
7.3.3 Durability of Various Surfaces in Waterfall/Jet Tests 230
7.3.4 Durability of Various Surfaces in AFM and Ball-on-Flat Tribometer Tests 231
7.3.5 Summary 236
7.4 Superhydrophobic Surfaces Using Nanoparticle Composites with Hierarchical Structure 236
7.4.1 Fabrication Details 236
7.4.2 Contact Angle of Surfaces Using Micropattern 238
7.4.3 Contact Angle of Surfaces Using Microparticles and Comparison to Micropatterns 239
7.4.4 Durability of Various Surfaces in AFM and Ball-on-Flat Tribometer Tests 241
7.4.5 Summary 244
7.5 Superhydrophobic Surfaces Using Nanoparticle Composites for Optical Transparency 244
7.5.1 Fabrication Details 246
7.5.2 Surface Roughness and Morphology 247
7.5.3 Contact Angle 248
7.5.4 Optical Transparency 248
7.5.5 Durability of Various Samples in AFM and Water Jet Tests 252
7.5.6 Summary 255
7.6 Superhydrophobic Surfaces Using Micropatterning, Nanoparticle Composite Coating and Ion Etching of PDMS for Optical Transparency 255
7.6.1 Micropatterning and Nanoparticle/Binder Coating 256
7.6.1.1 Fabrication Details 256
7.6.1.2 Contact Angle and Transmittance of Surfaces 258
7.6.1.3 Summary 259
7.6.2 Ion Etching 260
7.6.2.1 Fabrication Details 260
7.6.2.2 Surface Roughness and Morphology 261
7.6.2.3 Contact Angle and Transmittance of Surfaces 263
7.6.2.4 Durability in AFM Tests 265
7.6.2.5 Summary 266
7.7 Superhydrophobic Paper Surfaces 268
7.7.1 Fabrication Details 268
7.7.2 Contact Angle 269
7.7.3 Durability Test 270
7.7.4 Summary 270
7.8 Closure 270
References 270
8 Fabrication and Characterization of Micropatterned Structures Inspired by Salvinia molesta 274
8.1 Introduction 274
8.2 Characterization of Leaves and Fabrication of Inspired Structural Surfaces 275
8.3 Measurement of Contact Angle and Adhesion 278
8.3.1 Observation of Pinning and Contact Angle 278
8.3.2 Adhesion 279
8.4 Closure 281
References 282
9 Characterization of Rose Petals and Fabrication and Characterization of Superhydrophobic Surfaces with High and Low Adhesion 283
9.1 Introduction 283
9.2 Characterization of Two Kinds of Rose Petals and Their Underlying Mechanisms 284
9.3 Fabrication of Surfaces with High and Low Adhesion for Understanding of Rose Petal Effect 291
9.4 Fabrication of Mechanically Durable, Superhydrophobic Surfaces with High Adhesion 300
9.4.1 Samples with Hydrophilic ZnO Nanoparticles (Before ODP Modification) 301
9.4.2 Samples with Hydrophobic ZnO Nanoparticles (After ODP Modification) 305
9.4.3 Wear Resistance in AFM Wear Experiment 307
9.5 Closure 310
References 310
10 Strategies for Superliquiphobic/Philic Surfaces 312
10.1 Introduction 312
10.2 Oils and Surfactant-Containing Liquids 316
10.3 Strategies to Achieve Superoleophobicity in Air and Liquid Repellency 320
10.3.1 Roughness Techniques 322
10.3.2 Fluorination Techniques 324
10.3.2.1 Fluoropolymers 324
10.3.2.2 Fluorosilanes and Fluorothiols 324
10.3.2.3 Fluoroplasma 325
10.3.2.4 Fluorosurfactants (for Superhydrophilicity and Superoleophobicity) 325
10.3.3 Chemical Activation of Underlayer of a Coated Surface 325
10.3.4 Re-entrant Geometry 328
10.3.5 Coating Deposition Techniques 331
10.3.6 Summary 331
10.4 Strategies to Achieve Combinations of Superliquiphilicity/Phobicity 331
10.5 Model to Predict Oleophobic/Philic Nature of Surfaces 332
10.6 Validation of Oleophobicity/Philicity Model for Oil Droplets in Air and Water 335
10.6.1 Experimental Techniques 335
10.6.2 Fabrication of Oleophobic/Philic Surfaces 336
10.6.3 Characterization of Oleophobic/Philic Surfaces 337
10.6.3.1 Wetting Behavior on Flat and Micropatterned Epoxy Surfaces 337
10.6.3.2 Wetting Behavior on Flat and Micropatterned Surfaces with C20F42 341
10.6.3.3 Wetting Behavior on Nano- and Hierarchical Structures and Shark Skin Replica 343
10.6.4 Summary 345
10.7 Closure 345
References 346
11 Adaptable Fabrication Techniques for Mechanically Durable Superliquiphobic/philic Surfaces 349
11.1 Introduction 349
11.2 Characterization Techniques 353
11.2.1 Contact Angle and Tilt Angle 353
11.2.2 Scanning Electron Microscope (SEM) Imaging 353
11.2.3 Coating Thickness 354
11.2.4 Surfactant-Containing Liquid Repellency 354
11.2.5 High Temperature Superliquiphobicity 354
11.2.6 Wear Resistance 355
11.2.6.1 Macroscale Wear 355
11.2.6.2 Microscale Wear 355
11.2.6.3 Contact Pressures 356
11.2.7 Self-cleaning 357
11.2.8 Finger Touch Tests 357
11.2.8.1 Anti-smudge 357
11.2.8.2 Fingerprint Resistance 357
11.2.9 Anti-fogging 358
11.2.10 Anti-icing 358
11.2.11 Transparency 359
11.2.12 Oil-Water Separation 359
11.3 Nanoparticle/Binder Composite Coatings 359
11.3.1 Experimental Details 365
11.3.2 Characterization of Coatings Prepared Using Oxygen Plasma Treatment 368
11.3.3 Characterization of Coatings Applied Using UV-O Treatment 371
11.3.3.1 Wettability 371
11.3.3.2 Surface Morphology 374
11.3.3.3 Repellency of Surfactant-Containing Liquids 376
11.3.3.4 High Temperature Superliquiphobicity 377
11.3.3.5 Wear Resistance 379
11.3.3.6 Self-cleaning 381
11.3.3.7 Finger Touch Tests 382
11.3.3.8 Transparency 383
11.3.3.9 Oil-Water Separation 385
11.3.3.10 Summary 385
11.4 Layer-by-Layer Technique 385
11.4.1 Experimental Details 386
11.4.2 Results and Discussion 388
11.4.2.1 Wettability 388
11.4.2.2 Surface Morphology 391
11.4.2.3 Repellency of Surfactant Containing Liquids 391
11.4.2.4 Wear Resistance 391
11.4.2.5 Self-cleaning 394
11.4.2.6 Anti-smudge 394
11.4.2.7 Anti-fogging 397
11.4.2.8 Anti-icing 397
11.4.2.9 Transparency 399
11.4.2.10 Oil-Water Separation 400
11.4.3 Summary 400
11.5 Nanoparticle-Encapsulation Technique 402
11.5.1 Polycarbonate Surfaces 402
11.5.1.1 Experimental Details 403
11.5.1.2 Results and Discussion 403
11.5.1.3 Summary 409
11.5.2 Polypropylene Surfaces 409
11.5.2.1 Experimental Details 410
11.5.2.2 Results and Discussion 411
11.5.2.3 Summary 415
11.6 Liquid Impregnation Technique 416
11.6.1 Porous Polypropylene Surface Created Using Solvent-Nonsolvent Mixture 418
11.6.1.1 Experimental Details 419
11.6.1.2 Results and Discussion 419
11.6.1.3 Summary 423
11.6.2 Porous Polystyrene Surface Created Using Breath Figures 424
11.6.2.1 Experimental Details 425
11.6.2.2 Results and Discussion 426
11.6.2.3 Summary 428
11.7 Comparison of Various Roughness-Induced and Liquid Impregnation Techniques for Superoleophobicity 428
11.7.1 Comparison of Data 428
11.7.1.1 Wettability 429
11.7.1.2 Surface Morphology 431
11.7.1.3 Repellency of Surfactant-Containing Liquids 431
11.7.1.4 Wear Resistance 432
11.7.1.5 Self-cleaning, Anti-smudge, and Antifouling 433
11.7.1.6 Anti-icing and Anti-fogging 435
11.7.1.7 Transparency 435
11.7.1.8 Oil-Water Separation 436
11.7.1.9 Summary and Outlook 436
11.8 Closure 437
Appendix: Oil-Water Separation for Oil Spill Cleanup and Water Purification 437
Introduction 437
Common Methods for Oil Spill Cleanup 439
Dispersants 439
Controlled Burning 439
Sorbents 440
Skimmers 440
Booms 441
Proposed Bioinspired Net 442
Summary 444
References 444
12 Fabrication and Characterization of Mechanically Durable Superliquiphobic Surfaces 450
12.1 Introduction 450
12.2 Superoleophobic Aluminum Surfaces 450
12.2.1 Two-Step Technique Using Etching and Fluorination 451
12.2.1.1 Experimental Details 456
12.2.1.2 Characterization 456
12.2.1.3 Results and Discussion 457
12.2.1.4 Summary 466
12.2.2 Single Step Technique Using Fluorinated Nanoparticles 466
12.2.2.1 Experimental Details 466
12.2.2.2 Results and Discussions 468
12.2.2.3 Summary 476
12.3 Superoleophobic Stainless Steel Surfaces 477
12.3.1 Experimental Details 480
12.3.1.1 Substrate Materials 484
12.3.1.2 Sandblasting 484
12.3.1.3 Chemical Etching 484
12.3.1.4 Condensation Procedure 485
12.3.1.5 Nanoparticle-Binder Coating 487
12.3.1.6 Fluorosilane Coating 487
12.3.1.7 Characterization of Samples 488
12.3.2 Results and Discussion 488
12.3.2.1 Wettability 488
12.3.2.2 Self-cleaning 491
12.3.2.3 Anti-icing 491
12.3.2.4 Mechanical Durability 493
12.3.2.5 Corrosion Resistance of SS 430 494
12.3.3 Summary 499
12.4 Superoleophobic Synthetic Leather Surfaces 499
12.4.1 Experimental Details 500
12.4.2 Results and Discussion 502
12.4.2.1 Wettability 502
12.4.2.2 Self-cleaning 504
12.4.2.3 High Temperature Exposure 504
12.4.2.4 Wear Resistance 505
12.4.3 Summary 506
12.5 Closure 507
References 508
13 Shark Skin Surface for Fluid-Drag Reduction in Turbulent Flow 512
13.1 Introduction 512
13.2 Fluid Drag Reduction 514
13.2.1 Mechanisms of Fluid Drag 514
13.2.2 Shark Skin 517
13.3 Experimental Studies 518
13.3.1 Flow Visualization Studies 520
13.3.2 Riblet Geometries and Configurations 521
13.3.3 Riblet Fabrication 522
13.3.4 Drag Measurement Techniques 524
13.3.4.1 Open Channel 525
13.3.4.2 Closed Channel 530
13.3.5 Riblet Results and Discussion 531
13.3.5.1 Open Channel 532
13.3.5.2 Closed Channel 536
13.3.6 Summary 551
13.4 Fluid Flow Modeling 552
13.4.1 Computational Fluid Dynamic (CFD) Model 552
13.4.2 Modeling of Blade Riblets 555
13.4.2.1 Continuous Riblets 559
13.4.2.2 Segmented Riblets 559
13.4.2.3 Summary 563
13.4.3 Modeling of Blade, Sawtooth and Scalloped Riblets 564
13.4.3.1 Results and Discussion 567
13.4.3.2 Summary 570
13.5 Application of Riblets for Drag Reduction and Antifouling 572
13.5.1 Industrial Examples 572
13.5.2 Prototypes and Commercial Applications 573
13.6 Closure 577
References 579
14 Skimmer Bird Beak (Rynchops) Surface for Fluid Drag Reduction in Turbulent Flow 584
14.1 Introduction 584
14.2 Experimental and Computational Procedure 587
14.2.1 Sample Fabrication Process 587
14.2.2 Experimental Setup 589
14.2.3 Computational Modeling 589
14.3 Results and Discussion 590
14.3.1 Experimental Results 591
14.3.2 Modeling Results 592
14.4 Closure 594
References 596
15 Rice Leaf and Butterfly Wing Effect 598
15.1 Introduction 598
15.2 Inspiration from Living Nature 598
15.2.1 Ambient Species—Lotus Effect 599
15.2.2 Aquatic Species—Shark Skin and Fish Scales Effect 599
15.2.3 Ambient Species—Rice Leaf and Butterfly Wing Effect 599
15.3 Sample Fabrication 601
15.3.1 Actual Sample Replicas 601
15.3.2 Rice Leaf Inspired Surfaces 602
15.3.2.1 Micropatterned Replicas 605
15.3.2.2 Hot Embossed Plastic Sheets 606
15.4 Pressure Drop Measurement Technique 608
15.5 Results and Discussion 611
15.5.1 Surface Characterization 611
15.5.2 Pressure Drop Measurements 614
15.5.2.1 Water Flow 616
15.5.2.2 Oil Flow 621
15.5.2.3 Air Flow 623
15.5.2.4 Summary 625
15.5.3 Nondimensional Pressure Drop Model 626
15.5.4 Wettability 630
15.5.5 Drag Reduction Models 632
15.5.6 Self-cleaning Measurements 638
15.6 Closure 639
References 640
16 Bio- and Inorganic Fouling 642
16.1 Introduction 642
16.2 Fields Susceptible to Fouling 642
16.3 Biofouling and Inorganic Fouling Formation Mechanisms 648
16.3.1 Biofouling Formation 648
16.3.2 Inorganic Fouling Formation 649
16.3.3 Surface Factors 650
16.4 Antifouling Strategies from Living Nature 652
16.5 Current Prevention and Cleaning Techniques for Antifouling 658
16.5.1 Current Prevention Techniques 658
16.5.1.1 Medical Anti-biofouling 658
16.5.1.2 Marine Antifouling 659
16.5.1.3 Industrial Antifouling 660
16.5.2 Self-cleaning Surfaces and Cleaning Techniques 660
16.6 Nanomaterials for Anti-biofouling 661
16.6.1 Surface Treatment of Cotton Fabrics 665
16.6.2 Morphology and Contact Angle 666
16.6.3 Durability of the Treatment After Wash 668
16.6.4 Antimicrobial Properties 669
16.7 Nanostructured Surfaces for Antifouling 669
16.7.1 Fabrication of Micropatterned Samples 670
16.7.2 Anti-biofouling Measurements 671
16.7.3 Anti-inorganic Fouling Measurements 672
16.7.4 Results and Discussion 673
16.7.4.1 Anti-biofouling 673
16.7.4.2 Anti-inorganic Fouling 678
16.8 Closure 679
References 680
17 Bioinspired Strategies for Water Collection and Water Purification 686
17.1 Introduction 686
17.2 Water Collection—Lessons from Living Nature 690
17.2.1 Namib Desert Beetles 692
17.2.2 Lizards 692
17.2.3 Spider Webs 693
17.2.4 Cacti 695
17.2.5 Other Plant Species 695
17.2.6 Summary 696
17.3 Bioinspired Water Collection Approaches 696
17.3.1 Beetle-Inspired Water Collection 696
17.3.2 Spider-Web-Inspired Water Collection 699
17.3.3 Cacti-Inspired Water Collection 701
17.3.4 Summary 702
17.4 Bioinspired Water Desalination and Water Purification Approaches 703
17.4.1 Multi-cellular Structures 707
17.4.2 Aquaporins 709
17.4.2.1 Pore-Forming Molecules 709
17.4.2.2 Carbon Nanotubes 711
17.4.2.3 Self-assembled Block Copolymers 712
17.4.3 Steel Wire Mesh Coated with Superhydrophilic/Superoleophobic Coating 713
17.4.4 Dual pH- and Ammonia-Vapor-Responsive Electrospun Nanofibrous Polymer Membranes with Superliquiphilic/phobic Properties 715
17.4.5 Summary 716
17.5 Outlook 717
Appendix: Laplace Pressure Gradient on a Conical Surface 717
References 718
18 Role of Liquid Repellency on Fluid Slip, Fluid Drag, and Formation of Nanobubbles 723
18.1 Introduction 723
18.2 Measurement Techniques for Boundary Slip and Nanobubbles 724
18.2.1 Measurement of Boundary Slip 724
18.2.1.1 Analysis to Calculate the Slip Length Based on Liquid Drainage Method 725
18.2.1.2 AFM Measurement Technique 726
18.2.2 Imaging of Nanobubbles 728
18.3 Fluid Slip Measurements on Liquiphilic/phobic Surfaces 728
18.3.1 Hydrophilic/phobic Surfaces 728
18.3.2 Oleophilic/phobic Surfaces 729
18.3.3 Effect of Electric Field and Liquid pH on Fluid Slip 733
18.4 Generation of Nanobubbles on Hydrophobic Surfaces 740
18.4.1 Role of Nanobubbles on Fluid Slip and Drag 740
18.4.2 Coalescence and Stability of Nanobubbles 743
18.4.3 Nanobubble-Substrate Interaction 746
18.4.4 Effect of Electric Field and Liquid pH Values on Propensity of Nanobubbles 749
18.4.5 Applications of Speciality Fluids with Nanobubbles in Biomedicine 751
18.5 Closure 756
References 757
19 Gecko Adhesion 759
19.1 Introduction 759
19.2 Hairy Attachment Systems 760
19.3 Tokay Gecko 763
19.3.1 Construction of Tokay Gecko 763
19.3.2 Adhesion Enhancement by Division of Contacts and Multilevel Hierarchical Structure 766
19.3.3 Peeling 768
19.3.4 Self-cleaning 772
19.4 Attachment Mechanisms 774
19.4.1 van der Waals Forces 775
19.4.2 Capillary Forces 776
19.5 Adhesion Measurements and Data 778
19.5.1 Adhesion Under Ambient Conditions 778
19.5.1.1 Adhesion Force of a Single Seta 778
19.5.1.2 Adhesive Force of a Single Spatula 779
19.5.2 Effects of Temperature 780
19.5.3 Effects of Humidity 781
19.5.4 Effects of Hydrophobicity 782
19.6 Adhesion Modeling of Fibrillar Structures 784
19.6.1 Single Spring Contact Analysis 785
19.6.2 The Multi-level Hierarchical Spring Analysis 786
19.6.3 Adhesion Results of the Multi-level Hierarchical Spring Model 790
19.6.4 Capillary Effects 798
19.7 Adhesion Data Base of Fibrillar Structures 801
19.7.1 Fiber Model 801
19.7.2 Single Fiber Contact Analysis 802
19.7.3 Constraints 803
19.7.3.1 Non-buckling Condition 803
19.7.3.2 Non-fiber Fracture Condition 805
19.7.3.3 Non-sticking Condition 806
19.7.4 Numerical Simulation 807
19.7.5 Results and Discussion 809
19.8 Fabrication of Gecko Skin-Inspired Structures 813
19.8.1 Single Level Roughness Structures 813
19.8.2 Multi-level Hierarchical Structures 821
19.9 Closure 830
References 832
20 Insects Locomotion, Piercing, Sucking and Stinging Mechanisms 838
20.1 Introduction 838
20.2 Mosquitoes’ Locomotion and Painless Piercing 842
20.2.1 Locomotion 843
20.2.1.1 Standing on Water 844
20.2.1.2 Sticking to Any Surface 845
20.2.1.3 Flying in Air and Rain 848
20.2.1.4 Summary 850
20.2.2 Painless Piercing 850
20.2.2.1 Microanatomy 850
20.2.2.2 Feeding 852
20.2.2.3 Nanomechanical Property Measurements of Labium 854
20.2.2.4 Relevance of Nanomechanical Properties in Piercing Mechanism 859
20.2.3 Lessons from Mosquito Piercing and Conceptual Schematic of a Painless Mosquito-Inspired Microneedle 859
20.2.4 Summary 861
20.3 Wasp Stinging 862
20.3.1 Microanatomy and Stinging Process 862
20.3.2 Structure, Nanomechanical Properties and Modeling of the Penetration Process 865
20.3.2.1 Experimental Details 865
20.3.2.2 Results and Discussion 867
20.3.3 Conceptual Schematic of a Painless, Wasp-Inspired Microneedle 874
20.3.4 Summary 876
20.4 Closure 876
References 876
21 Structure and Mechanical Properties of Nacre 880
21.1 Introduction 880
21.2 Hierarchical Structure 882
21.2.1 Columnar and Sheet Structure 882
21.2.2 Mineral Bridges 884
21.2.3 Polygonal Nanograins 885
21.2.4 Inter-tile Toughening Mechanism 886
21.3 Mechanical Properties 887
21.4 Bioinspired Structures 891
21.5 Closure 892
References 894
22 Structural Coloration 897
22.1 Introduction 897
22.2 Physical Mechanisms of Structural Colors 900
22.2.1 Film Interference 900
22.2.2 Diffraction Gratings 902
22.2.3 Scattering 903
22.2.4 Photonic Crystals 903
22.2.5 Coloration Changes 904
22.3 Lessons from Living Nature 906
22.3.1 Film Interference 906
22.3.2 Diffraction Grating 912
22.3.3 Scattering 912
22.3.4 Photonic Crystals 915
22.3.5 Coloration Changes 918
22.4 Bioinspired Fabrication and Applications 920
22.5 Closure 922
References 922
23 Self-healing Materials and Defense Mechanisms 929
23.1 Introduction 929
23.2 Self-healing and Defense Mechanisms Found in Living Nature 932
23.2.1 Fauna 936
23.2.1.1 Vertebrates and Invertebrates 936
23.2.1.2 Vertebrate Hard Tissue 942
23.2.1.3 Vertebrate Soft Tissue 943
23.2.1.4 Invertebrate Hard Tissue 947
23.2.1.5 Invertebrate Soft Tissue 949
23.2.2 Flora 950
23.2.2.1 Herbaceous and Woody Plants 950
23.2.2.2 Woody Plants 955
23.2.3 Summary 957
23.3 Prevalent Self-healing Mechanisms 957
23.3.1 Fauna 959
23.3.1.1 Reversible Muscle Control 959
23.3.1.2 Clotting 960
23.3.1.3 Cellular Response 960
23.3.1.4 Layering 961
23.3.1.5 Protective Surfaces 961
23.3.2 Flora 962
23.3.2.1 Vascular Networks or Cells 962
23.3.2.2 Exposure 963
23.3.2.3 Replenishable and Functional Coatings 963
23.3.3 Summary 964
23.4 Examples of Bioinspired Self-healing Materials 964
23.4.1 Protective Coatings 964
23.4.2 Autogenous Healing 966
23.4.3 Shape Memory 966
23.4.4 Chemical Activity 967
23.4.5 Vascular Networks or Capsules 968
23.4.6 Bio-healing 969
23.4.7 External Stimuli–Sensitive Materials 970
23.4.8 New Approaches by Combination of Several Mechanisms 970
23.4.9 Summary 970
23.5 Closure 971
References 972
24 Outlook 977
Index 979