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 (Second Edition) 10
Preface (First Edition) 12
Contents 14
Biography and Photograph of Author 22
1 Introduction 24
1.1 Introduction 24
1.2 Biodiversity 25
1.3 Lessons from Nature 25
1.4 Golden Ratio and Fibonacci Numbers 30
1.5 Biomimetics in Art and Architecture---Bioarchitecture 35
1.6 Industrial Significance 39
1.7 Research Objective and Approach 42
1.8 Organization of the Book 42
References 42
2 Roughness-Induced Superliquiphilic/phobic Surfaces: Lessons from Nature 46
2.1 Introduction 46
2.2 Wetting States 46
2.3 Applications 48
2.4 Natural Superhydrophobic, Self-cleaning, Low Adhesion/Drag Reduction Surfaces with Antifouling 50
2.5 Natural Superhydrophobic and High Adhesion Surfaces 51
2.6 Natural Superoleophobic Self-cleaning and Low Drag Surfaces with Antifouling 52
2.7 Closure 53
References 53
3 Modeling of Contact Angle for a Liquid in Contact with a Rough Surface for Various Wetting Regimes 57
3.1 Introduction 57
3.2 Contact Angle Definition 57
3.3 Homogeneous and Heterogeneous Interfaces and the Wenzel, Cassie-Baxter and Cassie Equations 59
3.3.1 Limitations of the Wenzel and Cassie-Baxter Equations 64
3.3.2 Range of Applicability of the Wenzel and Cassie-Baxter Equations 67
3.4 Contact Angle Hysteresis 71
3.5 Stability of a Composite Interface and Role of Hierarchical Structure with Convex Surfaces 73
3.6 The Cassie-Baxter and Wenzel Wetting Regime Transition 77
3.7 Closure 81
References 82
4 Lotus Effect Surfaces in Nature 85
4.1 Introduction 85
4.2 Plant Leaves 85
4.3 Characterization of Superhydrophobic and Hydrophilic Leaf Surfaces 88
4.3.1 Experimental Techniques 88
4.3.2 SEM Micrographs 89
4.3.3 Contact Angle Measurements 89
4.3.4 Surface Characterization Using an Optical Profiler 92
4.3.5 Surface Characterization, Adhesion, and Friction Using an AFM 93
4.3.5.1 Comparison of Two AFM Measurement Techniques 93
4.3.5.2 Surface Characterization 94
4.3.5.3 Adhesive Force and Friction 98
4.3.6 Role of the Hierarchical Roughness 99
4.3.7 Summary 101
4.4 Various Self-cleaning Approaches 101
4.4.1 Comparison Between Superhydrophobic and Superhydrophilic Surface Approaches for Self-cleaning 102
4.4.2 Summary 104
4.5 Closure 104
References 105
5 Nanofabrication Techniques Used for Lotus-Like Structures 107
5.1 Introduction 107
5.2 Roughening to Create One-Level Structure 108
5.3 Coatings to Create One-Level Structures 112
5.4 Methods to Create Two-Level (Hierarchical) Structures 114
5.5 Closure 115
References 116
6 Fabrication and Characterization of Micro-, Nano- and Hierarchically Structured Lotus-Like Surfaces 119
6.1 Introduction 119
6.2 Experimental Techniques 121
6.2.1 Contact Angle, Surface Roughness, and Adhesion 121
6.2.2 Droplet Evaporation Studies 122
6.2.3 Bouncing Droplet Studies 122
6.2.4 Vibrating Droplet Studies 122
6.2.5 Microdroplet Condensation and Evaporation Studies Using ESEM 123
6.2.6 Generation of Submicron Droplets 123
6.2.7 Waterfall/Jet Tests 126
6.2.8 Wear and Friction Tests 127
6.2.9 Transmittance Measurements 128
6.3 Micro- and Nanopatterned Polymers 128
6.3.1 Contact Angle 130
6.3.2 Effect of Submicron Droplet on Contact Angle 131
6.3.3 Adhesive Force 132
6.3.4 Summary 133
6.4 Micropatterned Si Surfaces 133
6.4.1 Cassie-Baxter and Wenzel Transition Criteria 136
6.4.2 Effect of Pitch Value on the Transition 138
6.4.3 Observation of Transition During the Droplet Evaporation 140
6.4.4 Another Cassie-Baxter and Wenzel Transition for Different Series 144
6.4.5 Contact Angle Hysteresis and Wetting/Dewetting Asymmetry 146
6.4.6 Contact Angle Measurements During Condensation and Evaporation of Microdroplets on Micropatterned Surfaces 150
6.4.7 Observation of Transition During the Bouncing Droplet 154
6.4.8 Summary 158
6.5 Ideal Surfaces with Hierarchical Structure 158
6.6 Hierarchically Structured Surfaces with Wax Platelets and Tubules Using Nature's Route 159
6.6.1 Effect of Nanostructures with Various Wax Platelet Crystal Densities on Superhydrophobicity 164
6.6.2 Effect of Hierarchical Structure with Wax Platelets on the Superhydrophobicity 168
6.6.3 Effect of Hierarchical Structure with Wax Tubules on Superhydrophobicity 172
6.6.3.1 Majus Tubules 172
6.6.3.2 Lotus Tubules 174
6.6.4 Self-cleaning Efficiency of Hierarchically Structured Surfaces 178
6.6.5 Observation of Transition During the Bouncing Droplet 179
6.6.6 Observation of Transition During the Vibrating Droplet 184
6.6.6.1 Model for the Adhesion and Inertia Forces of the Vibrating Droplet 184
6.6.6.2 Vibration Study Results 186
6.6.7 Measurement of Fluid Drag Reduction 189
6.6.8 Summary 190
6.7 Mechanically Durable Superhydrophobic Surfaces 191
6.7.1 CNT Composites 192
6.7.1.1 Contact Angle 193
6.7.1.2 Durability of Various Surfaces in Waterfall/Jet Tests 195
6.7.1.3 Durability of Various Surfaces in AFM and Ball-on-Flat Tribometer Tests 196
6.7.1.4 Summary 201
6.7.2 Nanoparticle Composites with Hierarchical Structure 201
6.7.2.1 Experimental Details 201
6.7.2.2 Contact Angle of Surfaces Using Micropattern 203
6.7.2.3 Contact Angle of Surfaces Using Microparticles and Comparison to Micropatterns 204
6.7.2.4 Durability of Various Surfaces in AFM and Ball-on-Flat Tribometer Tests 205
6.7.2.5 Summary 208
6.7.3 Nanoparticle Composites for Optical Transparency 208
6.7.3.1 Experimental Details 210
6.7.3.2 Surface Roughness and Morphology 211
6.7.3.3 Wettability 212
6.7.3.4 Optical Transparency 213
6.7.3.5 Wear Resistance of Samples in Sliding and Water Jet Experiments 216
6.7.3.6 Summary 218
6.8 Superhydrophobic Paper Surfaces 219
6.9 Closure 219
References 220
7 Fabrication and Characterization of Micropatterned Structures Inspired by Salvinia molesta 226
7.1 Introduction 226
7.2 Characterization of Leaves and Fabrication of Inspired Structural Surfaces 228
7.3 Measurement of Contact Angle and Adhesion 230
7.3.1 Observation of Pinning and Contact Angle 230
7.3.2 Adhesion 231
7.4 Closure 233
References 233
8 Characterization of Rose Petals and Fabrication and Characterization of Superhydrophobic Surfaces with High and Low Adhesion 234
8.1 Introduction 234
8.2 Characterization of Two Kinds of Rose Petals and Their Underlying Mechanisms 235
8.3 Fabrication of Surfaces with High and Low Adhesion for Understanding of Rose Petal Effect 242
8.4 Fabrication of Mechanically Durable, Superhydrophobic Surfaces with High Adhesion 251
8.4.1 Samples with Hydrophilic ZnO Nanoparticles (Before ODP Modification) 252
8.4.2 Samples with Hydrophobic ZnO Nanoparticles (After ODP Modification) 254
8.4.3 Wear Resistance in AFM Wear Experiment 258
8.5 Closure 260
References 261
9 Modeling, Fabrication, and Characterization of Superoleophobic/Philic Surfaces 263
9.1 Introduction 263
9.2 Strategies to Achieve Superoleophobicity in Air 267
9.2.1 Fluorination Techniques 268
9.2.1.1 Fluoropolymers 268
9.2.1.2 Fluorosilanes and Fluorothiols 268
9.2.1.3 Fluorosurfactants 269
9.2.1.4 Other Fluorination Techniques 270
9.2.2 Re-entrant Geometry 270
9.3 Model to Predict Oleophobic/Philic Nature of Surfaces 272
9.4 Validation of Oleophobicity/Philicity Model for Oil Droplets in Air and Water 275
9.4.1 Experimental Techniques 275
9.4.2 Fabrication of Oleophobic/Philic Surfaces 276
9.4.3 Characterization of Oleophobic/Philic Surfaces 277
9.4.3.1 Wetting Behavior on Flat and Micropatterned Epoxy Surfaces 277
9.4.3.2 Wetting Behavior on Flat and Micropatterned Surfaces with C20F42 280
9.4.3.3 Wetting Behavior on Nano- and Hierarchical Structures and Shark Skin Replica 282
9.4.4 Summary 284
9.5 Mechanically Durable Nanoparticle Composite Coatings for Superoleophobicity 284
9.5.1 Experimental Details 291
9.5.2 Results and Discussion 293
9.5.2.1 Wettability of Coated Samples 293
9.5.2.2 Surface Topography and Coating Thickness 296
9.5.2.3 Wear Resistance of Coated Samples 297
9.5.2.4 Anti-smudge Properties of Coated Samples 299
9.5.2.5 Transparency of Coated Samples 301
9.5.3 Summary 301
9.6 Mechanically Durable Nanoparticle Composite Coatings for Superliquiphilicity and Superliquiphobicity Using Layer-by-Layer Technique 302
9.6.1 Experimental Details 305
9.6.1.1 Samples 307
9.6.1.2 Characterization Techniques 308
9.6.2 Results and Discussion 308
9.6.2.1 Wettability of Coated Samples 308
9.6.2.2 Wear Resistance of Coated Samples 309
9.6.2.3 Transparency of Coated Samples 311
9.6.2.4 Anti-fogging Property of Coated Samples 311
9.6.2.5 Anti-icing Property of Coated Samples 312
9.6.2.6 Self-cleaning Property of Coated Samples 313
9.6.2.7 Anti-smudge Property of Coated Samples 314
9.6.2.8 Oil--Water Separation Ability of Coated Samples 315
9.6.3 Summary 317
9.7 Mechanically Durable Superoleophobic Aluminum Surfaces 319
9.7.1 Experimental Details 323
9.7.1.1 Sample Preparation 323
9.7.1.2 Characterization 325
9.7.2 Results and Discussion 325
9.7.2.1 Wettability of Coated Samples 325
9.7.2.2 Surface Morphology and Roughness of Coated Samples 327
9.7.2.3 Wear Tests Using Tribometer 329
9.7.2.4 Self-cleaning Properties 330
9.7.2.5 Anti-smudge Properties 330
9.7.2.6 Air Pockets Measurements 330
9.7.2.7 Corrosion Tests 332
9.7.3 Summary 334
9.8 Mechanically Durable Superoleophobic Polymer Surfaces 334
9.8.1 Experimental Details 335
9.8.2 Results and Discussion 336
9.8.2.1 Wettability of Surfaces 336
9.8.2.2 Wear Resistance of Surface 337
9.8.3 Summary 339
9.9 Closure 339
References 340
10 Shark-Skin Surface for Fluid-Drag Reduction in Turbulent Flow 346
10.1 Introduction 346
10.2 Fluid Drag Reduction 348
10.2.1 Mechanisms of Fluid Drag 348
10.2.2 Shark Skin 350
10.3 Experimental Studies 351
10.3.1 Flow Visualization Studies 353
10.3.2 Riblet Geometries and Configurations 353
10.3.3 Riblet Fabrication 355
10.3.4 Drag Measurement Techniques 360
10.3.4.1 Open Channel 360
10.3.4.2 Closed Channel 363
10.3.5 Riblet Results and Discussion 365
10.3.5.1 Open Channel 365
10.3.5.2 Closed Channel 370
10.3.6 Summary 380
10.4 Fluid Flow Modeling 381
10.4.1 Riblet Geometry Models 383
10.4.2 Results and Discussion 386
10.4.2.1 Continuous Riblets 386
10.4.2.2 Segmented Riblets 386
10.4.3 Summary 389
10.5 Application of Riblets for Drag Reduction and Antifouling 392
10.6 Closure 395
References 396
11 Rice Leaf and Butterfly Wing Effect 402
11.1 Introduction 402
11.2 Inspiration from Living Nature 402
11.2.1 Ambient Species---Lotus Effect 402
11.2.2 Aquatic Species---Shark Skin and Fish Scales Effect 403
11.2.3 Ambient Species---Rice Leaf and Butterfly Wing Effect 403
11.3 Sample Fabrication 405
11.3.1 Actual Sample Replicas 405
11.3.2 Rice Leaf Inspired Surfaces 406
11.3.2.1 Micropatterned Replicas 409
11.3.2.2 Hot Embossed Plastic Sheets 409
11.4 Pressure Drop Measurement Technique 411
11.5 Results and Discussion 414
11.5.1 Surface Characterization 415
11.5.2 Pressure Drop Measurements 419
11.5.2.1 Water Flow 422
11.5.2.2 Oil Flow 422
11.5.2.3 Air Flow 427
11.5.2.4 Nondimensional Pressure Drop Model 427
11.5.3 Wettability 430
11.5.4 Drag Reduction Models 432
11.6 Closure 439
References 439
12 Bio- and Inorganic Fouling 442
12.1 Introduction 442
12.2 Fields Susceptible to Fouling 442
12.3 Biofouling and Inorganic Fouling Formation Mechanisms 446
12.3.1 Biofouling Formation 447
12.3.2 Inorganic Fouling Formation 449
12.3.3 Surface Factors 449
12.4 Antifouling Strategies from Living Nature 452
12.5 Antifouling: Current Prevention and Cleaning Techniques 456
12.5.1 Prevention Techniques 456
12.5.2 Self-cleaning Surfaces and Cleaning Techniques 459
12.6 Bioinspired Rice Leaf Surfaces for Antifouling 460
12.6.1 Fabrication of Micropatterned Samples 462
12.6.2 Anti-biofouling Measurements 463
12.6.3 Anti-inorganic Fouling Measurements 464
12.6.4 Results and Discussion 465
12.6.5 Anti-biofouling and Anti-inorganic Fouling Mechanisms 468
12.7 Closure 471
References 471
13 Gecko Adhesion 476
13.1 Introduction 476
13.2 Hairy Attachment Systems 477
13.3 Tokay Gecko 481
13.3.1 Construction of Tokay Gecko 481
13.3.2 Adhesion Enhancement by Division of Contacts and Multilevel Hierarchical Structure 483
13.3.3 Peeling 485
13.3.4 Self Cleaning 489
13.4 Attachment Mechanisms 491
13.4.1 van der Waals Forces 492
13.4.2 Capillary Forces 493
13.5 Adhesion Measurements and Data 495
13.5.1 Adhesion Under Ambient Conditions 495
13.5.1.1 Adhesion Force of a Single Seta 496
13.5.1.2 Adhesive Force of a Single Spatula 496
13.5.2 Effects of Temperature 497
13.5.3 Effects of Humidity 498
13.5.4 Effects of Hydrophobicity 498
13.6 Adhesion Modeling of Fibrillar Structures 499
13.6.1 Single Spring Contact Analysis 501
13.6.2 The Multi-level Hierarchical Spring Analysis 503
13.6.3 Adhesion Results of the Multi-level Hierarchical Spring Model 507
13.6.4 Capillary Effects 513
13.7 Adhesion Data Base of Fibrillar Structures 517
13.7.1 Fiber Model 518
13.7.2 Single Fiber Contact Analysis 518
13.7.3 Constraints 519
13.7.3.1 Non-buckling Condition 519
13.7.4 Non-fiber Fracture Condition 521
13.7.4.1 Non-sticking Condition 522
13.7.5 Numerical Simulation 523
13.7.6 Results and Discussion 524
13.8 Fabrication of Gecko Skin-Inspired Structures 528
13.8.1 Single Level Roughness Structures 529
13.8.2 Multi-level Hierarchical Structures 536
13.9 Closure 541
References 543
14 Structure and Mechanical Properties of Nacre 549
14.1 Introduction 549
14.2 Hierarchical Structure 551
14.2.1 Columnar and Sheet Structure 551
14.2.2 Mineral Bridges 553
14.2.3 Polygonal Nanograins 554
14.2.4 Inter-Tile Toughening Mechanism 555
14.3 Mechanical Properties 556
14.4 Bioinspired Structures 560
14.5 Closure 563
References 563
15 Structural Coloration 566
15.1 Introduction 566
15.2 Physical Mechanisms of Structural Colors 569
15.2.1 Film Interference 569
15.2.2 Diffraction Gratings 571
15.2.3 Scattering 572
15.2.4 Photonic Crystals 572
15.2.5 Coloration Changes 573
15.3 Lessons from Living Nature 574
15.3.1 Film Interference 575
15.3.2 Diffraction Grating 579
15.3.3 Scattering 582
15.3.4 Photonic Crystals 583
15.3.5 Coloration Changes 586
15.4 Bioinspired Fabrication and Applications 588
15.5 Closure 589
References 590
16 Outlook 597
Index 599