Introduction to Biomimetics and Bioinspiration: Materials and Surfaces for Green Science and Technology

Preface
Contents
About the Author
1 Introduction
	1.1 Biomimetics/Bioinspiration and Green Science and Technology
		1.1.1 Green Science and Technology
		1.1.2 Climate Change and Lack of Recycling Impact on Sustainable Environment
	1.2 Biodiversity
	1.3 Lessons from Living Nature
		1.3.1 Bacteria
		1.3.2 Plants
		1.3.3 Insects, Spiders, Lizards, and Frogs
		1.3.4 Aquatic Animals
		1.3.5 Birds
		1.3.6 Moth Eyes
		1.3.7 Fur and Skin of Polar Bear
		1.3.8 Seashells, Bones, and Teeth
		1.3.9 Spider Web
		1.3.10 Desert Species
		1.3.11 Arthropods
		1.3.12 Anti-Freeze Proteins (AFPs)
		1.3.13 Biological Systems—Self-healing Properties
		1.3.14 Biological Systems—Sensory Aid Devices
	1.4 Locomotion in Living Nature
		1.4.1 Walking
		1.4.2 Gear Systems for Precise Movement
	1.5 Biomimetics and Bioinspiration in Art and Architecture—Bioarchitecture
		1.5.1 Biomimetics in Arts and Architecture
		1.5.2 Bioinspiration in Arts and Architecture
	1.6 Unique Patterns Used by Nature: Golden Ratio and Fibonacci Numbers
	1.7 Industrial Applications
	1.8 Economic Impact
	1.9 Research Objective and Approach
	1.10 Organization of the Book
	References
2 Roughness-Induced Superliquiphilic/Phobic Surfaces: Wetting States and Lessons from Living Nature
	2.1 Introduction
	2.2 Wetting States
	2.3 Applications
	2.4 Natural Superhydrophobic, Self-cleaning, Low Adhesion/Drag Reduction Surfaces with Antifouling
	2.5 Natural Superhydrophobic and High Adhesion Surfaces
	2.6 Natural Superoleophobic Self-cleaning and Low Drag Surfaces with Antifouling
	2.7 Closure
	References
3 Modeling of Contact Angle for a Liquid in Contact with a Rough Surface for Various Wetting Regimes
	3.1 Introduction
	3.2 Contact Angle Definition
	3.3 Homogeneous and Heterogeneous Interfaces and the Wenzel, Cassie-Baxter and Cassie Equations
		3.3.1 Limitations of the Wenzel and Cassie-Baxter Equations
		3.3.2 Range of Applicability of the Wenzel and Cassie-Baxter Equations
	3.4 Contact Angle Hysteresis, Tilt Angle, and Energy Dissipation
	3.5 Stability of a Composite Interface and Role of Hierarchical Structure with Convex Surfaces
	3.6 The Cassie-Baxter and Wenzel Wetting Regime Transition
	3.7 Closure
	References
4 Plant Leaf Surfaces in Living Nature
	4.1 Introduction
	4.2 Plant Leaves
	4.3 Characterization of Superhydrophobic and Hydrophilic Leaf Surfaces
		4.3.1 Experimental Techniques
		4.3.2 SEM Micrographs
		4.3.3 Contact Angle Measurements
		4.3.4 Surface Characterization Using an Optical Profiler
		4.3.5 Surface Characterization, Adhesion, and Friction Using an AFM
		4.3.6 Role of the Hierarchical Roughness
		4.3.7 Summary
	4.4 Various Self-cleaning Approaches
		4.4.1 Comparison Between Superhydrophobic and Superhydrophilic Surface Approaches for Self-cleaning
		4.4.2 Summary
	4.5 Closure
	References
5 Nanofabrication Techniques Used for Superhydrophobic Surfaces
	5.1 Introduction
	5.2 Roughening to Create One-Level Structure
	5.3 Coatings to Create One-Level Structures
	5.4 Methods to Create Two-Level (Hierarchical) Structures
	5.5 Closure
	References
6 Strategies for Micropatterned, Nanopatterned, and Hierarchically Structured Lotus-like Surfaces
	6.1 Introduction
	6.2 Experimental Techniques
		6.2.1 Contact Angle, Surface Roughness, and Adhesion
		6.2.2 Droplet Evaporation Studies
		6.2.3 Bouncing Droplet Studies
		6.2.4 Vibrating Droplet Studies
		6.2.5 Microdroplet Condensation and Evaporation Studies Using ESEM
		6.2.6 Generation of Submicron Droplets
		6.2.7 Self-cleaning Studies
	6.3 Micro- and Nanopatterned Polymers
		6.3.1 Contact Angle
		6.3.2 Effect of Submicron Droplet on Contact Angle
		6.3.3 Adhesive Force
		6.3.4 Summary
	6.4 Micropatterned Si Surfaces
		6.4.1 Cassie-Baxter and Wenzel Transition Criteria
		6.4.2 Effect of Pitch Value on the Transition
		6.4.3 Observation of Transition During the Droplet Evaporation
		6.4.4 Another Cassie-Baxter and Wenzel Transition for Different Series
		6.4.5 Contact Angle Hysteresis and Wetting/Dewetting Asymmetry
		6.4.6 Contact Angle Measurements During Condensation and Evaporation of Microdroplets on Micropatterned Surfaces
		6.4.7 Observation of Transition During the Bouncing Droplet
		6.4.8 Summary
	6.5 Ideal Surfaces with Hierarchical Structure
	6.6 Hierarchically Structured Surfaces with Wax Platelets and Tubules Using Nature’s Route
		6.6.1 Effect of Nanostructures with Various Wax Platelet Crystal Densities on Superhydrophobicity
		6.6.2 Effect of Hierarchical Structure with Wax Platelets on the Superhydrophobicity
		6.6.3 Effect of Hierarchical Structure with Wax Tubules on Superhydrophobicity
		6.6.4 Self-cleaning Efficiency of Hierarchically Structured Surfaces
		6.6.5 Observation of Transition During the Bouncing Droplet
		6.6.6 Observation of Transition During the Vibrating Droplet
		6.6.7 Measurement of Fluid Drag Reduction
		6.6.8 Summary
	6.7 Closure
	References
7 Fabrication and Characterization of Mechanically Durable Superhydrophobic Surfaces
	7.1 Introduction
	7.2 Characterization Techniques
		7.2.1 Mechanical Durability
		7.2.2 Waterfall/Jet Tests
		7.2.3 Optical Transmittance Measurements
	7.3 Superhydrophobic Surfaces Using CNT Composites
		7.3.1 Fabrication Details
		7.3.2 Contact Angle
		7.3.3 Durability of Various Surfaces in Waterfall/Jet Tests
		7.3.4 Durability of Various Surfaces in AFM and Ball-on-Flat Tribometer Tests
		7.3.5 Summary
	7.4 Superhydrophobic Surfaces Using Nanoparticle Composites with Hierarchical Structure
		7.4.1 Fabrication Details
		7.4.2 Contact Angle of Surfaces Using Micropattern
		7.4.3 Contact Angle of Surfaces Using Microparticles and Comparison to Micropatterns
		7.4.4 Durability of Various Surfaces in AFM and Ball-on-Flat Tribometer Tests
		7.4.5 Summary
	7.5 Superhydrophobic Surfaces Using Nanoparticle Composites for Optical Transparency
		7.5.1 Fabrication Details
		7.5.2 Surface Roughness and Morphology
		7.5.3 Contact Angle
		7.5.4 Optical Transparency
		7.5.5 Durability of Various Samples in AFM and Water Jet Tests
		7.5.6 Summary
	7.6 Superhydrophobic Surfaces Using Micropatterning, Nanoparticle Composite Coating and Ion Etching of PDMS for Optical Transparency
		7.6.1 Micropatterning and Nanoparticle/Binder Coating
		7.6.2 Ion Etching
	7.7 Superhydrophobic Paper Surfaces
		7.7.1 Fabrication Details
		7.7.2 Contact Angle
		7.7.3 Durability Test
		7.7.4 Summary
	7.8 Closure
	References
8 Strategies for Superliquiphobic/Philic Surfaces
	8.1 Introduction
	8.2 Oils and Surfactant-Containing Liquids
	8.3 Strategies to Achieve Superoleophobicity in Air and Liquid Repellency
		8.3.1 Roughness Techniques
		8.3.2 Fluorination Techniques
		8.3.3 Chemical Activation of Underlayer of a Coated Surface
		8.3.4 Re-entrant Geometry
		8.3.5 Coating Deposition Techniques
		8.3.6 Summary
	8.4 Strategies to Achieve Combinations of Superliquiphilicity/Phobicity
	8.5 Model to Predict Oleophobic/Philic Nature of Surfaces
	8.6 Validation of Oleophobicity/Philicity Model for Oil Droplets in Air and Water
		8.6.1 Experimental Techniques
		8.6.2 Fabrication of Oleophobic/Philic Surfaces
		8.6.3 Characterization of Oleophobic/Philic Surfaces
		8.6.4 Summary
	8.7 Closure
	References
9 Adaptable Fabrication Techniques for Mechanically Durable Superliquiphobic/Philic Surfaces
	9.1 Introduction
	9.2 Characterization Techniques
		9.2.1 Contact Angle and Tilt Angle
		9.2.2 Surface Morphology
		9.2.3 Surfactant-Containing Liquid Repellency
		9.2.4 High Temperature Superliquiphobicity
		9.2.5 Wear Resistance
		9.2.6 Self-cleaning
		9.2.7 Finger Touch Tests
		9.2.8 Anti-icing
		9.2.9 Anti-fogging
		9.2.10 Optical Transparency
		9.2.11 Fluid Drag
		9.2.12 Oil–water Separation
	9.3 Nanoparticle-Binder Composite Coatings
		9.3.1 Experimental Details
		9.3.2 Characterization of Coatings Prepared Using Oxygen Plasma Treatment
		9.3.3 Characterization of Coatings Applied Using UV-O Treatment
	9.4 Layer-By-Layer Technique
		9.4.1 Experimental Details
		9.4.2 Results and Discussion
		9.4.3 Summary
	9.5 Nanoparticle-Encapsulation Technique
		9.5.1 Polycarbonate Surfaces
		9.5.2 Polypropylene Surfaces
	9.6 Liquid Impregnation Technique
		9.6.1 Porous Polypropylene Surface Created Using Solvent-Nonsolvent Mixture
		9.6.2 Porous Polystyrene Surfaces Created Using Breath Figures
	9.7 Comparison of Various Roughness-Induced and Liquid Impregnation Techniques for Superoleophobicity
		9.7.1 Comparison of Data
		9.7.2 Summary and Outlook
	9.8 Closure
	Appendix 9.A: Oil–Water Separation for Oil Spill Cleanup and Water Purification (Bhushan 2018, 2020)
		Appendix 9.A.1: Introduction
		Appendix 9.A.2: Common Methods for Oil Spill Cleanup
		Appendix 9.A.3: Proposed Bioinspired Net
		Appendix 9.A.4: Summary
	References
10 Fabrication and Characterization of Mechanically Durable Superliquiphobic Engineering Surfaces
	10.1 Introduction
	10.2 Superoleophobic Aluminum Surfaces
		10.2.1 Two-Step Technique Using Etching and Fluorination
		10.2.2 Single Step Technique Using Fluorinated Nanoparticles
	10.3 Superoleophobic Stainless Steel Surfaces
		10.3.1 Experimental Details
		10.3.2 Results and Discussion
		10.3.3 Summary
	10.4 Superoleophobic Titanium Surfaces
		10.4.1 Experimental Details
		10.4.2 Results and Discussion
		10.4.3 Summary
	10.5 Superoleophobic Cotton Surfaces
		10.5.1 Experimental Details
		10.5.2 Results and Discussion
		10.5.3 Summary
	10.6 Superoleophobic Synthetic Leather Surfaces
		10.6.1 Experimental Details
		10.6.2 Results and Discussion
		10.6.3 Summary
	10.7 Closure
	References
11 Shark Skin Surfaces for Fluid-Drag Reduction in Turbulent Flows
	11.1 Introduction
	11.2 Fluid Drag Reduction
		11.2.1 Mechanisms of Fluid Drag
		11.2.2 Shark Skin and Riblets Present
	11.3 Experimental Studies of Riblet-Inspired Surfaces
		11.3.1 Flow Visualization Studies
		11.3.2 Riblet Geometries and Configurations
		11.3.3 Riblet Fabrication
		11.3.4 Drag Measurement Techniques
		11.3.5 Riblet Results and Discussion
		11.3.6 Summary
	11.4 Fluid Flow Modeling of Riblets
		11.4.1 Computational Fluid Dynamic (CFD) Model
		11.4.2 Modeling of Blade Riblets
		11.4.3 Modeling of Blade, Sawtooth and Scalloped Riblets
	11.5 Application of Riblets for Drag Reduction and Antifouling
		11.5.1 Industrial Examples
		11.5.2 Prototypes and Commercial Applications
	11.6 Closure
	References
12 Gecko Adhesion
	12.1 Introduction
	12.2 Hairy Attachment Systems
	12.3 Tokay Gecko
		12.3.1 Construction of Tokay Gecko
		12.3.2 Adhesion Enhancement by Division of Contacts and Multilevel Hierarchical Structure
		12.3.3 Peeling
		12.3.4 Self-cleaning
	12.4 Attachment Mechanisms
		12.4.1 van der Waals Forces
		12.4.2 Capillary Forces
	12.5 Adhesion Measurements and Data
		12.5.1 Adhesion Under Ambient Conditions
		12.5.2 Effects of Temperature
		12.5.3 Effects of Humidity
		12.5.4 Effects of Hydrophobicity
	12.6 Adhesion Modeling of Fibrillar Structures
		12.6.1 Single Spring Contact Analysis
		12.6.2 The Multi-level Hierarchical Spring Analysis
		12.6.3 Adhesion Results of the Multi-level Hierarchical Spring Model
		12.6.4 Capillary Effects
	12.7 Adhesion Data Base of Fibrillar Structures
		12.7.1 Fiber Model
		12.7.2 Single Fiber Contact Analysis
		12.7.3 Constraints
		12.7.4 Numerical Simulation
		12.7.5 Results and Discussion
	12.8 Fabrication of Gecko Skin-Inspired Structures
		12.8.1 Single Level Roughness Structures
		12.8.2 Multi-level Hierarchical Structures
	12.9 Closure
	References
13 Bio- and Inorganic Fouling
	13.1 Introduction
	13.2 Fields Susceptible to Fouling
	13.3 Biofouling and Inorganic Fouling Formation Mechanisms
		13.3.1 Biofouling Formation
		13.3.2 Inorganic Fouling Formation
		13.3.3 Surface Factors
	13.4 Antifouling Strategies from Living Nature
	13.5 Current Prevention and Cleaning Techniques for Antifouling
		13.5.1 Current Prevention Techniques
		13.5.2 Self-cleaning Surfaces and Cleaning Techniques
	13.6 Nanomaterials for Anti-biofouling
		13.6.1 Surface Treatment of Cotton Fabrics
		13.6.2 Morphology and Contact Angle
		13.6.3 Durability of the Treatment After Wash
		13.6.4 Antimicrobial Properties
	13.7 Nanostructured Surfaces for Antifouling
		13.7.1 Fabrication of Micropatterned Samples
		13.7.2 Anti-biofouling Measurements
		13.7.3 Anti-inorganic Fouling Measurements
		13.7.4 Results and Discussion
	13.8 Closure
	References
14 Bioinspired Strategies for Water Harvesting from Fog and Condensation
	14.1 Introduction
		14.1.1 Water on Earth
		14.1.2 Water Consumption
		14.1.3 Water Contamination
		14.1.4 Lessons from Nature for Water Harvesting to Supplement Water Supply
		14.1.5 Scope of the Chapter
	14.2 Overview of Arid Desert Conditions, Water Sources, and Desert Plants and Animals
		14.2.1 Water Source
		14.2.2 Desert Plants and Animals
	14.3 Water Harvesting—Lessons from Living Nature
		14.3.1 Cactus
		14.3.2 Grass
		14.3.3 Desert Moss
		14.3.4 Bushes
		14.3.5 Namib Desert Beetles
		14.3.6 Lizards
		14.3.7 Rattlesnakes
		14.3.8 Spider Webs
	14.4 Bioinspired Flat and Conical Surfaces for Water Harvesting
		14.4.1 Flat Surfaces with Homogeneous and Heterogeneous Wettability
		14.4.2 Conical Surfaces with and Without Grooves and Homogeneous and Heterogeneous Wettability
		14.4.3 Experimental Apparatuses for Water Collection from Fog
		14.4.4 Results and Discussion
		14.4.5 Design Guidelines for Water Harvesting Systems
	14.5 Bioinspired Triangular Patterns on Flat Surfaces for Water Harvesting
		14.5.1 Samples with Triangular Patterns
		14.5.2 Experimental Apparatuses for Water Collection from Condensation
		14.5.3 Results and Discussion
	14.6 Commercial Applications and Various Water Harvesting Tower Designs
		14.6.1 Commercial Applications
		14.6.2 Projection of Water Collection Rates in Water Harvesting
		14.6.3 Design of Water Harvesters
		14.6.4 Operational and Maintenance Cost
		14.6.5 Scaleup and Commercialization Issues
	14.7 Closure
	Appendix 14.A: Laplace Pressure Gradient on a Conical Surface
	References
15 Mosquitoes’ Locomotion and Painless Piercing
	15.1 Introduction
	15.2 Mosquitoes’ Locomotion
		15.2.1 Standing on Water
		15.2.2 Sticking to Any Surface
		15.2.3 Flying in Air and Rain
		15.2.4 Summary
	15.3 Mosquitoes’ Painless Piercing
		15.3.1 Microanatomy
		15.3.2 Feeding
		15.3.3 Nanomechanical Property Measurements of Labium
		15.3.4 Lessons from Mosquito Piercing and Conceptual Schematic of a Painless Mosquito-Inspired Microneedle
		15.3.5 Summary
	15.4 Closure
	References
Index