Untethered Miniature Soft Robots

Preface ix 1 Introduction to Untethered Miniature Soft Robots 1 1.1 Introduction 1 1.2 Working Mechanisms of Untethered Soft Robots 2 1.2.1 Magnetic Actuation 2 1.2.2 Light Actuation 4 1.2.3 Acoustic Actuation 5 1.2.4 Thermal Actuation 6 1.2.5 Chemical Actuation 6 1.2.6 Biohybrid Actuation 7 1.3 Fabrication Methods of Untethered Soft Robots 7 1.3.1 Molding 7 1.3.2 3D Printing Techniques 10 1.3.3 Semiconductor and Microelectronic Techniques 11 1.3.4 Modular Assembly Based on Bonding Agents 12 1.4 Applications of Miniature Soft Robots 12 1.4.1 Biomedical Application 12 1.4.2 Environmental and Proprioceptive Sensing 13 1.4.3 Intelligent Electronics 15 1.4.4 Micromanipulation 16 1.5 Scope and Layout of the Book 16 1.5.1 Scope of the Book 16 1.5.2 Layout of the Book 17 2 Silicone Elastomers-Based Miniature Soft Robots 25 2.1 Introduction 25 2.2 Soft Elastomer-Based Robots with Programmable Magnetization Profiles 28 2.2.1 Untethered Soft Robots Based on Template-Aided Magnetizing 28 2.2.2 Small-Scale Soft Machines Based on Buckling Instability-Encoded Magnetization 29 2.2.3 Small-Scale Soft Machines Based on 3D Printing of Ferromagnetic Materials 32 2.2.4 3D Miniature Soft Machines Based on Bottom-up Heterogeneous Assembly 34 2.2.4.1 Voxel Fabrication and Magnetization 35 2.2.4.2 Jig-Assisted Assembly Approach 36 2.2.4.3 Demonstration of Miniature Soft Machines Fabricated by the Jig-Assisted Assembly Approach 40 2.3 Reprogrammable Soft Machines 41 2.4 Multi-Stimuli Responsive Transformation of Magneto-Elastomer Based Soft Structures 43 2.4.1 Solvent and Magnetic-Responsive Behavior of Magneto-Elastomers 44 2.4.2 Investigation of the Dynamic Transformations of Cellular Structures 47 2.5 Multimodal and Bioinspired Locomotion Adopted for Elastomer-Based Robot 50 2.6 Potential Biomedical Applications of Miniature Magnetic Soft Machines 55 2.7 Fluidic Pumping by the Magneto-Elastomers 60 2.8 Other Potential Applications of the Magneto-Elastomers 64 2.9 Summary 66 3 Carbon-Based Miniature Soft Robots with Rolled-up Concept 73 3.1 Introduction 73 3.2 The Choices of Carbon-Based Materials 74 3.3 TheWorking Mechanism of Carbon-Based Materials 76 3.3.1 Light-Induced Expansion 76 3.3.2 Light-Induced Shrinkage 81 3.3.3 Humidity-Induced Deformation 83 3.4 The Programming Shape Changes of Actuators and Their Applications 87 3.4.1 Light-Induced Local Modification 88 3.4.2 Non-light-Induced Local Modification 90 3.4.3 Self-Healing 93 3.4.4 Oriental Control of Elements in Actuators 97 3.5 Summary 99 4 Hydrogels-Based Miniature Soft Robots 107 4.1 Introduction 107 4.2 Fabrication of Reconfigurable Hydrogel Micromachines 109 4.2.1 Design and Characterization of Smart Hydrogel for 4D Printing 110 4.2.2 Reconfigurable Soft Microdevices Fabricated by Point-by-Point 4D Printing 113 4.2.3 Reconfigurable Soft Microdevices Fabricated by Asymmetric Bessel Beam 115 4.2.4 Reconfigurable Soft Microdevices Fabricated by Complex Laser Scanning Strategy 121 4.3 Modular Design of Reconfigurable Soft Robots Based on 4D Microscale Building Blocks 123 4.3.1 Designing Microscale Building Blocks 123 4.3.2 Modular Assembly of Building Blocks Based on DH Matrix 126 4.3.3 Inverse and Forward Design of Modular Morphing System 128 4.4 Application of Reconfigurable Soft Robots 130 4.4.1 pH-Responsive Microparticle and Cell Gripper 130 4.4.2 Localized Cancer Cell Treatment 132 4.5 Summary 134 5 Liquid Crystal Network and Elastomer-Based Miniature Soft Robots 141 5.1 Introduction 141 5.2 Stimuli-Responsiveness Based on Programmed Director Field 143 5.2.1 Programmed Voxelated Director Fields via Two Surface-Patterned Confining Glasses 143 5.2.2 Arbitrary Director Fields Formed via 3D Assembly 144 5.2.3 3DMicrostructures with Uniform and 2D Director Field Alignment 146 5.2.4 3D LCN Microstructures with Encoded 3D Director Field and their 3D-to-3D Shape Transformation 147 5.2.5 Thermal Shape Transformation of LCN Structures Based on 1D and 2D Voxels Assembly 149 5.2.6 Reversible 3D-to-3D Shape Transformation of the Assembled 3D LCE Structures 152 5.3 Magnetic Liquid Crystal Elastomer Composites for Miniature Machines 153 5.3.1 Material Designs of Magnetic LCE Systems 154 5.3.2 Multiple-Stimuli Responsiveness of Magnetic LCE Systems 158 5.3.3 Adaptive Locomotion of Magnetic LCE-Based Robots 161 5.4 Summary 165 6 Flexible Ferrofluid as Soft Robotic Agents 173 6.1 Introduction 173 6.2 Description of Ferrofluids 174 6.3 Deformation Behaviors of FDRs 174 6.3.1 The Influence of Magnetic Fields on the Deformation Behaviors of FDRs 175 6.3.1.1 Magnetic Fields Induced by Permanent Magnets 175 6.3.1.2 Magnetic Fields Induced by Electromagnetic Coils 181 6.3.2 The Influence of FDRs’ Parameters on their Deformation Behaviors 195 6.3.3 The Influence of Contacting Substrate on the Deformation Behaviors of FDR 197 6.4 Applications of FDRs 198 6.4.1 Cargo Capturing and Delivering 198 6.4.2 Objects Sorting 200 6.4.3 Liquid Pumping and Mixing 201 6.4.4 Liquid Skin of Soft Robots 203 6.4.5 Phase Transitional Metallic Ferrofluid-Based Gripper 206 6.5 Summary 206 7 Conclusions and Future Prospects 213 7.1 Introduction 213 7.2 Other Functional Materials Used for Miniature Soft Robots 213 7.2.1 Shape-Memory Materials 213 7.2.2 Biohybrid Materials 215 7.3 Multi-Material Integration Strategies 216 7.4 Multifunctional Integration for Miniature Soft Robots with Perception Capabilities 218 7.5 Perspectives Toward Intelligent and Autonomous Soft Robots 220 Abbreviations 223 References 224 Index 229