Li Zhang is Professor in the Department of Mechanical and Automation Engineering and Professor by Courtesy in the Department of Surgery at The Chinese University of Hong Kong (CUHK), China.Jiachen Zhang is Assistant Professor in the Department of Biomedical Engineering at City University of Hong Kong (CityU), China.Neng Xia is a Postdoctoral Fellow in the Department of Mechanical and Automation Engineering at The Chinese University of Hong Kong (CUHK), China.Yue Dong is Associate Professor in the Guangdong Provincial Key Laboratory of Intelligent Morphing Mechanisms and Adaptive Robotics, School of Mechanical Engineering and Automation, Harbin Institute of Technology, Shenzhen (HITSZ), China.

• Preface ix1 Introduction to Untethered Miniature Soft Robots 11.1 Introduction 11.2 Working Mechanisms of Untethered Soft Robots 21.2.1 Magnetic Actuation 21.2.2 Light Actuation 41.2.3 Acoustic Actuation 51.2.4 Thermal Actuation 61.2.5 Chemical Actuation 61.2.6 Biohybrid Actuation 71.3 Fabrication Methods of Untethered Soft Robots 71.3.1 Molding 71.3.2 3D Printing Techniques 101.3.3 Semiconductor and Microelectronic Techniques 111.3.4 Modular Assembly Based on Bonding Agents 121.4 Applications of Miniature Soft Robots 121.4.1 Biomedical Application 121.4.2 Environmental and Proprioceptive Sensing 131.4.3 Intelligent Electronics 151.4.4 Micromanipulation 161.5 Scope and Layout of the Book 161.5.1 Scope of the Book 161.5.2 Layout of the Book 172 Silicone Elastomers-Based Miniature Soft Robots 252.1 Introduction 252.2 Soft Elastomer-Based Robots with Programmable Magnetization Profiles 282.2.1 Untethered Soft Robots Based on Template-Aided Magnetizing 282.2.2 Small-Scale Soft Machines Based on Buckling Instability-Encoded Magnetization 292.2.3 Small-Scale Soft Machines Based on 3D Printing of Ferromagnetic Materials 322.2.4 3D Miniature Soft Machines Based on Bottom-up Heterogeneous Assembly 342.2.4.1 Voxel Fabrication and Magnetization 352.2.4.2 Jig-Assisted Assembly Approach 362.2.4.3 Demonstration of Miniature Soft Machines Fabricated by the Jig-Assisted Assembly Approach 402.3 Reprogrammable Soft Machines 412.4 Multi-Stimuli Responsive Transformation of Magneto-Elastomer Based Soft Structures 432.4.1 Solvent and Magnetic-Responsive Behavior of Magneto-Elastomers 442.4.2 Investigation of the Dynamic Transformations of Cellular Structures 472.5 Multimodal and Bioinspired Locomotion Adopted for Elastomer-Based Robot 502.6 Potential Biomedical Applications of Miniature Magnetic Soft Machines 552.7 Fluidic Pumping by the Magneto-Elastomers 602.8 Other Potential Applications of the Magneto-Elastomers 642.9 Summary 663 Carbon-Based Miniature Soft Robots with Rolled-up Concept 733.1 Introduction 733.2 The Choices of Carbon-Based Materials 743.3 TheWorking Mechanism of Carbon-Based Materials 763.3.1 Light-Induced Expansion 763.3.2 Light-Induced Shrinkage 813.3.3 Humidity-Induced Deformation 833.4 The Programming Shape Changes of Actuators and Their Applications 873.4.1 Light-Induced Local Modification 883.4.2 Non-light-Induced Local Modification 903.4.3 Self-Healing 933.4.4 Oriental Control of Elements in Actuators 973.5 Summary 994 Hydrogels-Based Miniature Soft Robots 1074.1 Introduction 1074.2 Fabrication of Reconfigurable Hydrogel Micromachines 1094.2.1 Design and Characterization of Smart Hydrogel for 4D Printing 1104.2.2 Reconfigurable Soft Microdevices Fabricated by Point-by-Point 4D Printing 1134.2.3 Reconfigurable Soft Microdevices Fabricated by Asymmetric Bessel Beam 1154.2.4 Reconfigurable Soft Microdevices Fabricated by Complex Laser Scanning Strategy 1214.3 Modular Design of Reconfigurable Soft Robots Based on 4D Microscale Building Blocks 1234.3.1 Designing Microscale Building Blocks 1234.3.2 Modular Assembly of Building Blocks Based on DH Matrix 1264.3.3 Inverse and Forward Design of Modular Morphing System 1284.4 Application of Reconfigurable Soft Robots 1304.4.1 pH-Responsive Microparticle and Cell Gripper 1304.4.2 Localized Cancer Cell Treatment 1324.5 Summary 1345 Liquid Crystal Network and Elastomer-Based Miniature Soft Robots 1415.1 Introduction 1415.2 Stimuli-Responsiveness Based on Programmed Director Field 1435.2.1 Programmed Voxelated Director Fields via Two Surface-Patterned Confining Glasses 1435.2.2 Arbitrary Director Fields Formed via 3D Assembly 1445.2.3 3DMicrostructures with Uniform and 2D Director Field Alignment 1465.2.4 3D LCN Microstructures with Encoded 3D Director Field and their 3D-to-3D Shape Transformation 1475.2.5 Thermal Shape Transformation of LCN Structures Based on 1D and 2D Voxels Assembly 1495.2.6 Reversible 3D-to-3D Shape Transformation of the Assembled 3D LCE Structures 1525.3 Magnetic Liquid Crystal Elastomer Composites for Miniature Machines 1535.3.1 Material Designs of Magnetic LCE Systems 1545.3.2 Multiple-Stimuli Responsiveness of Magnetic LCE Systems 1585.3.3 Adaptive Locomotion of Magnetic LCE-Based Robots 1615.4 Summary 1656 Flexible Ferrofluid as Soft Robotic Agents 1736.1 Introduction 1736.2 Description of Ferrofluids 1746.3 Deformation Behaviors of FDRs 1746.3.1 The Influence of Magnetic Fields on the Deformation Behaviors of FDRs 1756.3.1.1 Magnetic Fields Induced by Permanent Magnets 1756.3.1.2 Magnetic Fields Induced by Electromagnetic Coils 1816.3.2 The Influence of FDRs’ Parameters on their Deformation Behaviors 1956.3.3 The Influence of Contacting Substrate on the Deformation Behaviors of FDR 1976.4 Applications of FDRs 1986.4.1 Cargo Capturing and Delivering 1986.4.2 Objects Sorting 2006.4.3 Liquid Pumping and Mixing 2016.4.4 Liquid Skin of Soft Robots 2036.4.5 Phase Transitional Metallic Ferrofluid-Based Gripper 2066.5 Summary 2067 Conclusions and Future Prospects 2137.1 Introduction 2137.2 Other Functional Materials Used for Miniature Soft Robots 2137.2.1 Shape-Memory Materials 2137.2.2 Biohybrid Materials 2157.3 Multi-Material Integration Strategies 2167.4 Multifunctional Integration for Miniature Soft Robots with Perception Capabilities 2187.5 Perspectives Toward Intelligent and Autonomous Soft Robots 220Abbreviations 223References 224Index 229

Li Zhang is Professor in the Department of Mechanical and Automation Engineering and Professor by Courtesy in the Department of Surgery at The Chinese University of Hong Kong (CUHK), China.Jiachen Zhang is Assistant Professor in the Department of Biomedical Engineering at City University of Hong Kong (CityU), China.Neng Xia is a Postdoctoral Fellow in the Department of Mechanical and Automation Engineering at The Chinese University of Hong Kong (CUHK), China.Yue Dong is Associate Professor in the Guangdong Provincial Key Laboratory of Intelligent Morphing Mechanisms and Adaptive Robotics, School of Mechanical Engineering and Automation, Harbin Institute of Technology, Shenzhen (HITSZ), China.

• Preface ix1 Introduction to Untethered Miniature Soft Robots 11.1 Introduction 11.2 Working Mechanisms of Untethered Soft Robots 21.2.1 Magnetic Actuation 21.2.2 Light Actuation 41.2.3 Acoustic Actuation 51.2.4 Thermal Actuation 61.2.5 Chemical Actuation 61.2.6 Biohybrid Actuation 71.3 Fabrication Methods of Untethered Soft Robots 71.3.1 Molding 71.3.2 3D Printing Techniques 101.3.3 Semiconductor and Microelectronic Techniques 111.3.4 Modular Assembly Based on Bonding Agents 121.4 Applications of Miniature Soft Robots 121.4.1 Biomedical Application 121.4.2 Environmental and Proprioceptive Sensing 131.4.3 Intelligent Electronics 151.4.4 Micromanipulation 161.5 Scope and Layout of the Book 161.5.1 Scope of the Book 161.5.2 Layout of the Book 172 Silicone Elastomers-Based Miniature Soft Robots 252.1 Introduction 252.2 Soft Elastomer-Based Robots with Programmable Magnetization Profiles 282.2.1 Untethered Soft Robots Based on Template-Aided Magnetizing 282.2.2 Small-Scale Soft Machines Based on Buckling Instability-Encoded Magnetization 292.2.3 Small-Scale Soft Machines Based on 3D Printing of Ferromagnetic Materials 322.2.4 3D Miniature Soft Machines Based on Bottom-up Heterogeneous Assembly 342.2.4.1 Voxel Fabrication and Magnetization 352.2.4.2 Jig-Assisted Assembly Approach 362.2.4.3 Demonstration of Miniature Soft Machines Fabricated by the Jig-Assisted Assembly Approach 402.3 Reprogrammable Soft Machines 412.4 Multi-Stimuli Responsive Transformation of Magneto-Elastomer Based Soft Structures 432.4.1 Solvent and Magnetic-Responsive Behavior of Magneto-Elastomers 442.4.2 Investigation of the Dynamic Transformations of Cellular Structures 472.5 Multimodal and Bioinspired Locomotion Adopted for Elastomer-Based Robot 502.6 Potential Biomedical Applications of Miniature Magnetic Soft Machines 552.7 Fluidic Pumping by the Magneto-Elastomers 602.8 Other Potential Applications of the Magneto-Elastomers 642.9 Summary 663 Carbon-Based Miniature Soft Robots with Rolled-up Concept 733.1 Introduction 733.2 The Choices of Carbon-Based Materials 743.3 TheWorking Mechanism of Carbon-Based Materials 763.3.1 Light-Induced Expansion 763.3.2 Light-Induced Shrinkage 813.3.3 Humidity-Induced Deformation 833.4 The Programming Shape Changes of Actuators and Their Applications 873.4.1 Light-Induced Local Modification 883.4.2 Non-light-Induced Local Modification 903.4.3 Self-Healing 933.4.4 Oriental Control of Elements in Actuators 973.5 Summary 994 Hydrogels-Based Miniature Soft Robots 1074.1 Introduction 1074.2 Fabrication of Reconfigurable Hydrogel Micromachines 1094.2.1 Design and Characterization of Smart Hydrogel for 4D Printing 1104.2.2 Reconfigurable Soft Microdevices Fabricated by Point-by-Point 4D Printing 1134.2.3 Reconfigurable Soft Microdevices Fabricated by Asymmetric Bessel Beam 1154.2.4 Reconfigurable Soft Microdevices Fabricated by Complex Laser Scanning Strategy 1214.3 Modular Design of Reconfigurable Soft Robots Based on 4D Microscale Building Blocks 1234.3.1 Designing Microscale Building Blocks 1234.3.2 Modular Assembly of Building Blocks Based on DH Matrix 1264.3.3 Inverse and Forward Design of Modular Morphing System 1284.4 Application of Reconfigurable Soft Robots 1304.4.1 pH-Responsive Microparticle and Cell Gripper 1304.4.2 Localized Cancer Cell Treatment 1324.5 Summary 1345 Liquid Crystal Network and Elastomer-Based Miniature Soft Robots 1415.1 Introduction 1415.2 Stimuli-Responsiveness Based on Programmed Director Field 1435.2.1 Programmed Voxelated Director Fields via Two Surface-Patterned Confining Glasses 1435.2.2 Arbitrary Director Fields Formed via 3D Assembly 1445.2.3 3DMicrostructures with Uniform and 2D Director Field Alignment 1465.2.4 3D LCN Microstructures with Encoded 3D Director Field and their 3D-to-3D Shape Transformation 1475.2.5 Thermal Shape Transformation of LCN Structures Based on 1D and 2D Voxels Assembly 1495.2.6 Reversible 3D-to-3D Shape Transformation of the Assembled 3D LCE Structures 1525.3 Magnetic Liquid Crystal Elastomer Composites for Miniature Machines 1535.3.1 Material Designs of Magnetic LCE Systems 1545.3.2 Multiple-Stimuli Responsiveness of Magnetic LCE Systems 1585.3.3 Adaptive Locomotion of Magnetic LCE-Based Robots 1615.4 Summary 1656 Flexible Ferrofluid as Soft Robotic Agents 1736.1 Introduction 1736.2 Description of Ferrofluids 1746.3 Deformation Behaviors of FDRs 1746.3.1 The Influence of Magnetic Fields on the Deformation Behaviors of FDRs 1756.3.1.1 Magnetic Fields Induced by Permanent Magnets 1756.3.1.2 Magnetic Fields Induced by Electromagnetic Coils 1816.3.2 The Influence of FDRs’ Parameters on their Deformation Behaviors 1956.3.3 The Influence of Contacting Substrate on the Deformation Behaviors of FDR 1976.4 Applications of FDRs 1986.4.1 Cargo Capturing and Delivering 1986.4.2 Objects Sorting 2006.4.3 Liquid Pumping and Mixing 2016.4.4 Liquid Skin of Soft Robots 2036.4.5 Phase Transitional Metallic Ferrofluid-Based Gripper 2066.5 Summary 2067 Conclusions and Future Prospects 2137.1 Introduction 2137.2 Other Functional Materials Used for Miniature Soft Robots 2137.2.1 Shape-Memory Materials 2137.2.2 Biohybrid Materials 2157.3 Multi-Material Integration Strategies 2167.4 Multifunctional Integration for Miniature Soft Robots with Perception Capabilities 2187.5 Perspectives Toward Intelligent and Autonomous Soft Robots 220Abbreviations 223References 224Index 229

Li Zhang is Professor in the Department of Mechanical and Automation Engineering and Professor by Courtesy in the Department of Surgery at The Chinese University of Hong Kong (CUHK), China.Jiachen Zhang is Assistant Professor in the Department of Biomedical Engineering at City University of Hong Kong (CityU), China.Neng Xia is a Postdoctoral Fellow in the Department of Mechanical and Automation Engineering at The Chinese University of Hong Kong (CUHK), China.Yue Dong is Associate Professor in the Guangdong Provincial Key Laboratory of Intelligent Morphing Mechanisms and Adaptive Robotics, School of Mechanical Engineering and Automation, Harbin Institute of Technology, Shenzhen (HITSZ), China.

• Preface ix1 Introduction to Untethered Miniature Soft Robots 11.1 Introduction 11.2 Working Mechanisms of Untethered Soft Robots 21.2.1 Magnetic Actuation 21.2.2 Light Actuation 41.2.3 Acoustic Actuation 51.2.4 Thermal Actuation 61.2.5 Chemical Actuation 61.2.6 Biohybrid Actuation 71.3 Fabrication Methods of Untethered Soft Robots 71.3.1 Molding 71.3.2 3D Printing Techniques 101.3.3 Semiconductor and Microelectronic Techniques 111.3.4 Modular Assembly Based on Bonding Agents 121.4 Applications of Miniature Soft Robots 121.4.1 Biomedical Application 121.4.2 Environmental and Proprioceptive Sensing 131.4.3 Intelligent Electronics 151.4.4 Micromanipulation 161.5 Scope and Layout of the Book 161.5.1 Scope of the Book 161.5.2 Layout of the Book 172 Silicone Elastomers-Based Miniature Soft Robots 252.1 Introduction 252.2 Soft Elastomer-Based Robots with Programmable Magnetization Profiles 282.2.1 Untethered Soft Robots Based on Template-Aided Magnetizing 282.2.2 Small-Scale Soft Machines Based on Buckling Instability-Encoded Magnetization 292.2.3 Small-Scale Soft Machines Based on 3D Printing of Ferromagnetic Materials 322.2.4 3D Miniature Soft Machines Based on Bottom-up Heterogeneous Assembly 342.2.4.1 Voxel Fabrication and Magnetization 352.2.4.2 Jig-Assisted Assembly Approach 362.2.4.3 Demonstration of Miniature Soft Machines Fabricated by the Jig-Assisted Assembly Approach 402.3 Reprogrammable Soft Machines 412.4 Multi-Stimuli Responsive Transformation of Magneto-Elastomer Based Soft Structures 432.4.1 Solvent and Magnetic-Responsive Behavior of Magneto-Elastomers 442.4.2 Investigation of the Dynamic Transformations of Cellular Structures 472.5 Multimodal and Bioinspired Locomotion Adopted for Elastomer-Based Robot 502.6 Potential Biomedical Applications of Miniature Magnetic Soft Machines 552.7 Fluidic Pumping by the Magneto-Elastomers 602.8 Other Potential Applications of the Magneto-Elastomers 642.9 Summary 663 Carbon-Based Miniature Soft Robots with Rolled-up Concept 733.1 Introduction 733.2 The Choices of Carbon-Based Materials 743.3 TheWorking Mechanism of Carbon-Based Materials 763.3.1 Light-Induced Expansion 763.3.2 Light-Induced Shrinkage 813.3.3 Humidity-Induced Deformation 833.4 The Programming Shape Changes of Actuators and Their Applications 873.4.1 Light-Induced Local Modification 883.4.2 Non-light-Induced Local Modification 903.4.3 Self-Healing 933.4.4 Oriental Control of Elements in Actuators 973.5 Summary 994 Hydrogels-Based Miniature Soft Robots 1074.1 Introduction 1074.2 Fabrication of Reconfigurable Hydrogel Micromachines 1094.2.1 Design and Characterization of Smart Hydrogel for 4D Printing 1104.2.2 Reconfigurable Soft Microdevices Fabricated by Point-by-Point 4D Printing 1134.2.3 Reconfigurable Soft Microdevices Fabricated by Asymmetric Bessel Beam 1154.2.4 Reconfigurable Soft Microdevices Fabricated by Complex Laser Scanning Strategy 1214.3 Modular Design of Reconfigurable Soft Robots Based on 4D Microscale Building Blocks 1234.3.1 Designing Microscale Building Blocks 1234.3.2 Modular Assembly of Building Blocks Based on DH Matrix 1264.3.3 Inverse and Forward Design of Modular Morphing System 1284.4 Application of Reconfigurable Soft Robots 1304.4.1 pH-Responsive Microparticle and Cell Gripper 1304.4.2 Localized Cancer Cell Treatment 1324.5 Summary 1345 Liquid Crystal Network and Elastomer-Based Miniature Soft Robots 1415.1 Introduction 1415.2 Stimuli-Responsiveness Based on Programmed Director Field 1435.2.1 Programmed Voxelated Director Fields via Two Surface-Patterned Confining Glasses 1435.2.2 Arbitrary Director Fields Formed via 3D Assembly 1445.2.3 3DMicrostructures with Uniform and 2D Director Field Alignment 1465.2.4 3D LCN Microstructures with Encoded 3D Director Field and their 3D-to-3D Shape Transformation 1475.2.5 Thermal Shape Transformation of LCN Structures Based on 1D and 2D Voxels Assembly 1495.2.6 Reversible 3D-to-3D Shape Transformation of the Assembled 3D LCE Structures 1525.3 Magnetic Liquid Crystal Elastomer Composites for Miniature Machines 1535.3.1 Material Designs of Magnetic LCE Systems 1545.3.2 Multiple-Stimuli Responsiveness of Magnetic LCE Systems 1585.3.3 Adaptive Locomotion of Magnetic LCE-Based Robots 1615.4 Summary 1656 Flexible Ferrofluid as Soft Robotic Agents 1736.1 Introduction 1736.2 Description of Ferrofluids 1746.3 Deformation Behaviors of FDRs 1746.3.1 The Influence of Magnetic Fields on the Deformation Behaviors of FDRs 1756.3.1.1 Magnetic Fields Induced by Permanent Magnets 1756.3.1.2 Magnetic Fields Induced by Electromagnetic Coils 1816.3.2 The Influence of FDRs’ Parameters on their Deformation Behaviors 1956.3.3 The Influence of Contacting Substrate on the Deformation Behaviors of FDR 1976.4 Applications of FDRs 1986.4.1 Cargo Capturing and Delivering 1986.4.2 Objects Sorting 2006.4.3 Liquid Pumping and Mixing 2016.4.4 Liquid Skin of Soft Robots 2036.4.5 Phase Transitional Metallic Ferrofluid-Based Gripper 2066.5 Summary 2067 Conclusions and Future Prospects 2137.1 Introduction 2137.2 Other Functional Materials Used for Miniature Soft Robots 2137.2.1 Shape-Memory Materials 2137.2.2 Biohybrid Materials 2157.3 Multi-Material Integration Strategies 2167.4 Multifunctional Integration for Miniature Soft Robots with Perception Capabilities 2187.5 Perspectives Toward Intelligent and Autonomous Soft Robots 220Abbreviations 223References 224Index 229