<p>Preface xiii</p> <p><b>1 History of Flexible and Stretchable Devices 1<br /></b><i>Kuniharu Takei</i></p> <p>References 4</p> <p><b>2 Carbon Nanotube Based Flexible and Stretchable Electronics 7<br /></b><i>Le Cai and ChuanWang</i></p> <p>2.1 Introduction 7</p> <p>2.2 Carbon Nanotube Networks for Applications in Flexible Electronics 10</p> <p>2.2.1 Thin-Film Transistors (TFTs) 10</p> <p>2.2.2 Integrated Circuits 11</p> <p>2.2.3 Active Matrix Backplanes for Flexible Display, E-Skin and Imager 16</p> <p>2.3 Carbon Nanotube Networks for Applications in Stretchable Electronics 19</p> <p>2.3.1 Stretchable Conductors 21</p> <p>2.3.2 Stretchable Strain Sensor 23</p> <p>2.3.3 Stretchable Thin-Film Transistors 27</p> <p>2.4 Scalable Fabrication Process—Printing 35</p> <p>2.4.1 Digital Printing—Inkjet and Aerosol Jet 36</p> <p>2.4.2 Gravure Printing 41</p> <p>2.4.3 Printed ComplementaryMetal–Oxide Semiconductor (CMOS) Devices 41</p> <p>2.5 Conclusions and Outlook 44</p> <p>References 45</p> <p><b>3 Organic-Based Transistors and Sensors 53<br /></b><i>Aristide Gumyusenge, Tianbai Xu, XiaozhiWang, and Jianguo Mei</i></p> <p>3.1 Introduction 53</p> <p>3.2 Materials Consideration for Flexible Organic-Based Transistors 54</p> <p>3.2.1 How Flexibility is Achieved 54</p> <p>3.2.1.1 Flexible Substrates 54</p> <p>3.2.1.2 Flexible Electrodes 55</p> <p>3.2.2 Organic Dielectric Layer 56</p> <p>3.2.3 Organic Functional Layer 57</p> <p>3.3 State-of-the-Art Designs and Fabrication of Organic-Based Transistors 57</p> <p>3.3.1 Organic Field-Effect Transistors 58</p> <p>3.3.1.1 Structure 58</p> <p>3.3.1.2 Performance and Characterization 59</p> <p>3.3.2 Modifications of OFETs for Sensing Applications 60</p> <p>3.3.2.1 Electrolyte-Gated and Ion-Sensitive Organic Field-Effect Transistors 60</p> <p>3.3.2.2 Organic Electrochemical Transistors 62</p> <p>3.3.2.3 Operating Mechanisms 63</p> <p>3.4 Fabrication Techniques for Organic-Based Transistors and Sensors 63</p> <p>3.5 Flexible Organic Transistor-Based Sensors 65</p> <p>3.5.1 Flexible Organic Strain Sensors 65</p> <p>3.5.2 Flexible Organic Pressure Sensors 67</p> <p>3.5.3 Flexible Organic Temperature Sensors 69</p> <p>3.5.4 Flexible Organic Biosensors 70</p> <p>3.5.5 Flexible Organic Optical Sensors 73</p> <p>3.6 Summary and Outlook 74</p> <p>References 75</p> <p><b>4 Printed Transistors and Sensors 83<br /></b><i>Kenjiro Fukuda</i></p> <p>4.1 Introduction 83</p> <p>4.2 Printing Technologies for Electronics 84</p> <p>4.2.1 Inkjet Printing 85</p> <p>4.2.2 Gravure Printing 86</p> <p>4.2.3 Reverse-Offset Printing for High-Resolution Patterning 87</p> <p>4.3 Printed Transistors 88</p> <p>4.3.1 Fabrication of Fully Printed Transistors 88</p> <p>4.3.2 Profile Control of Inkjet-Printed Electrodes 89</p> <p>4.3.3 Mechanical Stability 91</p> <p>4.3.3.1 Calculation of Strain in the Devices 91</p> <p>4.3.3.2 Improvement of Adhesion 91</p> <p>4.3.4 Printed Organic Transistors with Uniform Electrical Performance 93</p> <p>4.3.5 Ultraflexible and Fully Printed Organic Circuits 94</p> <p>4.4 Printed Biosensors 97</p> <p>References 99</p> <p><b>5 Flexible Photovoltaic Systems 105<br /></b><i>Lichen Zhao, Deying Luo, and Rui Zhu</i></p> <p>5.1 Introduction 105</p> <p>5.1.1 Introduction of Flexible Photovoltaics 105</p> <p>5.1.2 Principles of Photovoltaics 106</p> <p>5.1.3 The Flexible Substrates 109</p> <p>5.1.3.1 Metals and the Alloys 109</p> <p>5.1.3.2 Polymers 110</p> <p>5.1.4 The Types of Flexible Photovoltaic Systems 110</p> <p>5.2 Flexible Inorganic Photovoltaic Systems 110</p> <p>5.2.1 Flexible Silicon Photovoltaics 110</p> <p>5.2.2 Flexible Copper Indium Gallium Selenide Photovoltaics 113</p> <p>5.3 Flexible Organic Photovoltaic Systems 115</p> <p>5.3.1 Fundamental Properties of OPV Materials 115</p> <p>5.3.2 Device Structure andWorking Mechanisms 116</p> <p>5.3.3 Materials and Methods for OPV 118</p> <p>5.3.4 Recent Advances in Flexible OPV 119</p> <p>5.4 Flexible Organic–Inorganic Hybrid Photovoltaic Systems 122</p> <p>5.4.1 Fundamental Properties of Perovskites 123</p> <p>5.4.2 Device Structure andWorking Mechanisms 124</p> <p>5.4.3 Materials and Methods for Flexible PerSCs 125</p> <p>5.4.4 Recent Advances for Flexible PerSCs 128</p> <p>5.5 Summary and Conclusion 132</p> <p>References 133</p> <p><b>6 Materials Design for Flexible Thermoelectric Power Generators 139<br /></b><i>Yoshiyuki Nonoguchi</i></p> <p>6.1 Introduction 139</p> <p>6.2 General Principles 140</p> <p>6.2.1 The Basic Principles of Thermoelectricity 140</p> <p>6.2.2 Density of State and the Seebeck Coefficient 141</p> <p>6.2.3 Energy Conversion Efficiency and Dimensionless Thermoelectric Figure of Merit ZT 142</p> <p>6.2.4 A Classical Requirement for Efficient Module Design 144</p> <p>6.3 Thermoelectric Materials Design 145</p> <p>6.3.1 Organic Solids and Conducting Polymers 145</p> <p>6.3.2 Carbon Nanotubes and Related Matters 149</p> <p>6.3.3 Useful Survey Methods for Discovering Efficient Thermoelectric Materials 154</p> <p>6.3.4 Prototype Thermoelectric Generators and Applications 154</p> <p>6.4 Outlook for Flexible Thermoelectric Generators 155</p> <p>References 156</p> <p><b>7 Flexible Supercapacitors Based on Two-Dimensional Materials 161<br /></b><i>Dianpeng Qi and Xiaodong Chen</i></p> <p>7.1 Introduction 161</p> <p>7.2 Flexible Supercapacitors Based on 2D Materials 162</p> <p>7.2.1 2D Electrode Materials for Flexible EDLCs 163</p> <p>7.2.2 2D Materials for Pseudocapacitive Supercapacitors 171</p> <p>7.2.3 2D Electrode Materials for Hybrid Flexible Supercapacitors 176</p> <p>7.3 Conclusions 179</p> <p>References 181</p> <p><b>8 Organometal Halide Perovskites for Next Generation Fully Printed and Flexible LEDs and Displays 199<br /></b><i>Thomas Geske, Sri Ganesh R. Bade, MattWorden, Xin Shan, Junqiang Li, and Zhibin Yu</i></p> <p>8.1 Introduction 199</p> <p>8.1.1 General Background for LEDs 200</p> <p>8.1.2 Fundamentals of Halide Perovskites 201</p> <p>8.1.3 Multilayer Perovskite LEDs 203</p> <p>8.2 Single Layer Perovskite LEDs 206</p> <p>8.3 Current Challenges 208</p> <p>8.4 Conclusions and Outlook 211</p> <p>Acknowledgments 211</p> <p>References 211</p> <p><b>9 Flexible Floating Gate Memory 215<br /></b><i>Ye Zhou, Su-Ting Han, and Arul Lenus Roy Vellaisamy</i></p> <p>9.1 Introduction 215</p> <p>9.2 Device Operation of Floating Gate Memory 216</p> <p>9.3 Charge Injection Mechanism in Floating Gate Memory 217</p> <p>9.3.1 The Hot-electron Injection Mechanism 217</p> <p>9.3.2 Fowler–Nordheim (F-N) Tunneling Mechanism 218</p> <p>9.3.3 Direct Tunneling Mechanism 219</p> <p>9.4 Flexible Nanofloating Gate Memory 219</p> <p>9.5 Characterization of Floating Gate Memory 221</p> <p>9.6 Flexibility of Floating Gate Memory 223</p> <p>9.7 Conclusion 225</p> <p>References 225</p> <p><b>10 Flexible and StretchableWireless Systems 229<br /></b><i>Aftab M. Hussain and Muhammad M. Hussain</i></p> <p>10.1 Introduction 229</p> <p>10.2 The Basics ofWireless Systems 230</p> <p>10.2.1 Wireless Systems 230</p> <p>10.2.2 Antennas 231</p> <p>10.2.3 Antenna Parameters 233</p> <p>10.3 Flexible, Stretchable Circuits 234</p> <p>10.3.1 Flexible, Stretchable Silicon Circuits 234</p> <p>10.3.2 Non-Silicon-Based Channels 236</p> <p>10.4 Flexible Antennas 239</p> <p>10.4.1 Micromachined Flexible Antennas 240</p> <p>10.4.2 Inkjet-Printed Antennas 240</p> <p>10.5 Stretchable Antennas 242</p> <p>10.5.1 Material Stretchability 242</p> <p>10.5.2 Design Stretchability 244</p> <p>10.6 Future Outlook 246</p> <p>References 247</p> <p><b>11 Conductive Nanosheets for Ultra-Conformable Smart Electronics 253<br /></b><i>Kento Yamagishi, Silvia Taccola, Shinji Takeoka, Toshinori Fujie, Virgilio Mattoli, and Francesco Greco</i></p> <p>11.1 Introduction 253</p> <p>11.2 Fabrication of Conductive Nanosheets 255</p> <p>11.2.1 Spin-Coating-Processed Conductive Nanosheets 255</p> <p>11.2.2 Roll-to-Roll (R2R) Gravure-Printing-Processed Conductive Nanosheets 258</p> <p>11.3 Characterization of Conductive Nanosheets 260</p> <p>11.3.1 Electrical Properties of Conductive Nanosheets 260</p> <p>11.3.2 Structural Properties of Conductive Nanosheets 262</p> <p>11.3.3 Mechanical Properties of Conductive Nanosheets 263</p> <p>11.3.4 Electrochemical Properties of Conductive Nanosheets 267</p> <p>11.4 Applications of Conductive Nanosheets 269</p> <p>11.4.1 Surface Electromyogram (EMG) Recording Using Conductive Nanosheets 269</p> <p>11.4.2 Humidity Sensors 272</p> <p>11.4.3 Microactuators 272</p> <p>11.4.4 Tattoo Conductive Nanosheets for Skin-Contact Applications 274</p> <p>11.5 Concluding Remarks 277</p> <p>Acknowledgments 278</p> <p>References 278</p> <p><b>12 Flexible Health-Monitoring Devices/Sensors 287<br /></b><i>Minjeong Ha, Seongdong Lim, and Hyunhyub Ko</i></p> <p>12.1 Introduction 287</p> <p>12.2 Flexible Sensors for Health Monitoring 288</p> <p>12.2.1 Detection Approaches for Physical Bio-Signals 289</p> <p>12.2.1.1 Pressure and Strain Sensors for Health Monitoring 289</p> <p>12.2.1.2 Temperature Sensors for Health Monitoring 293</p> <p>12.2.2 Detection Approaches for Biochemical Signals 295</p> <p>12.2.2.1 Flexible pH Sensors 297</p> <p>12.2.2.2 Flexible Blood Sugar Sensors 299</p> <p>12.2.2.3 Flexible Pulse Oximeters 299</p> <p>12.2.2.4 Other Flexible Chemical Sensors to Detect Volatile Organic Compounds 302</p> <p>12.2.3 Detection Approaches for Electrophysiological Signals 304</p> <p>12.3 Multifunctional Flexible Sensors for Multiple Bio-Signals 306</p> <p>12.4 Practical Applications of Flexible Health-Monitoring Devices 309</p> <p>12.4.1 Sports and Fitness 309</p> <p>12.4.2 Prosthetics and Rehabilitation 309</p> <p>12.4.3 WoundTherapy 311</p> <p>12.4.4 Telemedicine and Self-Diagnosis of Disease 311</p> <p>12.5 Conclusions and Future Perspective 312</p> <p>References 312</p> <p><b>13 Stretchable Health Monitoring Devices/Sensors 323<br /></b><i>Xian Huang</i></p> <p>13.1 Introduction 323</p> <p>13.2 Materials for Stretchable Health Monitoring Devices 323</p> <p>13.2.1 Physically Soft and Stretchable Materials 324</p> <p>13.2.2 Unique Stretchable Structures 324</p> <p>13.3 Health Monitoring Applications of Stretchable Devices 326</p> <p>13.3.1 Skin Sensors 326</p> <p>13.3.1.1 Skin Biophysical Signal Monitoring 329</p> <p>13.3.1.2 Biomolecule Analysis 332</p> <p>13.3.2 Implantable Devices 336</p> <p>13.3.2.1 Brain and Neural Probes 336</p> <p>13.3.2.2 Cardiovascular Monitoring 337</p> <p>13.3.3 BodyWearable Devices 337</p> <p>13.3.3.1 Rehabilitation 337</p> <p>13.3.3.2 Daily Health Tracking 341</p> <p>13.4 Future of Stretchable Electronic Devices 341</p> <p>References 342</p> <p><b>14 Flexible/Stretchable Devices for Medical Applications 351<br /></b><i>GwanJin Ko, JeongWoong Shin, and Suk-Won Hwang</i></p> <p>14.1 Introduction 351</p> <p>14.2 Materials, Synthesis and Composites for Flexible/Stretchable Systems 352</p> <p>14.3 Electronic/Optoelectronic Devices, Sensors and Systems 355</p> <p>14.4 Multifunctional Electronic Sensors and Power Scavenging Circuit for the Heart 358</p> <p>14.5 Electrophysiology and Optogenetics for the Brain 362</p> <p>14.6 Communication and Regulation for the Nervous System 364</p> <p>14.7 Skin-Like Electronics/Optoelectronics 367</p> <p>14.8 Transient, Bioresorbable Systems 370</p> <p>14.9 Conclusion and Outlook 373</p> <p>References 373</p> <p><b>15 Implantable Flexible Sensors for Neural Recordings 381<br /></b><i>Shota Yamagiwa, Hirohito Sawahata, and Takeshi Kawano</i></p> <p>15.1 Introduction 381</p> <p>15.1.1 Neuronal Signal Recordings 383</p> <p>15.1.1.1 EEG 383</p> <p>15.1.1.2 ECoG 384</p> <p>15.1.1.3 LFPs and Spikes 384</p> <p>15.1.2 Electrode Materials 385</p> <p>15.1.3 Electrode Impedance in Neural Recordings 385</p> <p>15.2 Flexible Needle Electrodes 387</p> <p>15.3 Flexible ECoG Electrodes 391</p> <p>15.4 Functionalities of Flexible Substrates 395</p> <p>15.4.1 Active Matrixes 395</p> <p>15.4.2 Dissolvable Films 395</p> <p>15.4.3 Stretchable Films 399</p> <p>15.4.4 Other Functionalities 403</p> <p>15.5 Flexible Devices for Chronic Applications 403</p> <p>15.5.1 Tissue Damage 403</p> <p>15.5.2 Packaging Technologies 405</p> <p>15.5.2.1 Rivet-Like Electric and Mechanic Interconnections 405</p> <p>15.5.2.2 Anisotropic Conductive Paste/Films 407</p> <p>15.5.3 Wireless Technologies 407</p> <p>15.6 Summary 407</p> <p>References 408</p> <p><b>16 Perspective in Flexible and Stretchable Electronics 411<br /></b><i>Kuniharu Takei</i></p> <p>Index 413</p>