Cover
Copyright
Preface
Part I: Sensing
1. 1 Wearable Organic Nano‐sensors
  1. 1.1 Introduction
  2. 1.2 Wearable Organic Sensors Based on Different Device Architectures
  3. 1.3 Summary and Perspective
  4. References
2. 2 Stimuli‐Responsive Electronic Skins
  1. 2.1 Introduction
  2. 2.2 Materials for Electronic Skins
  3. 2.3 Stimuli‐Responsive Behaviors
  4. 2.4 Understanding the Mechanism of Stimuli‐Responsive Materials Applied for Electronic Skins
  5. 2.5 Conclusion
  6. References
3. 3 Flexible Thermoelectrics and Thermoelectric Textiles
  1. 3.1 Introduction
  2. 3.2 Thermoelectricity and Thermoelectric Materials
  3. 3.3 Thermoelectric Generators
  4. 3.4 Wearable Thermoelectric Generators for Smart Clothing
  5. 3.5 Prospects and Challenges
  6. References
Part II: Energy
1. 4 Textile Triboelectric Nanogenerators for Energy Harvesting
  1. 4.1 Introduction
  2. 4.2 Fundamentals of Triboelectric Nanogenerators (TENGs)
  3. 4.3 Progresses in Textile TENGs
  4. 4.4 Conclusions and Perspectives
  5. References
2. 5 Flexible and Wearable Solar Cells and Supercapacitors
  1. 5.1 Introduction
  2. 5.2 Flexible and Wearable Solar Cells
  3. 5.3 Conclusions and Outlook
  4. Acknowledgments
  5. References
3. 6 Flexible and Wearable Lithium‐Ion Batteries
  1. 6.1 Introduction
  2. 6.2 Typical Lithium‐Ion Batteries
  3. 6.3 Electrode Materials for Flexible Lithium‐Ion Batteries
  4. 6.4 Flexible Lithium‐Ion Batteries Based on Electrolytes
  5. 6.5 Inactive Materials and Components of Flexible LIBs
  6. 6.6 Conclusions and Prospects
  7. References
Part III: Interacting
1. 7 Thermal and Humidity Management for Next‐Generation Textiles
  1. 7.1 Introduction
  2. 7.2 Passive Smart Materials
  3. 7.3 Energy‐Harvesting Materials
  4. 7.4 Active Smart Materials
  5. 7.5 Conclusion
  6. References
2. 8 Functionalization of Fiber Materials for Washable Smart Wearable Textiles
  1. 8.1 Introduction
  2. 8.2 Fiber Materials Functionalization for Conductivity
  3. 8.3 Waterproof Modification for Conductive Fiber Substrates
  4. 8.4 Washing Evaluations of Conductive Textiles
  5. 8.5 Conclusions
  6. References
3. 9 Flexible Microfluidics for Wearable Electronics
  1. 9.1 Introduction
  2. 9.2 Materials
  3. 9.3 Fabrication Technologies
  4. 9.4 Applications
  5. 9.5 Challenges
  6. References
Part IV: Integrating and Connecting
1. 10 Piezoelectric Materials and Devices Based Flexible Bio‐integrated Electronics
  1. 10.1 Introduction
  2. 10.2 Piezoelectric Materials
  3. 10.3 Piezoelectric Devices for Biomedical Applications
  4. 10.4 Conclusion
  5. References
2. 11 Flexible and Printed Electronics for Smart Clothes
  1. 11.1 Introduction
  2. 11.2 Printing Technology
  3. 11.3 Flexible Substrates
  4. 11.4 Application
  5. 11.5 Prospects
  6. References
3. 12 Flexible and Wearable Electronics: from Lab to Fab
  1. 12.1 Introduction
  2. 12.2 Materials
  3. 12.3 Printing Technologies
  4. 12.4 Flexible and Wearable Electronic Products
  5. 12.5 Strategy Toward Smart Clothing
  6. 12.6 Summary and Perspective
  7. References
  8. Notes
4. 13 Materials and Processes for Stretchable and Wearable e‐Textile Devices
  1. 13.1 Introduction
  2. 13.2 Materials for e‐Textiles
  3. 13.3 Device Applications
  4. 13.4 Summary and Perspectives
  5. References
Index
End User License Agreement

List of Tables

Chapter 3
1. Table 3.1 Exemplary high‐performance thermoelectric materials.
2. Table 3.2 Skin temperatures under ambient temperature (27 °C) and possible capab...
3. Table 3.3 Summary of some of the reported flexible TEGs.
Chapter 4
1. Table 4.1 The triboelectric series table.
Chapter 9
1. Table 9.1Soft lithographic methods for the fabrication of micro/nanopatterns.
Chapter 12
1. Table 12.1 Characteristics of some widely used substrate materials in commercial...
2. Table 12.2 Specifications for paper batteries from Enfucell.
3. Table 12.3 Three representative technological innovations during the development...
4. Table 12.4 The properties of typical commercial solar cell modules.
Chapter 13
1. Table 13.1 Performance parameters for various wearable e‐textile‐based devices.

List of Illustrations

Chapter 1
1. Figure 1.1 Relative change in resistance of respiration and pulse, in (a) and ...
2. Figure 1.2 Fabrication process and structure of the CSilkNM pressure sensor. (...
3. Figure 1.3 Various OTFT‐based flexible sensors. (a) Image of P‐29‐DPP‐SVS OFET...
4. Figure 1.4 (a) I_ds − V_gs transfer curves at V_ds = −1 V for an individual pixel...
5. Figure 1.5 (a) Fluorescence microscopic image of mechanically strained HUVECs ...
6. Figure 1.6 (a) Triggering a wireless alarm system by gentle finger tapping on ...
Chapter 2
1. Figure 2.1 Comparison of Young's modulus of different materials.
2. Figure 2.2 Different materials for electronic skins. (a) Liquid metals, (b) hy...
3. Figure 2.3 Schematic illustration of the self‐healing process upon stimuli.
4. Figure 2.4 Representative photographs of the stimuli‐responsive optical appear...
5. Figure 2.5 (a) Stimuli‐responsive actuations driven by pressurized gas and liq...
6. Figure 2.6 A photograph of the 3D printing process by FDM.
7. Figure 2.7 (a) Transmittance vs. temperature for the UCST‐type hydrogels with ...
Chapter 3
1. Figure 3.1 Different materials classified with respect to their thermal κ
2. Figure 3.2 (a) Module structure and (b) photograph of a thermoelectric module ...
3. Figure 3.3 Typical values of thermoelectric (TE) efficiency for different valu...
4. Figure 3.4 Schematic of the coiled‐up thermoelectric power generator.
5. Figure 3.5 (a) Photograph of fabricated flexible TEG on Kapton and (b) its sch...
6. Figure 3.6 (a) Schematic illustration of the fabrication process of the screen...
7. Figure 3.7 (a) Schematic and (b) image of a six‐leg inkjet‐printed composite T...
8. Figure 3.8 (a) Layer arrangement for the multilayered fabric. Carbon nanotubes...
9. Figure 3.9 (a) Chemical structure of PEDOT:PSS, (b) SEM image, and (c) digital...
10. Figure 3.10 Thermoelectric yarns and textiles and their fabrication. (a–c) Ill...
11. Figure 3.11 Structure design of the 3D fabric TEG.
Chapter 4
1. Figure 4.1 Fundamentals of the TENG. Inside the TENG, it is the Maxwell's disp...
2. Figure 4.2 The four fundamental working modes of TENGs.
3. Figure 4.3 A fiber TENG: (a) fabrication and (b) working mechanism of the fibe...
4. Figure 4.4 A woven textile TENG: (a) fabrication process, (b) working mechanis...
5. Figure 4.5 The textile TENG woven from core–shell fibers: (a) scheme and (b) p...
6. Figure 4.6 Structure illustration of a nanopatterned textile TENG.
7. Figure 4.7 A sliding‐mode textile TENG with interdigitated electrodes: (a) str...
8. Figure 4.8 A 3D woven textile TENG. (a) Fabrication process and (b) structure ...
9. Figure 4.9 The scheme of a self‐charging power textile that integrates energy‐...
Chapter 5
1. Figure 5.1 Schematic illustration of the working mechanism of a DSSC.
2. Figure 5.2 (a) Optical photograph of a twisted wire‐shaped flexible dye‐sensit...
3. Figure 5.3 (a) Schematic illustration of a stretchable DSSC. (b, c) SEM images...
4. Figure 5.4 Digital photograph of model device under different deformation mode...
5. Figure 5.5 (a) Conceptual morphology model with bicontinuous interpenetration ...
6. Figure 5.6 (a) Fabrication of the PSC textile. Photographs of the PSC textile ...
7. Figure 5.7 (a) Schematic illustration of the fabrication of a stretchable fibe...
8. Figure 5.8 (a) Scheme of the ultralight and flexible organic solar cell. (b) E...
9. Figure 5.9 (a) Structure of the OPV device. (b) Photograph of the OPV device w...
10. Figure 5.10 (a) Roll‐to‐roll machine, (b) roll‐to‐roll process of PEDOT:PSS:CN...
11. Figure 5.11 (a) Flexible PVSC in a mesoscopic structure. (b) Planar structure ...
12. Figure 5.12 (a) Schematic of radially stretchable solar cells. (b) Photograph ...
13. Figure 5.13 (a–c) Schematic representation of slot‐die coating on rigid glass ...
14. Figure 5.14 (a) Structure of the fiber‐shaped PVSC. (b) J–V curve of a coaxial...
15. Figure 5.15 Faradaic and capacitive energy storage. Summary of the characteris...
16. Figure 5.16 An overview of promising electrode materials used so far for flexi...
17. Figure 5.17 Recently developed innovative flexible supercapacitor (FSCs) devic...
18. Figure 5.18 (a) Optical images of the flexible rGO film supercapacitor with th...
19. Figure 5.19 Wearable applications of solid‐state SC yarns. (a) Schematic ill...
20. Figure 5.20 Schematics for the production of breathable and smart garments thr...
21. Figure 5.21 (a) Schematic illustration of the fabrication of a hierarchical co...
22. Figure 5.22 A chronology of the development of photo‐supercapacitors (PS
23. Figure 5.23 (a) Schematic diagram and photograph of a parallel‐like wire‐type
24. Figure 5.24 Schematic illustration of the structure of all‐solid‐state, coaxia...
25. Figure 5.25 (a) Charge–discharge profile of the energy‐harvesting and storing ...
Chapter 6
1. Figure 6.1 (a–c) Three main commercial cell types and (d) a schematic diagram ...
2. Figure 6.2 (a–c) Schematics of the sample fabrication stage. (d–f) The corresp...
3. Figure 6.3 (a) Schematic of the recyclable process for scalable controlled ass...
4. Figure 6.4 Photothermal reduction of graphene oxide. (a–c) Photographs of flas...
5. Figure 6.5 Schematic image of the preparation of freestanding flexible TiO₂/CN...
6. Figure 6.6 Schematic image of the preparation of PCNF paper.
7. Figure 6.7 (a) Photograph of as‐produced R‐CNTY wound on a roller, and low‐ an...
8. Figure 6.8 Schematic of the flexible solid polymer electrolyte interface layer...
9. Figure 6.9 Schematic illustration of PEO‐LLZTO ceramic/polymer solid electroly...
10. Figure 6.10 SEM images of microporous membrane separators prepared by (a) dry ...
11. Figure 6.11 Schematic illustration of the preparation process for polyethylene...
12. Figure 6.12 Different types of casing components for flexible lithium‐ion batt...
13. Figure 6.13 (a) Schematic diagram of an all‐flexible LED system. (b) Picture o...
14. Figure 6.14 Different materials used in flexible current collectors. (a) Metal...
Chapter 7
1. Figure 7.1 Fabrication process of the thermoresponsive membrane proposed by St...
2. Figure 7.2 Evaluation of thermal energy loss conducted by Stucki et al.
3. Figure 7.3 Illustration of Zhong et al.'s first design. (a) Nafion sheet schem...
4. Figure 7.4 Illustration of Zhong et al.'s second design. (a) Schematic of the ...
5. Figure 7.5 Personal humidity and heat management system proposed by Mu et al. ...
6. Figure 7.6 Mechanism and applications of coiled nylon fibers proposed by Haine...
7. Figure 7.7 Schematic illustrations of a TE module for power generation (a. See...
8. Figure 7.8 Silk‐based TE fabric proposed by Lu et al. (a) Schematic illustrati...
9. Figure 7.9 T‐shirts with integrated TEG devices developed by Hyland et al.
10. Figure 7.10 Shirt with hidden integrated TEGs developed by Leonov et al. (a) F...
11. Figure 7.11 (a) Schematic diagram of a typical FTEG unit. (b, c) The enlarged ...
12. Figure 7.12 Schematic diagrams of knitted panel.
13. Figure 7.13 (a) Schematic diagram of the thermal drawing process. (b) Single T...
14. Figure 7.14 Photographs of a shirt with an embedded TEG proposed by Kim et al....
15. Figure 7.15 Infrared images of rGO/PET fabric proposed by Wang et al. (a) Diff...
16. Figure 7.16 Wearable PTM devices proposed by Guo et al. (a) Multiple device de...
17. Figure 7.17 Design of temperature‐controlled smart jacket with an all‐fabric i...
Chapter 8
1. Figure 8.1 Schematic illustration of preparation procedure of the conductive P...
2. Figure 8.2 Changes in surface resistance of PEDOTPSS coated Kevlar threads: (a...
3. Figure 8.3 The evolution of R_i/R₀ vs. washing cycle.
4. Figure 8.4 Mechanism of PPy binding through SP to the textile surface.
5. Figure 8.5 Conductivity dependence of modified VS textile on amounts of Py and...
6. Figure 8.6 Conductivity dependence of polypropylene textile on amounts of Py a...
7. Figure 8.7 Plot of electrical resistance vs. length of yarns.
8. Figure 8.8 Schematic representation of the fabrication of superhydrophobic cot...
9. Figure 8.9 Chemical durability of bimetal coated cotton fabric: (a) sheet resi...
10. Figure 8.10 Washing durability of as‐coated samples after repeated washings.
11. Figure 8.11 Washability test of the conductive cotton yarns (60 minutes platin...
12. Figure 8.12 Schematic illustration of the process of preparing copper film on ...
13. Figure 8.13 Conductivity tests of the prepared conductive PET fabrics with (a)...
14. Figure 8.14 Electrical resistivity of patterns on (a) cotton fabrics and (b) A...
15. Figure 8.15 Photographs of (a) the fabrication process of the rGO deposited co...
16. Figure 8.16 Illustration of the surface modification of silk fabrics by GO.
17. Figure 8.17 Schematic diagram of the scalable production of graphene‐based wea...
18. Figure 8.18 Schematic representation of the printed supercapacitor fabrication...
19. Figure 8.19 The effects of washing times on electrical surface resistance of s...
Chapter 9
1. Figure 9.1 Fabrication steps for polyimide‐based microfluidic devices. (a) Pho...
2. Figure 9.2 Fabrication method of the microfluidic device by soft lithography. ...
3. Figure 9.3 Fabrication process of a typical microfluidic reactor by inkjet pri...
4. Figure 9.4 Schematic representation of the ABS scaffold‐removal fabrication me...
5. Figure 9.5 Lab‐on‐a‐chip device fabricated using templates printed with 3D pri...
6. Figure 9.6 Three‐dimensional microfluidic devices fabricated in layered paper ...
7. Figure 9.7 The fabrication process of MST with multi‐inlet‐single‐outlet desig...
8. Figure 9.8 The schematic illustration of the structure of the chrono‐sampling ...
9. Figure 9.9 (a) Schematic representation of the fabrication steps of the microf...
10. Figure 9.10 (a) Illustration and (b) a prototype of the wearable digital dropl...
11. Figure 9.11 Optical image of the flexible microfluidic chip integrated with a ...
12. Figure 9.12 Optical image of a three‐electrode electrochemical sensor on PDMS ...
13. Figure 9.13 Photographs of the flexible epidermal microfluidic system attached...
14. Figure 9.14 Positions of the sensors: index finger, thumb, and palm region.
15. Figure 9.15 (a) Schematic illustration of the actuation mechanisms of microflu...
16. Figure 9.16 (a) Schematic drawings of the microfluidic drug patch. (b) Optical...
17. Figure 9.17 Schematic illustration and photographs of the optofluidic neuro pr...
18. Figure 9.18 Demonstrations of the microfluidics‐based flexible display. (a) Mu...
Chapter 10
1. Figure 10.1 Scanning electron microscope (SEM) of various piezoelectric mate...
2. Figure 10.2 Schematic demonstration of the processes for fabricating PZT nanom...
3. Figure 10.3 Illustrations of coupling of the PZT nanomembrane under mechanical...
4. Figure 10.4 Needle‐shaped tissue modulus sensor based on membrane PZT actuator...
Chapter 11
1. Figure 11.1 Schematic of fabrication process for transparent triboelectric nan...
2. Figure 11.2 Images and schematic illustrations of the flexible integrated sens...
3. Figure 11.3 Schematic drawings of dynamic reconstruction of conductive nanonet...
4. Figure 11.4 Fabrication process, microstructures, and pressure‐sensing models ...
5. Figure 11.5 Illustration of a thin large‐area and lightweight tactile sensor. ...
6. Figure 11.6 Schematic, photographs, and mechanism of the tattoo‐patch acoustic...
7. Figure 11.7 Schematic of the fabrication process for assembled devices.
8. Figure 11.8 Flexible glove biosensor for detection of OP: fabrication, design,...
9. Figure 11.9 (a) The first eigenmode of wrinkled shape obtained from linear buc...
10. Figure 11.10 Highly skin‐conformal sensor array simply fabricated with graphen...
11. Figure 11.11 Illustration of the epidermal BFCs and the constituents of the an...
12. Figure 11.12 Mechanical resilience studies and effect of fuel coverage on the ...
13. Figure 11.13 Schematic illustration of the layer‐by‐layer assembly processes u...
14. Figure 11.14 Fabrication and characterization of the inkjet‐printed Supercapac...
15. Figure 11.15 Electrochemical measurements of Ni@MnO₂ nanocoral‐structured plan...
Chapter 12
1. Figure 12.1 Schematic illustration of the working process of piezoelectric dri...
2. Figure 12.2 Schematic illustration of the working principle of an aerosol jet ...
3. Figure 12.3 Schematic diagram of an e‐jet printer.
4. Figure 12.4 Schematic diagrams of three typical operating modes for commercial...
5. Figure 12.5 Structural schematic diagram of two typical kinds of commercial st...
6. Figure 12.6 (a) Structural schematic diagram of a typical kind of commercial s...
7. Figure 12.7 (a) Structural schematic diagram of a piece of paper battery; (b) ...
8. Figure 12.8 OLED flexible displays from Royole and BOE, China (a, b).
Chapter 13
1. Figure 13.1 Schematic of the materials, structures, and applications of e‐text...
2. Figure 13.2 (a) Schematic illustration of the dry spinning process to fabricat...
3. Figure 13.3 Cross‐section SEM image of the bundle (a) before and (b) after scr...
4. Figure 13.4 (a) SEM image of a CNT coated cotton fabric. Scale bar is 100 μm. ...
5. Figure 13.5 (a) Schematic illustration of the roll‐to‐roll synthetic process f...
6. Figure 13.6 (a) Joule heating performances of a piece of Ti₃AlC₂/PPy‐coated PE...
7. Figure 13.7 SEM images of (a) pristine electrospun PAN fibers and (b) PAniNR@P...
8. Figure 13.8 (a) Schematic of the vapor printing process for PEDOT deposition. ...
9. Figure 13.9 (a) Schematic illustration showing the 3D printing process using a...

Preface

When we study the history of clothing, we notice that its development depends on the revolution of materials and is relative to the industrial revolution. Materials development brings new functions to clothes and new opportunities to human society. We cannot help imagine what clothes will be like in the future. Many people have successfully taken forward the technology revolution in the clothing industry. For example, the so‐called smart and wearable devices have emerged and are integrated into clothes; these devices are able to monitor our health conditions or charge mobile phones or displays, which takes us one step closer to the smart clothing that we expect. In the future, most functions that digital devices offer will be integrated into smart clothes; with all these functions together, as our second skin, the new clothes will be an intelligent interface between humans and nature.

How likely is it that it will become a reality? Be aware of this example – a fantasy shoe that can deform was demonstrated in a science fiction movie “Back to the Future” in 1989, and 17 years later, the exact same shoe was released by Nike.

To this extent, we shall believe that smart clothing, delivered by wearable technologies, is coming very soon.

Actually, wearable and flexible electronics have achieved considerable developments within the past decade and have now come to a point where they can be utilized in substantial applications, including energy conversion, artificial skin, health monitoring, and so on. In view of their versatility, ease of use, and the vast market of practical applications, wearable electronics have rapidly “exploded” in the United States, China, Korea, and all over the world. The research fields of wearable and flexible electronics are now covered from applied physics, chemistry, mechanical engineering, to material science, biomedicine, and clothing technology. Researchers and the public now pay increasing attention to wearable and flexible electronics, due to their tremendous achievement and vast potential.

This book will give an overview of recent developments in wearable and flexible electronics and their potentialities in smart clothing. The book will consist of an introductory overview followed by four sections: from Sensing (Part I), Energy (Part II), Interacting (Part III) to Integrating and Connecting (Part IV).

Sensing is one of the most typical characters of smart clothes. Part I looks first at the emergence of wearable organic nano‐sensors (Chapter 1), and then moves forward to the stimuli‐responsive electronic skins (Chapter 2) and flexible thermoelectrics and thermoelectric textiles for various sensing applications (Chapter 3).

Then, the next key step is to enable the wearable electronics function continuously, e.g. what is the energy supply for the smart clothes applications? Part II then moves on to energy‐related topics. The first chapter in this part focuses on self‐powered triboelectric nanogenerators for energy harvesting in smart textiles (Chapter 4). Besides the mechanical energy‐harvesting techniques, solar cells and supercapacitors are also introduced for the smart clothes applications (Chapter 5). Lithium‐ion battery is the most widely and well‐commercialized energy supply for the current smart clothes industry; the development history, materials and microstructure design, and future prospects are well included in Chapter 6.

Then, how smart clothes interact with the human body is discussed in Part III. The first chapter in this section looks at the thermal and humidity management for the next‐generation smart clothes (Chapter 7). The second chapter looks at the functionalization of fiber materials for washable smart wearable textiles (Chapter 8). The two chapters (Chapters 7 and 8) bring together how to make smart clothes behave humanization design and particle for the real commercialization. Microfluidics in wearable electronics is discussed in the next chapter (Chapter 9) – one of the most emerging techniques for wearable electronics in health‐care applications, enabling the interaction between smart clothes and body fluids.

Even though many emerging technologies have been adopted for the development of smart clothes, only very limited real products are truly ubiquitous in current markets, compared with the conventional textile industry. How can the time‐induced ultimate demise of laboratory‐based wearable techniques be avoided? It is important to look at what end‐users really need, the promising strategy of moving from the lab to fab for industrialization, and the future challenges that should be conquered.

Part IV considers the following themes: “how to integrate?”– the authors focus on flexible bio‐integrated electronics for the health‐care targeted smart clothes (Chapter 10). Then, “how to fabricate?” – flexible and printed electronics are well discussed (Chapter 11). Chapter 12 and 13 complete the picture by looking at the fabrication of the actual products that are available in the markets or the cutting‐edge materials and processing for next‐generation e‐textiles devices.

Flexible and Wearable Electronics for Smart Clothing

Preface

Part I
Sensing