Green Energy and Technology

More information about this series at http://www.springer.com/series/8059

Zhong Lin Wang • Long LinJun Chen • Simiao Niu • Yunlong Zi

Triboelectric Nanogenerators

123

Zhong Lin WangSchool of Materials Science and EngineeringGeorgia Institute of TechnologyAtlanta, GAUSA

and

National Center for Nanoscience andTechnology (NCNST)

Beijing Institute of Nanoenergy andNanosystems, Chinese Academy ofSciences

BeijingChina

Long LinSchool of Materials Science and EngineeringGeorgia Institute of TechnologyAtlanta, GAUSA

Jun ChenSchool of Materials Science and EngineeringGeorgia Institute of TechnologyAtlanta, GAUSA

Simiao NiuSchool of Materials Science and EngineeringGeorgia Institute of TechnologyAtlanta, GAUSA

Yunlong ZiSchool of Materials Science and EngineeringGeorgia Institute of TechnologyAtlanta, GAUSA

ISSN 1865-3529 ISSN 1865-3537 (electronic)Green Energy and TechnologyISBN 978-3-319-40038-9 ISBN 978-3-319-40039-6 (eBook)DOI 10.1007/978-3-319-40039-6

Library of Congress Control Number: 2016944334

© Springer International Publishing Switzerland 2016This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material isconcerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproductionon microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation,computer software, or by similar or dissimilar methodology now known or hereafter developed.The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does notimply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws andregulations and therefore free for general use.The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed tobe true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty,express or implied, with respect to the material contained herein or for any errors or omissions that may have beenmade.

Printed on acid-free paper

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Preface

The first organic materials-based triboelectric nanogenerator (TENG) was inventedby my group in 2012. Using the electrostatic charges created on the surfaces of twodissimilar materials when they are brought into physical contact, the contact-induced triboelectric charges can generate a potential drop when the two surfacesare separated by a mechanical force, which can drive electrons to flow between thetwo electrodes built on the top and bottom surfaces of the two materials. Thefundamental studies and technological applications of TENG are experiencing arapid development and its applications cover a wide range of fields. This bookprovides a comprehensive review about the four modes of the TENGs, their the-oretical modeling, and the applications of TENGs for harvesting energy fromhuman motion, walking, vibration, mechanical triggering, rotating tire, wind,flowing water, and more. A TENG can also be used as a self-powered sensor foractively detecting the static and dynamic processes arising from mechanical agi-tation using the voltage and current output signals of the TENG, respectively, withpotential applications as mechanical sensors and for touch pad and smart skintechnologies. The potential of TENG for harvesting ocean wave energy is alsodiscussed as a potential approach for the blue energy. The objective of writing thisbook is to systematically introduce the TENG, so that it can serve as a text book anda reference book for promoting the fundamental development and technologicalapplications of TENG.

This book was written mainly based on the numerous papers we have authoredsince 2012, and many figures were adopted from our published work in the publicdomain. We like to thank my current and former group members and collaboratorswho have made outstanding contributions to the development of TENG (not inparticular order): Fengru Fan, Guang Zhu, Sihong Wang, Ya Yang, Zong-HongLin, Long Lin, Jun Chen, Yusheng Zhou, Simiao Niu, Jin Yang, Weiqing Yang,Xiaonan Wen, Xia Cao, Jun Zhou, Sang-Woo Kim, Yong Qin, Xing Fan, GangCheng, Li Zheng, Yunlong Zi, Chi Zhang, Changbao Han, Wei Tang, Aifang Yu,Hulin Zhang, Yannan Xie, Peng Bai, Qingshen Jing, Shengming Li, Yuanjie Su,Zhong-Qun Tian, Min-Hsin Yeh, Fang Yi, Zhaoling Li, Hengyu Guo, Zhen Wen,

v

Caofeng Pan, Tao Jiang, Sangmin Lee, Ying Liu, Zhen Wen, Changsheng Wu,Jie Wang, Chenguo Hu, Yi Xi, Te-Chien Hou, Xiangyu Chen, Jr-Hau He,Jong-Min Bai, Yong Ding, Po-Kang Yang, Ken Pradel, Xiuhan Li, XiaofengWang, Huifang Li, Yue Zhang, Ying Wu, Tao Zhou, Mengxiao Chen, LiminZhang, and Weiming Du. We also like to thanks to our collaborators: Profs. YueZhang, Zhong-Qun Tian, Christian Falconi, Sang-Woo Kim, Jeong-Min Baik, QingZhang, Haixia Zhang, and Magnus Willander.

Lastly and most importantly, I thank my family members for their years ofsupport and understanding. It was not possible to carry out such a research withouttheir support.

Zhong Lin WangSchool of Materials Science and Engineering

Georgia Institute of Technology, USABeijing Institute of Nanoenergy and Nanosystems

National Center for Nanoscienceand Technology (NCNST)

Chinese Academy of Sciences, Chinae-mail: zlwang@gatech.edu

Personal website:http://www.nanoscience.gatech.edu/

SCI publication record:http://www.researcherid.com/rid/E-2176-2011

vi Preface

Contents

1 Triboelectrification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1 Nano Energy and Mega Energy . . . . . . . . . . . . . . . . . . . . . . . 21.2 Triboelectric Effect. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31.3 Quantification of Triboelectrification. . . . . . . . . . . . . . . . . . . . 41.4 Materials for Triboelectrification . . . . . . . . . . . . . . . . . . . . . . 91.5 Van de Graaff Generator . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111.6 Triboelectric Nanogenerators . . . . . . . . . . . . . . . . . . . . . . . . . 13

1.6.1 Vertical Contact-Separation Mode . . . . . . . . . . . . . . . 131.6.2 Lateral Sliding Mode . . . . . . . . . . . . . . . . . . . . . . . . 131.6.3 Single-Electrode Mode . . . . . . . . . . . . . . . . . . . . . . . 141.6.4 Freestanding Triboelectric-Layer Mode . . . . . . . . . . . . 14

1.7 Perspectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Part I Fundamental Operation Modes

2 Triboelectric Nanogenerator: Vertical Contact-SeparationMode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232.1 Basic Principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232.2 Fundamental Theory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252.3 Basic Device Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

2.3.1 Spacer Structure. . . . . . . . . . . . . . . . . . . . . . . . . . . . 292.3.2 Arch-Shaped Structure . . . . . . . . . . . . . . . . . . . . . . . 322.3.3 Spring-Assisted Separation Structure. . . . . . . . . . . . . . 362.3.4 Multiple Layer Integration. . . . . . . . . . . . . . . . . . . . . 402.3.5 Microcavity-Nanoparticle Assembled Structure . . . . . . 41

2.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

vii

3 Triboelectric Nanogenerator: Lateral Sliding Mode . . . . . . . . . . . . 493.1 Basic Principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 493.2 Fundamental Theory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

3.2.1 Sliding-Mode TENG with Only One Unit . . . . . . . . . . 503.2.2 Grating TENGs . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

3.3 Basic Device Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . 643.3.1 Plain-Sliding Structure . . . . . . . . . . . . . . . . . . . . . . . 643.3.2 Linear-Grating Structure . . . . . . . . . . . . . . . . . . . . . . 673.3.3 Rotation-Disk Structure. . . . . . . . . . . . . . . . . . . . . . . 743.3.4 Rotation-Cylinder Structure . . . . . . . . . . . . . . . . . . . . 793.3.5 Case-Encapsulated Structure . . . . . . . . . . . . . . . . . . . 823.3.6 Liquid-Metal Structure . . . . . . . . . . . . . . . . . . . . . . . 84

3.4 Energy Conversion Efficiency . . . . . . . . . . . . . . . . . . . . . . . . 873.4.1 Solid–Solid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 873.4.2 Solid–Liquid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

3.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

4 Triboelectric Nanogenerator: Single-Electrode Mode . . . . . . . . . . . 914.1 Basic Principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 914.2 Fundamental Theory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

4.2.1 Basic Working Principle and ElectrostaticShield Effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

4.2.2 Effect of Electrode Gap Distance . . . . . . . . . . . . . . . . 964.2.3 Effect of Area Size (Length) . . . . . . . . . . . . . . . . . . . 974.2.4 Effect of Spacing Between Units for Scale up . . . . . . . 99

4.3 Basic Device Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1004.3.1 Contact-Separation Structure . . . . . . . . . . . . . . . . . . . 1004.3.2 Lateral Sliding Structure . . . . . . . . . . . . . . . . . . . . . . 104

4.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

5 Triboelectric Nanogenerator: FreestandingTriboelectric-Layer Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1095.1 Sliding Freestanding Triboelectric-Layer TENG . . . . . . . . . . . . 109

5.1.1 Basic Principle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1095.1.2 Fundamental Theory. . . . . . . . . . . . . . . . . . . . . . . . . 115

5.2 Contact Freestanding Triboelectric-Layer TENG . . . . . . . . . . . 1225.2.1 Basic Principle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1235.2.2 Fundamental Theory. . . . . . . . . . . . . . . . . . . . . . . . . 127

5.3 Advanced Device Structures . . . . . . . . . . . . . . . . . . . . . . . . . 1325.3.1 Linear-Grating Structure . . . . . . . . . . . . . . . . . . . . . . 1325.3.2 Rotation-Disk Structure I . . . . . . . . . . . . . . . . . . . . . 1385.3.3 Rotation-Disk Structure II . . . . . . . . . . . . . . . . . . . . . 141

viii Contents

5.4 Rolling Friction Operation Mode . . . . . . . . . . . . . . . . . . . . . . 1455.5 Energy Conversion Efficiency . . . . . . . . . . . . . . . . . . . . . . . . 1505.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153

6 Theoretical Modeling of Triboelectric Nanogenerators . . . . . . . . . . 1556.1 Inherent Capacitive Behavior and Governing

Equations: V-Q-x Relationship . . . . . . . . . . . . . . . . . . . . . . . . 1566.2 First-Order Lumped-Parameter Equivalent Circuit Model . . . . . 1576.3 Charge Reference State. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159

6.3.1 Influence of Charge Reference Stateon the Intrinsic Characteristics of TENGs . . . . . . . . . . 160

6.3.2 Influence of Charge Reference Stateon the Output Characteristics of TENGs . . . . . . . . . . . 161

6.3.3 Typical Charge Reference States . . . . . . . . . . . . . . . . 1626.4 Resistive Load Characteristics . . . . . . . . . . . . . . . . . . . . . . . . 163

6.4.1 Resistive Load Characteristicsand “Three-Working-Region” Behavior. . . . . . . . . . . . 163

6.4.2 Optimum Resistance. . . . . . . . . . . . . . . . . . . . . . . . . 1686.5 Capacitive Load and Charging Characteristics . . . . . . . . . . . . . 172

6.5.1 TENG Charging Characteristics UnderUnidirectional Mechanical Motion . . . . . . . . . . . . . . . 172

6.5.2 TENG Charging Performance Under PeriodicMechanical Motion . . . . . . . . . . . . . . . . . . . . . . . . . 174

6.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183

7 Figure-of-Merits for Quantifying TriboelectricNanogenerators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1857.1 Operation Cycles of Triboelectric Nanogenerators . . . . . . . . . . 186

7.1.1 V-Q Plot and Its Characteristics . . . . . . . . . . . . . . . . . 1867.1.2 Cycle of Energy Output . . . . . . . . . . . . . . . . . . . . . . 1877.1.3 Cycle of Maximized Energy Output . . . . . . . . . . . . . . 1887.1.4 Experimental Realization of the Operation Cycles . . . . 191

7.2 Figure-of-Merits of Triboelectric Nanogenerators . . . . . . . . . . . 1937.3 Structural Figure-of-Merit: Calculation and Simulation . . . . . . . 1947.4 Measurement of Material Figure-of-Merit . . . . . . . . . . . . . . . . 199

7.4.1 Measurement of Triboelectric SurfaceCharge Density . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199

7.4.2 Quantified Triboelectric Series Basedon Normalized Charge Density and DimensionlessMaterial Figure-of-Merit . . . . . . . . . . . . . . . . . . . . . . 201

7.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203

Contents ix

Part II Applications as a Sustainable Power Source

8 Harvesting Body Motion Energy. . . . . . . . . . . . . . . . . . . . . . . . . . 2078.1 Integrated Structure Triboelectric Nanogenerators . . . . . . . . . . . 2078.2 Fabric Based Triboelectric Nanogenerators . . . . . . . . . . . . . . . 212

8.2.1 Fiber Based Triboelectric Nanogenerators . . . . . . . . . . 2128.2.2 Textile Based Triboelectric Nanogenerators . . . . . . . . . 2148.2.3 Fiber Based Hybrid Nanogenerators . . . . . . . . . . . . . . 219

8.3 Paper Based Triboelectric Nanogenerators . . . . . . . . . . . . . . . . 2238.3.1 A Single Paper Based Triboelectric

Nanogenerators . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2238.3.2 A Paper Origami Based Triboelectric

Nanogenerators . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2258.4 Human Skin Based Single-Electrode Mode Triboelectric

Nanogenerators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2298.5 Sliding Freestanding-Triboelectric-Layer Mode

Triboelectric Nanogenerators . . . . . . . . . . . . . . . . . . . . . . . . . 2328.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235

9 Harvesting Vibration Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2379.1 Vibration Energy Harvesting with Basic Operation Modes . . . . 237

9.1.1 Vertical Contact-Separation Mode . . . . . . . . . . . . . . . 2379.1.2 Contact Single-Electrode Mode . . . . . . . . . . . . . . . . . 2409.1.3 Contact Freestanding-Triboelectric-Layer Mode . . . . . . 241

9.2 Vibration Energy Harvesting with Advanced StructuralDesigns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2429.2.1 Multi-directional Vibration Energy Harvesting . . . . . . . 2429.2.2 Multi-layer Structual Design . . . . . . . . . . . . . . . . . . . 2459.2.3 Liquid-Metal Based Structural Design. . . . . . . . . . . . . 247

9.3 Sound Wave Energy Harvesting. . . . . . . . . . . . . . . . . . . . . . . 2499.3.1 Organic Film Based TENG . . . . . . . . . . . . . . . . . . . . 2499.3.2 Rollable Paper Based TENG . . . . . . . . . . . . . . . . . . . 252

9.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256

10 Harvesting Wind Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25910.1 Wind Energy Harvesting Based on Rotational Structure . . . . . . 259

10.1.1 Rotational Sliding Freestanding-Triboelectric-LayerMode Wind-Driven Triboelectric Nanogenerators . . . . . 260

10.1.2 Other Rotational Structures for Wind EnergyHarvesting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265

10.2 Wind Energy Harvesting Based on Flutter-DrivenTriboelectrification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26910.2.1 The First Flutter-Driven TENG for Wind Energy

Harvesting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269

x Contents

10.2.2 Elasto-Aerodynamics-Driven TriboelectricNanogenerator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 274

10.3 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281

11 Harvesting Large-Scale Blue Energy. . . . . . . . . . . . . . . . . . . . . . . 28311.1 TENG for Water Wave Energy Harvesting . . . . . . . . . . . . . . . 283

11.1.1 Liquid-Solid Electrification-Based TENG . . . . . . . . . . 28311.1.2 TENG Based Hydrokinetics Energy Harvesting . . . . . . 29111.1.3 Dual Mode TENG for Electrostatic and Mechanical

Energies Harvesting . . . . . . . . . . . . . . . . . . . . . . . . . 29411.1.4 Fully Enclosed TENG for Water Wave Energy

Harvesting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29611.2 Network of TENGs for Blue Energy Harvesting . . . . . . . . . . . 30011.3 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 304References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305

12 Hybrid Cell Composed of Triboelectric Nanogenerator . . . . . . . . . 30712.1 AC–AC Hybrid Cell. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 308

12.1.1 Hybrid Electromagnetic and TriboelectricNanogenerator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 308

12.1.2 Hybrid Triboelectric-Piezoelectric/PyroelectricNanogenerator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 319

12.2 AC–DC Hybrid Cell. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33312.2.1 Hybrid Solar Cell and Triboelectric Nanogenerator. . . . 33312.2.2 Hybrid Thermoelectric Cell and Triboelectric

Nanogenerator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34112.2.3 Hybrid Electrochemical Cell and Triboelectric

Nanogenerator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34412.3 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 348References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 348

13 Applications in Self-powered Systems and Processes . . . . . . . . . . . 35113.1 Integration of TENG with Energy Storage Units

for Sustainably Driving Portable Electronics . . . . . . . . . . . . . . 35113.1.1 Direct Integration and Transformer Integration . . . . . . . 35113.1.2 Through Power Management Circuit Board . . . . . . . . . 359

13.2 TENG for Self-powered Electrochemical Applications . . . . . . . 36613.2.1 Self-powered Electrochemical Degradation . . . . . . . . . 36713.2.2 Self-powered Water Splitting . . . . . . . . . . . . . . . . . . . 37013.2.3 Self-powered Anticorrosion . . . . . . . . . . . . . . . . . . . . 37313.2.4 Self-powered Air Filtering. . . . . . . . . . . . . . . . . . . . . 37613.2.5 Self-powered Electrochemical Recovery . . . . . . . . . . . 38113.2.6 Self-powered Electrochromic Device for Smart

Window System. . . . . . . . . . . . . . . . . . . . . . . . . . . . 384

Contents xi

13.3 TENG for Self-powered Biomedical Stimulation . . . . . . . . . . . 38713.3.1 In-Vivo Implanted TENG for Self-powered

Pacemaker. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38713.3.2 Implantable Self-powered Laser Cure System

for Proliferation and Differentiation of Cells . . . . . . . . 39013.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 395

Part III Applications as Self-Powered Active Sensors

14 Self-powered Sensing for Human-Machine Interface . . . . . . . . . . . 40114.1 Self-powered Pressure/Touch Sensor . . . . . . . . . . . . . . . . . . . 401

14.1.1 Contact-Separation Mode Self-powered PressureSensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 402

14.1.2 Single-Electrode Mode Self-powered Touch Sensor . . . 40914.1.3 Dual-Mode Ultrasensitive Self-powered Pressure

Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41214.2 Self-powered Tactile Imaging . . . . . . . . . . . . . . . . . . . . . . . . 41714.3 Self-powered Smart Keyboard . . . . . . . . . . . . . . . . . . . . . . . . 42214.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 427References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 428

15 Self-powered Sensing for Vibration and BiomedicalMonitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43115.1 Self-powered Vibration Sensor. . . . . . . . . . . . . . . . . . . . . . . . 431

15.1.1 Position Tracking of the Vibration Source . . . . . . . . . . 43115.1.2 Vibration Amplitude Measurement . . . . . . . . . . . . . . . 434

15.2 Self-powered Acoustic Sensor for Voice Recording . . . . . . . . . 43615.2.1 Helmholtz-Cavity-Based Acoustic Sensor . . . . . . . . . . 43615.2.2 Ultrathin Paper-Based Acoustic Sensor . . . . . . . . . . . . 438

15.3 Self-powered Biomedical Monitoring . . . . . . . . . . . . . . . . . . . 44015.3.1 Eardrum Inspired Bionic Membrane Sensor . . . . . . . . . 44015.3.2 Membrane-Based Triboelectric Sensor . . . . . . . . . . . . 450

15.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 453References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 453

16 Self-powered Sensing for Tracking Moving Objects . . . . . . . . . . . . 45516.1 TENGs as Self-powered Linear Displacement Sensors . . . . . . . 45516.2 TENGs as Self-powered Active Rotation Sensors. . . . . . . . . . . 45816.3 TENGs for Self-powered Tracking of a Moving Object . . . . . . 46016.4 TENG as Self-powered Acceleration Sensors. . . . . . . . . . . . . . 46416.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 466References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 467

xii Contents

17 Self-powered Sensing for Chemical and EnvironmentalDetection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46917.1 Self-powered Chemical Sensors . . . . . . . . . . . . . . . . . . . . . . . 46917.2 Self-powered UV Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . 47517.3 Self-powered Environmental Monitoring . . . . . . . . . . . . . . . . . 47917.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 487References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 488

Journal Articles by Wang’s Group on TriboelectricNanogenerators (2012–2016) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 491

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 511

Contents xiii

Abbreviations

High-Frequency Terminologies

AC Alternating currentDC Direct currentFEP Fluorinated ethylene propyleneITO Indium tin oxideJSC Short-circuit current densityKapton PolyimideLED Light-emitting diodeLIB Lithium-ion batteryNG NanogeneratorOC Open-circuitPDMS PolydimethylsiloxanePE PolyethylenePET Polyethylene terephthalatePMMA Poly(methyl methacrylate)PNWs Polymer nanowiresPTFE PolytetrafluoroethylenePVDF Polyvinylidene fluorideSC Short-circuitSEM Scanning electron microscopyTENG Triboelectric nanogenerator

Chapter 1

AFM Atomic force microscopyCMOS Complementary metal–oxide–semiconductor field-effect transistorMOSFET Metal–oxide–semiconductor field-effect transistorSKPM Scanning Kevin probe microscopy

xv

Chapter 2

MACRS Minimum achievable charge reference stateNPs NanoparticlesPECVD Plasma-enhanced chemical vapor deposition

Chapter 3

MACRS Minimum achievable charge reference state

Chapter 4

F-TENG Freestanding-triboelectric-layer-based triboelectric nanogeneratorMACRS Minimum achievable charge reference stateSETENG Single-electrode triboelectric nanogenerator

Chapter 5

CF-TENG Contact-mode freestanding-triboelectric-layer-based triboelectricnanogenerator

FRD-TENG Free-rotating disk triboelectric nanogeneratorF-TENG Freestanding-triboelectric-layer-based triboelectric nanogeneratorGF-TENG Grating-structured freestanding-triboelectric-layer-based triboelec-

tric nanogeneratorICP Inductive coupling plasmaLE Left-hand electrodeMACRS Minimum achievable charge reference stateRE Right-hand electrodeRIE Reactive ion etchingR-TENG Rolling triboelectric nanogeneratorSF-TENG Sliding-mode freestanding-triboelectric-layer-based triboelectric

nanogenerator

Chapter 6

FEM Finite element methodFTENG Freestanding-triboelectric-layer-based triboelectric nanogeneratorMACRS Minimum achievable charge reference stateSETENG Single-electrode triboelectric nanogeneratorSPICE Simulation program with integrated circuit emphasis

xvi Abbreviations

Chapter 7

1S 1-side side effects2S 2-side side effectsAl AluminumCEO Cycles for energy outputCFT Contact freestanding triboelectric layerCMEO Cycles for maximized energy outputCS Contact-separationCu CopperFEM Finite element methodFOM Figure-of-meritsFOMDM Dimensionless material figure-of-meritsFOMM Material figure-of-meritsFOMP Performance figure-of-meritsFOMS Structural figure-of-meritsFOMS,max Maximum structural figure-of-meritsFT Freestanding triboelectric layerLM-TENG Liquid-metal-based TENGLS Lateral slidingMACRS Minimum achievable charge reference statePENG Piezoelectric nanogeneratorRH Relative humiditySE Single-electrodeSEC Single-electrode contactSFT Sliding freestanding triboelectric layerwt WeightZT Figure-of-merits of thermoelectric materials

Chapter 8

3D Three dimensionalAg SilverAl AluminumCCT Coated cotton threadCNT Carbon nanotubeCS Contact separationCu CopperEDX Energy dispersive X-ray spectrumEPD Electric potential differenceFBG Fiber-based triboelectric nanogeneratorFBHNG Fiber-based hybrid nanogeneratorGD Galvanostatically

Abbreviations xvii

GF-TENG Grating-structured triboelectric nanogeneratorLCD Liquid crystal displayNi NickelNR NanorodsPCCT Carbon nanotube coated cotton threadPENG Piezoelectric nanogeneratorpNG Paper-based nanogeneratorSFT Sliding freestanding triboelectric layerTi TitaniumZnO Zinc oxide

Chapter 9

3D Three dimensionalICP Inductively coupled plasmaOR Open ratio

Chapter 10

Al AluminumCu CopperICP Inductive coupling plasmaR-TENG Rotary-structured TENGSFT Sliding freestanding triboelectric layer

Chapter 11

AAO Anodic aluminum oxideEDLC Electric double-layer capacitorEMG Electromagnetic generatorLCD Liquid crystal displayTENG-NW Triboelectric nanogenerator-network

Chapter 12

AAO Anodic aluminum oxideAg SilverAl AluminumAl2O3 Aluminum oxideAu GoldBaTiO3 Barium titanate

xviii Abbreviations

Bi2Te3 Bismuth tellurideCu CopperEC Electrochemical cellEMG Electromagnetic generatorH2O WaterKapton PolyimideLCD Liquid crystal displayMNDS Micro/nano dual-scaleMO Methyl orangeNaCl Sodium chloridePA PolyamidePENG Piezoelectric nanogeneratorPFA PerfluoroalkyoxyPMN-PT Lead magnesium niobate—lead titanatePPENG Pyroelectric-piezoelectric nanogeneratorPVDF Polyvinylidene fluoridePZT Lead zirconate titanateSi SiliconSiN Silicon nitrideXRD X-ray diffractionZnO Zinc oxide

Chapter 13

AA Ascorbic acidADC Analog-to-digital converterALP Alkaline phosphataseBaCl2 Barium chlorideCO2 Carbon dioxideCP Cathodic protectionCr ChromiumCu CopperCuSO4 Copper(II) sulfateDMEM Dulbecco’s modified Eagle’s mediumDNA Deoxyribonucleic acidECD Electrochromic deviceECG ElectrocardiographEDS Energy dispersive X-ray spectrumELISA Enzyme-linked immunosorbent assayEMG Electromagnetic generatorGC Gas chromatographyH2O WaterHCl Hydrogen chlorideIC Integrated circuit

Abbreviations xix

ICCP Impressed current cathodic protectionKOH Potassium hydroxideLCD Liquid crystal displayMO Methyl orangeMTT 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromideNaCl Sodium chlorideNaHSO3 Sodium bisulfiteNi NickelNO2 Nitrogen dioxideNOX Nitrogen oxidePB Prussian bluePCB Print circuit boardPM Particulate MatterPt PlatinumRF-TENG Rotational freestanding TENGRKE Remote keyless entryrpm Revolutions per minuteR-TENG Rotational TENGSACP Sacrificial anode cathodic protectionSCPU Self-charging power unitSO2 Sulfur dioxideSOC State of chargeSPLC Self-powered low-level laser cureUV UltravioletXRD X-ray diffractionZnHCF Zinc hexacyanoferrate

Chapter 14

AgNWs Silver nanowiresCNT Carbon nanotubeDFT Discreet Fourier TransformationFAR False Acceptance RateFRR False Rejection RateIKB Intelligent keyboardKFE Key functional elementresis-sensor Resistive pressure sensorROC Receiver Operating CharacteristicSNR Signal-to-noise ratioTEAS Triboelectric active sensor

xx Abbreviations

Chapter 15

3D Three dimensionalAIx Augmentation indexBMS Bionic membrane sensorEM Euclidean metricFAR False acceptance rateFDPW First-derivatives-of-the-pulse-wavesFRR False rejection ratePWV Pulse wave velocityRI Reflection indexSTFT Short-time Fourier transform

Chapter 16

FEP Fluorinated ethylene propyleneFRD Free-rotating diskICP Inductively coupled plasmaLED Light-emitting diodeMCU Microcontroller unitPFA Perfluoroalkoxy alkaneRMS Root mean squareTES Triboelectric sensor

Chapter 17

3-MPA 3-mercaptopropionic acidAAO Anodic aluminum oxideDNA Deoxyribonucleic acidICP-MS Inductively coupled plasma mass spectrometryNPs NanoparticlesTNS TiO2 nanosheetTNW TiO2 nanowireUV UltravioletWD-TENG Water-driven triboelectric nanogeneratorXRD X-ray diffractionβ-CD β-cyclodextrin

Abbreviations xxi

Symbols

Chapter 1

z Critical tunneling distanceσ The dielectric surface charge densityσ1 The induced charge density on the top metalσ2 The induced charge density on the bottom metalσ1/ε0 Built-in electric fieldΔEvcc The change of vacuum energy level between the metal and

the dielectric surfacee The elementary chargeNs(E) The assumed surface density of statesΔEs The range of filled surface states

Chapter 2

VOC Open-circuit voltageISC Short-circuit currentd1 Thickness of dielectric 1d2 Thickness of dielectric 2ε0 Permittivity of vacuumεr1 Relative dielectric constant of dielectric 1εr2 Relative dielectric constant of dielectric 2x The distance between two triboelectric surfacesσ Surface triboelectric charge densityV The potential difference between two electrodesQ The amount of charge transfer between two electrodesηCT Short-circuit charge transfer efficiencyS The area size of a triboelectric nanogeneratorE1 The electric field strength inside dielectric 1

xxiii

E2 The electric field strength inside dielectric 2Eair The electric field strength inside the air gap between two

triboelectric surfacesd0 Effective thickness constantQSC The amount of charge transfer in short-circuit conditionC CapacitanceC1 Capacitance between Node 1 and Node 2C2 Capacitance between Node 2 and Node 3v Average velocityJSC Short-circuit current density

Chapter 3

VOC Open-circuit voltageISC Short-circuit currentd1 Thickness of dielectric 1d2 Thickness of dielectric 2ε0 Permittivity of vacuumεr1 Relative dielectric constant of dielectric 1εr2 Relative dielectric constant of dielectric 2x The distance between two triboelectric surfacesσ Surface triboelectric charge densityV The potential difference between two electrodesQ The amount of charge transfer between two electrodesηCT Short-circuit charge transfer efficiencyηCT-rectifieed Rectified short-circuit charge transfer efficiencyS The area size of a triboelectric nanogeneratord0 Effective thickness constantQSC The amount of charge transfer in short-circuit conditionw Width of the triboelectric layerv Average velocityn Number of grating unitsL Total length of the top platel Length of the one grating unitJSC Short-circuit current density

Chapter 4

VOC Open-circuit voltageISC Short-circuit currentJSC Short-circuit current densityε0 Permittivity of vacuumx The distance between two triboelectric surfaces

xxiv Symbols

σ Surface triboelectric charge densityV The potential difference between two electrodesQ The amount of charge transfer between two electrodesS The area size of a triboelectric nanogeneratorQSC The amount of charge transfer under short-circuit conditionηCT Short-circuit charge transfer efficiencyC CapacitanceC1 Capacitance that directly connects Node 1 and Node 2C2 Capacitance that directly connects Node 1 and Node 3C3 Capacitance that directly connects Node 2 and Node 3Ca The total capacitance between Node 1 and Node 2Cb The total capacitance between Node 1 and Node 3C0 The total capacitance between Node 2 and Node 3v Average velocityS Area of the triboelectric surfacel, w Length and width of the triboelectric layerdm Effective thickness of the metal electrodesg Gap distance between the electrodes

Chapter 5

VOC Open-circuit voltageISC Short-circuit currentJSC Short-circuit current densityl, L Length of the triboelectric layerε0 Permittivity of vacuumx The distance of the freestanding layer with reference to its

initial positionσ Surface triboelectric charge densityV The potential difference between two electrodesQ The amount of charge transfer between two electrodesS The area size of a triboelectric nanogeneratorQSC The amount of charge transfer under short-circuit conditionηCT Short-circuit charge transfer efficiencyC CapacitanceCi Capacitance that directly connects two nodesv Average velocityS Area of the triboelectric surfacew Width of the triboelectric layerd0 Effective thickness of the dielectric layerdi Thickness of the ith dielectric layerd, g Gap distance between the electrodesh, H Freestanding height, distance between the triboelectric layersT Period

Symbols xxv

QSC,max Maximum short-circuit charge transfers between twoelectrodes

R External load resistanceεri Dielectric constant of the ith dielectric layerΔσSC The amount of charge transfer density under short-circuit

conditionk The spring constant of a single springη Energy conversion efficiencyEoutput Electrical energy outputEinput Mechanical energy inputF Resistive force measured with a certain load resistanceF0 The resistive force measured with open-circuit condition

Chapter 6

σ Triboelectric surface charge densityV Voltage between two electrodesQ Charge transfers between two electrodesx Relative displacement between the triboelectric layersxmax Maximum relative displacement between the triboelectric

layersVOC(x) Open-circuit voltage between two electrodesQSC(x) Short-circuit charge transfers between two electrodesVOC,max Maximum open-circuit voltage between two electrodesQSC,max Maximum short-circuit charge transfers between two

electrodesT PeriodQ0 The initial charge on the electrode when the reference state is

pickedQ1 The charge amount on metal 1 under short-circuit conditionQ2 The charge amount on metal 2 under short-circuit conditionI Output currentImax The peak value of the output currentQC Initial charge on the load capacitanceR External load resistanceRopt Optimum load resistancePmax Peak instantaneous powerC(x), CT (x) Capacitance between two TENG electrodesCL Load capacitancev Average velocityS Area of the triboelectric surfaceg Gap distance between the electrodesε0 The permittivity of vacuuml, w Length and width of the triboelectric layer

xxvi Symbols

d0 Effective thickness of the dielectric layerdi Thickness of the ith dielectric layerdk Thickness of the Kapton layerεri Dielectric constant of the ith dielectric layerEC Energy stored in the load capacitorQM

k The total charges on the Node M at the beginning of the kthcycle

CL,opt Optimum load capacitance

Chapter 7

σ Triboelectric surface charge densityV Voltage between two electrodesQ Charge transfers between two electrodesx Relative displacement between the triboelectric layersxmax Maximum relative displacement between the triboelectric

layersVOC(x) Open-circuit voltage between two electrodesQSC(x) Short-circuit charge transfers between two electrodesV'(x) Absolute voltage at Q = QSC,max at displacement xVOC,max Maximum open-circuit voltage between two electrodesQSC,max Maximum short-circuit charge transfers between two

electrodesV'max Maximum achievable absolute voltage at Q = QSC,max

P Average output powerT PeriodE Output energy per cycleI Output currentQC Total cycling chargeR External load resistanceC(x), CTotal(x) Capacitance between two electrodesEm The largest possible output energy per cycleη Energy conversion efficiencyv Average velocityF Average dissipative forceA Area of the triboelectric surfaceε0 The permittivity of vacuuml, w Length and width of the triboelectric layerd0 Effective thickness of the dielectric layerdi Thickness of the ith dielectric layerεi Dielectric constant of the ith dielectric layerd, g Gap distanceσN Normalized triboelectric surface charge density

Symbols xxvii

Chapter 8

VOC Open-circuit voltageISC Short-circuit currentJSC Short-circuit current densityNTotal Total number of unit cellsn The number of unit cells along the edge lengthθ Separation angleθmax Maximum separation angleVA, VB Electric potential of A and B electrodesσ Triboelectric surface charge densityΔσ, σ2 Induced surface charge densityΔσSC Short-circuit surface charge density transferΔσSC-Rec Accumulated short-circuit surface charge density transferε0 The permittivity of vacuumεr Dielectric constant of the dielectric layer (PTFE)l Edge length of one unit celld1 Thickness of the first dielectric layerd Distance between electrodesR External load resistanceΔQ Charge transfers between two electrodes of TENG

Chapter 9

VOC Open-circuit voltageISC Short-circuit currentf0 Natural frequencym0 Massk Stiffness coefficientR External resistancePd Instantaneous peak power densityn The number of pinned fingersd0 The thickness of PTFEεr The relative permittivity of PTFEs The effective contact areav The relative velocityS Cross-sectional areaL' Effective length of the neckV Cavity volumec Speed of sound

xxviii Symbols

Chapter 10

Δx0 Original tensile deformation (of the spring)Δxmax Maximum vertical separation distancek Spring constantF(X0), F(Y0) The force on the tilted rectangle blades along the tangential

or axial directionn, a, b The number, length, and width of the rectangle fan bladesρair The density of the surrounding airθ The tilted angle of each bladeΔx The extra tensile deformation caused by the vertical

separationv1, v2, v3 The boundary wind speedsvwind The wind speedΔQSC, ΔQ Short-circuit (total) charge transfersVOC Open-circuit voltageC Capacitance between two electrodes of TENGISC Short-circuit current

Chapter 11

VOC Open-circuit voltageISC Short-circuit currentJsc Short-circuit current densityPTFE PolytetrafluoroethyleneQSC Short-circuit transferred chargesΔt Peak widthE0 Average powerEc Generated average power in one collisionEcv Generated power per second per unit volumeβ Volume ratiof Collision frequency

Chapter 12

E The induced electrodynamic potentialEm The maximum induced electrodynamic potentialB The magnetic flux densityl The length of the conductor stick; the width of the friction

surface perpendicular to the sliding directionv The velocity of the conductor stick cutting the magnetic

induction lines; the sliding velocity of the top metalσ The triboelectric charge density of the friction surface

Symbols xxix

n The turns of coils; the segments number of the diskS The area of a single turn of the coil; the area of the friction

diskω The rotational angular velocity of the coil/top metalΔΦ/Δt The change rate of magnetic flux in each coilΔQ/Δt The transfer rate of electric charge in each segmentEelectricity Generated electrical energyI The output current of the nanogeneratorR The loading resistanceVOC, VOC(TENG) Open-circuit voltage of TENGε0 The permittivity of vacuumdS, d Distance between electrodes; thickness of PVDF or PDMSVOC(Pyro) Pyroelectric open-circuit voltagep Pyroelectric coefficientD The thickness of the pyroelectric deviceΔT The change in temperatureεr Dielectric constant of the dielectric layer (PTFE)A' The total area of the PVDF in PPENGC The capacitance of the PVDF in PPENGA The frictional areaΔQ Transferred chargeΔV The voltage variationΔσ, σ1 Induced surface charge density variation; induced surface

charge densityΔP The polarization density variationdT/dt Changing rate of the temperatureσ, σ0 Triboelectric surface charge densityJ Current densityJSC Short-circuit current densityϕf The volume ratio of BaTiO3 nanoparticles in the composite

material

Chapter 13

VOC Open-circuit voltageISC, ITENG Short-circuit currentQSC Short-circuit transferred chargesηboard Board efficiencyηtotal Total efficiencyVtemp The voltage across the temporary capacitorVstore The voltage across the final storage capacitorVbattery The voltage across the battery

xxx Symbols

Ctemp The temporary capacitorCstore The storage capacitorC Weight losst Periodic test timeΔT TransmittanceC1,2 CapacitorsCT Total capacitorR1,2 ResistorsD1,2 DiodesTh,l Higher/lower timeq Pulse duty cycleIP Current output of a single stimulation pulsetP Pulse width

Chapter 14

VOC Open-circuit voltageΔσ Transferred charge densityJSC Short-circuit current densityd Vertical gap distance between the two triboelectric layersd0 Maximum gap distance between the two triboelectric layers

without pressureε0 Permittivity in vacuumσ Triboelectric charge densityQ The amount of induced charges on one electrode with

pressureQ0 The amount of induced charges on one electrode without

pressureS Effective area of electrodesdPDMS Thickness of the PDMS membraneεr,PDMS Relative dielectric constant of the PDMS membranep Applied pressurek Elastic property of the materials in the TEASp0 Low-end detection limitVpi The maximum peak value of the output voltage from

channel iVth The threshold voltagen The total number of channelsi Integral from 1 to ns4,k and dj,k Wavelet coefficientsj = 1, 2, 3, 4… k The number of translations of the wavelet for any given

scaleφ4,k(t) The father waveletsѱj,k(t) The mother wavelets

Symbols xxxi

f (t) Either voltage or current signal of the typing patternsS4 SmoothD4, D3, D2, and D1 A set of voltage or current components that provide

representations of the original signals at different resolutionlevels

S Sensitivity of the triboelectric active sensorI The current when applied pressure on the sensorIoff The current of sensor with no pressureV The voltage when applied pressure on the sensorVoff The voltage of sensor with no pressure

Chapter 15

VOC Open-circuit voltageISC Short-circuit currentPS Systolic peakPi Point of inflectionPD Dicrotic waveΔt Time delay

Chapter 16

VOC Open-circuit voltageISC Short-circuit current

Chapter 17

((I0 – I)/I0 Short-circuit current ratioððVoc � Vo

ocÞ=VoocÞ Open-circuit voltage ratio

ððJsc � JoscÞ=JoscÞ Short-circuit current density ratioVOC Open-circuit voltage

xxxii Symbols

Abstract

Triboelectric nanogenerator (TENG) was first invented by Zhong Lin Wang’sgroup in 2012 for converting small-scale mechanical energy into electricity by aconjunction of triboelectrification and electrostatic induction. TENG is a paradigmshift technology and has unpresented performances, with output area power densityup to 500 W/m2 and an instantaneous conversion efficiency of *70 %. TENG usesneither magnets nor coils; it is light in mass, low in density, low in cost, and can befabricated using most of the organic materials. Most importantly, in contrast toclassical electromagnetic generator, TENG works the best at low frequency (<5–10Hz); thus, it is the unique choice for harvesting low-frequency energy from bodymotion and ocean wave (the blue energy). TENG can also be used as a self-poweredsensor for actively detecting the static and dynamic processes arising frommechanical agitation using the voltage and current output signals, respectively, withapplications as mechanical sensors, physiological detection, motion sensing, touchpad, and electronic skin technologies. This book provides a comprehensive reviewabout the four modes of the TENGs, their theoretical modeling, and the applicationsof TENGs for harvesting energy from human motion, walking, vibration,mechanical triggering, rotating tire, wind, flowing water and more, for applicationsin portable/wearable electronics, biomedical devices, sensor networks, Internet ofthings, environmental sensing, and infrastructure monitoring and security.

xxxiii