123

Energy Systems in Electrical Engineering

Shanky SaxenaRitu SharmaB. D. Pant

Design and Development of MEMS based Guided Beam Type Piezoelectric Energy Harvester

Energy Systems in Electrical Engineering

Series Editor

Muhammad H. Rashid, Florida Polytechnic University, Lakeland, USA

More information about this series at http://www.springer.com/series/13509

Shanky Saxena · Ritu Sharma · B. D. Pant

Design and Developmentof MEMS based GuidedBeam Type PiezoelectricEnergy Harvester

Shanky SaxenaSchool of Electronics and ElectricalEngineeringLovely Professional UniversityPhagwara, Punjab, India

B. D. PantCouncil of Scientific and IndustrialResearchCentral Electronics Engineering ResearchInstitutePilani, Rajasthan, India

Ritu SharmaDepartment of Electronicsand Communication EngineeringMalaviya National Institute of TechnologyJaipur, Rajasthan, India

ISSN 2199-8582 ISSN 2199-8590 (electronic)Energy Systems in Electrical EngineeringISBN 978-981-16-0605-2 ISBN 978-981-16-0606-9 (eBook)https://doi.org/10.1007/978-981-16-0606-9

© The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer NatureSingapore Pte Ltd. 2021This work is subject to copyright. All rights are solely and exclusively licensed by the Publisher, whetherthe whole or part of the material is concerned, specifically the rights of translation, reprinting, reuseof illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, andtransmission or information storage and retrieval, electronic adaptation, computer software, or by similaror dissimilar methodology now known or hereafter developed.The use of general descriptive names, registered names, trademarks, service marks, etc. in this publicationdoes not imply, even in the absence of a specific statement, that such names are exempt from the relevantprotective laws and regulations and therefore free for general use.The publisher, the authors and the editors are safe to assume that the advice and information in this bookare believed to be true and accurate at the date of publication. Neither the publisher nor the authors orthe editors give a warranty, expressed or implied, with respect to the material contained herein or for anyerrors or omissions that may have been made. The publisher remains neutral with regard to jurisdictionalclaims in published maps and institutional affiliations.

This Springer imprint is published by the registered company Springer Nature Singapore Pte Ltd.The registered company address is: 152 Beach Road, #21-01/04 Gateway East, Singapore 189721,Singapore

This book is dedicated to my parents Mr. AnilKumar Saxena and Mrs. Raagni Saxena fortheir continuous support and inspiration topursue my interests in science. This book isalso dedicated to my late grandparents Mr. P.L. Saxena, Mrs. Satyawati Saxena, Mr. M. C.Saxena and Mrs. Sharda Saxena for theirlove and encouragement in all my endeavors.

Shanky Saxena

Foreword

In the current race of miniaturization of microelectronic circuits and systems, thepower required by these systems particularly by the Wireless Sensor Networks(WSNs) has reduced to a very low level. WSNs consist of manyMobile sensor nodes(MSNs) which are driven by miniaturized lithium-ion batteries that are exhaustibleand replacement is not feasible at remote locations. Energy harvesting provides anunending power source that is adequate to power these sensor nodes specificallyfor remote area applications. Energy harvester can convert freely available ambientenergy into electrical energy to provide an endless source of power for MSNs. InMicroelectromechanical system (MEMS) based energy harvesters, electrical andmechanical components are integrated into a single device, making them tiny andcompact which is suitable for remote area applications. MEMS-based piezoelec-tric vibration energy harvesters are a preferred choice because of their simplicityin design, operation, and compatibility with fabrication technology. The realiza-tion of cantilever-based piezoelectric energy harvesters has always been challengingbecause great care is required to develop and characterize each unit process leadingto the technology development for the fabrication of a specific device.

This monograph is focused on MEMS-based piezoelectric vibration energyharvesters. State of the art technologies have been reviewed to understand the avail-able technologies suitable for vibration energy harvesting. Analytical equationsgoverning the device key parameters have been introduced in the initial portionof the monograph. Simulation steps have been presented using snapshots and resultshave been depicted by graphs making it easy to comprehend. In the later sectionof the monograph, a detailed fabrication process on the development of microma-chining processes based on both wet and dry etching techniques has been discussed.Elaborate structural, material, morphological, topological, dynamic, and electricalcharacterization of the device has been presented. In the last section, a real-time prac-tical application is selected, and a piezoelectric energy harvester is designed whichis suitable to operate in the desired environment.

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viii Foreword

My compliments to the authors for putting together this valuable contribution inthe form of a monograph which would be of interest and use to graduate studentsand researchers alike.

January 2021 Muhammad Mustafa Hussain, Ph.D.Fellow, IEEE, APS and IoP

Department of Electrical Engineeringand Computer SciencesUniversity of California

Berkeley, CA, USA

Preface

The internet of things (IoT) is a network embedded with sensors, software and othertechnologies that allow to transmit and receive data. Increased use of sensors inIoT imposes a challenge to power these sensors operating at remote locations. Theuse of Lithium-ion batteries is not sustainable as they are not environment friendlyand requires timely replacement. Energy harvesting is a technology that convertsfreely available ambient energy into electrical energy. Vibration energy harvesting ispreferred because vibrations of different amplitude and frequency are freely availablein the environment. Piezoelectric type vibration energy harvesters are prominentlyused due to their simple operation and compatibility with MEMS fabrication tech-nology. Cantilever structure fixed from one end and free from the other are widelyused to realize a Piezoelectric vibration energy harvester.

In this monograph, a fixed-fixed or guided beam Piezoelectric Vibration EnergyHarvester has been designed, fabricated and tested for low-frequency operation.Device design has been done ensuring low-frequency operation, stable and reliabledevice operation and higher potential generation. Single beam, Cantilever array andguided beam structures have been designed and investigated using FEM. Fabrica-tion technology is one of the most significant steps in the realization of a device.Guided two-beam and four-beam piezoelectric energy harvester devices have beenfabricated. In both of these devices, a combination of wet and dry bulk microma-chining techniques has been utilized. Aqueous TMAH etching for wet bulk micro-machining, RIE (reactive ion etching) and DRIE (deep reactive ion etching) for drybulk micromachining processes have been used.

Elaborate characterizationof fabricated two-beamand four-beamdevices has beendone. Structural characterization has been done to determine the device dimensionsand quality of the deposited materials. The resonance frequency of the device isexperimentallyworked out using a LaserDopplerVibrometer (LDV) and ismeasuredto be 466 Hz for the guided two-beam device and 515 Hz for the guided four-beam device. Finally, vibration bench testing is done for the measurement of electricpotential and sensitivities of the two-beam and four-beam devices. Both the devicesoperate in the frequency range from 10 to 1000 Hz which is the desired frequencyrange for harvesting ambient vibrations.

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In the last section, design and FEM analysis for a piezoelectric energy harvesterhave been done for a real-time practical application.

This monograph is aimed at graduate students and researchers working in the fieldof energy harvesting. Analytical equations governing the energy harvester operationhave been discussed along with the stepwise FEM analysis which will be helpfulfor the students working in this field. Further, the mask layout design, fabricationand characterization techniques used are described in depth in the monograph usingsnapshots during each process which will be useful for researchers and engineersworking in this field.

Ajmer, IndiaJaipur, IndiaPilani, India

Shanky SaxenaRitu SharmaB. D. Pant

Acknowledgements

The authors would like to thank the scientific and technical staff from CSIR-CentralElectronics Engineering Research Institute, Pilani, India, Materials Research Centre,Malaviya National Institute of Technology, Jaipur, India, Acoustics and Vibrationstandards laboratory,National Physical Laboratory,Delhi, India, Structural SolutionsPvt. Ltd., Hyderabad, India, Prof. V. Gupta and Dr. M. Tomar, Delhi University,Delhi, India for their support, without their expertise, this work would not havebeen possible. The authors acknowledge IEEE, Springer and Elsevier for grantingpermission to reuse materials copyrighted by these publishers in this monograph.The authors would like to express their deep sense of gratitude to their parents andteachers who have led the foundation and made them competent enough to write thismonograph. We would like to thank Editor Prof. Muhammad H. Rashid, Associateeditor, Ms. Kamiya Khattar, and staff of Springer, for their professional and efficienteditorialwork on this book. Finally,wewould thankGod for bestowinggrace uponus,which helped us to keep going in the tough times and complete thiswork successfully.

Ajmer, IndiaJaipur, IndiaPilani, India

Shanky SaxenaRitu SharmaB. D. Pant

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Contents

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2 Energy Requirement in WSNs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.3 Energy Harvesting for WSNs—State of the Art . . . . . . . . . . . . . . . . . 31.4 Vibration-Based Energy Harvesters . . . . . . . . . . . . . . . . . . . . . . . . . . . 51.5 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111.6 Overview of Monograph . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

2 Piezoelectric Vibration Energy Harvesters: A Review . . . . . . . . . . . . . . 172.1 Discussion and Planning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

3 Design, Modeling and Comparison of Piezoelectric VibrationEnergy Harvesters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313.1 Single-Beam Cantilever-Type P-VEH . . . . . . . . . . . . . . . . . . . . . . . . . 313.2 Cantilever Generator Array . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 373.3 Clamped–Clamped or Guided Beam Structures . . . . . . . . . . . . . . . . . 393.4 Comparison . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 423.5 Effect of Shape of Seismic Mass on Potential Generated

by Piezoelectric Energy Harvester . . . . . . . . . . . . . . . . . . . . . . . . . . . . 433.6 Simulation of Different Geometries of Seismic Mass . . . . . . . . . . . . 453.7 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 473.8 Effect of PiezoelectricMaterial on Guided Beam Piezoelectric

Energy Harvester . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

4 Design and FEM Simulation of Guided Beam PiezoelectricEnergy Harvester . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 514.1 Design of Guided Four-Beam P-VEH . . . . . . . . . . . . . . . . . . . . . . . . . 514.2 FEM Analysis of Guided Four-Beam P-VEH . . . . . . . . . . . . . . . . . . . 53

4.2.1 Resonance Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 544.2.2 Displacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

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4.2.3 von Mises Stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 584.2.4 Electric Potential . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 584.2.5 Selection of Seismic Mass . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

4.3 Comparison of Guided Two-Beam and Four-BeamPiezoelectric Energy Harvester . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 604.3.1 Design, FEM and Comparison of Guided Two-Beam

and Four-Beam Piezoelectric Energy Harvester . . . . . . . . . . 614.3.2 Resonance Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 624.3.3 Displacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 634.3.4 von Mises Stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 644.3.5 Electric Potential . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

4.4 Design and Optimization of Split Electrodes for GuidedBeam Piezoelectric Energy Harvester . . . . . . . . . . . . . . . . . . . . . . . . . . 674.4.1 Effect of Length of Split Electrode on Resonance

Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 694.4.2 Effect of Length of Split Electrode on Change

in Capacitance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

5 Fabrication of Guided Beam Piezoelectric Energy Harvester . . . . . . . 735.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

5.1.1 Fabrication Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . 745.2 Design of Mask Layouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

5.2.1 Mask #1:TMAH Etch Mask for Pyramidal-ShapedSeismic Mass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

5.2.2 Mask #2: Bottom Electrode Patterning . . . . . . . . . . . . . . . . . 775.2.3 Mask #3: Piezoelectric Layer Patterning . . . . . . . . . . . . . . . . 775.2.4 Mask #4: Top Electrode Patterning . . . . . . . . . . . . . . . . . . . . 775.2.5 Mask #5: DRIE Etch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

5.3 Fabrication of Guided Beam Piezoelectric Energy Harvester . . . . . . 795.3.1 Device Fabrication Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 795.3.2 Device Fabrication (Batch 1) . . . . . . . . . . . . . . . . . . . . . . . . . 79

5.4 Detailed Unit Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 835.4.1 Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 835.4.2 Thermal Oxidation and LPCVD Nitride . . . . . . . . . . . . . . . . 835.4.3 Lithography (Mask #1) for Pyramidal-Shaped

Seismic Mass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 835.4.4 Reactive Ion Etching (RIE) for Oxide and Nitride

Etch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 855.4.5 Bulk Micromachining of Silicon

for Pyramidal-Shaped Seismic Mass . . . . . . . . . . . . . . . . . . . 855.4.6 Gold Sputtering and Bottom Electrode Patterning

(Mask #2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

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5.4.7 Piezoelectric Layer (Zinc Oxide)Sputtering and Patterning(Mask #3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

5.4.8 Gold Sputtering and Top Electrode Patterning (Mask#4) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

5.4.9 Lithography Mask #5 and Beam Release Using DRIE . . . . 895.4.10 Dicing and Device Release . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

5.5 Fabrication Process Optimization and Device Fabrication(Batch 2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 935.5.1 Fabrication Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 935.5.2 Fabrication of Structure on Front Side of Wafer . . . . . . . . . 935.5.3 Bulk Micromachining of Silicon

for Pyramidal-Shaped Seismic Mass . . . . . . . . . . . . . . . . . . . 945.5.4 Guided Beam Release and Thinning Using Deep

Reactive Ion Etching (DRIE) . . . . . . . . . . . . . . . . . . . . . . . . . 945.5.5 Dicing and Device Release . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

5.6 Design of the PCB and Packaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98

6 Testing and Characterization of Guided Beam PiezoelectricEnergy Harvester . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 996.1 Structural Characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1006.2 Dynamic Characterization Using Laser Doppler Vibrometer

(Batch1 Devices) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1046.2.1 LDV Measurement for Guided Two-Beam

Piezoelectric Energy Harvester . . . . . . . . . . . . . . . . . . . . . . . . 1056.2.2 LDV Measurement for Guided Four-Beam

Piezoelectric Energy Harvester . . . . . . . . . . . . . . . . . . . . . . . . 1056.3 Dynamic Characterization using LDV (Batch 2 Devices) . . . . . . . . . 106

6.3.1 LDV Measurement for Guided Two-Beam Device . . . . . . . 1076.3.2 LDV Measurement for Guided Four-Beam Device . . . . . . . 107

6.4 Static Capacitance Measurement and Device Packaging . . . . . . . . . . 1086.5 Vibration Shaker Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

6.5.1 Output Voltage/Power Versus Input Acceleration . . . . . . . . 1136.5.2 Output Voltage Versus Frequency . . . . . . . . . . . . . . . . . . . . . 114

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121

7 Design of MEMS-Based Piezoelectric Energy Harvesterfor Low-Frequency Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1237.1 Low-Frequency Vibration Energy Harvesting . . . . . . . . . . . . . . . . . . . 1247.2 Design of Cantilever Type P-VEH . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1247.3 Effect of Length and Thickness of Piezoelectric Layer

on Cantilever Type P-VEH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1247.3.1 Displacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1257.3.2 von Mises Stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1387.3.3 Electric Potential . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

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7.4 Effect of Length and Thickness of Beam on Cantilever TypeP-VEH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1647.4.1 Displacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1647.4.2 von Mises Stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1727.4.3 Electric Potential . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181

About the Authors

Shanky Saxena is anAssistant Professor in the School of Electronics and ElectricalEngineering at Lovely Professional University, Punjab, India. He received a degreein electronics and communication engineering from the University of Rajasthan,India, in 2008, and a master’s degree in communication and signal processing fromJaipur National University, Jaipur, India, in 2013. Dr. Saxena completed his Ph.D.from Malaviya National Institute of Technology, Jaipur, India, in 2019. He workedas a research scholar at the MEMS and Microsensors Department, CSIR-CentralElectronics Engineering Research Institute, Pilani, India, from 2013 to 2018. He is aSenior Member of IEEE USA and has over 9 years of teaching and research experi-encewithmore than 25 publications in theMEMSfield.His research interests includeMEMS-based piezoelectric vibration energy harvesters and energy harvesting forbio-medical applications.

Ritu Sharma is an Associate Professor in the Department of Electronics andCommunication Engineering, Malaviya National Institute of Technology (MNIT),Jaipur. She completed an M.Tech. in VLSI and a Ph.D. degree in photonics andoptics from the Department of Electronics and Communication Engineering, MNIT,in 2004 and 2011, respectively. Dr. Sharma is working on important projects inthe field of energy harvesters, optoelectronics and biosensors. Her research interestsinclude fabrication and characterization of piezoelectric energy harvesters, nanopho-tonic devices based on low-costmaterials, nanomaterials for nano-optoelectronic andnano-piezoelectric devices, MEMS, and nanoelectronic devices.

B. D. Pant worked as a Professor with AcSIR, and also an Emeritus Scientist withthe Smart Sensors Area of CSIR-CEERI Pilani, India. He received an M.E. degreein microelectronics from the Birla Institute of Technology and Science (BITS),Pilani, India, in 1994, and a Ph.D. degree in MEMS from Kurukshetra University,Kurukshetra, India, in 2010. Dr. Pant has worked on several important projects ofglobal interest e.g. the development of high-power piezoelectric materials, semicon-ductor devices, VLSICs, and MEMS. He has also led several projects on MEMSand NEMS. His interests are focused on developing MEMS technology and devices

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for medical, industrial, automotive, social security, and aerospace applications. Hiscurrent interests are Bio-MEMS, microfluidics, micro, and nano-energy harvesters.

Abbreviations

AFM Atomic force microscopyDI DeionizedDRIE Deep reactive-ion etchingEMF Electromotive forceFFT Fast Fourier transformLDV Laser doppler vibrometerMEMS Microelectromechanical systemsMFC Microbial fuel cellMSN Mobile sensor nodePB Piezoelectric bimorphPECVD Plasma-enhanced chemical vapor depositionPVDF Polyvinylidene fluorideP-VEH Piezoelectric vibration energy harvesterPZT Lead zirconate titanateSEM Scanning electron microscopeTMAH Tetramethylammonium hydroxideTPMS Tire pressure monitoring systemWSN Wireless sensor networkXRD X-ray diffraction

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Symbols

Al AluminumAlN Aluminum nitrideAu Goldb DampingC CapacitanceE Young’s modulusHCl HydrochloricI Moment of Inertiak Spring constantl Length of cantileverm Seismic massPt PlatinumSi SiliconSiO2 Silicon oxidet Thickness of beamW Width of cantileverx Distance between platesZnO Zinc oxide

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Chapter 1Introduction

Abstract This chapter introduces energy harvesting for wireless sensor networks.Mobile sensor nodes located at remote locations require powerwhich can be providedthrough available renewable energy. State-of-the-art technologies used for energyharvesting inWSNs have been presented to understand the amount of power requiredby the sensor nodes and the energy source suitable to power them. Vibration energyharvesting and its transduction mechanisms, i.e., electromagnetic, capacitive andpiezoelectric, used to scavenge vibration energy that can be realized in MEMStechnology are discussed.

Keyword Wireless sensor network ·Mobile sensor nodes · Piezoelectric ·Vibration energy harvesters

1.1 Introduction

Awireless sensor network (WSN) consisting of a large number of randomly deployedmobile sensor nodes (MSNs) was initially introducedwith a focus on intrusion detec-tion for tactical applications (Agrawal 2017). Since then, WSNs have been used indiverse applications such as measurement of microclimates in agriculture farms, onroad traffic monitoring, detection of human presence in workplaces and homes, andmany more (Bhatti et al. 2016). WSNs consist of several different functional parts,i.e., a transducer, an analog-to-digital converter, a wireless transmitter/receiver anda battery to power the system. WSNs have remote area applications such as pres-sure monitors for car tires, wireless weather stations and implantable/mobile medicaldevices. These WSNs are powered by small lithium-ion batteries which are efficientbut are not environmentally friendly and exhaustible (Knight et al. 2008). Replace-ment of these batteries typically in remote locations is practically not feasible. More-over, these batteries make the overall system heavy through addition of its weightand volume, thereby lowering the overall efficiency. These batteries also adverselyaffect the environment when discarded without necessary precautions (Liu 2012a).

WSNs powered with natural resources such as thermal energy, wind energy, solarenergy, vibration energy, etc. stand an effective solution for the aforesaid problem.Therefore, themain objective here is to design and develop an energy harvester device

© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021S.Saxena et al.,DesignandDevelopment ofMEMSbasedGuidedBeamTypePiezoelectricEnergy Harvester, Energy Systems in Electrical Engineering,https://doi.org/10.1007/978-981-16-0606-9_1

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2 1 Introduction

which can be embedded withMSNs that can be powered remotely for a longer periodor ideally for infinitely long time. The above idea has evolved from the fact that thelow-power nano- and microdevices have very low power requirements which can beeffectively met using an energy harvester or micropower generator.

1.2 Energy Requirement in WSNs

Recent advancements in microelectronics have reduced the device power consump-tion tomilliwatt ormicrowatt and even to the nanowatt levels throughminiaturization(Ardila et al. 2013). The small size, low power consumption and remote opera-tional capability of WSNs have gained a tremendous momentum of research in thisarea through the past decades. Table 1.1 summarizes some commercially availablewireless MSNs along with their power consumption levels (Knight et al. 2008).

As already stated, a WSN consists of multiple functional units, i.e., transducer,A/D converter, battery, memory, embedded processor and a transreceiver as shownin Fig. 1.1. A transducer or a sensor converts different form of energy (thermal,mechanical, etc.) to electrical energy and holds the responsibility of measuring thephysical parameters of the sensor locality (Agrawal 2017).

Table 1.1 Comparison of power consumption for commercially available MSNs (Knight et al.2008)

Node name Sleepmode(µA)

Transmitmode (mA)

Receivemode(mA)

Dutycycle(mA)

Operatingvoltage (V)

Batteriesrequired

Batterylife(days)

Fleck3 80 36.8 18.4 0.27 3.3 3 no. 440

XBeeTM 10 45 50 0.51 2.8 2 no. 230

MICAzTM – – – 0.70 2.7 2 no. 170

Fig. 1.1 WSN schematic depicting various functional units (Agrawal 2017)