DEVELOPMENT OF SURFACE ACOUSTIC WAVE SENSOR FOR FEMALE AEDES MOSQUITO

DEVELOPMENT OF SURFACE ACOUSTIC WAVE SENSOR FOR FEMALE AEDES MOSQUITO

DETECTION

by

ZAID T. SALIM (1431711498)

A thesis submitted in fulfillment of the requirements for the degree of Master of Science in Nano Electronic Engineering

Institute of Nano Electronic Engineering UNIVERSITI MALAYSIA PERLIS

2016

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THESIS DECLARATION UNIVERSITI MALAYSIA PERLIS

NOTES: * If the thesis is CONFIDENTIAL or RESTRICTED, please attach with the letter from the organization with period and reasons for confidentiality or restriction

DECLARATION OF THESIS

Author’s full name Zaid T. Salim Date of birth 01\01\1987

Title: Development of Surface Acoustic Wave Sensor for Female Aedes Mosquito Detection

Academic Session 2016/ 2017

Hereby declare that the thesis becomes the property of Universiti Malaysia Perlis (UniMAP) and to be placed at the library of UniMAP. This thesis is classified as:

CONFIDENTIAL (Contains confidential information under the Official Secret Act 1972)*

RESTRICTED (Contains restricted information as specified by the organization where research was done)*

OPEN ACCESS I agree that my thesis is to be made immediately available as hard copy or on-line open access (full text)

I, the author, give permission to the UniMAP to reproduce this thesis in whole or in part for the purpose of research or academic exchange only (except during a period of years, if so requested above).

Certified by:

_________________________ ______________________________

SIGNATURE SIGNATURE OF SUPERVISOR A5538079 Prof. Dr. Uda Hashim

(NEW IC NO. / PASSPORT No.) NAME OF SUPERVISOR Date: Date:

√

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ACKNOWLEDGMENTS

All praise and thanks to almighty God for his blessing through this work. I would like to thank my advisers Prof. Dr. Uda bin Hashim and Dr. Mohdameed Khairuddin bin Arshad for their guidance and support through the research. I also would like to thank all INEE staff for their kindness and hospitality. My dear brothers and sisters especially Evan, Saba and Makram, I’m really grateful for all your uncounted support and love. My father and mother, thank you for your care, support and prayers it is what kept me going all this time. Finally, I would like to thank University Malaysia Perlis (UniMAP) for providing me the suitable environment to make this project better.

Zaid Tareq Salim

Institution of Nano Electronics Engineering University Malaysia Perlis

Zaidtareq86@gmail.com

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TABLE OF CONTENTS

PAGE

THESIS DECLARATION i

ACKNOWLEDGMENTS ii

TABLE OF CONTENTS iii

LIST OF TABLES vii

LIST OF FIGURES viii

LIST OF SYMBOLS xi

LIST OF ABBREVIATIONS xiiii

ABSTRAK xv

ABSTRACT xvii

CHAPTER 1 INTRODUCTION

1.1 Overview 1

1.2 Research scope 2

1.3 Problem statement 2

1.4 Research objectives 3

1.5 Significance of research 3

1.6 Thesis outline 4

CHAPTER 2 LITERATURE REVIEW

2.1 Introduction 5

2.2 Dengue fever and Aedes mosquito 5

2.2.1 Dengue fever 5

2.2.2 Aedes mosquito 6

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2.2.3 Incidents of Dengue worldwide 8

2.3 Wing beat frequency based detection 10

2.4 Piezoelectricity 12

2.5 Acoustic wave technology 13

2.6 Acoustic wave propagation modes 14

2.6.1 Bulk acoustic wave 16

2.6.1.1 Thickness shear mode (TSM) 16

2.6.1.2 Shear horizontal-acoustic plate mode (SH-APM) 18

2.6.2 Surface acoustic wave (SAW) 19

2.6.2.1 Shear horizontal surface acoustic wave (SH-SAW) 20

2.6.2.2 Layered structure SAW device 21

2.6.2.3 Advantages of layered SAW structure 22

2.6.2.4 Material for SAW devices 23

2.6.3 Design of layered SAW devices 25

2.6.3.1 Lithium niobate as substrate 26

2.6.3.2 Zinc oxide as thin film material 26

2.7 Finite Element Method based modeling and simulation 27

2.7.1 FEM basic procedure 28

2.7.2 FEM formulation for piezoelectric devices 29 CHAPTER 3 METHODOLOGY AND CHARACTERIZATION TOOLS

3.1 Introduction 31

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3.2 Modeling and simulation 32

3.2.1 3D modeling and simulation of non-layered SAW device 32

3.2.1.1 Model description 32

3.2.2 3D modeling and simulation of layered SAW device 38

3.2.2.1 Model description 38

3.3 SAW device fabrication 39

3.3.1 Preparation of samples 40

3.3.2 IDTs design and fabrication 41

3.3.2.1 Vacuum thermal evaporation technique 43

3.3.2.2 Conventional photolithography 44

3.3.2.3 Wet etching 45

3.3.3 ZnO thin film deposition using RF Magnetron Sputtering 46

3.4 Characterization methods 49

3.4.1 ZnO thin film characterization 49

3.4.1.1 Field Emission-Scanning Electron Microscope (FE-SEM) 49

3.4.1.2 Atomic Force Microscope (AFM) 50

3.4.1.3 X-Ray Diffraction (XRD) 50

3.4.1.4 Photoluminescence (PL) 51

3.4.1.5 UV-visible spectrophotometer 52

3.4.2 SAW device characterization 52

3.4.3 Wing beat frequency and sound pressure level (SPL) measurements 54

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vi CHAPTER 4 RESULTS AND DISCUSSIONS

4.1 Introduction 55

4.2 Wing beat frequency and SPL measurements 56

4.3 Theoretical results 61

4.3.1 Non-layered SAW model results 61

4.3.2 Layered SAW model results 64

4.4 SAW device electrical characterization 67

4.5 ZnO layer characterization 70

4.5.1 Crystal structure analysis 70

4.5.2 Morphological study 72

4.5.3 Optical Properties 74

4.6 SAW device testing 78

CHAPTER 5 CONCLUSIONS AND FUTURE WORKS

5.1 Conclusions 81

5.2 Future works 83

REFERENCES 85

APPENDIX A INSRUMENTATION 95

LIST OF PUBLICATIONS 100

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LIST OF TABLES

NO. PAGE

2.1 The most common piezoelectric materials used in SAW

applications 25

3.1 Mask alignment specification and parameters 45 4.1 Electrical characteristics of the layered and non-layered SAW

devices 69

4.2 Structural properties of the ZnO nano-structure on Lithium Niobate

substrate 72

4.3 Optical properties of the ZnO nano-structure on LiNbO3 substrates 69

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LIST OF FIGURES

NO. PAGE

2.1 Dengue virus structure 6 2.2 Comparison between male (right side) and female (left side) Aedes

aegypte mosquito. 8

2.3 Dengue fever and dengue hemorrhagic fever cases reported to the

Malaysian ministry of health for the last ten years 9

2.4 Countries at risk of dengue infection 10

2.5 Measurements of wing beat frequencies of different mosquito

species 11

2.6 Measurements of Sound Pressure Level (SPL) produces by individual female and male mosquitoes with remote area

background 11

2.7 Schematic illustration of the piezoelectric effect 12 2.8 Schematic of a basic two port acoustic wave device 15 2.9 Schematic of a thickness shear mode (TSM) resonator 17 2.10 Schematic of a shear horizontal acoustic plate mode (SH-APM)

sensor 18

2.11 Schematic of a surface acoustic wave device with Rayleigh wave

displacement 20

2.12 Schematic of a shear horizontal surface acoustic wave (SH-SAW)

mode 21

3.1 A schematic illustration of the methodology used in this work 32 3.2 SAW device model geometry used in this work 33

3.3 Rotations specified by the Euler angles 34

3.4 The rotated systems specified by Euler angles used in this model 36

3.5 Tetrahedral mesh used in this model 37

3.6 The layered SAW device model geometry 39

3.7 Interdigital transducers (IDTs) design used in this work 42

3.8 Chromic Photomask used in this work 42

3.9 Schematic diagram of a vacuum thermal evaporation system 43 3.10 A schematic diagram of the sputter coating process 47 3.11 Schematic of the layered SAW device fabrication process 48

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3.12 Fabricated two ports layered SAW device 48

3.13 A schematic of a two port network 53

4.1 Comparison of average wing beat frequency of Aedes mosquito

and other mosquito species 57

4.2 SPL of male and female Adese mosquito at the fundamental

frequency compared with the lab background noise 57 4.3 Sound pressure level (SPL) produced by male and female Aedes

mosquito 58

4.4 Noise level produced by different environments: library, average

home and yard 59

4.5 Electrical characteristics of simulated mosquito signals 60

4.6 SAW displacement along the thickness 61

4.7 Displacement field Y component measured at point (0, 0, 0) (a) and

at point (0, 0, 400) (b). 62

4.8 SAW propagation modes in 41°, 64° and 128° YX LiNbO3 63 4.9 SAW device frequency response in 41°, 64° and 128° YX LiNbO3 64

4.10 SAW device frequency response with KhZnO 65

4.11 Calculated K² versus KhZnO 66

4.12 SAW displacement Y-component in layered and non-layered

structures 67

4.13 The frequency response of the layered and non-layered SAW

devices 68

4.14 Compartment between the simulation and the experimental results 70 4.15 XRD patterns of the ZnO nano-structure on LiNbO3 substrate 71 4.16 FESEM images of the ZnO grown on LiNbO3 substrate (a) high

magnification (b) low magnification 73

4.17 AFM image of the sputtered ZnO layer on the metalized region (a)

and non-metalized region (b) 74

4.18 Reflectance diagram of the ZnO grown on LiNbO3 substrate. 75 4.19 Optical energy band gap diagram of the ZnO grown on LiNbO3

substrate 77

4.20 PL diagram of the ZnO grown on LiNbO3 substrate 77 4.21 SAW device response to simulated (a) and real (b) mosquito

signals 78

4.22 SAW device response to female Aedes mosquito with variation in the distance

79

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4.23 SAW device response to female Aedes mosquito with variation in the background noise

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LIST OF SYMBOLS

𝐾𝐾² Electromechanical coupling coefficient

𝐻𝐻𝐻𝐻 Hertz

Å Angstrom

𝐾𝐾ℎ Film thickness

𝜆𝜆 SAW wavelength

𝑣𝑣_𝑝𝑝 Phase velocity

𝜔𝜔 Angular velocity

𝑘𝑘 Wave vector

𝑓𝑓_𝑜𝑜 Operational frequency

Λ IDT periodicity

𝑒𝑒 Piezoelectric coefficient

𝐸𝐸 Electric field

𝑆𝑆 Strain

𝜀𝜀 Electrical permittivity 𝐶𝐶^𝐸𝐸 Elasticity matrix

𝑣𝑣_𝑓𝑓 Free surface velocity 𝑣𝑣𝑚𝑚 Metalized surface velocity

𝑇𝑇 Stress vector

𝐷𝐷 Electrical displacement

𝑉𝑉 Electric potential

𝜌𝜌 Rho

𝜕𝜕 Partial deferential

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S Sum

𝑡𝑡_𝑠𝑠 Time step

ℎ Maximum mesh element size

𝐹𝐹 Lorentz force

𝑞𝑞 Particle charge

𝐵𝐵 Magnetic field

𝑑𝑑 Crystal grain size

𝛽𝛽 Full width at half maximum 𝜃𝜃 Diffraction Bragg^'s angle

𝑐𝑐 Lattice constant

𝜀𝜀_{𝑧𝑧𝑧𝑧} Film strain

R Reflectance

𝑒𝑒𝑉𝑉 Electron volt

G Radiation conductance

b Susceptance

𝑑𝑑𝐵𝐵 Decibel

𝑁𝑁 Number of electrode finger pairs

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LIST OF ABBREVIATIONS

DF Dengue fever

SAW Surface acoustic wave IDT Interdigital transducer SPL Sound pressure level

RNA Ribonucleic acid

DEN Dengue virus serotype DHF Dengue hemorrhagic fever

DSS Dengue shock syndrome

WHO World health organization

Ae Aedes

BAW Bulk acoustic wave

TSM Thickness shear mode

SH-APM Shear horizontal acoustic bulk mode SH-SAW Shear horizontal surface acoustic wave STW Surface transverse wave

FPW Flexural plate wave

SSBW Surface skimming bulk wave

TCF Temperature coefficient of frequency TCD Temperature coefficient of delay

ppm Part per million

FEM Finite element method

MEMS Micro-electromechanical system

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VHF Very high frequency

CFL Friedrichs Lewy condition FFT Fast Fourier transaction

RF Radio Frequency

XRD X-ray Diffraction

FESEM Field emission scanning electron microscope AFM Atomic force microscope

PL Photoluminescence

UV Ultraviolet

PR Positive resist

HMDS Hexametyldisilazane

Ra Roughness average

RMS Root mean square

Eg Energy gap

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Pembangunan Sensor Gelombang Akustik Permukaan untuk Pengesanan Nyamuk Aedes Betina

ABSTRAK

Kes demam denggi (DF) dan demam denggi berdarah telah menunjukkan peningkatan dalam masa sedekad yang lalu di seluruh dunia. Keadaan ini membawa kepada kerugian besar sesebuah ekonomi dan komplikasi kesihatan yang serius. Setakat ini, penawar yang mampu menyembuhkan DF dan peranti yang berkesan untuk mengawal dan mengesan nyamuk Aedes yang menjadi punca DF masih belum dihasilkan. Oleh itu, pembikinan peranti untuk pencegahan virus denggi sangat diperlukan. Dalam kajian ini, rekabentuk dan pembikinan peranti gelombang akustik permukaan (SAW) untuk mengesan nyamuk aedes betina akan dibentangkan. Kajian ini adalah yang pertama melaporkan tentang pengesanan nyamuk Aedes betina di dalam penempatan manusia menggunakan peranti SAW. Teknologi SAW boleh diaplikasikan untuk menghasilkan peranti yang amat peka kerana kepekaan usikan permukaan yang tinggi. Lapisan peranti SAW adalah terdiri daripada bahan zink oksida (ZnO)/pemindaharuh antara digit (IDT)/128˚ YX litium niobate (LiNbO³), komposisi struktur ini telah direka, dibikin, dan dicirikan di dalam tesis ini. Pertama sekali, peranti ini telah dicirikan secara teori menggunakan kaedah elemen terhingga didalam perisian “COMSOL Muliphysics” 4.3b.

Menggunakan perisian tersebut, respon frekuensi, mod perambatan SAW, kecekapan sesaran SAW, dan pekali gandingan elektromekanik akan dicirikan secara teori.

Ketebalan ZnO yang pelbagai digunakan untuk mendapatkan kondisi yang unggul.

Keputusan berangka akan disahkan menggunakan peranti yang sudah dihasilkan dan perkaitan yang baik diantara simulasi dan eksperimen telah diperolehi. Peranti SAW telah dihasilkan setelah penyelarasan terakhir parameter rekaan dilakukan, proses photolithografi lazim telah digunakan untuk menghasilkan dua IDT diatas substrat 128°

YX LiNbO3 untuk memancar dan menerima SAW. Proses terakhir melibatkan enapan ZnO yang setebal 1.5 µm menggunakan teknik pemercitan RF magnetron. Ciri-ciri struktur lapisan ZnO dikaji menggunakan pembelauan sinar-X. Struktur nano ZnO telah dienap secara sempurna diatas sampel dan diindeks kepada fasa heksagon yang mempunyai struktur “wurtzite”. Dua puncak pada (002) dan (201) satah pembelauan juga dilihat. Ciri morfologi struktur juga dikaji menggunakan daya atomic dan pancaran medan kemikroskopan elektron imbasan. Gambar yang diperbesar mendedahkan kepingan nano-siratan dan struktur bentuk cuping yang tumbuh secara rawak diatas substrat LiNbO3 yang menunjukkan keseragaman yang baik. Teknik foto pendarkilau dan Uv-vis digunakan untuk pencirian secara optikal. Tiga jenis sela jalur tenaga didedahkan, sela jalur tenaga yang kecil, sederhana dan besar yang wujud masing- masing berkait rapat dengan kepingan nano ZnO, nano siratan dan substrat LiNbO3. Peranti SAW juga dicirikan secara elektrik menggunakan penganalisa dua birai rangkaian vector. Respon frekuensi yang diperolehi ialah 158.8 MHz, manakala nilai K² yang dikira ialah 10.1 %, dan factor kualiti ialah 1,323. Respon peranti SAW diperoleh dengan signal nyamuk simulasi dan yang sebenar. Peranti ini mampu mengesan dan membezakan nyamuk Aedes jantan dan betina. Magnitud S11 dikurangkan kepada 0.6 dan 1.25 dB masing-masing dengan nyamuk Aedes jantan dan betina. Tambahan pula, peranti SAW mempamerkan kepekaan yang baik pada suasana tekanan bunyi yang

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rendah pada jarak diantara 40-55 dB, oleh itu, peranti ini sesuai digunakan di penempatan manusia.

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Development of Surface Acoustic Wave Sensor for Female Aedes Mosquito Detection

ABSTRACT

The cases of dengue fever (DF) and dengue hemorrhagic fever have been increasing worldwide in the last decade. These conditions lead to large economic losses and health complications. To date, a direct cure for DF and an efficient device to control or detect Aedes mosquitoes causing DF are unavailable. Therefore, the fabrication of a device to prevent dengue virus infection is necessary. In this study, the design and the fabrication of a surface acoustic wave (SAW) sensor for female Aedes mosquito detection are presented. This study is the first to report the detection of female Aedes mosquitoes in human habitations using a SAW sensor. SAW technology can be applied to create highly sensitive sensors because of its extreme sensitivity to surface perturbation. A layered SAW device based on the ZnO/interdigital transducer (IDT)/128° YX lithium niobate (LiNbO3) structure was designed, fabricated, and characterized in this thesis study. First, the device was characterized theoretically using the finite element method in COMSOL Multiphysics 4.3b. The frequency response, SAW propagation mode(s), SAW displacement efficiency, and electromechanical coupling coefficient were theoretically investigated. Various ZnO layer thicknesses were used to obtain the ideal conditions. Numerical results were verified with a fabricated device. A good correlation was obtained between the simulation and experimental results. The SAW device was fabricated after setting the final design parameters, and conventional photolithography was used to produce two IDTs on 128° YX LiNbO3 substrate to transmit and receive SAWs. Finally, a 1.5 µm ZnO layer was coated using the RF magnetron sputtering technique. The structural properties of the ZnO layer were studied using the X-ray diffraction technique. The ZnO nanostructure was grown successfully on the sample and indexed to the hexagonal phase with a wurtzite structure. Two peaks on the (002) and (201) diffraction planes were also observed. The morphological properties of the structure were investigated using the atomic force and field emission scanning electron microscopes. The high-magnification images revealed a nanoflake–corolla lobe-like structure randomly grown on the LiNbO3 substrate that was uniform in all substrate dimensions. Photoluminescence and Uv-vis techniques were used to study the optical properties. Three energy band gaps were revealed, and the small, medium, and large energy band gaps were related to the nanoflake ZnO, nanocorolla lobe, and LiNbO3

substrate, respectively. The SAW device was characterized electrically using a two-port vector network analyzer. The frequency response was 158.8 MHz, the measured K² value was 10.1%, and the quality factor was 1,323. The SAW device response was investigated with simulated and actual mosquito signals. This device could detect and distinguish between male and female Aedes mosquitoes. The S11 magnitude was reduced by 0.6 and 1.25 dB with female and male Aedes mosquitoes, respectively. Furthermore, the SAW sensor exhibited good sensitivity in low sound pressure environments in the range of 40–55 dB, thereby making it suitable for human habitations.

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1 CHAPTER 1

INTRODUCTION

1.1 Overview

The presents of female Aedes mosquito in or around human habitation can cause fatal diseases. Most commonly, dengue fever (DF) is one of the dangerous diseases transmitted to human through a bite caused by the females of this mosquito genus. The focus of this thesis work is to develop a surface acoustic wave (SAW) sensor for the detection of female Aedes mosquito in human habitation.

It is entrenched that SAW devices show a high sensitivity towards various physical and chemical phenomena. As sensors, they can offer innovative solutions for a wide range of applications (Borrero, Bravo, Mora, Velásquez, & Segura-Quijano, 2013). These devices are simple, inherently robust and competitively priced.

Furthermore, they can be passive (no power source) and wireless (can be operated remotely) which make it suitable to operate in extreme conditions and harsh environments (Elhosni et al., 2015). Recently, a large number of applications has been reported in the literature of SAW devices such as SAW chemical, pressure, temperature sensors as well as many other commercial applications (Flewitt et al., 2015; Li, Dhagat,

& Jander, 2012; Raj, Nimal, Parmar, Sharma, & Gupta, 2012; Rodriguez-Madrid, Iriarte, Williams, & Calle, 2013; Wei et al., 2010; Xuan et al., 2013) which makes it a very promising approach for developing a SAW sensor for the detecting of female Aedes mosquito.

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2 1.2 Research scope

The scope of this work focuses on developing a high performance SAW sensor for the detection of female Aedes mosquito using wing beat frequency as sensing mechanisms. This includes the following:

1. Explore previous studies to identify the necessary properties, characteristics and parameter that can affect the device performance.

2. Theoretical study by modeling and simulation to investigate the critical parameters and identify the best conditions.

3. Utilizing different characterization techniques to validate and test the device electrically.

1.3 Problem statement

Aedes mosquito genus are the main vectors for transmitting the viruses that

cause dengue fever, yellow fever, West Nile fever, chikungunya, and Eastern equine encephalitis along with many other less harmful diseases. At present, there is no device to control or detect the present of Aedes mosquito around humans. Furthermore, current control methods have not stopped the spread of Aedes mosquito worldwide. There is no effective vaccine or specific treatment for dengue fever with Aedes female mosquitoes depends on humans to get a blood meal in order to lay fertile eggs. According to the last ten years statistics there is a significant increase in the incidence of dengue fever (Mudin, 2015).

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3 1.4 Research objectives

The aim of this research is to develop a novel surface acoustic wave sensor for the detection of female Aedes mosquito based on the mosquito’s wing beat frequency as a sensing mechanism which is in the range between 400-500 Hz. This objective will be accomplished by achieve the following:

1. To determine the wing beat frequency range of Aedes mosquito and other common mosquito species.

2. To design and fabricate a high performance SAW device for detecting signals in the mosquito’s wing beat frequency range.

3. To examine the performance of the fabricated SAW device under lab and field conditions.

1.5 Significance of research

The significance of this study includes, firstly, the modeling and simulation of two port SAW device based on ZnO/IDT/128º YX LiNbO3 as a pre-fabrication step to obtain a high performance and sensitivity. During this theoretical analysis, the influence of the ZnO layer thickness to the SAW device frequency response, SAW displacement and coupling coefficient was investigated. Secondly, wing beat frequency produced by the mosquito’s flight tone was measured with the sound pressure level (SPL). Finally, the sensor was characterized electrically, and the sensor’s performance was investigated with simulated and real mosquito signals. To the best of our knowledge, this is the first attempt toward fabricating a device for the detection of female Aedes mosquito.

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4 1.6 Thesis outline

This thesis consists of five chapters.

Chapter 1 presents a short introduction about SAW sensors and Aedes mosquito. Also present the research scope, problem statement, objectives and significant of the research.

Chapter 2 reviews the literature and scientific background of Aedes mosquito and dengue fever and their incidents worldwide. Furthermore, it reports a brief overview about acoustic wave devices and technology along with the theory of piezoelectricity and its applications.

Chapter 3 details the methodology includes the FEM model description for non-layered and layered SAW devices, the experimental work and techniques performed in order to fabricate and characterize both the SAW device and the coting.

Chapter 4 presents the measured wing beat frequency and SPL of Aedes mosquito and two other mosquito species. The theoretical results obtained by the FEM modeling and simulation. The structural, morphological and optical properties of the coated layer are illustrated in this chapter. Finally, the electrical characteristics of the SAW device along with the sensitivity toward simulated and real mosquito signals are detailed.

Chapter 5 provides the study conclusions and future work.

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5 CHAPTER 2

LITERATURE REVIEW

2.1 Introduction

In this chapter, firstly, a literature review of dengue fever and virus is presented along with the incident of Aedes mosquito worldwide. Furthermore, the theory and application of piezoelectricity is described. The most common acoustic wave devices and acoustic wave propagation modes is summarized. Finally, this chapter is ended with a brief overview about the modeling and simulation of layered SAW devices.

2.2 Dengue fever and Aedes mosquito 2.2.1 Dengue fever

Dengue fever is one of the most dangerous mosquito-borne diseases that become a serious health concern (Gubler, 2002). In the period between the 18^th and 19^th centuries, sailing ships were the main factor that helped expanding both the mosquito vector (genus Aedes) and the virus responsible for dengue fever worldwide. By using the water stored in the ships, the mosquitoes were able to complete their life cycle and spread to new areas when it reaches a new port (Murray, Quam, & Wilder-Smith, 2013).

Dengue virus mature particle is spherical with a diameter of 50 nm containing a multiple copies of three structural proteins (host-derived membrane bilayer, single- standard RNA genome and seven nonstructural proteins) (X. Zhang et al., 2013) as illustrated in figure 2.1.

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Figure 2.1: Dengue virus structure.

Dengue virus can be classified into four serotypes (DEN-1, DEN-2, DEN-3 and DEN-4) and a new surprising serotype (DEN-5) is discovered recently (Normile, 2013).

These serotypes return from the genus Flavivirus, and the family Flaviviridae (Calisher

& Gould, 2003). The Symptomatic infections of dengue virus include three categories:

undifferentiated fever, dengue fever (DF) and dengue hemorrhagic fever (DHF).

Furthermore DHF was classified into four grades of severity, with grades three and four DHF develops into dengue shock syndrome (DSS) (Ranjit & Kissoon, 2011). A large number of mosquito species are responsible for transmitting many types of diseases to humans and animals.

2.2.2 Aedes mosquito

The genus Aedes considered the main vector for numerous fatal diseases. The most prominent species in this genus are Aedes Aegypte and Aedes Albopictus (Añez &

Rios, 2013). This species are responsible for transmitting dengue fever, West Nile fever, chikungunya and Eastern equine encephalitis viruses and many other less harmful diseases to humans (Tolle, 2009). The females of this species can transmit all serotypes

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