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Dissertations / Theses on the topic 'Surface Acoustic Wave'
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Haskell, Reichl B. "A Surface Acoustic Wave Mercury Vapor Sensor." Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/HaskellRB2003.pdf.
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Hong, Stanley Seokjong 1977. "Surface acoustic wave optical modulation." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/86715.
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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2001.Includes bibliographical references (leaves 50-54).
by Stanley Seokjong Hong.
M.Eng.
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Hay, Robert Russell. "Digitally-tunable surface acoustic wave resonator." [Boise, Idaho] : Boise State University, 2009. http://scholarworks.boisestate.edu/td/58/.
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McNeil, Robert Peter Gordon. "Surface acoustic wave quantum electronic devices." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610718.
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Kaplan, Emrah. "Surface acoustic wave enhanced electroanalytical sensors." Thesis, University of Glasgow, 2015. http://theses.gla.ac.uk/6557/.
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In the last decade, miniaturised “lab-on-a-chip” (LOC) devices have attracted significant interest in academia and industry. LOC sensors for electrochemical analysis now commonly reach picomolar in sensitivities, using only microliter-sized samples. One of the major drawbacks of this platform is the diffusion layer that appears as a limiting factor for the sensitivity level. In this thesis, a new technique was developed to enhance the sensitivity of electroanalytical sensors by increasing the mass transfer in the medium. The final device design was to be used for early detection of cancer diseases which causes bleeding in the digestive system. The diagnostic device was proposed to give reliable and repeatable results by additional modifications on its design. The sensitivity enhanced-sensor model was achieved by combining the surface acoustic wave (SAW) technology with the electroanalytical sensing platform. The technique was practically tested on a diagnostic device model and a biosensing platform. A novel, substrate (TMB) based label-free Hb sensing method is developed and tested. Moreover, the technique was further developed by changing the sensing process. Instead of forming the sensitive layer on the electrodes it was localised on polystyrene wells by a rapid one-step process. Results showed that the use of acoustic streaming, generated by SAW, increases the current flow and improves the sensitivity of amperometric sensors by a factor of 6 while only requiring microliter scale sample volumes. The heating and streaming induced by the SAW removes the small random contributions made by the natural convection and temperature variation which complicate the measurements. Therefore, the method offers stabilised conditions for more reliable and repeatable measurements. The label-free detection technique proved to be giving relevant data, according to the hemoglobin concentration. It has fewer steps than ELISA and has only one antibody. Therefore, it is quick and the cross-reactivity of the second antibody is eliminated from the system. The additional modifications made on the technique decreased the time to prepare the sensing platform because the passivation steps (i.e., pegylation), prior to structuring a sensitive layer were ignored. This avoidance also increased the reliability and repeatability of the measurements.
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Kenny, Thomas Donald. "Identification of High-Velocity Pseudo-surface Acoustic Wave Substrate Orientations and Modeling of Surface Acoustic Wave Structures." Fogler Library, University of Maine, 2011. http://www.library.umaine.edu/theses/pdf/KennyT2011.pdf.
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Banerjee, Markus K. "Acoustic wave interactions with viscous liquids spreading in the acoustic path of a surface acoustic wave sensor." Thesis, Nottingham Trent University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302521.
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Thorn, Adam Leslie. "Electron dynamics in surface acoustic wave devices." Thesis, University of Cambridge, 2009. https://www.repository.cam.ac.uk/handle/1810/224176.
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Gallium arsenide is piezoelectric, so it is possible to generate coupled mechanical and electrical surface acoustic waves (SAWs) by applying a high-frequency voltage to a transducer on the surface of GaAs. By combining SAWs with existing low-dimensional nanostructures one can create a series of dynamic quantum dots corresponding to the minima of the travelling electric wave, and each dot carries a single electron at the SAW velocity (~ 2800 m/s). These devices may be of use in developing future quantum information processors, and also offer an ideal environment for probing the quantum mechanical behaviour of single electrons. This thesis describes a numerical and theoretical study of the dynamics ofan electron in a range of geometries. The numerical techniques for solving thetime-dependent Schrödinger equation with an arbitrary time-dependent potential will be described in Chapter 2, and then applied in Chapter 3 to calculate the transmission of an electron through an Aharonov-Bohm (AB) ring. It will be seen that an important property of the techniques used in this thesis is that they can be easily adapted to study realistic geometries, and we will see features in the AB oscillations which do not arise in simplified analytic descriptions. In Chapter 4, we will then study a device consisting of two parallel SAW channels separated by a controllable tunnelling barrier. We will use numerical simulations to investigate the effect of electric and magnetic fields upon the electron dynamics, and develop an analytic model to explain the simulation results. From the model, it will be apparent that it is possible to use this device to rotatethe state of the electron to an arbitrary superposition of the first two eigenstates. We then introduce coherent and squeezed states in Chapter 5, which are ex-cited states of the quantum harmonic oscillator. Coherent and squeezed electronicstates may be of use in quantum information processing, and could also arise dueto unwanted perturbations in a SAW device. We will discuss how these statescan be controllably generated in a SAW device, and also discuss how they couldthen be detected. In Chapter 6 we describe how to use the motion of a SAW to create a rapidly-changing potential in the frame of the electron, leading to a nonadiabatic excita-tion. The nonadiabatically-excited state oscillates from side to side within a 1Dchannel on a few-picosecond timescale, and this motion can be probed by placing a tunnelling barrier at one side of the channel. Numerical simulations will beperformed to show how this motion can be controlled, and the simulation resultswill be seen to be in good agreement with recent experimental work performed by colleagues. Finally, we will show that this device can be used to measure the initial state of an electron which is an arbitrary superposition of the first twoeigenstates.
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Astley, Michael Robert. "Surface-acoustic-wave-defined dynamic quantum dots." Thesis, University of Cambridge, 2008. https://www.repository.cam.ac.uk/handle/1810/261973.
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The strain associated with a surface acoustic wave (SAW) propagating across a piezoelectric medium creates a travelling electric potential. Gallium Arsenide is such a piezoelectric material, and so SAWs can be used with existing semiconductor technologies for creating complex low-dimensional nanostructures. A SAW travelling along an empty quasi-one-dimensional channel creates a series of dynamic quantum dots which can transport electrons at the SAW velocity (∼ 2800 ms−1 ), allowing high-frequency operations to be carried out on the electron without the need for fast pulsed-gate techniques. Such dynamic quantum dot devices can provide valuable insights into fundamental physical phenomena and could have technological applications in quantum information processing. This thesis details investigations into SAW-defined dynamic quantum dot devices. Chapter 1 introduces the scientific background to the experiments described in this thesis; Chapter 2 provides details of the processing and measurement techniques used to perform these experiments. Chapter 3 consists of a study into the effect that reflections have on the acousto-electric current generated in a SAW channel. Reflections create a modulation to the channel entrance potential which is critical in determining the magnitude of the acousto-electric current. As the frequency of the SAW is varied, a particular reflection creates a periodic interference with the main SAW driving the current which can be observed in the Fourier transform of the acousto-electric current’s frequency dependence. The period of these oscillations is directly related to the distance which the reflection has travelled relative to the main SAW, which allows the principle reflection mechanisms to be characterised. Reflections persisted on a SAW device for large amounts of time, giving rise to much of the “noise” seen in the frequency dependence, and the pattern of reflections was found to be chaotic. Chapters 4-8 show the results obtained with a device where two SAW channels were linked by a tunnel barrier. This device allowed quantum mechanical tunnelling of electrons from the dynamic quantum dots to be observed over a subnanosecond timescale. Chapter 5 describes how the escape rates of the electrons from dynamic quantum dots can be measured using a rate equation analysis, and these rates are fit to a simple tunnelling model to derive the addition energies of the dynamic quantum dots. In Chapter 6 the tunnelling current was found to contain low-visibility oscillations, which cannot be explained by simple models. It is thought that these oscillations are caused by the non-adiabatic time-evolution of the electron wave function when the tunnel barrier is lowered suddenly. Chapter 7 shows how a crosstalk current through a short constriction is sensitive to local potential changes in an analogous manner to a quantum point contact, and how this effect can be used to detect the occupation of dynamic quantum dots in a nearby SAW channel. Chapter 8 collects some minor observations which have been made whilst studying the tunnel barrier device. In Chapter 9 I present the conclusions of the experiments presented in this thesis, and provide some ideas for future directions this work may take.
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Du, X. "Surface acoustic wave devices for microfluidic applications." Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.598662.
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This project investigates the use of surface acoustic waves (SAWs) for applications in low cost, low voltage, digital microfluidic systems. To be able to produce surface acoustic waves, the substrate of the microfluidic device needs to be a piezoelectric material. This study explored the use of two different substrates: 128° Y-cut lithium Niobate (LiNbO3) and RF magnetron sputtered Zinc Oxide(ZnO) on Silicon (Si) (100). The SAW device incorporates aluminium InterDigital Transducers (IDTs) on LiNbO3 and ZnO/Si piezoelectric material that acts as an excitation agent to create a surface wave on the substrate. When the signal through the IDT matches the correct frequency, a mechanical wave propagates away from the IDT on the substrate surface. Droplet mixing and movement experiments demonstrate a linear relationship between the applied voltage and droplet movement. Other factors tested are the surface treatment effect on droplet movement and surface temperature effects caused by the SAW mechanical wave. Before droplets could be moved a hydrophobic coating had to be deposited on the surface. The surface coating utilizes the octadecytrichlorosilane (OTS) for both its chemical inertness and bio-compatibility. The OTS coating is smooth and thin and does not effect the propagation of the SAW. The propagation mode of the acoustic wave is determined by the structure of the SAW devices and materials. A higher order harmonic mode wave appears in addition to the fundamental Rayleigh wave for LiNbO3 samples. The Rayleigh mode and higher mode- Sezawa mode can be induced for the ZnO/Si SAW devices. These different wave modes have been utilized to induce streaming and manipulate liquid droplets for microfluidic application.
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Gell, Jennifer Rachel. "Surface-acoustic-wave (SAW) driven light sources." Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599350.
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This thesis concentrates on the interaction between SAWs (surface acoustic wave) and low-dimensional systems studied using optical techniques. In particular SAW-driven luminescence from a lateral p-n junction is demonstrated. The lateral p-n junction is formed by molecular beam epitaxy regrowth on a patterned GaAs substrate. Silicon is used as an amphoteric dopant to create a high mobility two-dimensional electron gas on flat (100) planes and a two-dimensional hole gas on angled (311)A facets. A lateral p-n junction is formed at the interface between these planes. SAWs with a frequency of ~1 GHz are generated using an interdigitated transducer. When a continuous radio frequency (RF) signal is used to excite the transducer, SAW-driven light emission from the p-n junction is demonstrated by peaks in the current/light emission at the resonant frequency of the transducer. To investigate the nature of the luminescence further, short RF pulses are used to drive the transducer. The short pulses temporally isolate the SAW-driven light emission from any emission due unwanted pick-up of the free space electromagnetic wave. In the final section the modulation of the emission energies of a single self-assembled quantum dot by a SAW is investigated. The compression and expansion of the crystal due to the strain wave causes the energy of the dot lines to oscillate around their equilibrium values. The shape of the SAW broadened emission lines was seen to depend on the nature of the transition in the dot offering an alternative way of identifying charged and neutral species in this sample. The modulation of the dot energy levels by the SAW is used to control the time of photon emission from the system.
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Sehra, Gurmukh S. "Surface acoustic wave based flavour sensor system." Thesis, University of Warwick, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.416148.
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Meng, Qingbin. "Surface acoustic wave controlled semiconductor optical source." Thesis, University of Bath, 2009. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.518122.
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A semiconductor optical source monolithically integrated with a surface acoustic wave (SAW) Bragg-cell to operate as a functional device is proposed in this thesis. The practical structure of such an integrated device is demonstrated and design guidelines are presented. Compared with conventional optical beam processed devices, this functional integrated semiconductor optical source (FISOS) is revised to be compact in size, flexible in function and potentially robust in performance. The FISOS is analyzed as two sub-divisions, optical source and acoustic processor, which have the common substrate structure. The optical beams excited from the optical source part of the device undergoes a scattering in the Bragg grating formed by SAWs that are generated by an IDT positioned on top of the acoustic processing part of device. By altering the property (power, frequency, etc.) of the SAW, versatile functionalities such as modulation, filtering, beam steering and so on of the optical beams can be realized in this optical source device.
A multilayer structure based on GaN/InGaN MQWs grown on sapphire is designed for the FISOS to be blue light emitting and efficiently launching SAWs. An etch-down technique employed in the SAW processing part is taken to improve the overlap between the optical and acoustic waves and then the interaction efficiency. Optimizations to the geometrical dimensions of the FISOS, such the width of the ridge waveguide, the position of the IDT and the etching depth, etc., are discussed in the given structure.
Numerical models are investigated to access the operational characteristics and then to provide design guidelines for the proposed integrated device. The Bragg diffraction of optical waves occurring within the acoustic waves in the proposed structure are simulated as a two-dimensional interaction between two guided optical modes and an acoustic surface wave.
The modal distributions and propagation velocities of SAWs in a multilayer system are calculated using Adler’s matrix method. The electrical characteristics of an IDT, such as impedance, insertion loss, electromechanical constant and so on are also discussed.
Transverse and lateral optical modes in the given multilayer structure are analyzed by the transfer matrix method. The interaction of optical waves and acoustic waves are modeled using the rigorous grating diffraction theory. Starting from Floquet’s theory, the well-known coupled-wave method and modal method can both be derived from the rigorous grating diffraction theory. Discussions of some useful approximate methods are also presented. In this thesis, the simulations of the acoustooptic interaction are performed using the coupled-wave method.
From the simulation results, the angular distribution profile and spatial profile of the output of the FISOS are evaluated. An improvement to the expression of the diffraction efficiency in such an integrated device is proposed. The so-called beam diffraction efficiency gives a more complete measure to the acoustooptic diffraction and is used to investigate the features of FISOS different from conventional acoustooptic devices. Contour plots of the beam efficiency varying with acoustic frequency and power in a FISOS is demonstrated to be a convenient and powerful approach in the device design.
The operational performances of an integrated deflector and a modulator in FISOS are analyzed to investigate the feasibility of FISOS. The trade-off of the efficiency-resolution in an integrated deflector design is discussed. Short interaction length, high acoustic frequency and narrow ridge are proved to be helpful for a larger number of resolvable spots with a fairly high efficiency. In the case of the integrated modulator, given that the figure of merit Q is fixed, it is demonstrated that the smaller the Q, the longer the interaction length, larger ridge width and lower acoustic frequency will give rise to a larger bandwidth, though the highest efficiency might appear at a higher frequency.
Some practical issues such as the misalignment of planar elements on the device and the incoherence of the integrated optical source are also discussed. A modified working frequency can be used to compensate the efficiency loss in the former case; in the latter case, it is demonstrated that a distortion of beam diffraction efficiency versus acoustic power with an incoherent optical source arises due to the wide spectrum of the incident optical waves.
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Gizeli, Electra. "New acoustic wave sensor geometries." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282004.
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Bright, Victor M. "Shear horizontal surface acoustic waves." Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/14831.
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Kitabayashi, Hiroyuki. "Surface acoustic wave filters on diamond layered structures /." *McMaster only, 2001.
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Alghane, Mansuor Mohamed. "Surface acoustic wave streaming in a microfluidic system." Thesis, Heriot-Watt University, 2013. http://hdl.handle.net/10399/2645.
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Khalid, Muhammad Arslan. "Engineering surface acoustic wave sensing and diagnostic devices." Thesis, University of Glasgow, 2017. http://theses.gla.ac.uk/30999/.
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Globally, over 50% of deaths occur due to the top 10 global diseases which include cardiovascular disease, cancer and infectious diseases. Low and middle-income countries (LMICs) are disproportionately affected. 80% of all deaths due to non-communicable diseases occur in low and middle income countries and with numbers on the rise. In these disadvantaged and vulnerable populations, diseases are often detected late. The treatment required is therefore increasingly extensive and expensive. Early detection, treatment and monitoring coupled with life-style changes can reduce mortality and morbidity. Many laboratory and clinical diagnostic tests have been developed. However, in order to provide healthcare in resource poor areas near the patient side (point-of-care), portable and low-cost bioanalytical assays are required. Lab-on-a-chip technology has emerged as a contender for point-of-care testing and monitoring but due to the complexity of the systems, there has been limited success in miniaturisation of fully integrated assays. This thesis takes a new approach to make use of existing and readily available mobile technologies to engineer on-chip, integrated, portable and low-cost microfluidic platforms using surface acoustic waves (SAW). The ability of SAW to manipulate fluids has been used to develop therapeutic and sensing devices. In the first application, SAW acoustic streaming was used to mechanically ‘clot’ or ‘solidify’ a droplet of human whole blood containing anti-coagulants in as quickly as 6 seconds. To analyse this mechanical process of a change in state, in small sample volumes, a new method which used light deflection from the surface perturbations was developed which could potentially replace clinical thromboelastography. The higher order acoustic streaming is known to be significantly influenced by a fluid’s viscosity. In a second application, as a proof of concept, it was demonstrated that the drop vibration due to SAW streaming together with the light deflection method can be used to study the relative viscosity response in samples. Furthermore, to aid the development of an integrated digital microfluidics, such as a blood monitoring device, a low cost (~$65) smart-phone based SAW platform prototype has been built using additive manufacturing technologies. Many lab-on-chip devices rely on optical detection such as microscopes. SAW already have shown promise in fluid manipulation and can eliminate the need for external pumps in sample processing. However, optical detection remains a challenge to create truly point-of-care devices. In this thesis, integration of SAW with portable lens-free microscopy that offers a large field of view (FOV) (~30 mm2) is demonstrated. Furthermore, a new method has been proposed for label-free visualisation of waves in fluids and to study their rheological response by analysing the wave relaxation process. This method can potentially be developed into a high-throughput viscosity sensor for disease diagnostics. Finally, by coupling SAW in transmissive superstrates (a low-cost disposable chip), acoustically tuneable nanolenses were created which allowed the detection of sub-micron particles in liquids without super-resolution techniques. As an application of this technique, detection of herpes simplex virus (type I) has been shown. In summary, this thesis presents the potential of SAW through its integration with mobile platforms such as a smartphone or lens-free microscope to engineer label-free, low-cost and high-throughput sensing and testing devices.
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Friedlander, Jeffrey B. "Wireless Strain Measurement with Surface Acoustic Wave Sensors." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1306874020.
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Chiu, Ching-Sang Denner Warren W. "Report on the Office of Naval Research USA-China Conference on Shallow Water Acoustics, December 18-21, 1995." Monterey, CA : Naval Postgraduate School, 1997. http://catalog.hathitrust.org/api/volumes/oclc/37486128.html.
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Reese, Owein. "Homogenization of acoustic wave propagation in a magnetorheological fluid." Link to electronic thesis, 2004. http://www.wpi.edu/Pubs/ETD/Available/etd-0430104-101629.
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Sen, Rahul. "Acoustic scattering by discontinuities in waveguides." Diss., Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/81021.
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The scattering of acoustic waves by boundary discontinuities in waveguides is analyzed using the Method of Matched Asymptotic Expansions (MAE). Existing theories are accurate only for very low frequencies. In contrast, the theory developed in this thesis is valid over the entire range of frequencies up to the first cutoff frequency. The key to this improvement lies in recognizing the important physical role of the cutoff cross-modes of the waveguide, which are usually overlooked. Although these modes are evanescent, they contain information about the interaction between the local field near the discontinuity and the far-field. This interaction has a profound effect on the far-field amplitudes and becomes increasingly important with frequency. The cutoff modes also present novel mathematical problems in that current asymptotic techniques do not offer a rational means of incorporating them into a mathematical description. This difficulty arises from the non-Poincare form of the cross-modes, and its resolution constitutes the second new result of this thesis. We develop a matching scheme based on block matching intermediate expansions in a transform domain. The new technique permits the matching of expansions of a more general nature than previously possible, and may well have useful applications in other physical situations where evanescent terms are important. We show that the resulting theory leads to significant improvements with just a few cross-mode terms included, and also that there is an intimate connection with classical integral methods. Finally, the theory is extended to waveguides with slowly varying shape. We show that the usual regular perturbation analysis of the wave regions must be completely abandoned. This is due to the evanescent nature of the cross-modes, which must be described by a WKB approximation. The pressure field we so obtain includes older results. The new terms account for the cutoff cross-modes of the variable waveguide, which play a central role in extending the dynamic range of the theory.Ph. D.
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Kavalov, Dimitar A. "Surface acoustic wave neural networks for RF signal processing." Thesis, Oxford Brookes University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249406.
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Nash, Geoffrey Richard. "Surface acoustic wave investigations of low dimensional electron systems." Thesis, University of Bath, 1996. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320474.
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Tew, R. "Imaging theory of surface-breaking discontinuities." Thesis, University of Oxford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380008.
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Srinivasan, krishnan. "Nanomaterial sensing layer based surface acoustic wave hydrogen sensors." [Tampa, Fla.] : University of South Florida, 2005. http://purl.fcla.edu/fcla/etd/SFE0001325.
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Tran, Tuan A. "Extrinsic Fabry-Perot interferometer for surface acoustic wave measurement." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-10242009-020318/.
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Blaess, Guido. "Häusung von Surface-acoustic-wave-Sensoren für die Bioanalytik." Karlsruhe : Forschungszentrum Karlsruhe, 2006. http://d-nb.info/983159173/34.
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Schuler, Leo Pius. "Wireless identification and sensing using surface acoustic wave devices." Thesis, University of Canterbury. Electrical Engineering, 2003. http://hdl.handle.net/10092/1081.
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Wireless Surface Acoustic Wave (SAW) devices were fabricated and tested using planar Lithium Niobate (LiNbO₃) as substrate. The working frequencies were in the 180 MHz and 360 MHz range. Using a network analyser, the devices were interrogated with a wireless range of more than 2 metres. Trials with Electron Beam Lithography (EBL) to fabricate SAW devices working in the 2450 MHz with a calculated feature size of 350 nm are discussed. Charging problems became evident as LiNbO₃ is a strong piezoelectric and pyroelectric material. Various attempts were undertaken to neutralise the charging problems. Further investigation revealed that sputtered Zinc Oxide (ZnO) is a suitable material for attaching SAW devices on irregularly shaped material. DC sputtering was used and several parameters have been optimised to achieve the desired piezoelectric effect. ZnO was sputtered using a magnetron sputtering system with a 75 mm Zn target and a DC sputter power of 250 Watts. Several trials were performed and an optimised material has been prepared under the following conditions: 9 sccm of Oxygen and 6 sccm of Argon were introduced during the process which resulted in a process pressure of 1.2x10⁻² mbar. The coatings have been characterised using Rutherford Backscattering, X-ray diffraction, SEM imaging, and Atomic force microscopy. SAW devices were fabricated and tested on 600 nm thick sputtered ZnO on a Si substrate with a working frequency of 430 MHz. The phase velocity has been calculated as 4300m/s. Non-planar samples have been coated with 500 nm of sputtered ZnO and SAW structures have been fabricated on using EBL. The design frequency is 2450 MHz, with a calculated feature size of 1 µm. The surface roughness however prevented a successful lift-off. AFM imaging confirmed a surface roughness in the order of 20 nm. Ways to improve manufacturability on these samples have been identified.
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Schuler, Leo P. "Wireless identification and sensing using surface acoustic wave devices." Thesis, University of Canterbury. Engineering, 2003. http://hdl.handle.net/10092/8565.
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Wireless Surface Acoustic Wave (SAW) devices were fabricated and tested using planar Lithium Niobate (LiNbO₃) as substrate. The working frequencies were in the 180 MHz and 360 MHz range. Using a network analyser, the devices were interrogated with a wireless range of more than 2 metres. Trials with Electron Beam Lithography (EBL) to fabricate SAW devices working in the 2450 MHz with a calculated feature size of 350 nm are discussed. Charging problems became evident as LiNbO₃ is a strong piezoelectric and pyroelectric material. Various attempts were undertaken to neutralise the charging problems.
Further investigation revealed that sputtered Zinc Oxide (ZnO) is a suitable material for attaching SAW devices on irregularly shaped material. DC sputtering was used and several parameters have been optimised to achieve the desired piezoelectric effect.
ZnO was sputtered using a magnetron sputtering system with a 75 mm Zn target and a DC sputter power of 250 Watts. Several trials were performed and an optimised material has been prepared under the following conditions: 9 sccm of Oxygen and 6 seem of Argon were introduced during the process which resulted in a process pressure of 1.2x10⁻² mbar. The coatings have been characterised using Rutherford Backscattering, X-ray diffraction, SEM imaging, and Atomic force microscopy. SAW devices were fabricated and tested on 600 nm thick sputtered ZnO on a Si substrate with a working frequency of 430 MHz. The phase velocity has been calculated as 4300m/s.
Non-planar samples have been coated with 500 nm of sputtered ZnO and SAW structures have been fabricated on using BBL. The design frequency is 2450 MHz, with a calculated feature size of 1 μm. The surface roughness however prevented a successful lift-off. AFM imaging confirmed a surface roughness in the order of 20 nm. Ways to improve manufacturability on these samples have been identified.
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Gates, Michael Richard. "Surface acoustic wave investigations of spin and pseudospin systems." Thesis, University of Nottingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247121.
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Rimsa, Roberts. "Surface acoustic wave microfluidic pumps for on-chip diagnostics." Thesis, University of Leeds, 2018. http://etheses.whiterose.ac.uk/22524/.
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Most of point-of-care diagnostics and lab-on-chip devices that do on-chip sample preparation require active fluid actuation. In a laboratory setting, this is done via bulky benchtop equipment such as syringe pumps, peristaltic pumps and pressure systems. However, integration of a pumping unit onto the device allows for increased portability and decreased footprint of the device. Although there are multiple examples of realised micropumps based on different technologies, no one solution offers a combination of small footprint, low costs, scalable manufacturing and high performance required for point-of-care devices. Surface acoustic wave (SAW)-based micropumps are an exciting alternative to the current micropump systems due their small footprint and simplicity of manufacturing, yet many of the SAW micropumps presented to date suffer from poor performance and/or utilisation of open channels, which can be a problem regarding contamination. The SAW micropump demonstrated here uses a novel planar design and SAW scattering effects to significantly improve the pump performance and maintain closed channels, which is a pre-requisite for point-of-care applications. This thesis evaluates the fabrication of SAW devices and microfluidic channels using soft lithography. After evaluating the SAW device design concerning electrical characteristics both experimentally and theoretically, the first iteration of SAW micropumps utilising SAW momentum along the piezoelectric substrate is presented and characterised in terms of fluid flow velocity profiles and volume flow rates produced. Subsequently, a concept of a more efficient SAW micropump is presented based on out of the plane interaction between SAW and liquid. To fully utilise this interaction a protocol on the development of 3D microfluidic channels is introduced followed by a discussion on SAW-liquid coupling setting the scene for a demonstration of efficient and closed-loop SAW micropump that delivers pressure gradients up to an order of magnitude higher than the best to-date reported values at a similar input power levels. Finally, the newly developed pump is utilised in an on-chip flow cytometer to showcase the advanced flow manipulations, showing the potential applications of the SAW micropump beyond simple fluid actuation.
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Miller, James Henry 1957. "Estimation of sea surface wave spectra using acoustic tomography." Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/44595.
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Thesis (Sc. D.)--Joint Program in Oceanographic Engineering (Massachusetts Institute of Technology, Dept. of Ocean Engineering; and the Woods Hole Oceanographic Institution), 1987.Bibliography: p. 164-171.
Vita.
by James Henry Miller.
Sc.D.
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Srinivasan, Krishnan. "Nanomaterial Sensing Layer Based Surface Acoustic Wave Hydrogen Sensors." Scholar Commons, 2005. https://scholarcommons.usf.edu/etd/873.
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This thesis addresses the design and use of suitable nanomaterials and surface acoustic wave sensors for hydrogen detection and sensing.
Nanotechnology is aimed at design and synthesis of novel nanoscale materials. These materials could find uses in the design of optical, biomedical and electronic devices. One such example of a nanoscale biological system is a virus. Viruses have been given a lot of attention for assembly of nanoelectronic materials. The tobacco mosaic virus (TMV) used in this research represents an inexpensive and renewable biotemplate that can be easily functionalized for the synthesis of nanomaterials. Strains of this virus have been previously coated with metals, silica or semiconductor materials with potential applications in the assembly of nanostructures and nanoelectronic circuits. Carbon nanotubes are another set of well-characterized nanoscale materials which have been widely investigated to put their physical and chemical properties to use in design of transistors, gas sensors, hydrogen storage cells, etc. Palladium is a well-known material for detection of hydrogen. The processes of absorption and desorption are known to be reversible and are known to produce changes in density, elastic properties and conductivity of the film. Despite these advantages, palladium films are known to suffer from problems of peeling and cracking in hydrogen sensor applications. They are also required to be cycled for a few times with hydrogen before they give reproducible responses.
The work presented in this thesis, takes concepts from previous hydrogen sensing techniques and applies them to two nanoengineered particles (Pd coated TMV and Pd coated SWNTs) as SAW resonator sensing materials. Possible sensing enhancements to be gained by using these nanomaterial sensing layers are investigated. SAW resonators were coated with these two different nano-structured sensing layers (Pd-TMV and Pd-SWNT) which produced differently useful hydrogen sensor responses. The Pd-TMV coated resonator responded to hydrogen with nearly constant increases in frequency as compared to the Pd-SWNT coated device, which responded with concentration-dependent decreases in frequency of greater magnitude upon hydrogen exposure. The former behavior is more associated with acousto-electric phenomena in SAW devices and the later with mass loading. The 99% response times were 30-40 seconds for the Pd-TMV sensing layer and approximately 150 seconds for the Pd-SWNT layer. Both the films showed high robustness and reversibility at room temperature. When the Pd film was exposed to hydrogen it was observed that it produced decreases in frequency to hydrogen challenges, conforming to mass loading effect. It was also observed that the Pd film started degrading with repeated exposure to hydrogen, with shifts after each exposure going smaller and smaller.
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Kim, Yoonkee. "Surface acoustic wave propagation in multilayered and multichannel waveguide structures." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/15060.
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Furnell, G. D. "A study of acoustic wave propagation within curved ducting systems /." Title page, table of contents and abstract only, 1989. http://web4.library.adelaide.edu.au/theses/09PH/09phf987.pdf.
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Berry, David Leonard. "Acoustic scattering by near-surface inhomogeneities in porous media." Thesis, Open University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254021.
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Johari, Houri. "Micromachined capacitive silicon bulk acoustic wave gyroscopes." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/31656.
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Thesis (Ph.D)--Mechanical Engineering, Georgia Institute of Technology, 2009.Committee Chair: Dr. Farrokh Ayazi; Committee Co-Chair: Dr. F. Levant Degertekin; Committee Member: Dr. Paul Kohl; Committee Member: Dr. Peter Hesketh; Committee Member: Dr. Suresh K. Sitaraman. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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RUIZ, ALBERTO. "SURFACE ACOUSTIC WAVE VELOCITY MEASUREMENTS ON SURFACE-TREATED METALS BY LASER-ULTRASONIC SPECTROSCOPY." University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1077302192.
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Parmar, Biren Jagadish. "Development Of Point-Contact Surface Acoustic Wave Based Sensor System." Thesis, Indian Institute of Science, 2006. https://etd.iisc.ac.in/handle/2005/279.
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Surface Acoustic Waves (SAW) fall under a special category of elastic waves that need a material medium to propagate. The energy of these waves is confined to a limited depth below the surface over which they propagate, and their amplitudes decay with increasing depth. As a consequence of their being a surface phenomenon, they are easily accessible for transduction. Due to this reason, a lot of research has been carried out in the area, which has resulted in two very popular applications of SAW - SAW devices and in Non-Destructive Testing and Evaluation.
A major restriction of SAW devices is that the SAW need a piezoelectric medium for generation, propagation and reception. This thesis reports the attempt made to overcome this restriction and utilize the SAW on non-piezoelectric substrates for sensing capabilities. The velocity of the SAW is known to be dependent purely on the material properties, specifically the elastic constants and material density. This dependence is the motivation for the sensor system developed in the present work.
Information on the survey of the methods suitable for the generation and reception of SAW on non-piezoelectric substrates has been included in the thesis. This is followed by the theoretical and practical details of the method chosen for the present work - the point source/point receiver method. Advantages of this method include a simple and inexpensive fabrication procedure, easy customizability and the absence of restrictions due to directivity of the SAW generated. The transducers consist of a conically shaped PZT element attached to a backing material. When the piezoelectric material on the transmitter side is electrically excited, they undergo mechanical oscillations. When coupled to the surface of a solid, the oscillations are transferred onto the solid, which then acts as a point source for SAW. At the receiver, placed at a distance from the source on the same side, the received mechanical oscillations are converted into an electrical signal as a consequence of the direct piezoelectric effect. The details of the fabrication and preliminary trials conducted on metallic as well as non-metallic samples are given.
Various applications have been envisaged for this relatively simple sensor system. One of them is in the field of pressure sensing. Experiments have been carried out to employ the acoustoelastic property of a flexible diaphragm made of silicone rubber sheet to measure pressure. The diaphragm, when exposed to a pressure on one side, experiences a varying strain field on the surface. The velocity of SAW generated on the stressed surface varies in accordance with the applied stress, and the consequent strain field generated. To verify the acoustoelastic phenomenon in silicone rubber, SAW velocities have been measured in longitudinal and transverse directions with respect to that of the applied tensile strain. Similar measurements are carried out with a pressure variant inducing the strain. The non-invasive nature of this setup lends it to be used for in situ measurement of pressure.
The second application is in the field of elastography. Traditional methods of diagnosis to detect the presence of sub-epidermal lesions, some tumors of the breast, liver and prostate, intensity of skin irritation etc have been mainly by palpation. The sensor system developed in this work enables to overcome the restrictive usage and occasional failure to detect minute abnormal symptoms. In vitro trials have been conducted on tissue phantoms made out of poly (vinyl alcohol) (PVA-C) samples of varying stiffnesses. The results obtained and a discussion on the same are presented.
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Lin, Xin-Yu, and 林信宇. "Composite Surface Acoustic Wave Substrate." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/80342744786128229150.
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碩士正修科技大學
電子工程研究所
98
The (100) oriented Aluminum nitrogen (AlN) thin films have excellent bulk acoustic wave (BAW) and surface acoustic wave (SAW) properties. In this study, the piezoelectric 64°-YX LiNbO3 substrate was used to fabricate the SAW devices. We also deposited (100) oriented AlN thin film on this lithium niobate (LiNbO3) substrate to form a new composite substrate (AlN/LiNbO3) using reactive radio frequency magnetron sputtering method. The SAW devices were fabricated on the composite substrate and the effects of AlN film thickness on the composite substrate properties have been investigated. The SAW interdigital transducer electrodes were deposited on the top of those substrates by the sputtering and photolithography methods in the process. The network analyzer was used to measure the center frequency and electromechanical coupling coefficient (K2) of the SAW devices. The spectrum analyzer was used to estimate the temperature coefficient of frequency (TCF). The SAW filter fabricated by the LiNbO3 substrate showed the center frequency, TCF and K2 are 45.66 MHz, -62.49 ppm/℃ and 11.07%, respectively. On the other hand, the SAW filter fabricated by the composite substrate with AlN film thickness is 0.5 μm. It is found that center frequency, TCF and K2 are 46.13 MHz, -58.62 ppm/℃ and 9.79%, respectively. When the composite substrate with 1 μm-thickness AlN film, the SAW filter showed the center frequency, TCF and K2 are 46.22MHz, -53.41 ppm/℃ and 7.21%, respectively. The experimented results showed the center frequency, TCF and K2 are 46.39 MHz, -50.11 ppm/℃ and 6.54%, respectively. In this study, AlN thin films were successfully prepared on the LiNbO3 substrate by reactive RF magnetron sputtering method. The results exhibited the composite substrate can increase the SAW velocity, and improve the temperature coefficient of frequency.
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Chiu, Shih-Chuan, and 邱仕釧. "Design of Surface Acoustic Wave Gyroscope." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/5wt3wa.
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碩士國立交通大學
機械工程系所
93
The preliminary design and performance evaluation of a radio frequency MEMS gyroscope, based on a surface acoustic wave resonator (SAWR) and a surface acoustic wave sensor (SAWS) is presented in this work. In addition, the method to convert the transmitted power into exact particle displacement is introduced to predict the sensing resolution of this MEMS gyroscope. Microelectromechanical systems (MEMS) sensors have received more attention over the last decade. They generally have the advantages of being lightweight, small in size, low power consumption and low cost, due to standard IC fabrication techniques. The gyroscopes, operated on the surface acoustic wave, are expected to have a better performance limitations over current MEMS vibratory gyroscope designs, for example, low cost, better robustness and reliability.
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Young, Ming-Sheng, and 楊明昇. "Characteristics of Surface Acoustic Wave Sensor." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/81672173386487190179.
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碩士國立成功大學
電機工程學系
89
This paper is primarily divided into two sections. In section 1, the design and fabrication of IF SAW device are described. In section 2, the sensing property of SAW gas sensor for ethanol vapor is discussed. Based on sensing requirement, the first condition for SAW device design is low insertion loss that promising whole oscillation circuit can work normally. We choose LiNbO3 to be substrate and construct grating reflectors. The insertion loss of SAW device with 30 pairs grating reflections is 4 ~ 4.5dB, and that with 50 pairs grating reflectors is about 3.5dB. By using mass loading effect, SAW device may regard as ethanol vapor density sensor. The response due to changes in the medium density on the SAW transmission path causes transmission velocity change and resonant frequency shift. This is the basic principle of a SAW gas sensor. In order to increase sensitivity, coating stearic acid as sensing film on the transmission path is used. For different film depth, we discuss the responses of resonant frequency shift and find out the optimum. At last, the improvements of sensor system, range and stability are given.
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Wang, Bing-Yu, and 王炳昱. "2.45GHz Surface Acoustic Wave RFID device." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/04739017499281301108.
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碩士國立中興大學
機械工程學系所
100
Currently, surface acoustic radio frequency identification (SAW RFID) tag received increasing attention because of several advantages such as large reliable reading range, low power consumptions, able to operate high temperature range from -40C to 400C and able to be used in harsh environment. One pair of metallic interdigital transducers (IDT) and several reflectors are on the surface of SAW tags. When an electrical signal is applied to IDT, a mechanical acoustic wave will be triggered and transferred to reflector. The time-dependent reflection waves return to IDT, and mechanical waves retransform to AC signals through direct piezoelectric effect. When different patterns of AC signals are measured and recorded, different individual tags will be identified. For SAW RFID tags, the central frequency and number of possible codes are two of most important parameters. In this study, SAW RFID device were operated in high harmonic modes at 2.45GHz. Moreover, encoding scheme was studied to increase the information capacity of SAW tags. In this thesis, the 2.45GHz center frequency of Surface Acoustic Waves Radio Frequency Identification (SAW RFID) tag was developed. The substrate of SAW RFID was 128°Y-X cut Lithium Niobate (LiNbO3) piezoelectric substrate. The width of the IDT and reflectors were designed as 400nm to achieve center frequency of SAW tag as 2.45 GHz. The time position encoding and phase encoding were used to enhance the information capacity of SAW tags. The IDT and reflectors were deposited on the LiNbO3 piezoelectric substrate successfully by E-beam lithography and lift-off technique.
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Pu, Rui Zhen, and 蒲瑞臻. "Study of Diamond Surface Acoustic Wave Filter." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/73906707995566481528.
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碩士國立臺北科技大學
材料及資源工程系碩士班
91
This study have focused on three parts of the diamond surface acoustic wave（SAW）filter, including ultrasonic pulse experiment of material, make smooth diamond thin film, and deposition ZnO thin film. Diamond film and oriented ZnO thin film can be used in high frequency, high power and good temperature stability of SAW filters. Materials study for diamond SAW filter is the objective in this study. First, the elastic properties of materials are determined by ultrasonic pulse experiment. The effects of crystal structure and elastic constant or the acoustic wave echo velocity, in different direction structure and under various acoustic wave, were determined. Results indicated that longitudinal wave velocities in (111) direction of diamond single crystal and diamond thick film are the fastest. The two steps elastic modulus equation derived from elastic modulus, Young’s modulus (1223Gpa) and Bulk modulus (481Gpa), confirmed that (111) face in diamond have the fastest wave velocities. Second, this study investigated the application of diamond thin film by HF-CVD method. The system pressure and CH4/H2 flow rates were fixed in this experiment. The effects of the hot filament distance (15mm, 10mm) and the substrate temperature（700℃, 900℃）on the dimond thin film were performed in order to obtain high flateness and low roughness. The results showed that increasing substrate temperature results in low nucleation, which leads to a large graim and better crystallinality. The average surface roughness（Ra）is 7nm. When the substrate temperature is lower the nucleation is high, which nesults in a smaller grain size and poor crystallinality. The average surface roughness（Ra）is 3nm. Third, this study investigated the ZnO thin film prepared by RF magnetron sputter. Oiriented (002) ZnO thin film was successfully deposited on glass substrate. The results indicated the process parameters（RF power, the ratio of oxygen/argon mass flow）affect the thin film characteristics such as deposition rate, grain size and grain orientation. The optimal conditions for sputtering are 150W of RF power and 1/2 of oxygen/argon mass flow ratio. Under such circumstance, the deposition rate of the film was 0.8μm/hr, and a (002) C-axis oriented columnar grain structure of ZnO film was formed.
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Nian, Yi-Wei, and 粘益維. "Optimal Design of Surface Acoustic Wave Devices." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/5hk358.
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碩士國立臺南大學
材料科學系碩士班
102
This studied plan is to propose an innovated process for fabricating the flexible SAW devices by sol-gel technology and fully ink jet technology. The ZnO solution is prepared by sol-gel technology. We design inter digital transducer (IDT) pattern and deposits ZnO solution on the flexible polyimide plastic (PI) substrate by fully ink jet process. Next, the frequency of SAW device can be measured by the function generator and spectrum analyzer. Here, 7.2MHz is the maximum gain of this device, it will be observed as the SAW center operating frequency. Through the comparison between the predicted value and experimental center frequency, the experimental center frequencies agree with the predicted value. The analysis of surface acoustic wave propagation characteristics is processed by the Finite Element Method (FEM).To discuss various designed parameters affect the central frequency response,and the numerical model will be built for optimization. The electrode thickness is reduced from 1um to 0.5um,and the frequency is raised from 7.2MHz to 7.8MHz . I simulate aluminum nitride (AlN) as piezoelectric materials and the electrode thickness is reduced from 1um to 0.5um,and the frequency is raised from 13.4MHz to 13.9MHz.
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Feng, Yi-Shuo, and 馮顗碩. "A New-Type Surface Acoustic Wave Filter." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/88178144542455205846.
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碩士國立臺灣大學
機械工程學研究所
102
This thesis proposed that if we bond a piezoelectric material on substrate which deposited the electrodes and etched trenches between the electrodes, we can exclude mass and stiffness effect by IDTs (Inter digital transducers) on substrate. Through this method, we can let the SAW propagate on clean and flat piezoelectric material achieves more accurate filtering effect. This method not only eliminates the cost of trimming, but also provides the good protection ability to the filter. First, this thesis chose the ST-cut quartz piezoelectric as material to transfer SAW, and used Z-cut quartz as bottom substrate and build IDTs on its top. Then we etched a trench between the IDTs. Last of all we used SU8-1040 to bond ST-cut quartz and Z-cut quartz together. Through the above method we successfully manufacture a two ports SAW filter by ST-cut quartz. The electrode period is 88μm and the theoretical value of center frequency is 35.8773MHz. The center frequency of the filter with the theoretical error only one-thousandth, and the surface of wave propagation is between two wafers, it will let the filter hermetic packaged directly. By eliminating the step of trimming and extra package, we can develop a low-cost and small SAW filters.
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Chiu, Chun-HO, and 邱俊豪. "A New-Type Surface Acoustic Wave Filter." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/01521144110049783333.
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碩士國立臺灣大學
機械工程學研究所
101
It is proposed that the saw(surface acoustic wave) propagation characteristics in a half–space piezoelectric crystal will change as the depth or duty cycle ratio of the periodic electrodes is tuned. Considering the saw propagation in half-space piezoelectric crystal with periodic electrodes, which are conductors and have mass and stiffness, periodic electrodes affect the saw propagation with the three reasons. Mass and stiffness effects belong to mechanical effects, while being conductors affecting the electric potential of the substrate belongs to electric effects. The behavior of a piezoelectric crystal can be expressed by constitutive equations. Besides, displacement and electric field in a periodic structure are expressed by Floquet Theorem. A general form of saw propagation in a half-space piezoelectric substrate can be expressed by solving the wave equations. The homogeneous solution can be solved by a periodic BVP(boundary value problem), including periodic boundary conditions and electrical boundary conditions. An alternative voltage is given as the input to the IDT(interdigital transducer) in the derivation of the actuator. By the methods described above, the frequency response can be obtained. The frequency corresponding to the peak in the frequency response plot can be tuned by adjusting the depth or duty cycle ratio of the electrodes. The filter part is placed between two transducers, which are one actuator and one receiver. The wavelength of the saw fits the period of the electrode in the filter, so only saw meeting the periodic boundary condition exists. And one can change the selected frequency by adjusting the depth or duty cycle ratio of the electrodes. In the derivation of the saw receiver, the concept of impedance matching is applied. Assumed there is a saw that makes the electric potential difference of the IDT to be 1 volt. The charge density is obtained by integrating electric displacement. And the current can be derived by taking time derivative on the charge density. The impedance can be easily shown by the ratio of voltage difference to the current. The three parts and a pair of extra reflectors are synthesized to be the saw device. All these parts can be adjusted by tuning the depth or duty cycle ratio of the electrodes. Moreover, when it comes to the yield, tuning the duty cycle ratio is preferred due to its easier way in fabrications than tuning the depth.
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Chen, Han-Jan, and 陳漢珍. "An Integrable Surface Acoustic Wave Notch Filter." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/41093301022907822665.
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碩士國立成功大學
微電子工程研究所碩博士班
90
Although Surface Acoustic Wave Notch Filter was investigated in the past, the structures of these devices often needed the extra lumped-element : resistance R、capacitance C and inductance L so that the devices are complex and integrated hardly. From this, we offer a simple planar structure of the SAW notch filters that have smaller size and can be fabricated easily. It has several advantages such as easy-integrated; smaller size and no power dissipation. We adopt the interdigital transducers and delay line to fabricate the SAW notch filter. In this paper, we use an interdigital transducer finger width 8 mm with conventional photolithography process; lift-off technique; piezoelectric materials to fabricate on the 128° rotated YX-cut Lithium Niobate (LiNbO3). Finally, we get the frequency responses of the SAW notch filter: the center frequency 113.4 MHz; the 3dB bandwidth 0.36 %; the insertion loss S21= –10.583 dB.
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Hung, Chia-hsun, and 洪嘉珣. "Study of Broadband Surface Acoustic Wave Antenna." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/34683406321781827716.
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碩士國立臺南大學
電機工程研究所
99
In recent years, antenna developments have been fueled by the rapid development of modern wireless communication systems. In particular, communication products have become an indispensable part of people''s daily lives. An antenna plays the important role in communication systems as it has independent properties that affect the wireless radio frequency (RF) receiver as a whole. In the past, antennas have studied in radar and satellite equipment extensively, so the sizes are very large. Recent portable communication developments in the study of light-weight, compact, rugged, lower cost optical transmitters and receivers. A novel miniaturized broadband surface acoustic wave (SAW) antenna using interdigital transducers (IDTs) and microstrip structure is proposed. The antenna with size of 0.8×1×0.5 cm3 is designed on the piezoelectric materials to fabricate 128°rotated Y-cut lithium niobate (LiNbO3) piezoelectric substrate. The antenna is constructed using four cross-coupled half-wave length square open-loop strips and two 16-m-width interdigital transducers (IDTs) of 42 pairs, utilizing the semiconductor process including lithography and evaporation. The impedance bandwidth (S11 < -10 dB) is achieved over the frequency range from 4.8 to 7 GHz for WLAN/WiMAX bands. This proposed antenna with broadband matched impedance, low cost, easy to manufacture and compact size can be suitable for communication products of WLAN/WiMAX applications.