Download or read book Capacitive Micromachined Ultrasonic Transducers for Non destructive Testing Applications written by Lawrence Lai Pong Wong and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Ultrasound is a popular technique for industrial non-destructive testing (NDT) applications. By sending ultrasonic waves into an object and observing the amplitude and the delay of the reflected or transmitted waves, one can characterize the material, measure the thickness of the object, and detect discontinuities (flaws) as well as the size, location, and orientation of the defects in the object. Traditionally, ultrasonic transducers for NDT are made with piezoelectric crystals. Meanwhile, another class of ultrasonic transducers known as capacitive micromachined ultrasonic transducers (CMUTs) have become popular in medical ultrasound research because of their large bandwidths and other attributes that allow them to be integrated into the tip of a catheter. However, CMUTs have not been widely adopted in ultrasonic NDT applications. In this thesis, three important CMUTs characteristics that could potentially make them attractive for NDT applications are introduced and demonstrated. First, CMUTs can be beneficial to NDT because the fabrication techniques of CMUTs can easily be used to implement high-frequency, high-density phased arrays, which are essential for high resolution scanning. Surface scanning using a 2-D row-column addressed CMUT array was demonstrated. Secondly, CMUTs can be integrated with supporting microelectronic circuits, thus one can implement a highly integrated transducer system, which can be useful in structural health monitoring NDT applications. Front-end microelectronic circuits that include a transmit pulser and a receive amplifier were designed, tested, and characterized. Thirdly, CMUTs are suitable for air-coupled applications because of their low acoustic impedance at resonance. Air-coupled CMUTs fabricated in a standard RF-MEMS process were characterized and tested. This thesis concludes with an analysis of the potential usefulness of CMUTs for ultrasonic NDT. While many ultrasonic NDT applications are better off being performed using conventional piezoelectric transducers, CMUTs can and should be used in certain NDT applications that can take advantage of the beneficial characteristics of this exciting transducer technology.
Download or read book Capacitive Micromachined Ultrasonic Transducers written by Dilruba Zaman Jeba and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Capacitive micromachined ultrasonic transducers (CMUTs) have been developed as an alternative to piezoelectric transducers for ultrasonic imaging in non-destructive testing applications. These CMUTs offer substantial advantages over their piezoelectric counterparts, which include a highly miniaturized system, easy integration with electronic control circuitry, a wider bandwidth, and a higher sensitivity. In this thesis, the design, fabrication and characterization of several single and array CMUT devices are reported. Many sizes of CMUTs, aiming to operate at different resonant frequencies, were fabricated using a PolyMUMPs sacrificial technique. An analytical and finite element model was used to further understanding of the physical behaviour of the transducer. The basic functionality of the CMUT devices was investigated through capacitance and electrical impedance measurements. These devices showed greater change in the capacitance and impedance data while operating close to their collapse voltages. This higher change in both capacitance and impedance is a result of a larger membrane displacement. The acoustic output power is directly related to the magnitude of the membrane's displacement. The transducers performance thus can be enhanced by operating close to their collapse voltage and obtained higher sensitivity. The optical characterization, performed on the single devices and on the 1-D arrays, provided a better understanding of the membrane vibration modes and displacement profiles at different resonant frequency modes. Acoustic measurements were performed to demonstrate the transmission capability of the CMUTs. The generated acoustic signals were detected using a commercial detector. These acoustic experiments demonstrated that these CMUTs can potentially be used as ultrasonic transducers alternative to piezoelectric transducers.
Download or read book Transducers for Ultrasonic Flaw Detection written by V. N. Bindal and published by Alpha Science Int'l Ltd.. This book was released on 1999 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: As a large variety of transducers are required for the current needs of NDT applications, this book gives a consolidated account regarding the basic principles, applications, advantages and limitations, design considerations, materials and methods used for their evaluation and calibration etc. by the technocrats and professionals involved in ultrasonic NDT.
Download or read book Fabrication of Capacitive Micromachined Ultrasonic Transducers Based on Adhesive Wafer Bonding written by Zhenhao Li and published by . This book was released on 2017 with total page 107 pages. Available in PDF, EPUB and Kindle. Book excerpt: Capacitive micromachined ultrasonic transducers (CMUTs) can be used for medical imaging, non-destructive testing or medical treatment applications. It can also be used as gravimetric sensors for gas sensing or immersion bio-sensing. Although various CMUT fabrication methods have been reported, there are still many challenges to address. Conventional fabrication methods can be categorized as either surface micromachining or the wafer bonding method. These methods have design trade-offs and limitations associated with process complexity, structural parameter optimization and wafer materials selection. For example, surface micromachining approaches can suffer from complicated fabrication processes. In addition, structural parameters cannot be fully optimized due to feasibility concerns during fabrication. In contrast, the development of wafer bonding techniques enabled CMUTs to be fabricated in a straightforward way and structural parameters can be easily optimized when compared with a surface micromachining approach. However, the yield of the traditional wafer bonded CMUTs is very sensitive to contaminations and the surface quality at the bonding interface. Although the difficulties of the wafer bonding process are not always reported, they definitely exist for every researcher who wants to fabricate their own CMUTs. As a result, this dissertation work aims to develop a CMUT fabrication process with fewer fabrication constraints, low-cost and low process temperature for CMOS integration. The developed CMUT fabrication processes reported in the thesis applied photosensitive polymer adhesive for wafer bonding in order to make a process with good tolerance to contaminations and defects on the wafer surface, present a wide range of material selection at the bonding interface and require low process temperature (less than 250°C). These features can benefit CMUT fabrication with increased yield better design flexibility and lower cost. Having maximum process temperature of 250°C, the developed processes can also be CMOS compatible. Furthermore, a novel CMUT structure, which can only be achieved by the reported technique, was developed showing more than doubled ultrasound receive sensitivity when compared with conventional CMUT structures. The fabrication processes were developed systematically and the details of process development will be presented in this thesis.
Download or read book Interface Engineering of Capacitive Micromachined Ultrasonic Transducers for Medical Applications written by Der-Song Lin and published by Stanford University. This book was released on 2011 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: Capacitive micromachined ultrasonic transducers (CMUTs), have been widely studied in academia and industry over the last decade. CMUTs provide many benefits over traditional piezoelectric transducers including improvement in performance through wide bandwidth, and ease of electronics integration, with the potential to batch fabricate very large 2D arrays with low-cost and high-yield. Though many aspects of CMUT technology have been studied over the years, packaging the CMUT into a fully practical system has not been thoroughly explored. Two important interfaces of packaging that this thesis explores are device encapsulation (the interface between CMUTs and patients) and full electronic integration of large scale 2D arrays (the interface between CMUTs and electronics). In the first part of the work, I investigate the requirements for the CMUT encapsulation. For medical usage, encapsulation is needed to electrically insulate the device, mechanically protect the device, and maintain transducer performance, especially the access of the ultrasound energy. While hermetic sealing can protect many other MEMS devices, CMUTs require mechanical interaction to a fluid, which makes fulfilling the previous criterion very challenging. The proposed solution is to use a viscoelastic material with the glass-transition-temperature lower than room temperature, such as Polydimethylsiloxane (PDMS), to preserve the CMUT static and dynamic performance. Experimental implementation of the encapsulated imaging CMUT arrays shows the device performance was maintained; 95 % of efficiency, 85% of the maximum output pressure, and 91% of the fractional bandwidth (FBW) can be preserved. A viscoelastic finite element model was also developed and shows the performance effects of the coating can be accurately predicted. Four designs, providing acoustic crosstalk suppression, flexible substrate, lens focusing, and blood flow monitoring using PDMS layer were also demonstrated. The second part of the work, presents contributions towards the electronic integration and packaging of large-area 2-D arrays. A very large 2D array is appealing for it can enable advanced novel imaging applications, such as a reconfigurable array, and a compression plate for breast cancer screening. With these goals in mind, I developed the first large-scale fully populated and integrated 2D CMUTs array with 32 by 192 elements. In this study, I demonstrate a flexible and reliable integration approach by successfully combining a simple UBM preparation technique and a CMUTs-interposer-ASICs sandwich design. The results show high shear strength of the UBM (26.5 g), 100% yield of the interconnections, and excellent CMUT resonance uniformity ([lowercase Sigma] = 0.02 MHz). As demonstrated, this allows for a large-scale assembly of a tile-able array by using an interposer. Interface engineering is crucial towards the development of CMUTs into a practical ultrasound system. With the advances in encapsulation technique with a viscoelastic polymer and the combination of the UBM technique to the TSV fabrication for electronics integration, a fully integrated CMUT system can be realized.
Download or read book New Developments in Ultrasonic Transducers and Their Application to Nondestructive Testing written by J. C. BACON and published by . This book was released on 1961 with total page 1 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ultrasonic Transducers for Nondestructive Testing written by Maurice G. Silk and published by CRC Press. This book was released on 1984-01-01 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Simulation of a Capacitive Micromachined Ultrasonic Transducer with a Parylene Membrane and Graphene Electrodes written by David Sadat and published by . This book was released on 2012 with total page 113 pages. Available in PDF, EPUB and Kindle. Book excerpt: Medical ultrasound technology accounts for over half of all imaging tests performed worldwide. In comparison to other methods, ultrasonic imaging is more portable and lower cost, and is becoming more accessible to remote regions where traditionally no medical imaging can be done. However, conventional ultrasonic imaging systems still rely on expensive PZT-based ultrasound probes that limit broader applications. In addition, the resolution of PZT based transducers is low due to the limitation in hand-fabrication methods of the piezoelectric ceramics. Capacitive Micromachined Ultrasonic Transducers (CMUTs) appears as an alternative to the piezoelectric (PZT) ceramic based transducer for ultrasound medical imaging. CMUTs show better ultrasound transducer design for batch fabrication, higher axial resolution of images, lower fabrication costs of the elements, ease of fabricating large arrays of cells using MEMS fabrication, and the extremely important potential to monolithically integrate the 2D transducer arrays directly with IC circuits for real-time 3D imaging. Currently most efforts on CMUTs are silicon based. Problems with current silicon-based CMUT designs include low pressure transmission and high-temperature fabrication processes. The pressure output from the silicon based CMUTs cells during transmission are too low when compared to commercially available PZT transducers, resulting in relatively blurry ultrasound images. The fabrication of the silicon-based cells, although easier than PZT transducers, still suffers from inevitable high temperature process and require specialized and expensive equipment. Manufacturing at an elevated temperature hinders the capability of fabricating front end analog processing IC circuits, thus it is difficult to achieve true 3D/4D imaging. Therefore novel low temperature fabrication with a low cost nature is needed. A polymer (Parylene) based CMUTs transducer has been investigated recently at UCF and aims to overcome limitations posted from the silicon based counterparts. This thesis describes the numerical simulation work and proposed fabrication steps of the Parylene based CMUT. The issue of transducer cost and pressure transmission is addressed by proposing the use of low cost and low temperature Chemical Vapor Deposition (CVD) fabrication of Parylene-C as the structural membrane plus graphene for the membrane electrodes. This study focuses mainly on comparing traditional silicon-based CMUT designs against the Parylene-C/Graphene CMUT based transducer, by using MEMS modules in COMSOL. For a fair comparison, single CMUT cells are modeled and held at a constant diameter and the similar operational frequency at the structural center. The numerical CMUT model is characterized for: collapse voltage, membrane deflection profile, center frequency, peak output pressure transmission over the membrane surface, and the sensitivity to the change in electrode surface charge. This study took the unique approaches in defining sensitivity of the CMUT by calculating the membrane response and the change in the electrode surface charge due to an incoming pressure wave. Optimal design has been achieved based on the simulation results. In comparison to silicon based CMUTs, the Parylene/Graphene based CMUT transducer produces 55% more in volume displacement and more than 35% in pressure output. The thesis has also laid out the detailed fabrication processes of the Parylene/Graphene based CMUT transducers. Parylene/Graphene based ultrasonic transducers can find wide applications in both medical imaging and Non destructive evaluation (NDE).
Download or read book Ultrasonic Transducers written by K Nakamura and published by Elsevier. This book was released on 2012-08-23 with total page 749 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ultrasonic transducers are key components in sensors for distance, flow and level measurement as well as in power, biomedical and other applications of ultrasound. Ultrasonic transducers reviews recent research in the design and application of this important technology. Part one provides an overview of materials and design of ultrasonic transducers. Piezoelectricity and basic configurations are explored in depth, along with electromagnetic acoustic transducers, and the use of ceramics, thin film and single crystals in ultrasonic transducers. Part two goes on to investigate modelling and characterisation, with performance modelling, electrical evaluation, laser Doppler vibrometry and optical visualisation all considered in detail. Applications of ultrasonic transducers are the focus of part three, beginning with a review of surface acoustic wave devices and air-borne ultrasound transducers, and going on to consider ultrasonic transducers for use at high temperature and in flaw detection systems, power, biomedical and micro-scale ultrasonics, therapeutic ultrasound devices, piezoelectric and fibre optic hydrophones, and ultrasonic motors are also described. With its distinguished editor and expert team of international contributors,Ultrasonic transducers is an authoritative review of key developments for engineers and materials scientists involved in this area of technology as well as in its applications in sectors as diverse as electronics, wireless communication and medical diagnostics. Reviews recent research in the design and application of ultrasonic transducers Provides an overview of the materials and design of ultrasonic transducers, with an in-depth exploration of piezoelectricity and basic configurations Investigates modelling and characterisation, applications of ultrasonic transducers, and ultrasonic transducers for use at high temperature and in flaw detection systems
Download or read book Ultrasound in Food Processing written by Mar Villamiel and published by John Wiley & Sons. This book was released on 2017-05-08 with total page 503 pages. Available in PDF, EPUB and Kindle. Book excerpt: Part I: Fundamentals of ultrasound This part will cover the main basic principles of ultrasound generation and propagation and those phenomena related to low and high intensity ultrasound applications. The mechanisms involved in food analysis and process monitoring and in food process intensification will be shown. Part II: Low intensity ultrasound applications Low intensity ultrasound applications have been used for non-destructive food analysis as well as for process monitoring. Ultrasonic techniques, based on velocity, attenuation or frequency spectrum analysis, may be considered as rapid, simple, portable and suitable for on-line measurements. Although industrial applications of low-intensity ultrasound, such as meat carcass evaluation, have been used in the food industry for decades, this section will cover the most novel applications, which could be considered as highly relevant for future application in the food industry. Chapters addressing this issue will be divided into three subsections: (1) food control, (2) process monitoring, (3) new trends. Part III: High intensity ultrasound applications High intensity ultrasound application constitutes a way to intensify many food processes. However, the efficient generation and application of ultrasound is essential to achieving a successful effect. This part of the book will begin with a chapter dealing with the importance of the design of efficient ultrasonic application systems. The medium is essential to achieve efficient transmission, and for that reason the particular challenges of applying ultrasound in different media will be addressed. The next part of this section constitutes an up-to-date vision of the use of high intensity ultrasound in food processes. The chapters will be divided into four sections, according to the medium in which the ultrasound vibration is transmitted from the transducers to the product being treated. Thus, solid, liquid, supercritical and gas media have been used for ultrasound propagation. Previous books addressing ultrasonic applications in food processing have been based on the process itself, so chapters have been divided in mass and heat transport, microbial inactivation, etc. This new book will propose a revolutionary overview of ultrasonic applications based on (in the authors’ opinion) the most relevant factor affecting the efficiency of ultrasound applications: the medium in which ultrasound is propagated. Depending on the medium, ultrasonic phenomena can be completely different, but it also affects the complexity of the ultrasonic generation, propagation and application. In addition, the effect of high intensity ultrasound on major components of food, such as proteins, carbohydrates and lipids will be also covered, since this type of information has not been deeply studied in previous books. Other aspects related to the challenges of food industry to incorporate ultrasound devices will be also considered. This point is also very important since, in the last few years, researchers have made huge efforts to integrate fully automated and efficient ultrasound systems to the food production lines but, in some cases, it was not satisfactory. In this sense, it is necessary to identify and review the main related problems to efficiently produce and transmit ultrasound, scale-up, reduce cost, save energy and guarantee the production of safe, healthy and high added value foods.
Download or read book Air coupled Capacitive Micromachined Ultrasonic Transducers Based on Annular Cell Geometry written by Shuai Na and published by . This book was released on 2017 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt: Air-coupled ultrasound is gaining increasing industry momentum due to the demands and development of non-destructive evaluation (NDE) of aerospace composite materials. Currently, the micromachining technology has advanced such that vacuum cavities sealed by thin plates, known as Capacitive Micromachined Ultrasonic Transducers (CMUTs), can be fabricated through silicon micromachining processes in a low cost manner. Given the thin plates, a CMUT is able to vibrate with a low mechanical impedance and thus a high coupling efficiency with the ambient atmosphere. Nevertheless, air-coupled applications are still highly limited by the transmit power of air-coupled CMUTs. A circle is the routine geometry in most CMUT cell designs. Even though efforts have been put forward to address the limitations of circular design in terms of sensitivity, more investigation about other cell geometries is prudent. In this work, a novel air-coupled CMUT design with annular cell geometry is proposed. Finite element analysis and experimental studies demonstrated its significant improvement in transmit efficiency over the conventional circular-cell CMUTs. A lumped element model was constructed to facilitate a better understanding and provide an efficient design technique of the annular CMUT. Three optimization schemes were developed to optimize the transmit efficiency and achieve a reasonable comparison between the novel annular and conventional circular CMUT cells. Based on the lumped models, a design optimization flow chart was constructed to facilitate the analytical optimization of the three schemes. To further enhance the transmit power as well as offer depth focusing, a 9-element concentric annular-cell array was designed, fabricated, and characterized. A pillar-free etching process was developed to create the deep large-area cavities. The cross-talk between neighbouring cells and the plate-cracking phenomenon were discussed with suggestions for improvement being provided. This study provides a systematic framework for designing and studying annular-cell CMUTs and demonstrates their great potential in transmitting high-power ultrasound in air.
Download or read book Ultrasonics written by Dale Ensminger and published by CRC Press. This book was released on 2024-02-21 with total page 904 pages. Available in PDF, EPUB and Kindle. Book excerpt: Updated, revised, and restructured to reflect the latest advances in science and applications, the fourth edition of this best-selling industry and research reference covers the fundamental physical acoustics of ultrasonics and transducers, with a focus on piezoelectric and magnetostrictive modalities. It then discusses the full breadth of ultrasonics applications involving low power (sensing) and high power (processing) for research, industrial, and medical use. This book includes new content covering computer modeling used for acoustic and elastic wave phenomena, including scattering, mode conversion, transmission through layered media, Rayleigh and Lamb waves and flexural plates, modern horn design tools, Langevin transducers, and material characterization. There is more attention on process monitoring and advanced nondestructive testing and evaluation (NDT/NDE), including phased array ultrasound (PAUT), long-range inspection, using guided ultrasonic waves (GUW), internally rotary inspection systems (IRIS), time-of-flight diffraction (TOFD), and acoustic emission (AE). These methods are discussed and applied to both metals and nonmetals using illustrations in various industries, including now additionally for food and beverage products. The topics of defect sizing, capabilities, and limitations, including the probability of detection (POD), are introduced. Three chapters provide a new treatment of high-power ultrasonics, for both fluids and solids, and again, with examples of industrial engineering, food and beverage, pharmaceuticals, petrochemicals, and other process applications. Expanded coverage is given to medical and biological applications, covering diagnostics, therapy, and, at the highest powers, surgery. Key Features Provides an overview of fundamental analysis and transducer technologies needed to design and develop both measurement and processing systems Considers applications in material characterization and metrology Covers ultrasonic nondestructive testing and evaluation and high-power ultrasonics, which involves interactions that change the state of material Highlights medical and biomedical applications of ultrasound, focusing on the physical acoustics and the technology employed for diagnosis, therapy, surgery, and research This book is intended for both the undergraduate and graduate scientists and engineers, as well as the working professional, who seeks to understand the fundamentals together with a holistic treatment of the field of ultrasonics and its diversity of applications.
Download or read book Ultrasonic Transducers Design and Application written by D A Hutchins and published by . This book was released on 1992-08-01 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Micromachined Ultrasonic Transducers written by Butrus T. Khuri-Yakub and published by . This book was released on 2005-11-01 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt: The aim of this book is to teach the design and construction of micromachined ultrasonic transducers, an area rapidly increasing in popularity, and contrast and compare these transducers to each other and to traditional piezoelectric transducers. Micromachined ultrasonic transducers are gaining wide acceptance because of the use of silicon micromachining for their manufacture. This also enables capabilities of these transducers that outperform piezoelectric transducers and enable configurations that are practically impossible otherwise. This book teaches the principles of operations of micromachined ultrasonic transducers. The theory of their operation and the technology of their manufacturing will be discussed and compared to that of traditional piezoelectric transducers. Specific to the field of ultrasonic transducers, Micromachined Ultrasonic Transducers is directed at the communities that use ultrasound in the frequency range of kHz to many MHz for use in airborne and immersion applications.
Download or read book Piezoelectric Micromachined Ultrasound Transducers for Air coupled Applications written by Stefon Eric Shelton and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Ultrasound transducers are used for many applications including medical imaging, non-destructive testing, obstruction detection, flow sensing, and gesture recognition. Piezoelectric micromachined ultrasound transducers (PMUTs) offer an attractive alternative to traditional bulk piezoelectric ultrasonic sensors, due to their compact size, increased transduction efficiency, and integrated array configuration. In this work, the development of aluminum nitride PMUTs for air coupled use is presented. The transducer consists of a circular composite diaphragm actuated using an aluminum nitride piezoelectric layer. An equivalent circuit model for a single clamped plate PMUTs has been developed and the design equations are presented and compared with finite element method simulations and measured values. The use of an acoustic resonator tube to boost the output pressure and increase the bandwidth of micro-scale transducers is demonstrated. The developed fabrication process for AlN PMUTs is presented. Clamped plate transducers operating from 100-300 kHz are characterized in the mechanical, electrical, and acoustic domains. The output pressure of the transducers at 5 cm is 90 mPa/V and the receive sensitivity is 0.8 mV/Pa. A flexurally suspended design with increased linearity and a piston-like mode shape is presented and the effect of perforations in the membrane surface determined. Finally, fabrication of PMUT arrays and sources of frequency mismatch, including geometric and the effects of residual stress are discussed. Through process improvements, across-die frequency matching of 1.5% is achieved which is well within the 6.6% fractional bandwidth of the transducer. The array acoustic performance is quantified and the on axis pressure is found to increase linearly with the number of exited elements and the beam-width of a 2D array is 20°.
Download or read book Novel Applications of Capacitive Micromachined Ultrasonic Transducers written by and published by . This book was released on 2007 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt:
