Download or read book The Design Fabrication and Characterization of Capacitive Micromachined Ultrasonic Transducers for Imaging Applications written by Andrew Stephan Logan and published by . This book was released on 2010 with total page 155 pages. Available in PDF, EPUB and Kindle. Book excerpt: Capacitive micromachined ultrasonic transducers (CMUTs) have proven themselves to be excellent candidates for medical ultrasonic imaging applications. The use of semiconductor fabrication techniques facilitates the fabrication of high quality arrays of uniform cells and elements, broad acoustic bandwidth, the potential to integrate the transducers with the necessary electronics, and the opportunity to exploit the benefits of batch fabrication. In this thesis, the design, fabrication and testing of one- and two-dimensional CMUT arrays using a novel wafer bonding process whereby the membrane and the insulation layer are both silicon nitride is reported. A user-grown insulating membrane layer avoids the need for expensive SOI wafers, permits optimization of the electrode size, and allows more freedom in selecting the membrane thickness, while also enjoying the benefits of wafer bonding fabrication. Using a row-column addressing scheme for an NxN two-dimensional array permits three-dimensional imaging with a large reduction in the complexity of the array when compared to a conventional 2D array with connections to all N2 elements. Only 2N connections are required and the image acquisition rate has the potential to be greatly increased. A simplification of the device at the imaging end will facilitate the integration of a three-dimensional imaging CMUT array into either an endoscope or catheter which is the ultimate purpose of this research project. To date, many sizes of transducers which operate at different frequencies have been successfully fabricated. Initial characterization in terms of resonant frequency and, transmission and reception in immersion has been performed on most of the device types. Extensive characterization has been performed with a linear 32 element array transducer and a 32x32 element row-column transducer. Two- and three-dimensional phased array imaging has been demonstrated.

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 Design Fabrication and Characterization of Ultrasound Transducers and Arrays for Biomedical Imaging and Therapy written by Huaiyu Wu and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Capacitive Micromachined Ultrasonic Transducers with Substrate embedded Springs written by Byung Chul Lee and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: After the first capacitive micromachined ultrasonic transducer (CMUT) was invented in 1994, it became one of the candidate technologies to advance the state-of-the-art of medical ultrasound imaging. Benefiting from its fabrication technique based on the semiconductor industry, CMUT technology has broadened the medical and therapeutic applications such as real-time volumetric ultrasound imaging, catheter-based forward-looking intravascular ultrasound (IVUS), photoacoustic imaging, high-intensity focused ultrasound (HIFU) and so on. In spite of many advantages, however, CMUT technology has been criticized with its relatively low transmit sensitivity (~10 kPa/V) or low average volume displacement efficiency (0.1 nm/V) as well as large drive and bias voltage requirements (in a range of a few hundreds of volts). In order to resolve these issues and open up new potential of clinical applications, this dissertation describes the design, fabrication, and system implementation of CMUTs with substrate-embedded springs, so-called post-CMUT (PCMUT). Since PCMUT structure resembles an ideal piston transducer, the improvements in performance mainly stem from the higher average displacement of the top plate for a given gap height. The overview of the first generation PCMUT is introduced and two main issues in simulation and fabrication aspects of the first generation PCMUT is discussed. To further improve the PCMUT device, a 3D finite element analysis (FEA) model of the PCMUT is demonstrated to predict the performance of the first generation PCMUT. In addition, the design guideline of the second generation PCMUT is proposed for achieving the maximum fractional bandwidth (100 %) as well as with the highest transmit sensitivity (~28 kPa/V). The second generation PCMUT is fabricated by using three combination MEMS processes: usage of two silicon-on-insulator (SOI) wafers, wafer bonding process, and wafer polishing process. The second generation PCMUT achieves high transmit sensitivity (~21 kPa/V) or large average volume displacement efficiency (1.1 nm/V) with a low bias voltage (55 V). Compared to a commercial piezoelectric transducer, the second generation PCMUT improves 2.75 times of the maximum output pressure and 5.25 times of the average volume displacement efficiency with respect to the same voltage. After fabrication and performance characterization of the second generation PCMUT, this dissertation demonstrates the feasibility of PCMUT to use it in medical imaging system by integrating PCMUT with a custom-built integrated circuit (IC). Photoacoustic imaging is also presented for one of its application examples.

Download or read book Micromachined Ultrasonic Transducers written by and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Microfabricated ultrasonic transducers have been generated which operate in both liquids and gases. Air coupled through transmission of aluminum was observed for the first time using a pair of 2.3 MHz transducers. The dynamic range of the transducers was 110 dB, and the received signal had an SNR of 30 dB. Air coupled through transmission of steel and glass has also been observed. A theoretical model for the transducers has been refined and agrees well with experimental results. A robust microfabrication process has been developed and was used to generate air transducers which resonate from 2 to 12 MHz, as well as immersion transducers that operate in water from 1 to 20 MHz with a 60 dB dynamic range. Optimized immersion and air transducers have been designed and a dynamic range above 110 dB is anticipated. This development effort finds applications in hydrophones, medical ultrasound, nondestructive evaluation, ranging, flow metering, and scanning tip force sensing and lithography.

Download or read book Design Fabrication and Analysis of a Micromachined Ultrasonic Transducer written by Michael George Pollack and published by . This book was released on 1998 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Design Fabrication and Characterization of Micromachined Piezoelectric T beam Transducers written by Zheqian Zhang and published by . This book was released on 2010 with total page 83 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Piezoelectric and Acoustic Materials for Transducer Applications written by Ahmad Safari and published by Springer Science & Business Media. This book was released on 2008-09-11 with total page 483 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book discusses the underlying physical principles of piezoelectric materials, important properties of ferroelectric/piezoelectric materials used in today’s transducer technology, and the principles used in transducer design. It provides examples of a wide range of applications of such materials along with the appertaining rationales. With contributions from distinguished researchers, this is a comprehensive reference on all the pertinent aspects of piezoelectric materials.

Download or read book Flexible Two dimensional Ultrasonic Transducer Array written by Vishal Kulkarni and published by . This book was released on 2012 with total page 67 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book MEMS Technology for Biomedical Imaging Applications written by Qifa Zhou and published by MDPI. This book was released on 2019-10-23 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt: Biomedical imaging is the key technique and process to create informative images of the human body or other organic structures for clinical purposes or medical science. Micro-electro-mechanical systems (MEMS) technology has demonstrated enormous potential in biomedical imaging applications due to its outstanding advantages of, for instance, miniaturization, high speed, higher resolution, and convenience of batch fabrication. There are many advancements and breakthroughs developing in the academic community, and there are a few challenges raised accordingly upon the designs, structures, fabrication, integration, and applications of MEMS for all kinds of biomedical imaging. This Special Issue aims to collate and showcase research papers, short commutations, perspectives, and insightful review articles from esteemed colleagues that demonstrate: (1) original works on the topic of MEMS components or devices based on various kinds of mechanisms for biomedical imaging; and (2) new developments and potentials of applying MEMS technology of any kind in biomedical imaging. The objective of this special session is to provide insightful information regarding the technological advancements for the researchers in the community.

Download or read book Design Fabrication and Characterization of High Frequency Ultrasound Transducers written by Nithin Jose and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Capacitive Micromachined Ultrasonic Transducers CMUTs for Therapeutic Applications written by Hyo-Seon Yoon and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: High-intensity focused ultrasound (HIFU) is a noninvasive method to treat a variety of diseases. Most of the HIFU machines in clinic typically consist of a piezoelectric transducer array and an imaging system for temperature monitoring and anatomical location guidance. One of the limitations of piezoelectric transducers is self-heating, which requires cooling systems to protect both transducers and patients. Capacitive micromachined ultrasonic transducers (CMUTs) are another type of transducers fabricated with silicon micromachining. CMUTs are promising candidates as therapeutic transducers, as they experience a lot less self-heating compared to piezoelectric transducers. This dissertation mainly focuses on describing the design, simulation, fabrication, characterization, and experimental results of CMUTs for HIFU applications. Single-element transducers are fabricated using local oxidation of silicon (LOCOS)-wafer-bonding process. The measurement part compares the self-heating of a PZT and a CMUT, and discusses the charging issue of CMUTs. Geometric focusing using multiple single-element CMUTs is also demonstrated. The fabrication of 1-D CMUT arrays to enhance the output pressure for HIFU applications is discussed. Higher output pressure of a CMUT cell can be achieved by adding one extra fabrication step to the existing fabrication process. Two-dimensional transducer arrays are required for electronic focusing and beam steering. An 8-channel continuous wave (CW) excitation system is developed to drive a 2-D CMUT array. This 8-channel system minimizes the system complexity without significant loss of focusing capability, compared to a full system with hundreds to thousands of channels. The first successful 2-D CMUT array fabricated using the thick-buried-oxide (BOX) process is presented. The breakdown issue of the insulation layer observed in the test stage is investigated as well. Another type of 2-D CMUT array fabricated using the sacrificial-release process is also tested for HIFU applications. Using the 8-channel CW excitation system, the 2-D CMUT array has proven to be able to produce enough output pressure for thermal ablation. This dissertation presents the result of ex-vivo experiments, which created thermal lesions on bovine tissue using a CMUT array for the first time.

Download or read book Modeling Design and Characterization of Capacitive Micromachined Ultrasonic Transducers CMUTs written by Alessandro Caronti and published by . This book was released on 2003 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Design and Analysis of Capacitive Micromachined Ultrasonic Transducers written by Kendalle Alexia Howard and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Currently, capacitive micromachined ultrasonic transducers (CMUTs) have emerged as an alternative to the well-established piezoelectric micromachined ultrasonic transducers (PMUTs). The micromachining technology has attracted MEMS researchers to assess the capabilities of CMUT devices to be introduced in various ultrasonic imaging applications. This thesis develops design characterization and simulations for square, hexagon, and circular CMUT cell structures to determine an ideal structure for operating CMUT applications. CMUT cells will be analytically modeled and simulated by Finite Element Modeling (FEM) using COMSOL Multiphysics to highlight the factors influencing the acoustic pressure output maximization. Based on the preliminary results, the hexagon membrane has the highest array packaging density while the more flexible circular membrane has the least amount of stress to operate. This research introduces factors significant for determining the CMUT design for applications with operating frequency ranges of approximately 1.5 MHz.

Download or read book Design and Characterization of Capacitive Micromachined Ultrasonic Transducers Using Finite Element Modeling written by Bradley John Kirchmayer and published by . This book was released on 2006 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 Characterization of Multiple Moving Membrane Capacitive Micromachined Ultrasonic Transducer written by Md. Iftekharul Islam and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A newly developed multiple moving membrane capacitive micromachined ultrasonic transducer (M3-CMUT) is fabricated and characterized in this thesis. Unlike the single vibrating membrane in the conventional capacitive micromachined ultrasonic transducer (CMUT), the novel design involves two deflectable membranes suspended over a fixed bottom electrode. In the presence of bias, both of the membranes deflect simultaneously, which results in a smaller cavity compared to a CMUT. To understand the basics of a capacitive transducer, an equivalent mass-spring-capacitor model of CMUT was reported. The results of this analytical model were used to develop the finite element models (FEM) of CMUT and more complex M3-CMUT in COMSOL Multiphysics software. The electromechanical analysis of these models was conducted to observe their operating conditions. Following the modeling and analysis, several single-cell, 1-D, and 2-D arrays of these devices were fabricated using PolyMUMPs technology, a sacrificial fabrication technique for the MEMS transducers. The electrical and acoustic characterizations of the fabricated devices were performed to measure the actual transducer properties. The measured data and the model results were found to be in good agreement. It was observed from the electrical impedance measurements that a higher membrane deflection was achieved in the double membrane device. The reduction in the cavity of M3-CMUT enhanced the sensitivity of the transducer. The acoustic characterization using a pitch-catch experimental setup demonstrated that the novel M3-CMUT could be used as an ultrasonic transducer. The velocity and attenuation of the acoustic waves, when the transducer used as both the transmitter and the receiver, were found to be very close to the theoretical value.