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Gao B, Zhang S, He C, Wang R, Yang Y, Jia L, Wang Z, Wu Y, Hu S, Zhang W. Research on Broadband Matching Method for Capacitive Micromachined Ultrasonic Transducers Based on PDMS/TiO 2 Particles. MICROMACHINES 2022; 13:1827. [PMID: 36363848 PMCID: PMC9695076 DOI: 10.3390/mi13111827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Revised: 10/23/2022] [Accepted: 10/23/2022] [Indexed: 06/16/2023]
Abstract
The study of impedance matching between a transducer and its working medium is an important part of acoustic transducer design. The traditional quarter wavelength matching (Q-matching) scheme is not suitable for broadband capacitive micromachined ultrasonic transducers. To mitigate this issue, a 0-3 composite broadband matching layer based on polydimethylsiloxane (PDMS) substrate/TiO2 particles is designed to achieve electrical insulation and efficient acoustic energy transfer of underwater capacitive micromachined ultrasonic transducer (CMUT) devices. In this work, the coherent potential approximation model is used to analyze the properties of 0-3 composite materials. Samples are prepared for performance testing to determine the proportion of TiO2 particles that enable the 0-3 composite materials to have the same longitudinal acoustic impedance as water. The CMUT device is packaged by a spin coating and pouring process, and its performance tests are carried out. The experimental results show that the central frequency of the transducer remains at 1.74 MHz, the -6 dB fractional bandwidth increases from 97.3% to 100.3%, the 3 dB directional main beam width increases from 8.3° to 10.3°, the side lobes decrease significantly, and the device has good reception sensitivity. These values imply that the 0-3 composite material has good matching performance, and this matching scheme has the advantages of high efficiency and wide bandwidth. This broadband matching method endows CMUTs with great advantages in underwater detection systems, and it facilitates underwater ultrasonic imaging of CMUT.
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Affiliation(s)
- Bizhen Gao
- State Key Laboratory of Dynamic Measurement Technology, School of Instrumentand Electronics, North University of China, Taiyuan 030051, China
| | - Sai Zhang
- State Key Laboratory of Dynamic Measurement Technology, School of Instrumentand Electronics, North University of China, Taiyuan 030051, China
- Department of Physics, The Institute of Ultrasonic Testing, Jiangsu University, Zhenjiang 212013, China
| | - Changde He
- State Key Laboratory of Dynamic Measurement Technology, School of Instrumentand Electronics, North University of China, Taiyuan 030051, China
| | - Renxin Wang
- State Key Laboratory of Dynamic Measurement Technology, School of Instrumentand Electronics, North University of China, Taiyuan 030051, China
| | - Yuhua Yang
- State Key Laboratory of Dynamic Measurement Technology, School of Instrumentand Electronics, North University of China, Taiyuan 030051, China
| | - Licheng Jia
- State Key Laboratory of Dynamic Measurement Technology, School of Instrumentand Electronics, North University of China, Taiyuan 030051, China
| | - Zhihao Wang
- State Key Laboratory of Dynamic Measurement Technology, School of Instrumentand Electronics, North University of China, Taiyuan 030051, China
| | - Yang Wu
- State Key Laboratory of Dynamic Measurement Technology, School of Instrumentand Electronics, North University of China, Taiyuan 030051, China
| | - Shumin Hu
- State Key Laboratory of Dynamic Measurement Technology, School of Instrumentand Electronics, North University of China, Taiyuan 030051, China
| | - Wendong Zhang
- State Key Laboratory of Dynamic Measurement Technology, School of Instrumentand Electronics, North University of China, Taiyuan 030051, China
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Khan TM, Taşdelen AS, Yilmaz M, Atalar A, Köymen H. High-Intensity Airborne CMUT Transmitter Array With Beam Steering. JOURNAL OF MICROELECTROMECHANICAL SYSTEMS 2020; 29:1537-1546. [DOI: 10.1109/jmems.2020.3026094] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Affiliation(s)
- Talha Masood Khan
- Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, Turkey
| | - Akif Sinan Taşdelen
- Bilkent University Acoustic and Underwater Technologies Research Center (BASTA), Bilkent University, Ankara, Turkey
| | - Mehmet Yilmaz
- Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, Turkey
| | - Abdullah Atalar
- National Nanotechnology Research Center (UNAM), Bilkent University Acoustic and Underwater Technologies Research Center (BASTA), Bilkent University, Ankara, Turkey
| | - Hayrettin Köymen
- National Nanotechnology Research Center (UNAM), Bilkent University Acoustic and Underwater Technologies Research Center (BASTA), Bilkent University, Ankara, Turkey
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Gerardo CD, Cretu E, Rohling R. Fabrication and testing of polymer-based capacitive micromachined ultrasound transducers for medical imaging. MICROSYSTEMS & NANOENGINEERING 2018; 4:19. [PMID: 31057907 PMCID: PMC6220174 DOI: 10.1038/s41378-018-0022-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 04/04/2018] [Accepted: 05/14/2018] [Indexed: 05/04/2023]
Abstract
The ultrasonic transducer industry is dominated by piezoelectric materials. As an emerging alternative, capacitive micromachined ultrasound transducers (CMUTs) offer wider bandwidth, better integration with electronics, and ease of fabricating large arrays. CMUTs have a sealed cavity between a fixed electrode and a suspended metalized membrane. Manufacturing cost and sensitivity are limiting factors in current CMUTs that depend on the fabrication equipment and, especially, on the materials used. For widespread use of CMUTs, a much lower fabrication cost that uses inexpensive materials, which maintain or improve upon existing sensitivity, is needed. Herein, a new fabrication process is described for polymer-based CMUTs (polyCMUTs) using the photopolymer SU-8 and Omnicoat. The first ultrasound B-mode image of a wire phantom created with a 64-element linear array using synthetic aperture beamforming techniques is presented. A 12 V AC signal superimposed on a 10 VDC signal was used on the transmission side, and only a bias-tee, with no amplifiers, was used on the receiving side. The low operational voltage and high sensitivity of this device can be partially attributed to a pre-biasing condition on the membrane. By using a novel sacrificial layer combined with a top electrode embedded inside the membrane, we demonstrated that SU-8 can be used to manufacture CMUTs inexpensively. Moreover, the fabrication used relatively simple equipment, and the number of fabrication steps was reduced compared to traditional CMUT fabrication. This new fabrication process has the potential to increase the use of CMUTs in the ultrasound market, including the market for wearable transducers.
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Affiliation(s)
- Carlos D. Gerardo
- Department of Electrical and Computer Engineering, University of British Columbia, 2332 Main Mall, Vancouver, BC Canada
| | - Edmond Cretu
- Department of Electrical and Computer Engineering, University of British Columbia, 2332 Main Mall, Vancouver, BC Canada
| | - Robert Rohling
- Department of Electrical and Computer Engineering, University of British Columbia, 2332 Main Mall, Vancouver, BC Canada
- Department of Mechanical Engineering, University of British Columbia, 6250 Applied Science Ln, Vancouver, BC Canada
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Bayram B. Radiation impedance study of a capacitive micromachined ultrasonic transducer by finite element analysis. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2015; 138:614-623. [PMID: 26328680 DOI: 10.1121/1.4923361] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
In this study, radiation impedance of a capacitive micromachined ultrasonic transducer composed of square-shaped membranes arranged in m × m configuration (m = 1 - 5) is investigated using finite element analysis (FEA) of a commercially available software package(ANSYS). Radiation impedance is calculated for immersed membranes operating in conventional and collapse modes. Individual membrane response within the multi-membrane configuration is analyzed, and excited modes and their effects on radiation impedance and the pressure spectra are reported. This FEA provides an accurate behavior of the acoustic coupling of a thin membrane in a multi-membrane configuration, and extends above the anti-resonance frequency. The first resonance frequency of the membrane is excited for m × m (m ≥ 3) configuration in conventional mode and for m × m (m ≥ 2) configuration in collapse mode. Therefore, this frequency is determined to be responsible for the adverse effects observed in radiation impedance and pressure spectrum. A membrane configuration, which is missing the central membrane from the full m × m configuration is proposed, and is investigated with the FEA. This study is beneficial for the design of precise transducers suited for biomedical applications.
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Affiliation(s)
- Baris Bayram
- Department of Electrical and Electronics Engineering, Middle East Technical University, Ankara 06800, Turkey
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Oguz HK, Atalar A, Köymen H. Equivalent circuit-based analysis of CMUT cell dynamics in arrays. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2013; 60:1016-1024. [PMID: 23661137 DOI: 10.1109/tuffc.2013.2660] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Capacitive micromachined ultrasonic transducers (CMUTs) are usually composed of large arrays of closely packed cells. In this work, we use an equivalent circuit model to analyze CMUT arrays with multiple cells. We study the effects of mutual acoustic interactions through the immersion medium caused by the pressure field generated by each cell acting upon the others. To do this, all the cells in the array are coupled through a radiation impedance matrix at their acoustic terminals. An accurate approximation for the mutual radiation impedance is defined between two circular cells, which can be used in large arrays to reduce computational complexity. Hence, a performance analysis of CMUT arrays can be accurately done with a circuit simulator. By using the proposed model, one can very rapidly obtain the linear frequency and nonlinear transient responses of arrays with an arbitrary number of CMUT cells. We performed several finite element method (FEM) simulations for arrays with small numbers of cells and showed that the results are very similar to those obtained by the equivalent circuit model.
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Affiliation(s)
- H K Oguz
- Electrical and Electronics Engineering Department, Bilkent University, Ankara, Turkey.
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Köymen H, Atalar A, Aydoğdu E, Kocabaş C, Oğuz HK, Olçum S, Ozgurluk A, Unlügedik A. An improved lumped element nonlinear circuit model for a circular CMUT cell. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2012; 59:1791-1799. [PMID: 22899125 DOI: 10.1109/tuffc.2012.2383] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
This paper describes a correction and an extension in the previously published large signal equivalent circuit model for a circular capacitive micromachined ultrasonic transducer (CMUT) cell. The force model is rederived so that the energy and power is preserved in the equivalent circuit model. The model is able to predict the entire behavior of CMUT until the membrane touches the substrate. Many intrinsic properties of the CMUT cell, such as the collapse condition, collapse voltage, the voltage-displacement interrelation and the force equilibrium before and after collapse voltage in the presence of external static force, are obtained as a direct consequence of the model. The small signal equivalent circuit for any bias condition is obtained from the large signal model. The model can be implemented in circuit simulation tools and model predictions are in excellent agreement with finite element method simulations.
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Affiliation(s)
- Hayrettin Köymen
- Electrical and Electronics Engineering Department, Bilkent University, Ankara, Turkey.
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