Design of capacitive micromachined ultrasonic transducer (CMUT) linear array for underwater imaging

Sensor Review ◽  
2016 ◽  
Vol 36 (1) ◽  
pp. 77-85 ◽  
Author(s):  
Rui Zhang ◽  
Wendong Zhang ◽  
Changde He ◽  
Jinlong Song ◽  
Linfeng Mu ◽  
...  
Keyword(s):  
Electromechanical Coupling ◽  
Linear Array ◽  
Ultrasonic Transducer ◽  
Impedance Matching ◽  
Market Potential ◽  
Electromechanical Coupling Coefficient ◽  
High Angular Resolution ◽  
Underwater Imaging ◽  
Content Type ◽  
Capacitive Micromachined Ultrasonic Transducer

Purpose – The purpose of this paper was to develop a novel capacitive micromachined ultrasonic transducer (CMUT) reception and transmission linear array for underwater imaging at 400 kHz. Compared with traditional CMUTs, the developed transducer array offers higher electromechanical coupling coefficient and higher directivity performance. Design/methodology/approach – The configuration of the newly developed CMUT reception and transmission array was determined by the authors’ previous research into new element structures with patterned top electrodes and into directivity simulation analysis. Using the Si-Silicon on insulator (Si-SOI) bonding technique and the principle of acoustic impedance matching, the CMUT array was fabricated and packaged. In addition, underwater imaging system design and testing based on the packaged CMUT 1 × 16 array were completed. Findings – The simulation results showed that the optimized CMUT array configuration was selected. Furthermore, the designed configuration of the CMUT 1 × 16 linear array was good enough to guarantee high angular resolution. The underwater experiments were conducted to demonstrate that this CMUT array can be of great benefit in imaging applications. Practical implications – Based on our research, the CMUT linear array has good directivity and good impedance matching with water and can be used for obstacle avoidance, distance measurement and imaging underwater. Originality/value – This research provides a basis for CMUT directivity theory and array design. CMUT array presented in this paper has good directivity and has been applied in the underwater imaging, resulting in a huge market potential in underwater detection systems.

Simulation Analysis and Performance Testing Investigation of Capacitive Micromachined Ultrasonic Transducer

2018 ◽  
Vol 32 (09) ◽  
pp. 1858004 ◽  
Author(s):  
Hongliang Wang ◽  
Yunfei Lv ◽  
Chaojie Wang ◽  
Xiangjun Wang ◽  
Changde He ◽  
...  
Keyword(s):  
Electromechanical Coupling ◽  
Simulation Analysis ◽  
Ultrasonic Transducer ◽  
Performance Testing ◽  
Test System ◽  
Ultrasonic Waves ◽  
Electromechanical Coupling Coefficient ◽  
Response Analysis ◽  
Underwater Imaging ◽  
Capacitive Micromachined Ultrasonic Transducer

In various applications of ultrasonic waves, the ultrasonic transducer is the key device of ultrasonic testing and ultrasonic imaging. Compared with the traditional piezoelectric transducer, the capacitive micromachined ultrasonic transducer (CMUT) has many striking advantages, such as low impedance, high bandwidth, easy integration and low cost, and it is expected to become a next generation of mainstream products. In this paper, a CMUT structure for underwater-imaging applications is designed, and the finite element model is established by using COMSOL software, then the modal analysis, harmonic response analysis, electromechanical coupling analysis and transient analysis are carried out. As a consequence, the key parameters of CMUT are obtained, namely resonance frequency, voltage collapse and electromechanical coupling coefficient. For the processed CMUT line array consisting of 16 elements, a test system is built and the emission performance, receiving performance, directivity, bandwidth and preliminary imaging of the designed transducer are tested and analyzed. The results show that the designed CMUT array can meet the requirements of underwater-imaging applications.

Research on optimization sparse method for capacitive micromachined ultrasonic transducer array: heuristic algorithm

Sensor Review ◽  
2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Tian Zhang ◽  
Wendong Zhang ◽  
XingLing Shao ◽  
Yang Wu
Keyword(s):  
Large Scale ◽  
Linear Array ◽  
Ultrasonic Transducer ◽  
Side Lobe ◽  
Hardware Complexity ◽  
Content Type ◽  
Sparse Array ◽  
Imaging Results ◽  
Capacitive Micromachined Ultrasonic Transducer ◽  
Imaging Artifacts

Purpose Because of the small size and high integration of capacitive micromachined ultrasonic transducer (CMUT) component, it can be made into large-scale array, but this lead to high hardware complexity, so the purpose of this paper is to use less elements to achieve better imaging results. In this research, an optimized sparse array is studied, which can suppress the side lobe and reduce the imaging artifacts compared with the equispaced sparse array with the same number of elements. Design/methodology/approach Genetic algorithm is used to sparse the CMUT linear array, and Kaiser window apodization is added to reduce imaging artifacts, the beam pattern and peak-to-side lobe ratio are calculated, point targets imaging comparisons are performed. Furthermore, a 256-elements CMUT linear array is used to carry out the imaging experiment of embedded mass and forearm blood vessel, and the imaging results are compared quantitatively. Findings Through the imaging comparison of embedded mass and forearm blood vessel, the feasibility of optimized sparse array of CMUT is verified, and the purpose of reducing the hardware complexity is achieved. Originality/value This research provides a basis for the large-scale CMUT array to reduce the hardware complexity and the amount of calculation. At present, the CMUT array has been used in medical ultrasound imaging and has huge market potential.

Design and Experiment of Capacitive Micromachined Ultrasonic Transducer Array for High-Frequency Underwater Imaging

2020 ◽  
Vol 13 ◽  
Author(s):  
Yuanyu Yu ◽  
Jiujiang Wang ◽  
Xin Liu ◽  
Sio Hang Pun ◽  
Weibao Qiu ◽  
...  
Keyword(s):  
Ultrasound Imaging ◽  
High Frequency ◽  
Ultrasonic Transducer ◽  
Center Frequency ◽  
Design Parameters ◽  
Underwater Imaging ◽  
Release Process ◽  
Steel Wires ◽  
Capacitive Micromachined Ultrasonic Transducer ◽  
Frequency Ultrasound

Background:: Ultrasound is widely used in the applications of underwater imaging. Capacitive micromachined ultrasonic transducer (CMUT) is a promising candidate to the traditional piezoelectric ultrasonic transducer. In underwater ultrasound imaging, better resolutions can be achieved with a higher frequency ultrasound. Therefore, a CMUT array for high-frequency ultrasound imaging is proposed in this work. Methods:: Analytical methods are used to calculate the center frequency in water and the pull-in voltage for determining the operating point of CMUT. Finite element method model was developed to finalize the design parameters. The CMUT array was fabricated with a five-mask sacrificial release process. Results:: The CMUT array owned an immersed center frequency of 2.6 MHz with a 6 dB fractional bandwidth of 123 %. The pull-in voltage of the CMUT array was 85 V. An underwater imaging experiment was carried out with the target of three steel wires. Conclusion:: In this study, we have developed CMUT for high-frequency underwater imaging. The experiment showed that the CMUT can detect the steel wires with the diameter of 100 μm and the axial resolution was 0.582 mm, which is close to one wavelength of ultrasound in 2.6 MHz.

Fabrication of a 40 MHz Single Element Ultrasonic Transducer Using a PMN-PT Single Crystal

2006 ◽  
Vol 321-323 ◽  
pp. 978-983 ◽  
Author(s):  
Dong Guk Paeng ◽  
Hyung Ham Kim ◽  
Sang Goo Lee ◽  
Sung Min Rhim ◽  
Min Joo Choi
Keyword(s):  
Single Crystal ◽  
High Frequency ◽  
Electromechanical Coupling ◽  
Ultrasonic Transducer ◽  
Electromechanical Coupling Coefficient ◽  
Single Element ◽  
Transducer Arrays ◽  
High Dielectric ◽  
Pulse Echo ◽  
Piezoelectric Constants

PMN-PT, a piezoelectric single crystal, has been known to be a better material for transducer arrays due to its high electromechanical coupling coefficient (k33) and high dielectric and piezoelectric constants. It may also be good even for high frequency single element transducers using relatively high kt and low attenuation and velocity dispersion. However, it’s challenging to fabricate high frequency transducers using PMN-PT since it is easily breakable and requires small area and thickness of the transducer. A KLM model was used to simulate a 40 MHz single element transducer including 2 matching layers and a conductive backing. The simulation showed that the PMN-PT transducer turned out to be better in sensitivity and bandwidth than a 40 MHz LiNbO3 transducer. A 40 MHz PMN-29%PT transducer was fabricated and the pulse echo signals were obtained and analyzed. Its sensitivity was found to be –48 dB and –6dB bandwidth was about 48 %.

scholarly journals Fabrication and Characterization of High-Frequency Ultrasound Transducers Based on Lead-Free BNT-BT Tape-Casting Thick Film

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 3166 ◽  
Author(s):  
Junshan Zhang ◽  
Wei Ren ◽  
Yantao Liu ◽  
Xiaoqing Wu ◽  
Chunlong Fei ◽  
...  
Keyword(s):  
Thick Film ◽  
High Frequency ◽  
Electromechanical Coupling ◽  
Ultrasonic Transducer ◽  
Tape Casting ◽  
Lead Free ◽  
Center Frequency ◽  
Electromechanical Coupling Coefficient ◽  
High Frequency Ultrasound ◽  
Casting Method

A lead-free 0.94(Na0.5Bi0.5) TiO3-0.06 BaTiO3 (BNT-BT) thick film, with a thickness of 60 μm, has been fabricated using a tape-casting method. The longitudinal piezoelectric constant, clamped dielectric permittivity constant, remnant polarization and coercive field of the BNT-BT thick film were measured to be 150 pC/N, 1928, 13.6 μC/cm2, and 33.6 kV/cm, respectively. The electromechanical coupling coefficient kt was calculated to be 0.55 according to the measured electrical impedance spectrum. A high-frequency plane ultrasound transducer was successfully fabricated using a BNT-BT thick film. The performance of the transducer was characterized and evaluated by the pulse-echo testing and wire phantom imaging operations. The BNT-BT thick film transducer exhibits a center frequency of 34 MHz, a −6 dB bandwidth of 26%, an axial resolution of 77 μm and a lateral resolution of 484 μm. The results suggest that lead-free BNT-BT thick film fabricated by tape-casting method is a promising lead-free candidate for high-frequency ultrasonic transducer applications.

scholarly journals Development of an Accurate Resonant Frequency Controlled Wire Ultrasound Surgical Instrument

Sensors ◽  
2020 ◽  
Vol 20 (11) ◽  
pp. 3059 ◽  
Author(s):  
Jungsuk Kim ◽  
Kyeongjin Kim ◽  
Sun-Ho Choe ◽  
Hojong Choi
Keyword(s):  
Resonant Frequency ◽  
Error Rate ◽  
Electromechanical Coupling ◽  
Ultrasonic Transducer ◽  
Surgical Instruments ◽  
Electromechanical Coupling Coefficient ◽  
Frequency Error ◽  
Network Analyzer ◽  
Surgical Instrument ◽  
Torque Wrench

Our developed wire ultrasound surgical instrument comprises a bolt-clamped Langevin ultrasonic transducer (BLUT) fabricated by PMN-PZT single crystal material due to high mechanical quality factor and electromechanical coupling coefficient, a waveguide in the handheld instrument, and a generator instrument. To ensure high performance of wire ultrasound surgical instruments, the BLUT should vibrate at an accurate frequency because the BLUT’s frequency influences hemostasis and the effects of incisions on blood vessels and tissues. Therefore, we implemented a BLUT with a waveguide in the handheld instrument using a developed assembly jig process with impedance and network analyzers that can accurately control the compression force using a digital torque wrench. A generator instrument having a main control circuit with a low error rate, that is, an output frequency error rate within ±0.5% and an output voltage error rate within ±1.6%, was developed to generate the accurate frequency of the BLUT in the handheld instrument. In addition, a matching circuit between the BLUT and generator instrument with a network analyzer was developed to transfer displacement vibration efficiently from the handheld instrument to the end of the waveguide. Using the matching circuit, the measured S-parameter value of the generator instrument using a network analyzer was −24.3 dB at the resonant frequency. Thus, our proposed scheme can improve the vibration amplitude and accuracy of frequency control of the wire ultrasound surgical instrument due to developed PMN-PZT material and assembly jig process.

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