Capacitive micromachined ultrasonic transducer: transmission performance evaluation under different driving parameters and membrane stress for underwater imaging applications

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.

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Design and performance analysis of capacitive micromachined ultrasonic transducer (CMUT) array for underwater imaging

Microsystem Technologies ◽

10.1007/s00542-015-2716-z ◽

2015 ◽

Vol 22 (12) ◽

pp. 2939-2947 ◽

Cited By ~ 6

Author(s):

Rui Zhang ◽

Chenyang Xue ◽

Changde He ◽

Yongmei Zhang ◽

Jinlong Song ◽

...

Keyword(s):

Performance Analysis ◽

Ultrasonic Transducer ◽

Underwater Imaging ◽

Capacitive Micromachined Ultrasonic Transducer ◽

And Performance

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Simulation Analysis and Performance Testing Investigation of Capacitive Micromachined Ultrasonic Transducer

International Journal of Pattern Recognition and Artificial Intelligence ◽

10.1142/s0218001418580041 ◽

2018 ◽

Vol 32 (09) ◽

pp. 1858004 ◽

Cited By ~ 2

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.

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

Sensor Review ◽

10.1108/sr-05-2015-0076 ◽

2016 ◽

Vol 36 (1) ◽

pp. 77-85 ◽

Cited By ~ 5

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.

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Design of a hexagonal air-coupled capacitive micromachined ultrasonic transducer for air parametric array

Nanotechnology and Precision Engineering ◽

10.1063/10.0003504 ◽

2021 ◽

Vol 4 (1) ◽

pp. 013004

Author(s):

Xiaoli Zhang ◽

Hui Zhang ◽

Dachao Li

Keyword(s):

Ultrasonic Transducer ◽

Capacitive Micromachined Ultrasonic Transducer ◽

Parametric Array

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An Investigation of Silica Aerogel to Reduce Acoustic Crosstalk in CMUT Arrays

Sensors ◽

10.3390/s21041459 ◽

2021 ◽

Vol 21 (4) ◽

pp. 1459

Author(s):

Varshitha Yashvanth ◽

Sazzadur Chowdhury

Keyword(s):

Silica Aerogel ◽

Ultrasonic Transducer ◽

Fluid Interface ◽

Fractional Bandwidth ◽

Neighboring Element ◽

Element Analysis ◽

Average Improvement ◽

Capacitive Micromachined Ultrasonic Transducer ◽

Scholte Wave ◽

Fea Simulation

This paper presents a novel technique to reduce acoustic crosstalk in capacitive micromachined ultrasonic transducer (CMUT) arrays. The technique involves fabricating a thin layer of diisocyanate enhanced silica aerogel on the top surface of a CMUT array. The silica aerogel layer introduces a highly nanoporous permeable layer to reduce the intensity of the Scholte wave at the CMUT-fluid interface. 3D finite element analysis (FEA) simulation in COMSOL shows that the developed technique can provide a 31.5% improvement in crosstalk reduction for the first neighboring element in a 7.5 MHz CMUT array. The average improvement of crosstalk level over the −6 dB fractional bandwidth was 22.1%, which is approximately 5 dB lower than that without an aerogel layer. The results are in excellent agreement with published experimental results to validate the efficacy of the new technique.

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A Review on Analytical Modeling for Collapse Mode Capacitive Micromachined Ultrasonic Transducer of the Collapse Voltage and the Static Membrane Deflections

Micromachines ◽

10.3390/mi12060714 ◽

2021 ◽

Vol 12 (6) ◽

pp. 714

Author(s):

Jiujiang Wang ◽

Xin Liu ◽

Yuanyu Yu ◽

Yao Li ◽

Ching-Hsiang Cheng ◽

...

Keyword(s):

Analytical Modeling ◽

Ultrasonic Transducer ◽

Governing Equations ◽

Von Karman ◽

Von Kármán Equations ◽

Collapse Mode ◽

Capacitive Micromachined Ultrasonic Transducer ◽

Gap Height ◽

Von Kármán ◽

Analytical Expressions

Analytical modeling of capacitive micromachined ultrasonic transducer (CMUT) is one of the commonly used modeling methods and has the advantages of intuitive understanding of the physics of CMUTs and convergent when modeling of collapse mode CMUT. This review article summarizes analytical modeling of the collapse voltage and shows that the collapse voltage of a CMUT correlates with the effective gap height and the electrode area. There are analytical expressions for the collapse voltage. Modeling of the membrane deflections are characterized by governing equations from Timoshenko, von Kármán equations and the 2D plate equation, and solved by various methods such as Galerkin’s method and perturbation method. Analytical expressions from Timoshenko’s equation can be used for small deflections, while analytical expression from von Kármán equations can be used for both small and large deflections.

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