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Design and characterization of a multi-ring nested cmut array for hydrophone

Journal of Semiconductors 2024年第11期45卷 58-62页

作者： Licheng Jia Rihui Xue Fansheng Meng The Key Laboratory of Instrumentation Science and Dynamic Measurement North University of ChinaTaiyuan 030051China

This paper presents the design,fabrication,packaging,and characterization of a high-performance cmut *** array,which features rectangular cells fabricated using a sacrificial release process,achieves a receiving sensitivity of-231.44 d B(re:1 V/μPa)with a 40 d B ***,the cmut array exhibits a minimal sensitivity variation of just 0.87 d B across a temperature range of 0 to 60°***,the output voltage non-linearity at 1 k Hz is approximately 0.44%.These test results demonstrate that the reception performance of the 67-element cmut array is superior to that of commercial *** high performance and compact design of this cmut array underscore its significant commercial potential for hydrophone applications.

关键词： cmut array mirco-electro-mechanical systems(mems) receiving sensitivity non-linearity

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A cmut array Based on Annular Cell Geometry for Air-coupled Applications

A CMUT Array Based on Annular Cell Geometry for Air-coupled ...

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IEEE International Ultrasonics Symposium (IUS)

作者： Na, Shuai Wong, Lawrence L. P. Chen, Albert I. H. Li, Zhenhao Macecek, Mirek Yeow, John T. W. Univ Waterloo Dept Syst Design Engn Adv Micro Nanodevices Lab Waterloo ON N2L 3G1 Canada Techno Sci Inc Concord ON L4K 3Y5 Canada

ISBN: (纸本)9781467398978

An annular cell has been reported with improved transmit sensitivity over a conventional circular cell for air-coupled cmuts. The particular geometry of an annular cell also allows multi of them to be arranged in a concentric layout such that high-intensity ultrasound can be focused in the depth direction. This paper presents a 9.3-mm-diameter cmut array consisting of four concentric annular cells. The wafer-bonded cmut has a plate thickness of 18.3 mu m and cell width of 930 mu m. Under atmospheric pressure, the ratio of average-to-maximum displacement (RAMD) of the annular cells was measured to be 0.53 using a profilometer. At 200-V DC bias and 20-Vpp AC actuation voltage, the frequency response of the maximum displacement was measured using a laser Doppler vibrometer, and a resonance frequency of 182.5 kHz was observed. At the same DC bias, the resonance frequency of the array was also measured to be 182.5 kHz using a vector network analyzer. Based on the frequency response, the acoustic filed of the cmut array was simulated to have an 11.4-mm natural focal depth with -3-dB beam width of 3.14 mm. This study demonstrates the potential of using concentric annular-cell cmut array to generate focused ultrasound in air.

关键词： cmut array annular cell air-coupled ultrasound

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

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SENSOR REVIEW 2016年第1期36卷 77-85页

作者： Zhang, Rui Zhang, Wendong He, Changde Song, Jinlong Mu, Linfeng Cui, Juan Zhang, Yongmei Xue, Chenyang North Univ China Minist Educ Key Lab Instrumentat Sci & Dynam Measurement Taiyuan Peoples R China North China Univ Technol Sch Comp Sci Beijing Peoples R China

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 x 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 x 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.

关键词： cmut array Echo processing Underwater imaging Directivity analysis

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Fabrication of 2-D Capacitive Micromachined Ultrasonic Transducer (cmut) array through Silicon Wafer Bonding

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MICROMACHINES 2022年第1期13卷 99-99页

作者： Wang, Ziyuan He, Changde Zhang, Wendong Li, Yifan Gao, Pengfei Meng, Yanan Zhang, Guojun Yang, Yuhua Wang, Renxin Cui, Jiangong Wang, Hongliang Zhang, Binzhen Ren, Yongfeng Zhen, Guoyong Jiao, Xinquan Zhang, Sai North Univ China State Key Lab Dynam Testing Technol Taiyuan 030051 Peoples R China

Capacitive micromachined ultrasound transducers (cmuts) have broad application prospects in medical imaging, flow monitoring, and nondestructive testing. cmut arrays are limited by their fabrication process, which seriously restricts their further development and application. In this paper, a vacuum-sealed device for medical applications is introduced, which has the advantages of simple manufacturing process, no static friction, repeatability, and high reliability. The cmut array suitable for medical imaging frequency band was fabricated by a silicon wafer bonding technology, and the adjacent array devices were isolated by an isolation slot, which was cut through the silicon film. The cmut device fabricated following this process is a 4 x 16 array with a single element size of 1 mm x 1 mm. Device performance tests were conducted, where the center frequency of the transducer was 3.8 MHz, and the 6 dB fractional bandwidth was 110%. The static capacitance (29.4 pF) and center frequency (3.78 MHz) of each element of the array were tested, and the results revealed that the array has good consistency. Moreover, the transmitting and receiving performance of the transducer was evaluated by acoustic tests, and the receiving sensitivity was -211 dB @ 3 MHz, -213 dB @ 4 MHz. Finally, reflection imaging was performed using the array, which provides certain technical support for the research of two-dimensional cmut arrays in the field of 3D ultrasound imaging.

关键词： MEMS sensors cmut array FEM high-sensitivity broadband

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Analytical-Finite Element Hybrid Model for cmut arrays with Arbitrary Membrane Geometry

Analytical-Finite Element Hybrid Model for CMUT Arrays with ...

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IEEE International Ultrasonics Symposium (IUS)

作者： Zahorian, Jaime Satir, Sarp Degertekin, F. Levent Georgia Inst Technol Dept Elect Engn Dept Mech Engn Atlanta GA 30332 USA

ISBN: (纸本)9781467345620;9781467345613

Finite Element Analysis (FEA) of cmut arrays offers flexibility with membrane geometry, but it can become computationally expensive as the transducer array and fluidic space increases in size. The objective is to combine the modeling flexibility of 3D FEA with the computational effectiveness of 2D numerical methods to analyze and design cmut arrays with arbitrary membrane shapes. Effective numerical methods for cmut arrays combine finite difference (FD) approximations of thin plate equations with fluid coupling through the use of the Boundary Element Method. As such, the array can be modeled with a 2D surface mesh, but the thin plate approximations limit the analysis to cmuts with high aspect ratios and uniform surfaces. A hybrid method using static FEA (COMSOL 4.2a) of an individual cmut membrane was used to generate an equivalent stiffness matrix associated with the mesh density of the 2D surface, eliminating the dependence on the thin plate approximation. This FEA need only be performed once for a given geometry and mesh density as it is reused for an entire array. The resonant frequency of square cmuts with 2 mu m thickness in vacuum was evaluated using FD and hybrid methods. The hybrid method shows good agreement with full FEA, while the FD method deviated for low aspect ratios. Hybrid analysis of mass-loaded cmuts with an aluminum electrode for operation at similar to 40 MHz shows good agreement FEA analysis while reducing the computation time by a factor of 20 for a simple array simulation.

关键词： cmut array Finite Element Analysis Analytical Model

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An Investigation of Silica Aerogel to Reduce Acoustic Crosstalk in cmut arrays

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SENSORS 2021年第4期21卷 1459-1459页

作者： Yashvanth, Varshitha Chowdhury, Sazzadur Univ Windsor Dept Elect & Comp Engn Windsor ON N9B 3P4 Canada

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.

关键词： cmut array acoustic crosstalk Scholte wave crosslinked silica aerogel biomedical NDE

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Characterization of one-dimensional capacitive micromachined ultrasonic immersion transducer arrays

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IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL 2001年第3期48卷 750-760页

作者： Jin, XC Oralkan, Ö Degertekin, FL Khuri-Yakub, BT Stanford Univ Edward L Ginzton Lab Stanford CA 94305 USA Georgia Inst Technol George W Woodruff Sch Mech Engn Atlanta GA 30332 USA

In this paper, we report on the characterization of 1-D arrays of capacitive micromachined ultrasonic transducers (cmut). A 275- x 5600-mum 1-D cmut array element is experimentally characterized, and the results are found to be in agreement with theoretical predictions. As a receiver, the transducer has a 0.28-fm/root Hz displacement sensitivity, and, as a transmitter, it produces 5 kPa/V of output pressure at the transducer surface at 3 MHz with a DC bias of 35 V, The transducer has more than 100% fractional bandwidth around 3 MHz, which makes it suitable for ultrasound imaging. The radiation pattern of isolated single elements, as well as those of array elements are measured, and two major sources of acoustical cross talk are identified. A weakly dispersive non-leaky interface wave (Stoneley wave) is observed to be propagating at the silicon substrate-fluid interface at a speed close to the speed of sound in the fluid. This wave causes internal reflections, spurious resonance, and radiation from the edges of the silicon substrate. The large lateral component of the particle velocity generated by the membranes at the edge of the cmut array elements is found to be the source of this interface wave. Lowest order Lamb waves in the silicon substrate are also found to contribute to the cross talk between elements. These waves are excited at the edges of individual vibrating membranes, where they are anchored to the substrate. and result in a narrowing of the beam profile of the array elements. Several methods, such as trench isolation and wafer thinning, are proposed and implemented to modify the acoustical cross coupling between array elements.

关键词： .radiation pattern ultrasonics ferroelectrics transducers frequency control DC bias Ultrasonic Immersion cmut array Stoneley

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Analytical-Finite Element Hybrid Model for cmut arrays with Arbitrary Membrane Geometry

Analytical-Finite Element Hybrid Model for CMUT Arrays with ...

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IEEE International Ultrasonics Symposium

作者： Jaime Zahorian Sarp Satir F. Levent Degertekin Department of Electrical Engineering Department of Mechanical Engineering Georgia Institute of Technology Atlanta USA

ISBN: (纸本)9781467345613

Finite Element Analysis (FEA) of cmut arrays offers flexibility with membrane geometry, but it can become computationally expensive as the transducer array and fluidic space increases in size. The objective is to combine the modeling flexibility of 3D FEA with the computational effectiveness of 2D numerical methods to analyze and design cmut arrays with arbitrary membrane shapes. Effective numerical methods for cmut arrays combine finite difference (FD) approximations of thin plate equations with fluid coupling through the use of the Boundary Element Method. As such, the array can be modeled with a 2D surface mesh, but the thin plate approximations limit the analysis to cmuts with high aspect ratios and uniform surfaces. A hybrid method using static FEA (COMSOL 4.2a) of an individual cmut membrane was used to generate an equivalent stiffness matrix associated with the mesh density of the 2D surface, eliminating the dependence on the thin plate approximation. This FEA need only be performed once for a given geometry and mesh density as it is reused for an entire array. The resonant frequency of square cmuts with 2 μm thickness in vacuum was evaluated using FD and hybrid methods. The hybrid method shows good agreement with full FEA, while the FD method deviated for low aspect ratios. Hybrid analysis of mass-loaded cmuts with an aluminum electrode for operation at ～40 MHz shows good agreement FEA analysis while reducing the computation time by a factor of 20 for a simple array simulation.

关键词： cmut array Finite Element Analysis Analytical Model

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An Accurate Model for Fluid Loading on Circular cmuts

An Accurate Model for Fluid Loading on Circular CMUTs

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IEEE International Ultrasonics Symposium (IUS)

作者： Azmy, Bichoy El-Gamal, Mourad El-Henawy, Adel Ragai, Hani Ain Shams Univ Cairo Egypt McGill Univ Montreal PQ Canada

ISBN: (纸本)9781457712524

An accurate analytical model is presented for circular cmut arrays operating in immersion. Our model emphasises the fluid loading and its effects on circular cmuts performance when operated as an element of large array. The model can accurately predict the series and parallel resonance frequencies as well as the bandwidth of a cmut array in immersion. cmut acoustical impedance, in its exact closed form, augments the conventional cmut equivalent circuit. cmut material density is replaced with a frequency dependent equivalent density that accounts for the distributed fluid loading. Data fitting against an FEM model is used to determine the equivalent density dimensional dependence. A correction is also suggested for the equivalent circuit transformer ratio. Test cases are presented to illustrate the accuracy of the proposed model as well as its speed as compared to its FEM counterpart.

关键词： Circular cmut cmut array fluid loading parallel resonance acoustical impedance

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Breast Acoustic Parameter Reconstruction Method Based on Capacitive Micromachined Ultrasonic Transducer array

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MICROMACHINES 2021年第8期12卷 963-963页

作者： Pei, Yu Zhang, Guojun Zhang, Yu Zhang, Wendong North Univ China State Key Lab Dynam Testing Technol Taiyuan 030051 Peoples R China

Ultrasound computed tomography (USCT) systems based on capacitive micromachined ultrasonic transducer (cmut) arrays have a wide range of application prospects. For this paper, a high-precision image reconstruction method based on the propagation path of ultrasound in breast tissue are designed for the cmut ring array;that is, time-reversal algorithms and FBP algorithms are respectively used to reconstruct sound speed distribution and acoustic attenuation distribution. The feasibility of this reconstruction method is verified by numerical simulation and breast model experiments. According to reconstruction results, sound speed distribution reconstruction deviation can be reduced by 53.15% through a time-reversal algorithm based on wave propagation theory. The attenuation coefficient distribution reconstruction deviation can be reduced by 61.53% through FBP based on ray propagation theory. The research results in this paper will provide key technological support for a new generation of ultrasound computed tomography systems.

关键词： USCT cmut array sound speed acoustic attenuation reconstruction method

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