Electronic Nose System Based on a Functionalized Capacitive Micromachined Ultrasonic Transducer (CMUT) Array for Selective Detection of Plant Volatiles

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 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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Design and Characterization of low frequency Capacitive Micromachined Ultrasonic Transducer (CMUT)

2020 IEEE International Conference on Systems, Man, and Cybernetics (SMC) ◽

10.1109/smc42975.2020.9282903 ◽

2020 ◽

Author(s):

Mayank B. Thacker ◽

Douglas A. Buchanan

Keyword(s):

Ultrasonic Transducer ◽

Low Frequency ◽

Capacitive Micromachined Ultrasonic Transducer

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Non-Invasive Method to Detect Infection with Mycobacterium tuberculosis Complex in Wild Boar by Measurement of Volatile Organic Compounds Obtained from Feces with an Electronic Nose System

Sensors ◽

10.3390/s21020584 ◽

2021 ◽

Vol 21 (2) ◽

pp. 584

Author(s):

Kelvin de Jesús Beleño-Sáenz ◽

Juan Martín Cáceres-Tarazona ◽

Pauline Nol ◽

Aylen Lisset Jaimes-Mogollón ◽

Oscar Eduardo Gualdrón-Guerrero ◽

...

Keyword(s):

Volatile Organic Compounds ◽

Wild Boar ◽

Organic Compounds ◽

Electronic Nose ◽

Bovine Tuberculosis ◽

Human Beings ◽

Non Invasive ◽

Testing Phase ◽

Volatile Organic ◽

Electronic Nose System

More effective methods to detect bovine tuberculosis, caused by Mycobacterium bovis, in wildlife, is of paramount importance for preventing disease spread to other wild animals, livestock, and human beings. In this study, we analyzed the volatile organic compounds emitted by fecal samples collected from free-ranging wild boar captured in Doñana National Park, Spain, with an electronic nose system based on organically-functionalized gold nanoparticles. The animals were separated by the age group for performing the analysis. Adult (>24 months) and sub-adult (12–24 months) animals were anesthetized before sample collection, whereas the juvenile (<12 months) animals were manually restrained while collecting the sample. Good accuracy was obtained for the adult and sub-adult classification models: 100% during the training phase and 88.9% during the testing phase for the adult animals, and 100% during both the training and testing phase for the sub-adult animals, respectively. The results obtained could be important for the further development of a non-invasive and less expensive detection method of bovine tuberculosis in wildlife populations.

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