Novel High-Frequency Air Transducers

Schiller, S.; Hsieh, Cheng‐Yang; Chou, C.-H.; Khuri‐Yakub, Butrus T.

doi:10.1007/978-1-4684-5772-8_100

Cited by 18 publications

(5 citation statements)

References 2 publications

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“…One of the main difficulties has been the provision of low-loss matching layers with the required acoustic impedance, as few materials will suffice for the purpose. In Manuscript received November 24, 1993; revised April 29, 1994; accepted July 11, 1994 this regard, numerous options have been investigated, such as cork [7], balsa wood [7], [8], silicone rubber [7], foam plastics [9], aerogels [8], [10], multi-horns [11], and even multiple matching layers [12], [13]. Additional work has focused upon reducing the impedance of the active element through the use of 1-3 connectivity composite elements [4], [6], which leads to an increase in bandwidth and sensitivity.…”

Section: Introductionmentioning

confidence: 99%

The design and characterization of micromachined air-coupled capacitance transducers

Schindel

Hutchins

Zou

et al. 1995

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

271

104

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Air-coupled capacitance transducers have been manufactured using anisotropically etched silicon backplates and commercially available dielectric films (Kapton and Mylar). The small backplate pits which result from etching, provide well ordered and highly uniform air layers between the backplate surface and thin dielectric film. Such uniformity allows the transducers to be manufactured with reproducible characteristics (a property difficult to achieve through conventional manufacturing). Impulse response studies in generation and detection, have indicated well-damped, wideband behavior, with bandwidths extending from <100 kHz to 2.3 MHz (at the 06 dB points). These bandwidths are investigated as a function of excitation pulse width, applied bias potential, and dielectric film thickness. An estimate of detection sensitivity is also provided by comparison with a calibrated laser interferometer.

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Section: Introductionmentioning

confidence: 99%

The design and characterization of micromachined air-coupled capacitance transducers

Schindel

Hutchins

Zou

et al. 1995

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

271

104

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“…Attempts to maximize the energy transfer from the piezoelectric element to the air and vice versa have achieved moderate success. [1][2][3] However, the increased complexity of the more efficient devices reduces their reliability and increases their cost.…”

Section: ͓S0003-6951͑95͒00252-6͔mentioning

confidence: 99%

Micromachined ultrasonic transducers: 11.4 MHz transmission in air and more

Ladabaum

Khuri-Yakub

Spoliansky³

1996

Applied Physics Letters

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The fabrication and modeling of novel, capacitive, ultrasonic air transducers is reported. Transmission experiments in air at 11.4, 9.2, and 3.1 MHz are shown to correspond with theory. The transducers are made using surface micromachining techniques, which enable the realization of center frequencies ranging from 1.8 to 11.6 MHz. The bandwidth of the transducers ranges from 5% to 20%, depending on processing parameters. Custom circuitry is able to detect 10 MHz capacitance fluctuations as small as 10−18 F, which correspond to displacements on the order of 10−3 Å, in a bandwidth of 2 MHz with a signal to noise ratio of 20 dB. Such detection sensitivity is shown to yield air transducer systems capable of withstanding over 100 dB of signal attenuation, a figure of merit that has significant implications for ultrasonic imaging, nondestructive evaluation, gas flow and composition measurements, and range sensing.

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“…The research in the field of air-coupled ultrasonic transducers is a growing trend in various applications of the nondestructive testing (NDT) of composite materials [ 1 , 2 ]. The appearance of air-coupled ultrasonic transducers has led to the development of some novel NDT techniques [ 3 , 4 ] representing a certain alternative to traditional ultrasonic NDT [ 5 , 6 ]. The most important advantage of air-coupled transducers is the absence of added mass and immersion liquids [ 7 ].…”

Section: Introductionmentioning

confidence: 99%

Developing Novel Gas Discharge Emitters of Acoustic Waves in Air for Nondestructive Testing of Materials

Derusova

Нехорошев

Shpil’noi

et al. 2022

Sensors

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This study was devoted to the development of novel devices and a methodology intended for generating ultrasonic waves in an air medium by using atmospheric pressure gas discharge. In the proposed electrode system, the discharge process was accompanied by the generation of acoustic waves on the emitter surface and, consequently, in the ambient air. The gas discharge emitter vibrations were analyzed by applying the technique of Scanning Laser Doppler Vibrometry (SLDV). It was shown that the magnitude of displacements matched the corresponding characteristics of classical piezoelectric and magnetostrictive transducers. The use of the Fast Fourier transform procedure supplied amplitude–frequency spectra of vibrations generated by the gas discharge emitter. The amplitude–frequency spectrum analysis showed that the proposed emitter was able to generate acoustic waves in the air with frequencies from 50 Hz to 100 kHz, and such a device can be used for the nondestructive testing (NDT) of materials. The results of the statistical analysis of vibration displacements in the repetitive pulsed mode were discussed. A non-stable characteristic of the vibration displacement of the emitter membrane was demonstrated. The parameters of such instability were associated with the features of gas discharge processes. In the experiments, the proposed gas discharge emitter was used in combination with SLDV for inspecting carbon-fiber-reinforced polymer composites. The experiments demonstrated the possibility of using an air-coupled gas discharge transmitter to generate acoustic waves in NDT applications.

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Novel High-Frequency Air Transducers

Cited by 18 publications

References 2 publications

The design and characterization of micromachined air-coupled capacitance transducers

The design and characterization of micromachined air-coupled capacitance transducers

Micromachined ultrasonic transducers: 11.4 MHz transmission in air and more

Developing Novel Gas Discharge Emitters of Acoustic Waves in Air for Nondestructive Testing of Materials

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