Acoustics and Underwater Technologies Research Center (BASTA)

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Browsing Acoustics and Underwater Technologies Research Center (BASTA) by Author "Khan, Talha Masood"

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    Beam steering in a half-frequency driven airborne CMUT transmitter array
    (IEEE Computer Society, 2019) Khan, Talha Masood; Taşdelen, Akif Sinan; Yılmaz, Mehmet; Atalar, Abdullah; Köymen, Hayrettin
    An airborne Capacitive Micromachined Ultrasonic Transducer (CMUT) transmit array was designed using electromechanical modelling for unbiased airborne operation. The array elements are designed for maximum swing at 10V p-p unbiased drive, whereas conventional practice is to bias CMUT close to the collapsed voltage to achieve higher swing. The devices were fabricated using a customized single photolithographic process with a combination of wet and dry etching. The wafer level fabrication enabled the usage of 2x2 and 3x3 arrays. Driving CMUTs in an unbiased mode at half frequency drives the ‘static pressure’ depressed silicon membrane at a larger swing without letting it collapse. The 2x2 array displays 3.375 kHz bandwidth when characterized in air. The phase and amplitude differences due to the dispersion of resonance frequencies of the elements are compensated for beamformed and beamsteered airborne operation.
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    High-Intensity airborne CMUT transmitter array with beam steering
    (IEEE, 2020) Khan, Talha Masood; Taşdelen, Akif Sinan; Yılmaz, Mehmet; Atalar, Abdullah; Köymen, Hayrettin
    A 2×2 high-intensity CMUT transmit array that is capable of two-dimensional beam steering is presented. The device uses an ac drive voltage at half the ultrasound frequency without any dc bias, enabling the usage of the entire gap height. The device is designed using a large signal equivalent model approach. A fabrication method that requires a single lithographic mask has been used. The fabricated devices are operated at 76 kHz to beam steer at various angles. An equivalent element pressure of 144 dB// 20 μ Pa at the transducer surface was measured. The entire half-space can be steered without any sidelobes and the beam obtained from the array is in excellent agreement with the theoretical predictions. [2020-0253]