Browsing by Subject "cMUT"

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    Experimental characterization of capacitive micromachined ultrasonic transducers
    (IEEE, 2007) Ölçüm, Selim; Atalar, Abdullah; Köymen, Hayrettin; Oğuz, Kağan; Şenlik, Muhammed N.
    In this paper, capacitive micromachined ultrasonic transducers are fabricated using a sacrificial surface micromachining process. A testing procedure has been established in order to measure the absolute transmit and receive sensitivity spectra of the fabricated devices. The experiments are performed in oil. Pulse-echo experiments are performed and the results are compared to the pitch-catch measurements using calibrated transducers.
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    Nonuniform membranes in capacitive micromachined ultrasonic transducers
    (2005) Şenlik, Muhammed N.
    Capacitive micromachined ultrasonic transducers (cMUT) are used to receive and transmit ultrasonic signals. The device is constructed from many small, in the order of microns, circular membranes, which are connected in parallel. When they are immersed in water, the bandwidth of the cMUT is limited by the membrane’s second resonance frequency, which causes an increase in the mechanical impedance of the membrane. In this thesis, we propose a new membrane shape to shift the second resonance frequency to higher values, in addition to keeping the impedance of the membrane as small as possible. The structure consists of a very thin membrane with a rigid mass at the center. The stiffness of the central region moves the second resonance to a higher frequency. This membrane configuration is shown to work better compared to conventionally used uniform membranes during both reception and transmission. The improvement in the bandwidth is more than %30 with an increase in the gain.