Now showing items 1-20 of 33

    • Analytic modeling of loss and cross-coupling in capacitive micromachined ultrasonic transducers 

      Bozkurt, A.; Degertekin, F. L.; Atalar, Abdullah; Khuri-Yakub, B. T. (IEEE, Piscataway, NJ, United States, 1998)
      The structural loss mechanism of capacitive micromachined ultrasonic transducer (cMUT) is investigated using finite element analysis and the normal mode theory. A single micromachined transducer membrane on an infinite ...
    • Bandwidth improvement in a cMUT array with mixed sized elements 

      Bayram, Can; Olcum, Selim; Şenlik, Muhammed N.; Atalar, Abdullah (IEEE, 2005-09)
      A capacitive micromachined ultrasonic transducer (cMUT) is typically fabricated by concatenation of several cMUT cells with identical physical dimensions. If the membrane thickness is kept fixed, the radius of the cMUT ...
    • Bandwidth, power and noise considerations in airborne cMUTs 

      Şenlik, Muhammed N.; Olcum, Selim; Köymen, Hayrettin; Atalar, Abdullah (IEEE, 2009-09)
      Capacitive micromachined ultrasonic transducers (cMUTs) offer wider bandwidth in air due to their low mechanical impedances. The impedance mismatch between the air and transducer decreases with the smaller device dimensions ...
    • CMUT array element in deep-collapse mode 

      Olcum, Semih; Yamaner F.Y.; Bozkurt, A.; Köymen, Hayrettin; Atalar, Abdullah (IEEE, 2011)
      Collapse and deep-collapse mode of operations have boosted the pressure outputs of capacitive micromachined ultrasonic transducers (CMUTs) considerably. In this work, we demonstrate a CMUT element operating in the deep-collapse ...
    • Comparative analysis of different approaches to target classification and localization with sonar 

      Ayrulu, Birsel; Barshan, Billur (IEEE, 2001-08)
      The comparison of different classification and fusion techniques was done for target classification and localization with sonar. Target localization performance of artificial neural networks (ANN) was found to be better ...
    • Design charts to maximize the gain-bandwidth product of capacitive micromachined ultrasonic transducers 

      Ölçüm, Selim; Şenlik, Muhammed Niyazi; Bayram, Can; Atalar, Abdullah (IEEE, 2005)
      In this work we define a performance measure for capacitive micromachined ultrasonic transducers (cMUT) in the form of a gain-bandwidth product to investigate the conditions that optimize the gain and bandwidth with respect ...
    • Designing transmitting CMUT cells for airborne applications 

      Ünlügedik, A.; Taşdelen, A.; Atalar, Abdullah; Köymen, Hayrettin (Institute of Electrical and Electronics Engineers Inc., 2014)
      We report a new mode of airborne operation for capacitive micromachined ultrasonic transducers (CMUT), in which the plate motion spans the entire gap without collapsing and the transducer is driven by a sinusoidal voltage ...
    • Electrically unbiased driven airborne capacitive micromachined ultrasonic transducer design 

      Ünlügedik, Aslı; Atalar, Abdullah; Kocabaş, Coşkun; Oğuz, H. Kağan; Köymen, Hayrettin (IEEE, 2012)
      We present a design method for airborne capacitive micromachined ultrasonic transducers (CMUT). We use an equivalent lumped element circuit to model both electrical and mechanical properties of CMUT and analyze it in ...
    • An equivalent circuit for collapse operation mode of CMUTs 

      Olcum, Selim; Yamaner F.Y.; Bozkurt, A.; Köymen, Hayrettin; Atalar, Abdullah (IEEE, 2010)
      Collapse mode of operation of the capacitive mi-cromachined ultrasonic transducers (CMUTs) was shown to be a very effective way for achieving high output pressures. However, no accurate model exists for understanding the ...
    • An equivalent circuit model for transmitting capacitive micromachined ultrasonic transducers in collapse mode 

      Olcum, S.; Yamaner, F. Y.; Bozkurt, A.; Köymen, Hayrettin; Atalar, Abdullah (IEEE, 2011)
      The collapse mode of operation of capacitive micromachined ultrasonic transducers (CMUTs) was shown to be a very effective way to achieve high output pressures. However, no accurate analytical or equivalent circuit model ...
    • Equivalent circuit-based analysis of CMUT cell dynamics in arrays 

      Oğuz, H. K.; Atalar, Abdullah; Köymen, Hayrettin (IEEE, 2013)
      Capacitive micromachined ultrasonic transducers (CMUTs) are usually composed of large arrays of closely packed cells. In this work, we use an equivalent circuit model to analyze CMUT arrays with multiple cells. We study ...
    • Estimation of object location and radius of curvature using ultrasonic sonar 

      Sekmen, A. Ş.; Barshan, B. (Elsevier, 2001-07)
      Acoustic sensors are very popular in time-of-flight (TOF) ranging systems since they are inexpensive and convenient to use. One of the major limitations of these sensors is their low angular resolution which makes object ...
    • Experimental characterization of capacitive micromachined ultrasonic transducers 

      Ölçüm, Selim; Atalar, Abdullah; Köymen, Hayrettin; Oğuz, Kağan; Şenlik, Muhammed N. (IEEE, 2007)
      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 ...
    • A fast method of calculating diffraction loss between two facing transducers 

      Atalar, Abdullah (IEEE, 1988)
      A fast method of calculating the diffraction loss between two facing circular ultrasonic transducers of unequal size is presented. This problem is directly applicable for minimization of diffraction loss in acoustic lens ...
    • Fresnel lamb wave and V-groove lenses with tunable mode selectivity 

      Yaralıoğlu, Göksen Göksenin; Atalar, Abdullah; Köymen, Hayrettin (IEEE, 1995)
      The Lamb wave and V-groove lenses are distinguished by their high surface wave excitation efficiencies. However, due to the fixed incidence angle, a particular lens can only be used for materials having surface wave ...
    • Improved performance of cMUT with nonuniform membranes 

      Şenlik, Muhammed N.; Olcum, Selim; Atalar, Abdullah (IEEE, 2005-09)
      When capacitive micromachined ultrasonic transducers are immersed in water, the bandwidth of the device is limited by the membrane's second resonance frequency. At this frequency no mechanical power to immersion medium can ...
    • Interaction between a cMUT cell and a liquid medium around the parallel resonance frequency 

      Şenlik, Muhammed N.; Atalar, Abdullah; Olçum, Selim (IEEE, 2007-10)
      In this paper, we present how a capacitive micromachined ultrasonic transducer (cMUT) couples to the immersion medium, based on an accurate parametric model. We show that the velocity of cMUT membrane can be written as a ...
    • Microfabricated ultrasonic transducers: towards robust models and immersion devices 

      Ladabaum, I.; Jin, X.; Soh, H. T.; Pierre, F.; Atalar, Abdullah; Khuri-Yakub, B. T. (IEEE, 1996-11)
      The successful fabrication of ultrasonic immersion transducers is reported. Transducers are observed to operate from 1 MHz to 20 MHz in water, with the frequency range limited by electronics, not the transducers. Transmission ...
    • Micromachinable leaky wave air transducers 

      Değertekin, F. L.; Atalar, Abdullah; Khuri-Yakub, B. T. (IEEE, 1997-11)
      In this paper, ultrasonic air transducers which use the lowest order antisymmetric (A/sub 0/) mode Lamb waves in a thin plate as a means of efficient coupling of ultrasonic energy to air are discussed. For a silicon plate ...
    • A new detection method for capacitive micromachine ultrasonic transducers 

      Ergun, A. S.; Temelkuran, B.; Özbay, Ekmel; Atalar, Abdullah (IEEE, 2001)
      Capacitive micromachine ultrasonic transducers (cMUT) have become an alternative to piezoelectric transducers in the past few years. They consist of many small circular membranes that are connected in parallel. In this ...