Now showing items 1-12 of 12

    • 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 ...
    • 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 ...
    • 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 ...
    • A novel equivalent circuit model for CMUTs 

      Oğuz, H. Kağan; Olcum, Selim; Senlik, Muhammed N.; Atalar, Abdullah; Köymen, Hayrettin (IEEE, 2009-09)
      A nonlinear equivalent circuit for immersed transmitting capacitive micromachined ultrasonic transducers (CMUTs) is presented. The velocity profile across the CMUT surface maintains the same form over a wide frequency ...
    • An optical microcantilever with integrated grating coupler 

      Olcum, Selim; Karademir, Ertuğrul; Taş. Vahdettin; Akça, İmran; Kocabaş, Aşkın; Atalar, Abdullah; Aydınlı, Aydınlı (IEEE, 2009-06)
      In this paper, we have fabricated an optical cantilever with an integrated grating coupler. We have used an inexpensive and repeatable method for integrating the grating to the silicon cantilever with a microfabrication ...
    • Optimizing CMUT geometry for high power 

      Yamaner F.Y.; Olcum, Selim; Bozkurt, A.; Köymen, Hayrettin; Atalar, Abdullah (IEEE, 2010)
      Capacitive micromachined ultrasonic transducers (CMUTs) have demonstratedvarious advantages over piezoelectric transducers. However, current CMUT designsproduce low output pressures with high harmonic distortions. Optimizing ...
    • Radiation impedance and equivalent circuit for immersed CMUT array element 

      Şenlik, Muhammed N.; Atalar, Abdullah; Köymen, Hayrettin; Olcum, Selim (IEEE, 2006-10)
      In this paper, we present equivalent circuit for immersed capacitive micromachined ultrasonic transducers (cMUT), based on an accurate parametric model. We also present an accurate approximation for the radiation impedance ...
    • Radiation impedance of an array of circular capacitive micromachined ultrasonic transducers in collapsed state 

      Özgürlük, Alper; Atalar, Abdullah; Köymen, Hayrettin; Olcum, Selim (IEEE, 2011-10)
      Radiation impedance is one of the important parameters in designing efficient and wideband capacitive micro-machined ultrasonic transducer (CMUT) arrays. It determines how much acoustical power is generated in the surrounding ...
    • Stagger tuned cMUT array for wideband airborne applications 

      Olcum, Selim; Atalar, Abdullah; Köymen Hayrtettin; Şenlik, Muhammed N. (IEEE, 2006-10)
      In this study, we explore the limits of cMUTs in air-borne applications. First we investigate the ways of increasing the bandwidth of a single cMUT cell in air. The effect of array operation is also considered in order to ...
    • Tunable surface plasmon resonance on an elastomeric substrate 

      Olcum, Selim; Kocabaş, Aşkın; Ertaş, Gülay; Atalar, Abdullah; Aydınlı, Atilla (Optical Society of American (OSA), 2009-05)
      In this study, we demonstrate that periods of metallic gratings on elastomeric substrates can be tuned with external strain and hence are found to control the resonance condition of surface plasmon polaritons. We have ...
    • Wafer bonded capacitive micromachined underwater transducers 

      Olcum, Selim; Oǧuz, Kaan; Şenlik, Muhammed N.; Yamaner F. Y.; Bozkurt, A.; Atalar, Abdullah; Köymen, Hayrettin (IEEE, 2009-09)
      In this work we have designed, fabricated and tested CMUTs as underwater transducers. Single CMUT membranes with three different radii and 380 microns of thickness are fabricated for the demonstration of an underwater CMUT ...