Yazar "Qureshi, Muhammad Shakeel" seçeneğine göre listele

Listeleniyor 1 - 3 / 3
  • Küçük Resim
    Yayın
    Annular CMUT arrays for side looking intravascular ultrasound imaging
    (IEEE, 2007) Zahorian, Jaime; Güldiken, Rasim Oytun; Gürün, Gökçe; Qureshi, Muhammad Shakeel; Balantekin, Müjdat; Değertekin, Fahrettin Levent; Carlier, Stephane; Şişman, Alper; Karaman, Mustafa
    Although side looking intravascular ultrasound (SL-IVUS) imaging systems using single element piezoelectric transducers set the resolution standard in the assessment of the extent of coronary artery disease, improvements in transducer performance are needed to perform harmonic imaging and high resolution imaging of vulnerable plaque. With their small channel count; annular arrays exploiting the inherent broad bandwidth of CMUTs and electronic focusing capability of integrated electronics provide a path for desired SL-IVUS imaging catheters. In this paper, we first describe the design, low temperature fabrication of an 8401 mu m diameter, 8 element CMUT annular array. Testing of the individual elements in oil shows a uniform device behavior with 100% fractional bandwidth around 20MHz without including the effects of attenuation and diffraction. We also present linear scan imaging results obtained on wire targets in oil, tissue and tissue mimicking phantoms using both unfocused and dynamically focused transducers. The results for axial and lateral resolution are in agreement predicted by the simulations and show the feasibility of this approach for high resolution SL-IVUS imaging.
  • Küçük Resim
    Yayın
    Forward-looking IVUS imaging using a dual-annular ring CMUT array: Experimental results
    (IEEE, 2007) Güldiken, Rasim Oytun; Zahorian, Jaime S.; Gürün, Gökçe; Qureshi, Muhammad Shakeel; Balantekin, Müjdat; Tekeş, Coşkun; Hasler, Paul E.; Karaman, Mustafa; Carlier, Stephane; Değertekin, Fahrettin Levent
    This paper presents the experimental results on forward-looking Intravascular ultrasound (FL-IVUS) using dual-annular-ring CMUT arrays. The array has a diameter of 1mm including bondpads which consists of separate, concentric 24 transmit and 32 receive ring arrays built on the same silicon substrate. This configuration has the potential for Independent optimization of each array and uses the silicon area more effectively without any drawback. For imaging experiments, we designed and constructed a custom integrated circuit using a standard 0.5 mu m CMOS process for data acquisition. A sample pulse-echo signal received from the oil-air Interface (plane reflector) at 6mm had a center frequency of 11MHz with 95% fractional 6-dB bandwidth. The measured SNR of the echo was 24 dB with no averaging. B-scan image of a wire-phantom was generated to test the resolution.
  • Küçük Resim
    Yayın
    Front-end CMOS electronics for monolithic integration with CMUT arrays: Circuit design and initial experimental results
    (2008) Gürün, Gökçe; Qureshi, Muhammad Shakeel; Balantekin, Müjdat; Güldiken, Rasim Oytun; Zahorian, Jaime S.; Peng, Shengyu; Basu, Arindam; Karaman, Mustafa; Hasler, Paul E.; Değertekin, Fahrettin Levent
    This paper discusses design of CMOS-ASICs for monolithic integration of CMUT arrays by post-CMOS fabrication. We describe design strategies for monolithic integration and demonstrate the advantages of CMUT-on-CMOS approach. On the same wafer, separate sets of IC cells are designed to interface different types of CMUT arrays for IVUS and ICE applications. Circuit topologies include resistive feedback transimpedance amplifiers on the receiver side, along with multiplexers and buffers. Gains and bandwidths of receiving amplifiers are optimized separately to fit different array specifications such as number of elements, element size and operation bandwidth. To drive CMUTs a high voltage pulser array is designed in the same 3.3V unmodified CMOS technology by combining existing technological layers in an unconventional way. CMUT arrays are then built on top of the custom made 8" wafer containing these circuits fabricated in a 0.35µm standard CMOS process. We present initial characterization of the CMO electronics and pulse-echo measurements obtained post-CMOS fabricated CMUT elements.