[Front cover] IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control - Dec. 2005

Forward-Viewing CMUT Arrays for Medical Imaging: the cover image shows a 64-element forward-viewing annular array fabricated using the standard CMUT fabrication process. Experiments measured the operating frequency, bandwidth and the transmit/receive efficiency of the array elements. The annular array elements, designed for imaging applications in the 20 MHz range, had a resonance frequency of 13.5 MHz in air. The immersion pulse-echo data collected from a plane reflector showed that the device operates in the 5-26 MHz range with a fractional bandwidth of 135%. The output pressure at the surface of the transducer was measured to be 24 kPa/V. These values translate into a dynamic range of 131.5 dB for 1-V excitation in 1-Hz bandwidth with a commercial low noise receiving circuitry. The forward-viewing annular CMUT array is suitable for mounting on the front surface of a cylindrical catheter probe and can provide Doppler information for measurement of blood flow and guiding information for navigation through blood vessels in intravascular ultrasound imaging. Image courtesy of Utkan Demirci, Omer Oralkan, A. Sanli Ergun, Mustafa Karaman, B.T. Khuri-Yakub. U. Demirci is with Harvard Medical School, Center for Engineering in Medicine - BioMEMs Resource Center, Charlestown, MA. O. Oralkan, A. S. Ergun and B.T. Khuri-Yakub are with Stanford University, Electrical Engineering, Stanford, CA. M. Karaman is with Isik University, Electrical Engineering, Istanbul, Turkey. See article U. Demirci, A. S. Ergun, O. Oralkan, M. Karaman, and B. T. Khuri-Yakub, "Forward-viewing CMUT arrays for medical imaging," IEEE Trans. Ultrason., Ferroelect., Freq. Contr., vol. 51, no. 7, pp. 887-895, Jul. 2004.