2.14 – Ultrasonic Transduction

Piezoelectricity has long been the dominant transduction mechanism to detect and generate ultrasound. Recently, capacitive micromachined ultrasonic transducers (cMUTs) based on electrostatic transduction have emerged as an alternative to piezoelectric transducers. Wide bandwidth in immersion operation, ease of fabricating large arrays, and potential for integration with electronics are some of the advantages offered by cMUT technology. This chapter explains the theory and modeling of this modern type of electrostatic transducers. Both analytical and numerical models are presented. Fabrication processes based on surface and bulk micromachining techniques are explained. Examples of imaging systems based on this new technology are also described.

[1]  C Wykes,et al.  The performance of capacitive ultrasonic transducers using v-grooved backplates , 1991 .

[2]  D. Hutchins,et al.  Low-temperature micromachined cMUTs with fully-integrated analogue front-end electronics , 2002, 2002 IEEE Ultrasonics Symposium, 2002. Proceedings..

[3]  F. L. Degertekin,et al.  Fabrication and characterization of cMUTs for forward looking intravascular ultrasound imaging , 2003, IEEE Symposium on Ultrasonics, 2003.

[4]  Gregory T. A. Kovacs,et al.  High-voltage devices and circuits fabricated using foundry CMOS for use with electrostatic MEM actuators , 1996 .

[5]  W. Benecke,et al.  Derivation of a 1D CMUT model from FEM results for linear and nonlinear equivalent circuit simulation , 2003, IEEE Symposium on Ultrasonics, 2003.

[6]  R. Phillips,et al.  Output levels and bioeffects indices from diagnostic ultrasound exposure data reported to the FDA , 1994, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[7]  O. Oralkan,et al.  Integrated ultrasonic imaging systems based on CMUT arrays: recent progress , 2004, IEEE Ultrasonics Symposium, 2004.

[8]  G. P. Singh,et al.  High-voltage-tolerant I/O buffers with low-voltage CMOS process , 1999, IEEE J. Solid State Circuits.

[9]  B. Khuri-Yakub,et al.  Capacitive micromachined ultrasonic transducers: next-generation arrays for acoustic imaging? , 2002, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[10]  Timothy J. Maloney,et al.  Basic ESD and I/O Design , 1998 .

[11]  Reinhard Lerch,et al.  Micromachined transducer design for minimized generation of surface waves , 1999, 1999 IEEE Ultrasonics Symposium. Proceedings. International Symposium (Cat. No.99CH37027).

[12]  P.-C. Eccardt,et al.  Micromachined transducers for ultrasound applications , 1997, 1997 IEEE Ultrasonics Symposium Proceedings. An International Symposium (Cat. No.97CH36118).

[13]  Riccardo Carotenuto,et al.  Micromachined ultrasonic transducers using silicon nitride membrane fabricated in PECVD technology , 2000, 2000 IEEE Ultrasonics Symposium. Proceedings. An International Symposium (Cat. No.00CH37121).

[14]  W. P. Mason.  Electromechanical transducers and wave filters , 1942 .

[15]  A. L. Robinson,et al.  Applications of microelectronics and microfabrication to ultrasound imaging systems , 1992, IEEE 1992 Ultrasonics Symposium Proceedings.

[16]  Paulina S. Kuo,et al.  Capacitive micromachined ultrasonic transducers (CMUTs) for photoacoustic imaging , 2006, SPIE BiOS.

[17]  O. Oralkan,et al.  An endoscopic imaging system based on a two-dimensional CMUT array: real-time imaging results , 2005, IEEE Ultrasonics Symposium, 2005..

[18]  K. Suzuki,et al.  A silicon electrostatic ultrasonic transducer , 1989, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[19]  D. Hutchins,et al.  Cost-effective and manufacturable route to the fabrication of high-density 2D micromachined ultrasonic transducer arrays and (CMOS) signal conditioning electronics on the same silicon substrate , 2001, 2001 IEEE Ultrasonics Symposium. Proceedings. An International Symposium (Cat. No.01CH37263).

[20]  I. Ladabaum,et al.  Microfabricated ultrasonic transducers monolithically integrated with high voltage electronics , 2004, IEEE Ultrasonics Symposium, 2004.

[21]  Ching-Hsiang Cheng,et al.  Silicon Micromachined Ultrasonic Transducers , 2000 .

[22]  Geng Ku,et al.  Imaging of tumor angiogenesis in rat brains in vivo by photoacoustic tomography. , 2005, Applied optics.

[23]  O. Oralkan,et al.  3-D ultrasound imaging using a forward-looking CMUT ring array for intravascular/intracardiac applications , 2006, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[24]  B. Khuri-Yakub,et al.  Improved equivalent circuit and finite element method modeling of capacitive micromachined ultrasonic transducers , 2003, IEEE Symposium on Ultrasonics, 2003.

[25]  R. Esenaliev,et al.  Sensitivity of laser opto-acoustic imaging in detection of small deeply embedded tumors , 1999 .

[26]  D.N. Stephens,et al.  Optimizing the beam pattern of a forward-viewing ring-annular ultrasound array for intravascular imaging , 2002, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[27]  P.A. Lewin,et al.  The Influence of Front-End Hardware on Digital Ultrasonic Imaging , 1984, IEEE Transactions on Sonics and Ultrasonics.

[28]  O. Oralkan,et al.  Photoacoustic imaging using a two-dimensional CMUT array , 2005, IEEE Ultrasonics Symposium, 2005..

[29]  Gisela Hess,et al.  A subminiature condenser microphone with silicon nitride membrane and silicon back plate , 1989 .

[30]  B. Khuri-Yakub,et al.  Surface micromachined capacitive ultrasonic transducers , 1998, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[31]  D. Schindel,et al.  The design and characterization of micromachined air-coupled capacitance transducers , 1995, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[32]  Vladimir I. Prodanov,et al.  7V tristate-capable output buffer implemented in standard 2.5 V CMOS process , 2001, Proceedings of the IEEE 2001 Custom Integrated Circuits Conference (Cat. No.01CH37169).

[33]  Eberhard Brunner,et al.  How Ultrasound System Considerations Influence Front-End Component Choice , 2002 .

[34]  Anne-Johan Annema,et al.  5.5-V I/O in a 2.5-V 0.25-/spl mu/m CMOS technology , 2001 .

[35]  Hussein Ballan,et al.  High Voltage Devices and Circuits in Standard CMOS Technologies , 1998 .