Micromachined ultrasonic capacitance transducers for immersion applications

Investigations into the characteristics of water-coupled ultrasonic capacitance transducers have been undertaken for a range of transducer configurations. The radiated fields have been scanned in water using a miniature hydrophone detector, and the results compared to theory based on a plane piston approach. Micromachined backplates in conjunction with thin Mylar and mica membranes have been investigated, together with aperture modifications such as an annulus and Fresnel zone plate. The measured results agree well with theory, thus demonstrating that wideband predictable performance (>8 MHz) is obtainable with such transducers. Additionally, pulse-echo C-scans of a Plexiglas plate containing an artificial defect have been undertaken with the capacitance transducer, in order to demonstrate that the capacitance transducer has sufficient sensitivity to allow routine nondestructive testing within immersion applications.

[1]  D. Hutchins,et al.  Radiated Fields of Ultrasonic Transducers , 1990 .

[2]  Gerald R. Harris,et al.  Review of transient field theory for a baffled planar piston , 1981 .

[3]  D. Schindel,et al.  Applications of micromachined capacitance transducers in air-coupled ultrasonics and nondestructive evaluation , 1995, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[4]  D. R. Bacon,et al.  Characteristics of a PVDF Membrane Hydrophone for Use in the Range 1-100 MHz , 1982, IEEE Transactions on Sonics and Ultrasonics.

[5]  N. Hsu,et al.  Ultrasonic Transducers for Materials Testing and Their Characterization , 1979 .

[6]  A matched impedance, electrostatic approach to hydrophone design , 1981 .

[7]  David A. Hutchins,et al.  The capacitance transducer as a standard ultrasonic source in solids , 1995 .

[8]  A. D. Bond,et al.  The influence of waveform distortion on hydrophone spatial‐averaging corrections—Theory and measurement , 1992 .

[9]  S. Marin,et al.  The use of ultrasonics for gauging and proximity sensing in air , 1986 .

[10]  Kohji Ogura,et al.  Receiving Characteristics of d31-zero Piezo-Rubber Hydrophone , 1993 .

[11]  A. G. Bashford,et al.  Focussing of ultrasonic waves in air using a micromachined Fresnel zone-plate , 1997 .

[12]  L. Eyraud,et al.  PcC2. 1. 3. 1 PZT-Polymer composites for high pressure hydrophone application , 1992 .

[13]  P. A. Lewin,et al.  Miniature piezoelectric polymer ultrasonic hydrophone probes , 1981 .

[14]  A. Safari,et al.  Perforated PZT composites for hydrophone applications , 1983 .

[15]  David A. Hutchins,et al.  Ultrasonic measurements in polymeric materials using air-coupled capacitance transducers , 1994 .

[16]  L. Sutherland,et al.  Atmospheric Absorption of Sound , 1972 .

[17]  J S Heyman,et al.  Broadband electrostatic acoustic transducer for ultrasonic measurements in liquids. , 1979, The Review of scientific instruments.

[18]  Moises Levy,et al.  Characteristics of ultrasonic micromachined capacitance transducers in water , 1996 .

[19]  Yuan Yiquan,et al.  A new multilayer planar PVDF standard hydrophone and its applications , 1995 .

[20]  Michael J. Anderson,et al.  BROADBAND ELECTROSTATIC TRANSDUCERS : MODELING AND EXPERIMENTS , 1995 .

[21]  Tetsuji Miyata,et al.  Properties of Hydrophone with Porous Piezoelectric Ceramics , 1991 .

[22]  Capacitance transducers for generating ultrasonic fields in liquids and gases , 1993 .

[23]  S. M. Kramer,et al.  Characteristics of wide-band planar ultrasonic transducers using plane and edge wave contributions , 1988, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

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

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

[26]  C. M. Fortunko,et al.  Absorption of ultrasonic waves in air at high frequencies (10–20 MHz) , 1992 .

[27]  D. Schindel,et al.  Capacitance devices for the controlled generation of ultrasonic fields in liquids , 1991, IEEE 1991 Ultrasonics Symposium,.

[28]  Gerald R. Harris,et al.  Transient field of a baffled planar piston having an arbitrary vibration amplitude distribution , 1981 .

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

[30]  Henry E. Bass,et al.  Atmospheric Absorption of Sound: Theoretical Predictions , 1972 .

[31]  Yasuhiro Nakamura,et al.  Study of surface elastic wave induced on backing material and diffracted field of a piezoelectric polymer film hydrophone , 1993 .

[32]  A. Varaprasad,et al.  PZT-polymer composites for transducers of hydrophone systems , 1988 .

[33]  I. Ladabaum,et al.  Micromachined ultrasonic transducers (MUTs) , 1995, 1995 IEEE Ultrasonics Symposium. Proceedings. An International Symposium.