Micromachined ultrasonic capacitance transducers for immersion applications

Bashford, A.G.; Schindel, D.W.; Hutchins, David A.

doi:10.1109/58.660148

Cited by 35 publications

(13 citation statements)

References 37 publications

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“…From these measurements, it seems clear that the fully micromachined capacitance transducers show great promise in high frequency applications in liquids, as indeed has been indicated by previous work [12]. The striking feature about the present measurements is the wide operation bandwidth available, which has not been observed before in devices reported previously using smaller cells and with a vacuum between the membrane and the substrate.…”

Section: Experiments In Liquidssupporting

confidence: 67%

Novel, wide bandwidth, micromachined ultrasonic transducers

Noble

Jones

Robertson

et al. 2001

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Surface micromachined, capacitive ultrasonic transducers have been fabricated using a low thermal budget, CMOS-compatible process. This process allows inherent control of parameters such as membrane size and thickness, cavity size and the intrinsic stress in the membrane to be achieved. Devices fabricated using this process exhibit interesting properties for transduction in air at frequencies in excess of 1 MHz when driven from a standard ultrasonic voltage source. Experiments have been performed with devices containing silicon nitride membranes of variable thicknesses over a 2 m thick air cavity and with device dimensions of up to 5 mm square. This is much larger than has been reported for a device with a single membrane. Calibration measurements using 1/8 inch microphones in air, and miniature PVDF hyrdophones in water, have been performed. The dependence on d.c. bias voltage is examined, involving static membrane deflection measurements and received peak voltages. Pulse-echo and pitch-catch mode operation have been achieved. Interferometric measurements of membrane displacement have been performed in air to illustrate the membrane deflection characteristics. Operation in liquids is also discussed.

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Section: Experiments In Liquidssupporting

confidence: 67%

Novel, wide bandwidth, micromachined ultrasonic transducers

Noble

Jones

Robertson

et al. 2001

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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“…For a piezoelectric transducer, the turns ratio n [C/m 3 ] is given by [8] n piezo = h 33 ε l (2) where ε is the dielectric constant, h 33 [V/m] is the piezoelectric deformation constant, and l [m] is the transducer thickness. For a capacitive transducer, we have [9] …”

Section: A Emission Of Ultrasonic Energy Into Solidmentioning

confidence: 99%

MEMS ultrasonic transducers for the testing of solids

Oppenheim

Jain

Greve

2003

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Arrays of capacitive diaphragm ultrasonic transducers could potentially be used for non-destructive ultrasonic testing and structural monitoring. In this paper, we consider the efficiency of coupling of these transducers to solid media. We show that efficient coupling can be realized by using a silicone coating as a coupling medium. We present the results of experimental characterization of ultrasonic transducers coupled to solids in this way. We show that these transducers can be used with piezoelectric emitting transducers within the range from 1 to 5 MHz, and we demonstrate the use of several transducers as a phased array to determine the direction and distance of an ultrasonic source.

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“…Two other references 5,6 discuss one-dimensional transducer arrays and present initial imaging results, in which solids immersed within fluids are detected. Other investigators of MEMS ultrasonics include Schindel 7,8 with numerous contributions to immersion applications, and Eccardt 9,10 , with the demonstration of surface micromachined transducers in a modified CMOS process.…”

Section: Introductionmentioning

confidence: 99%

Experiments in ultrasonic flaw detection using a MEMS transducer

2003

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In earlier work we developed a MEMS phased array transducer, fabricated in the MUMPs process, and we reported on initial experimental studies in which the device was affixed into contact with solids. We demonstrated the successful detection of signals from a conventional ultrasonic source, and the successful localization of the source in an off-axis geometry using phased array signal processing. We now describe the predicted transmission and coupling characteristics for such devices in contact with solids, demonstrating reasonable agreement with experimental behavior. We then describe the results of flaw detection experiments, as well as results for fluid-coupled detectors.

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Micromachined ultrasonic capacitance transducers for immersion applications

Cited by 35 publications

References 37 publications

Novel, wide bandwidth, micromachined ultrasonic transducers

Novel, wide bandwidth, micromachined ultrasonic transducers

MEMS ultrasonic transducers for the testing of solids

Experiments in ultrasonic flaw detection using a MEMS transducer

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