Improved pulse-echo imaging performance for flexure-mode pMUT arrays

Dausch, David; Gilchrist, Kristin H.; Carlson, James R.; Castellucci, John; Chou, Derrick; Ramm, Olaf T. von

doi:10.1109/ultsym.2010.5935826

Cited by 32 publications

(18 citation statements)

References 9 publications

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“…In recent years, thin film piezoelectric micro-machined ultrasonic transducers (pMUTs) have garnered attention for a wide variety of applications including range finding [1], non-destructive testing (NDT), object detection [2], and medical applications [3], [4]. Although significant advances have been achieved with bulk systems, the labor intensive manufacturing process restrains the realization of cost effective, small form factor and 2D arrays for advanced imaging [5].…”

Section: Introductionmentioning

confidence: 99%

“…Despite achievements in pMUT research [1], [3], [4], [12]- [18], predictive modeling and optimization capabilities are limited in improving reduced effective electromechanical coupling k 2 ef f and bandwidth in fabricated devices. In the most mature recent projects, fabricated pMUT designs are based heavily on geometry specific finite element models [19] with analytical models commonly limited to resonant frequency determination [4], [16], [20], [21]. A lack of available models leading to performance shortcomings demonstrate a need for more robust, fundamental understanding of pMUT performance.…”

Section: Introductionmentioning

confidence: 99%

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Experiment and simulation validated analytical equivalent circuit model for piezoelectric micromachined ultrasonic transducers

Smyth

Kim

2015

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

100

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An analytical Mason equivalent circuit is derived for a circular, clamped plate piezoelectric micro-machined ultrasonic transducer (pMUT) design in 31 mode considering an arbitrary electrode configuration at any axisymmetric vibration mode. The explicit definition of lumped parameters based entirely on geometry, material properties and defined constants enables straightforward and wide ranging model implementation for future pMUT design and optimization. Beyond pMUTs, the acoustic impedance model is developed for universal application to any clamped, circular plate system and operating regimes including relevant simplifications are identified via the wave number-radius product ka. For the single electrode fundamental vibration mode case, sol-gel P b (Zr0.52) T i0.48O3 (PZT) pMUT cells are micro-fabricated with varying electrode size to confirm the derived circuit model with electrical impedance measurements. For the first time, experiment and finite element simulation results are successfully applied to validate extensive electrical, mechanical and acoustic analytical modeling of a pMUT cell for wide ranging applications including medical ultrasound, non-destructive testing, and range finding.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experiment and simulation validated analytical equivalent circuit model for piezoelectric micromachined ultrasonic transducers

Smyth

Kim

2015

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

100

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“…Since the effect of residual stress is felt largely along the edge of the plate, a simply supported boundary condition has been introduced resulting in improved device coupling [6] and acoustic pressure [7]. Other authors have added a bias voltage to overcome the effects of residual stress, but this requires the PMUT to operate at high voltages similar to those required for the CMUT [6], [8], [9]. For significant acoustic pressure output improvement, the voltage has even been driven past the coercive voltage where the initial domain switching has enabled transmission sensitivity as high as 20kPa/V at a distance of 20mm [8].…”

Section: Introductionmentioning

confidence: 99%

“…Other authors have added a bias voltage to overcome the effects of residual stress, but this requires the PMUT to operate at high voltages similar to those required for the CMUT [6], [8], [9]. For significant acoustic pressure output improvement, the voltage has even been driven past the coercive voltage where the initial domain switching has enabled transmission sensitivity as high as 20kPa/V at a distance of 20mm [8]. In the absence of a large applied DC bias voltage, acoustic power output is limited and transmit sensitivity is low [5], [6].…”

Section: Introductionmentioning

confidence: 99%

Working equations of a circular multimorph piezoelectric micromachined ultrasonic transducer

Sammoura

Smyth

Kim

2012

IECON 2012 - 38th Annual Conference on IEEE Industrial Electronics Society

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This paper makes the distinction between the moment and electrical neutral axis location in a circular, simply supported, multimorph piezoelectric micromachined ultrasonic transducer (PMUT) for application to transduction. The derivation applies to an arbitrary n layer stack of piezoelectric and structural materials forming a multimorph. Based on neutral axis location, the plate vibration equation is derived generally and can be applied separately for transmission and receiving modes. From the electrical neutral axis, the charge equation is derived and is related to the location of the neutral axis through an added voltage-dependent term. Tn governing transducer equations, the voltage dependent added capacitance creates symmetry between the electrical and mechanical domains enabling theoretical calculation of the electrical input impedance, future derivation of equivalent circuit parameters for a multimorph PMUT, and design of high-power ultrasonic imaging arrays.

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“…However, saw cutting cannot achieve an element pitch smaller than 100 μm, making micromachining an attractive option for high frequency (>10 MHz) arrays requiring half-wavelength (λ/2) element pitch. Previous PMUTs were fabricated by a through-wafer etching approach [14], [15], resulting in low fill-factor, small element count, and therefore poor acoustic efficiency. Here, we present PMUTs with 10-20× higher density (1061 transducers/mm 2 ) than the highest density PMUT arrays realized to date, 56 transducers/mm 2 [14] and 123 transducers/mm 2 [15].…”

mentioning

confidence: 99%

A High Fill-Factor Annular Array of High Frequency Piezoelectric Micromachined Ultrasonic Transducers

Heidari

Horsley

2015

J. Microelectromech. Syst.

100

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This paper presents a 1.2-mm diameter high fill-factor array of 1261 piezoelectric micromachined ultrasonic transducers (PMUTs) operating at 18.6 MHz in fluid for intravascular ultrasound imaging. At 1061 transducers/mm 2 , the PMUT array has a 10-20 times higher density than previous PMUT arrays realized to date. Aluminum nitride (AlN)-based PMUTs described in this paper are fabricated using a process compatible with the fabrication of inertial sensors, radio frequency (RF) resonators, and CMOS integrated circuits. The PMUTs are released using a front-side sacrificial etch through etching holes that are subsequently sealed by a thin layer of parylene. Finite element method and analytical results, including resonant frequency, pressure sensitivity, output acoustic pressure, and directivity are given to guide the PMUT design effectively, and are shown to match well with measurement results. Due to the PMUTs thin membrane (750-nm AlN/800-nm SiO 2 ) and small diameter, a single 25-µm PMUT has approximately omnidirectional directivity and no near-field zone with irregular pressure pattern. PMUTs are characterized in both the frequency and time domains. Measurement results show a large displacement response of 2.5 nm/V at resonance and good frequency matching in air, high center frequency of 18.6 MHz and wide bandwidth of 4.9 MHz, when immersed in fluid. Phased array simulations based on measured PMUT parameters show a tightly focused high-output pressure acoustic beam. [2014-0114] Index Terms-Aluminum nitride (AlN), piezoelectric, ultrasonic, transducer, micromachined ultrasonic transducer (MUT), piezoelectric MUT (PMUT).

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Improved pulse-echo imaging performance for flexure-mode pMUT arrays

Cited by 32 publications

References 9 publications

Experiment and simulation validated analytical equivalent circuit model for piezoelectric micromachined ultrasonic transducers

Experiment and simulation validated analytical equivalent circuit model for piezoelectric micromachined ultrasonic transducers

Working equations of a circular multimorph piezoelectric micromachined ultrasonic transducer

A High Fill-Factor Annular Array of High Frequency Piezoelectric Micromachined Ultrasonic Transducers

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