Calculation and measurement of electromechanical coupling coefficient of capacitive micromachined ultrasonic transducers

Yaralioglu, G.G.; Ergun, A.S.; Bayram, B.; Hæggström, Edward; Khuri‐Yakub, Butrus T.

doi:10.1109/tuffc.2003.1197968

Cited by 192 publications

(117 citation statements)

References 8 publications

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“…The value of this capacitance can be found by the parallel plate approximation [19]: Typically, many cMUT cells are connected together to form a transducer. An extra capacitance arises because of the interconnections between the cMUT electrodes.…”

Section: Mason Model Corrected By Finite-element Methods Simulationsmentioning

confidence: 99%

Optimization of the gain-bandwidth product of capacitive micromachined ultrasonic transducers

Ölçüm

Senlik

Atalar

2005

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

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Abstract-Capacitive micromachined ultrasonic transducers (cMUT) have large bandwidths, but they typically have low conversion efficiencies. This paper defines a performance measure in the form of a gain-bandwidth product and investigates the conditions in which this performance measure is maximized. A Mason model corrected with finite-element simulations is used for the purpose of optimizing parameters. There are different performance measures for transducers operating in transmit, receive, or pulse-echo modes. Basic parameters of the transducer are optimized for those operating modes. Optimized values for a cMUT with silicon nitride membrane and immersed in water are given. The effect of including an electrical matching network is considered. In particular, the effect of a shunt inductor in the gain-bandwidth product is investigated. Design tools are introduced, which are used to determine optimal dimensions of cMUTs with the specified frequency or gain response.

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Section: Mason Model Corrected By Finite-element Methods Simulationsmentioning

confidence: 99%

Optimization of the gain-bandwidth product of capacitive micromachined ultrasonic transducers

Ölçüm

Senlik

Atalar

2005

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

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“…With the rapid development of microelectromechanical systems (MEMS) technology, micromachined ultrasonic transducers (MUTs) based on capacitive (CMUT) and piezoelectric (PMUT) transduction have been demonstrated with significantly reduced device sizes for high-resolution applications, low power consumption and better acoustic impedance matching to the medium 1,2 . In general, CMUTs suffer from limited vertical deformation, nonlinear drive effects and high DC bias voltages, but they have high electromechanical coupling factors 3 . With improvements in piezoelectric materials technology, PMUTs are beginning to pose an alternative to CMUTs.…”

Section: Introductionmentioning

confidence: 99%

Monolithic ultrasound fingerprint sensor

et al. 2017

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This paper presents a 591 × 438-DPI ultrasonic fingerprint sensor. The sensor is based on a piezoelectric micromachined ultrasonic transducer (PMUT) array that is bonded at wafer-level to complementary metal oxide semiconductor (CMOS) signal processing electronics to produce a pulse-echo ultrasonic imager on a chip. To meet the 500-DPI standard for consumer fingerprint sensors, the PMUT pitch was reduced by approximately a factor of two relative to an earlier design. We conducted a systematic design study of the individual PMUT and array to achieve this scaling while maintaining a high fill-factor. The resulting 110 × 56-PMUT array, composed of 30 × 43-μm 2 rectangular PMUTs, achieved a 51.7% fill-factor, three times greater than that of the previous design. Together with the custom CMOS ASIC, the sensor achieves 2 mV kPa − 1 sensitivity, 15 kPa pressure output, 75 μm lateral resolution, and 150 μm axial resolution in a 4.6 mm × 3.2 mm image. To the best of our knowledge, we have demonstrated the first MEMS ultrasonic fingerprint sensor capable of imaging epidermis and sub-surface layer fingerprints. INTRODUCTIONFingerprint sensors capture an electronic image of a human fingerprint through various physical mechanisms, including optical, capacitive, pressure and acoustic mechanisms. Capacitive fingerprint sensors are the standard for identity authentication in numerous applications because of their performance and low cost; the latter is due to the fact that these sensors can be manufactured in a standard integrated circuit manufacturing process. Ultrasonic fingerprint sensors have many advantages over capacitive sensors, including being insensitive to contamination and moisture on the finger. In addition, ultrasonic waves used in pulse-echo imaging can penetrate the finger's epidermis, collecting images of sub-surface features. However, ultrasonic fingerprint sensors previously provided a low resolution or were too difficult to manufacture. With the rapid development of microelectromechanical systems (MEMS) technology, micromachined ultrasonic transducers (MUTs) based on capacitive (CMUT) and piezoelectric (PMUT) transduction have been demonstrated with significantly reduced device sizes for high-resolution applications, low power consumption and better acoustic impedance matching to the medium

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“…Although impossible to operate too close to the collapse, the practically achievable values are quite large. Coupling coefficients of more than 70 % have been demonstrated [17,18]. One of the reasons for the large coupling is the fact that the electrostatic force acts vertical to the membrane, i.e.…”

Section: Introductionmentioning

confidence: 99%

Micromachined Ultrasonic Transducers and Acoustic Sensors Based on Piezoelectric Thin Films

Muralt¹

2005

Electroceramic-Based MEMS

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A review is given on the current state of the art in piezoelectric micromachined ultrasonic transducers (pMUT). It is attempted to quantify the limits of pMUT's with respect to the electromechanical coupling, and to relate current achievements. Best reported results so far is a coupling coefficient k 2 of 6 %. This was achieved with 2 µm thick PZT thin films on a 5 µm thick silicon layer obtained by micromachining from a SOI wafer. The material properties are the most important part for a good performance, however, design contributes as well. Electrode size, layer thickness relation, and border conditions must be dimensioned correctly. Main needs for future research are identified in design, micromachining and further improvements of PZT films. Applications are shortly reviewed. 38 Electroceramic-Based MEMS: Fabrication-Technology and Applications

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Calculation and measurement of electromechanical coupling coefficient of capacitive micromachined ultrasonic transducers

Cited by 192 publications

References 8 publications

Optimization of the gain-bandwidth product of capacitive micromachined ultrasonic transducers

Optimization of the gain-bandwidth product of capacitive micromachined ultrasonic transducers

Monolithic ultrasound fingerprint sensor

Micromachined Ultrasonic Transducers and Acoustic Sensors Based on Piezoelectric Thin Films

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