Tent-Plate AlN PMUT With a Piston-Like Shape Under Liquid Operation

Ledesma, Eyglis; Zamora, Iván; Uranga, A.; Barniol, N.

doi:10.1109/jsen.2020.2995643

Cited by 21 publications

(19 citation statements)

References 25 publications

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“…To validate the proposed MFPW algorithm for ultrasound distance measurements in liquid, an 80 µm squared piezoelectric micromachined ultrasonic transducer (PMUT), fabricated with the MEMS-on-CMOS process from Silterra was used [ 16 , 17 ]. In this case the PMUT is composed of 1.2 μm AlScN (Aluminium Nitride doped with 9.5 % Scandium) sandwiched between aluminum electrodes and covered by 1.5 μm Silicon Nitride as elastic layer [ 18 ].…”

Section: Resultsmentioning

confidence: 99%

High Accuracy Ultrasound Micro-Distance Measurements with PMUTs under Liquid Operation

Zamora

Ledesma

Uranga

et al. 2021

Sensors

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Ultrasonic systems driven by multi-frequency continuous waves (MFCW) have been used for range distance measurement, offering high accuracy in long and medium range distance estimation. However, the use of continuous waves in very short-distance measurements causes large errors due to multipath reflections. This paper presents a new strategy to estimate very short relative distances with high accuracy based on the use of multi-frequency pulsed waves (MFPW). The proposed strategy allows to avoid the multipath reflections that appear when continuous waves are used, and it improves the achieved accuracy compared to the original MFCW method. To validate it, an 80 µm square AlScN piezoelectric micromachined ultrasonic transducer (PMUT) was chosen as a transmitter while a hydrophone was utilized as a target and receiver, immersed in fluorinert (FC-70) as a propagation medium. Three independent and consecutive tone-burst signals were transmitted successively. The selected frequencies are f1 = 2.3962 MHz, f2 = 2.327 MHz and f3 = 2.1195 MHz, giving first and second-order resolutions of 6.88 and 0.79 µm/°, respectively. Experimental results show a ±6.2 μm measured range error in a range of 3.5 mm, and therefore it represents a good candidate for ultrasound micro-profilometer applications under liquid operation.

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Section: Resultsmentioning

confidence: 99%

High Accuracy Ultrasound Micro-Distance Measurements with PMUTs under Liquid Operation

Zamora

Ledesma

Uranga

et al. 2021

Sensors

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“…The bottom electrode is common for all PMUT devices, and the gap between consecutive elements is 25 µm. Every single element consists of a squared AlN-PMUT with a 40 µm side, fabricated using the MEMS-on-CMOS SilTerra technology [16,21]. The top electrode size was optimized to maximize the membrane velocity and consequently the output pressure.…”

Section: Multielement Ring Array Designmentioning

confidence: 99%

Multielement Ring Array Based on Minute Size PMUTs for High Acoustic Pressure and Tunable Focus Depth

Ledesma

Zamora

Uranga

et al. 2021

Sensors

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This paper presents a multielement annular ring ultrasound transducer formed by individual high-frequency PMUTs (17.5 MHz in air and 8.7 MHz in liquid) intended for high-precision axial focalization and high-performance ultrasound imaging. The prototype has five independent multielement rings fabricated by a monolithic process over CMOS, allowing for a very compact and robust design. Crosstalk between rings is under 56 dB, which guarantees an efficient beam focusing on a range between 1.4 mm and 67 µm. The presented PMUT-on-CMOS annular array with an overall diameter down to 669 µm achieves an output pressure in liquid of 4.84 kPa/V/mm2 at 1.5 mm away from the array when the five channels are excited together, which is the largest reported for PMUTs. Pulse-echo experiments towards high-resolution imaging are demonstrated using the central ring as a receiver. With an equivalent diameter of 149 µm, this central ring provides high receiving sensitivity, 441.6 nV/Pa, higher than that of commercial hydrophones with equivalent size. A 1D ultrasound image using two channels is demonstrated, with maximum received signals of 7 mVpp when a nonintegrated amplifier is used, demonstrating the ultrasound imaging capabilities.

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“…Another type of micromachined ultrasonic transducer (MUT) is to use a layer of piezoelectric material as the vibrating part, and PZT and aluminum nitride (AlN) are the most commonly used piezoelectric materials [ 27 ]. CMUT works under a larger DC bias than PMUT, needs a smaller cavity, owns a larger bandwidth than PMUT [ 28 ], employs a more complicated fabrication process than PMUT [ 28 , 29 ], consumes more power than PMUT does [ 29 ].…”

Section: Introductionmentioning

confidence: 99%

A Review on Analytical Modeling for Collapse Mode Capacitive Micromachined Ultrasonic Transducer of the Collapse Voltage and the Static Membrane Deflections

Wang

Liu²,

et al. 2021

Micromachines

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Analytical modeling of capacitive micromachined ultrasonic transducer (CMUT) is one of the commonly used modeling methods and has the advantages of intuitive understanding of the physics of CMUTs and convergent when modeling of collapse mode CMUT. This review article summarizes analytical modeling of the collapse voltage and shows that the collapse voltage of a CMUT correlates with the effective gap height and the electrode area. There are analytical expressions for the collapse voltage. Modeling of the membrane deflections are characterized by governing equations from Timoshenko, von Kármán equations and the 2D plate equation, and solved by various methods such as Galerkin’s method and perturbation method. Analytical expressions from Timoshenko’s equation can be used for small deflections, while analytical expression from von Kármán equations can be used for both small and large deflections.

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Tent-Plate AlN PMUT With a Piston-Like Shape Under Liquid Operation

Cited by 21 publications

References 25 publications

High Accuracy Ultrasound Micro-Distance Measurements with PMUTs under Liquid Operation

High Accuracy Ultrasound Micro-Distance Measurements with PMUTs under Liquid Operation

Multielement Ring Array Based on Minute Size PMUTs for High Acoustic Pressure and Tunable Focus Depth

A Review on Analytical Modeling for Collapse Mode Capacitive Micromachined Ultrasonic Transducer of the Collapse Voltage and the Static Membrane Deflections

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