Ultrasonic transducer

Résumé

Ultrasonic transducers and ultrasonic sensors are devices that generate or sense ultrasound energy. They can be divided into three broad categories: transmitters, receivers and transceivers. Transmitters convert electrical signals into ultrasound, receivers convert ultrasound into electrical signals, and transceivers can both transmit and receive ultrasound. Applications and performance Ultrasound can be used for measuring wind speed and direction (anemometer), tank or channel fluid level, and speed through air or water. For measuring speed or direction, a device uses multiple detectors and calculates the speed from the relative distances to particulates in the air or water. To measure tank or channel liquid level, and also sea level (tide gauge), the sensor measures the distance (ranging) to the surface of the fluid. Further applications include: humidifiers, sonar, medical ultrasonography, burglar alarms and non-destructive testing. Systems typically use a transducer th

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https://en.wikipedia.org/wiki/Ultrasonic_transducer

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Vibration Mode of MEMS Ultrasonic Sensors on Buckled Diaphragms with Piezoelectric Resonance Frequency Modification

Paul Muralt, Kaoru Yamashita

Vibration mode and resonance frequency of piezoelectric MEMS ultrasonic sensors was investigated on buckled diaphragm structures. The buckling of the diaphragms was introduced intrinsically through residual stress control of the piezoelectric film, and extrinsically through converse piezoelectric stress. Several vibration modes were generated on the diaphragms as the response to an ultrasound pulse, and their natural frequencies changed with the buckling deflection. The intrinsic buckling increased the natural frequency and some vibration modes were superposed and degraded. The extrinsic buckling once decreased the natural frequency in a small buckling range, and increased it in a large one, which made the vibration mode simplified and thus improved piezoelectric output waveforms would be expected.

IEEE2019

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Piezoelectric micromachined ultrasonic transducers with thick PZT sol gel films

Florian Calame, Paul Muralt

Springer US2007

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Piezoelectric micromachined ultrasonic transducers based on PZT thin films

Nicolas Ledermann, Paul Muralt, Nava Setter

This paper describes fabrication and characterization results of piezoelectric micromachined ultrasonic transducers (pMUTs) based on 2-mu m-thick Pb(Zr0.53Ti0.47O3) (PZT) thin films. The applied structures are circular plates held at four bridges, thus partially unclamped. A simple analytical model for the fully clamped structure is used as a reference to optimize design parameters such as thickness relations and electrodes, and to provide approximate predictions for coupling coefficients related to previously determined thin film properties. The best coupling coefficient was achieved with a 270-mu m plate and amounted to k(2) = 5.3%. This value compares well with the calculated value based on measured small signal dielectric (epsilon = 1050) and piezoelectric (e(31,f) = 15 Cm-2) properties of the PZT thin film at 100 kV/cm dc bias. The resonances show relatively large Q-factors, which can be partially explained by the small diameters as compared to the sound wavelength in air and in the test liquid (Fluorinert 77). A transmit-receive experiment with two quasi-identical pMUTs was performed showing significant signal transmission up to a distance of 20 cm in air and 2 cm in the test liquid.

2005

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