Simulation and experimental characterization of a 2-D capacitive micromachined ultrasonic transducer array element

Capacitive Micromachined Ultrasonic Transducer (CMUT) is a promising ultrasonic transducer in medical diagnosis and therapeutic applications that demand a high output pressure. The concept of a CMUT with an annular embossed pattern on a membrane working in collapse mode is proposed to further improve the output pressure. To evaluate the performance of an embossed CMUT cell, both the embossed and uniform membrane CMUT cells were fabricated in the same die with a customized six-mask sacrificial release process. An annular nickel pattern with the dimension of 3 μ m × 2 μ m (width × height) was formed on a full top electrode CMUT to realize an embossed CMUT cell. Experimental characterization was carried out with optical, electrical, and acoustic instruments on the embossed and uniform CMUT cells. The embossed CMUT cell achieved 27.1% improvement of output pressure in comparison to the uniform CMUT cell biased at 170 V voltage. The fractional bandwidths of the embossed and uniform CMUT cells were 52.5% and 41.8%, respectively. It substantiated that the embossed pattern should be placed at the vibrating center of the membrane for achieving a higher output pressure. The experimental characterization indicated that the embossed CMUT cell has better operational performance than the uniform CMUT cell in collapse region.

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Experimental Characterization of A Piezoelectric Transducer Array Taking into Account Crosstalk Phenomenon

International Journal of Engineering and Technology Innovation ◽

10.46604/ijeti.2020.4348 ◽

2020 ◽

Vol 10 (1) ◽

pp. 01-14

Author(s):

Abdelmajid Bybi ◽

Driss Khouili ◽

Christian Granger ◽

Mohammed Garoum ◽

Ahmed Mzerd ◽

...

Keyword(s):

Piezoelectric Transducer ◽

Ultrasonic Transducer ◽

Critical Role ◽

Experimental Characterization ◽

Transducer Array ◽

The Third ◽

Transducer Arrays ◽

Piezoelectric Elements ◽

Thickness Mode

Ultrasonic transducer arrays are generally composed of several piezoelectric elements arranged in 1D or 2D ways. Crosstalk is an undesirable phenomenon decreasing the performance of these devices. It generates parasitic displacements at the elements' radiating surfaces, which changes the directivity of the array. Furthermore, the transducer's displacement plays a critical role in terms of the focal area and transferred intensities. The objective of this paper is to characterize a piezoelectric array composed of seven-elements made of PZ 27 ceramic experimentally. It investigates the effects of the crosstalk phenomenon on the array's performance in particular. The results have shown that the array's elements vibrate mainly in thickness mode, but the displacement is not uniform along their length due to the contribution of a parasitic length mode. Moreover, the major parasitic displacements are obtained on the neighboring passive elements: about -7.3 dB, -11 dB, and -12 dB, on the first, the second, and the third elements, respectively.

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