Design and Characterization of low frequency Capacitive Micromachined Ultrasonic Transducer (CMUT)

As cMUTs (capacitive Micromachined Ultrasonic Transducer) offer numerous advantages over traditional transducers in terms of efficiency, bandwidth, and cost, they are expected to replace piezoelectric transducers in many applications. In particular, 2D-array cMUTs have aroused great interest in the medical engineering society because of their ability to materialize a true volumetric ultrasonic image. In this study, single element cMUTs with 32 x 32 and 64 x 64 cells were successfully fabricated. The diameter and thickness of the membrane are 35 and 1000 nm, respectively, with a sacrificial layer thickness of 600 nm. The electric characteristics of the fabricated cMUT were measured. Tests on the efficiencies of the cMUT in terms of wave generation and in terms of detection according to the bias and pulse voltage were performed in an air atmosphere.

Download Full-text

Fabrication and Characterization of Capacitive Micromachined Ultrasonic Transducer

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.297-300.2225 ◽

2005 ◽

Vol 297-300 ◽

pp. 2225-2232 ◽

Cited By ~ 1

Author(s):

Ki Bok Kim ◽

Bong Young Ahn ◽

Hae Won Park ◽

Young Joo Kim

Keyword(s):

Ultrasonic Transducer ◽

Capacitive Micromachined Ultrasonic Transducer ◽

Fabrication And Characterization

Download Full-text

Performance of a Nozzle to Control Bath Level Oscillations and Turbulence of the Metal-Flux Interface in Slab Molds

Metals ◽

10.3390/met12010140 ◽

2022 ◽

Vol 12 (1) ◽

pp. 140

Author(s):

María Guadalupe González-Solórzano ◽

Rodolfo Davila Morales ◽

Javier Guarneros ◽

Carlos Rodrigo Muñiz-Valdés ◽

Alfonso Nájera Bastida

Keyword(s):

Ultrasonic Transducer ◽

Low Frequency ◽

Outer Wall ◽

Slide Valve ◽

Physical Experiments ◽

Dependent Behavior ◽

Mathematical Simulations ◽

Partial Opening ◽

Metal Flux

The characterization of the turbulent flow of liquid steel in a slab mold using a commercial nozzle was carried out through physical experiments and mathematical models. Six ultrasonic sensors were located at each side of the nozzle to obtain real-time plotting of the bath levels during the experimental time. An ultrasonic transducer located in the mold, 20 mm below the meniscus, determines the velocities and the turbulent variables along with the distance from the narrow face to the position of the nozzle’s outer wall. These data, together with the mathematical simulations, demonstrated a high correlation of bath level oscillations and the time-dependent behavior of the discharging jets. The flow inside the mold shows low-frequency non-symmetric patterns without a severe turbulent in the meniscus. The source of this instability is the partial opening of the slide valve gate used to control the mass flow of liquid.

Download Full-text

Experimental Characterization of an Embossed Capacitive Micromachined Ultrasonic Transducer Cell

Micromachines ◽

10.3390/mi11020217 ◽

2020 ◽

Vol 11 (2) ◽

pp. 217

Author(s):

Yuanyu Yu ◽

Jiujiang Wang ◽

Xin Liu ◽

Sio Hang Pun ◽

Shuang Zhang ◽

...

Keyword(s):

Ultrasonic Transducer ◽

Experimental Characterization ◽

Release Process ◽

Output Pressure ◽

Collapse Mode ◽

Acoustic Instruments ◽

Capacitive Micromachined Ultrasonic Transducer ◽

Collapse Region ◽

High Output

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.

Download Full-text