Acoustic Doppler velocity measurement system using capacitive micromachined ultrasound transducer array technology

Abstract

This paper describes the design, fabrication, modeling, and characterization of a small (1 cm(2) transducer chip) acoustic Doppler velocity measurement system using microelectromechanical systems capacitive micromachined ultrasound transducer (cMUT) array technology. The cMUT sensor has a 185 kHz resonant frequency to achieve a 13° beam width for a 1 cm aperture. A model for the cMUT and the acoustic system which includes electrical, mechanical, and acoustic components is provided. Furthermore, this paper shows characterization of the cMUT sensor with a variety of testing procedures including Laser Doppler Vibrometry (LDV), beampattern measurement, reflection testing, and velocity testing. LDV measurements demonstrate that the membrane displacement at the center point is 0.4 nm/V(2) at 185 kHz. The maximum range of the sensor is 60 cm (30 cm out and 30 cm back). A velocity sled was constructed and used to demonstrate measureable Doppler shifts at velocities from 0.2 to 1.0 m/s. The Doppler shifts agree well with the expected frequency shifts over this range.

Photoacoustic imaging of visually evoked cortical and subcortical hemodynamic activity in mouse brain: feasibility study with piezoelectric and capacitive micromachined ultrasonic transducer (CMUT) arrays

“…We previously developed lightweight 1-dimensional (1D) [ 10 ] and 2D [ 11 ] wearable CMUT arrays for mice on flexible circuit boards with wireless communication or flexible cable connections to backend electronics. CMUT arrays have successful applications in Doppler velocity measurement [ 12 , 13 ], intravascular US [ 14 ], PAT [ 15 , 16 ] and US therapy [ 17 – 19 ].…”

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

“…The CMUT can work in transmit mode to produce ultrasound, and can work in reception mode to receive ultrasound, as well. Therefore, it has been used in a variety of applications, such as nondestructive evaluation (NDE) [ 1 , 2 , 3 ], volumetric imaging [ 4 , 5 ], medical imaging [ 6 , 7 , 8 ], HIFU [ 9 , 10 ], gas sensor [ 11 , 12 , 13 ], hydrophone [ 14 ], pressure sensor [ 15 , 16 , 17 ], Doppler velocity measurement [ 18 ] and fingerprint sensing [ 19 , 20 ].…”

Optimization of multi-pulse sequences for nonlinear contrast agent imaging using a cMUT array

“…An AC voltage is applied across the electrodes in order to generate an electrostatic force, which leads to membrane vibrations and the generation of acoustic waves. cMUTs are known for having a wide frequency bandwidth (Huang et al 2006, Savoia et al 2012, Novell et al 2013a) and are currently under development in the field of ultrasound for Doppler imaging (Shin et al 2013), intravascular ultrasound (Tekes et al 2012), photoacoustic imaging (Vaithilingam et al 2009, Chen et al 2012) and high-intensity focused ultrasound (Bayram et al 2005, Wong et al 2010). …”