Background::
Ultrasound is widely used in the applications of underwater imaging. Capacitive micromachined
ultrasonic transducer (CMUT) is a promising candidate to the traditional piezoelectric ultrasonic transducer. In underwater
ultrasound imaging, better resolutions can be achieved with a higher frequency ultrasound. Therefore, a CMUT array for
high-frequency ultrasound imaging is proposed in this work.
Methods::
Analytical methods are used to calculate the center frequency in water and the pull-in voltage for determining
the operating point of CMUT. Finite element method model was developed to finalize the design parameters. The CMUT
array was fabricated with a five-mask sacrificial release process.
Results::
The CMUT array owned an immersed center frequency of 2.6 MHz with a 6 dB fractional bandwidth of 123 %.
The pull-in voltage of the CMUT array was 85 V. An underwater imaging experiment was carried out with the target of
three steel wires.
Conclusion::
In this study, we have developed CMUT for high-frequency underwater imaging. The experiment showed
that the CMUT can detect the steel wires with the diameter of 100 μm and the axial resolution was 0.582 mm, which is
close to one wavelength of ultrasound in 2.6 MHz.
Capacitive micromachined ultrasonic transducer (CMUT) technology has enjoyed rapid development in the last decade. Advancements both in fabrication and integration, coupled with improved modelling, has enabled CMUTs to make their way into mainstream ultrasound imaging systems and find commercial success. In this review paper, we touch upon recent advancements in CMUT technology at all levels of abstraction; modeling, fabrication, integration, and applications. Regarding applications, we discuss future trends for CMUTs and their impact within the broad field of biomedical imaging.
Three-Side Buttable Integrated Ultrasound Chip With a 16$\,\times\,$16 Reconfigurable Transceiver and Capacitive Micromachined Ultrasonic Transducer Array for 3-D Ultrasound Imaging Systems
