Design, fabrication and characterization of a capacitive micromachined ultrasonic probe for medical imaging

Abstract

In this paper we report the design, fabrication process, and characterization of a 64-elements capacitive micromachined ultrasonic transducer (cMUT), 3 MHz center frequency, 100% fractional bandwidth. Using this transducer, we developed a linear probe for application in medical echographic imaging. The probe was fully characterized and tested with a commercial echographic scanner to obtain first images from phantoms and in vivo human body. The results, which quickly follow similar results obtained by other researchers, clearly show the great potentiality of this new emerging technology. The cMUT probe works better than the standard piezoelectric probe as far as the axial resolution is concerned, but it suffers from low sensitivity. At present this can be a limit, especially for in depth operation. But we are strongly confident that significant improvements can be obtained in the very near future to overcome this limitation, with a better transducer design, the use of an acoustic lens, and using well matched, front-end electronics between the transducer and the echographic system

Broadband Reduction of the Second Harmonic Distortion During Nonlinear Ultrasound Wave Propagation

“…In transmission, the imaging signal and multiple-component SHRS are split such that low-frequency elements transmit imaging signal, and high-frequency elements emit multiple-component SHRS. The other possibility is to use the cMUT technology (Caliano et al 2005). Ultrasound cMUT probes have shown to have even larger than 80% bandwidth.…”

Building CMUTs for imaging applications from top to bottom

“…In Fig. 5 the images of a partially reflecting cyst phantom (a) and a cross of nylon wires (b), both immersed in uniform parenchyma mimicking the human body, are reported, showing that the new technological approach provides high contrast and definition images, improved respect to those obtained by standard CMUTs [9] and comparable to those obtained by standard piezoelectric transducers.…”

Wideband acoustic activation and detection of droplet vaporization events using a capacitive micromachined ultrasonic transducer

“…The fixed bottom electrode and the movable top electrode in this structure are separated by a sub-micron vacuum gap. 25 An ac voltage is applied across the electrodes in order to generate an electrostatic force, which leads to plate vibrations and the generation of acoustic waves. Compared to traditional piezoelectric technology, CMUTs are known for having a fractional frequency bandwidth usually wider than 100%.…”