Capacitive micromachined ultrasonic transducer (CMUT) for MR-guided noninvasive therapeutic ultrasound applications

In the last decade, noninvasive therapeutic ultrasound guided by magnetic resonance imaging (MRI) has increased in popularity for diseases such as cancer and heart arrhythmias. While piezoelectric transducers are the dominant technology for therapeutic ultrasound applications, recently capacitive micromachined ultrasonic transducers (CMUTs) have demonstrated competitive performance and ease of fabrication. In this paper, we present a CMUT design for MR-guided therapeutic ultrasound, with circular cells and center mass (piston) that fulfills the requirements for therapy of upper abdominal cancers, i.e. 1 MPa peak to peak output pressure at 2.5 MHz. In particular, we discuss the choice of cell shape and membrane topography and their influences on output pressure of the device.