Fabrication and Characterization of Large-Area Flexible Capacitive Micromachined Ultrasound Transducers

Conventional Capacitive Micromachined Ultrasound Transducers (CMUTs) are generally produced on silicon wafers, limiting the size, form factor, hence applications, of the transducer arrays. In this paper, we unveil a CMUT fabrication technique that can enable the realization of high-density ultrasound arrays on large-area flexible substrates for a variety of new applications in ultrasonic sensing. We also compare optical inspection and electrical characterization methods to measure the pull-in voltage and resonance frequency of the fabricated CMUTs and show that these methods can be used to assess the yield and uniformity of the fabrication process.