MAE Seminar: “From CMUTs to CPUTs: Micromachined Capacitive Ultrasound Transducers for Imaging and Sensing “

It has been nearly 30 years since the introduction of Capacitive Micromachined Ultrasonic Transducers (CMUTs). Although initially considered for in air ultrasonic applications for non-destructive testing, CMUTs have found their place in medical imaging mostly due to the advantages in electronics integration for large 2D arrays and miniaturized systems. Large 2D arrays with integrated CMOS electronics (CMUT-on-CMOS) enabled low cost handheld ultrasound systems with 3D imaging capability, whereas miniaturization enabled catheter-based imaging for applications like volumetric intravascular ultrasound (IVUS) imaging. More recently, we have been investigating a new concept, Capacitive Parametric Ultrasonic Transducer (CPUT), which uses micromachined capacitors as part of a parametric resonance-based structure that operates without a need for DC bias. CPUT structures provide more flexible designs for parametric resonance enhanced transduction as their response can be controlled by electrical components. CPUTs can be driven into resonance with both electrical and mechanical inputs leading to a large array of sensing applications. In this talk, we will briefly discuss the historical development of CMUT technology and then focus on our work on high frequency CMUT-on-CMOS IVUS devices operating in the 20-50MHz range. In the second part of the talk, we will describe CPUTs with examples on auto-parametric damping of MEMS sensors, acoustic sensors with improved directivity and phononic frequency comb generation with potential applications in sensors.