Capacitive micromachined ultrasonic transducers for medical imaging and therapy

TLDR

CMUTs have been extensively studied for two decades, evolving from air‑coupled devices to primarily medical imaging and therapy applications. This paper provides a concise overview of CMUTs, including their basic structure and operating principles. The authors describe successive fabrication generations, monolithic and hybrid integration with supporting ICs, and prototype arrays with integrated front‑end electronics used for 2‑D/3‑D imaging and ablative therapy. Experimental results demonstrate that CMUTs constitute a viable MEMS technology for a wide range of medical diagnostic and therapeutic applications.

Abstract

Capacitive micromachined ultrasonic transducers (CMUTs) have been subject to extensive research for the last two decades. Although they were initially developed for air-coupled applications, today their main application space is medical imaging and therapy. This paper first presents a brief description of CMUTs, their basic structure, and operating principles. Our progression of developing several generations of fabrication processes is discussed with an emphasis on the advantages and disadvantages of each process. Monolithic and hybrid approaches for integrating CMUTs with supporting integrated circuits are surveyed. Several prototype transducer arrays with integrated frontend electronic circuits we developed and their use for 2-D and 3-D, anatomical and functional imaging, and ablative therapies are described. The presented results prove the CMUT as a MEMS technology for many medical diagnostic and therapeutic applications.