Review of Ultrasonic Sensing Techniques in Micromachining Applications

Abstract Ultrasonic sensors fabricated using microelectromechanical systems (MEMS) technology are characterized by their miniaturization, high integration, and low power consumption. In recent years, these sensors gain significant attention and become a major research focus. The rapid advancement of micromachining technology has further highlights their importance. Capacitive microelectromechanical ultrasonic transducers (CMUT), piezoelectric microelectromechanical ultrasonic transducers (PMUT), and triboelectric microelectromechanical ultrasonic transducers (TMUT) demonstrate broad application potential in fields such as non‐destructive testing, medical imaging, and environmental monitoring due to their unique advantages. This review comprehensively examines these three types of ultrasonic sensors, beginning with detailed descriptions of the structures and working principles of CMUT, PMUT, and TMUT, as well as their mechanisms for generating and receiving ultrasonic signals. It also explores the manufacturing processes involved in sensor fabrication, addressing key steps and challenges in micromachining. Additionally, the review discusses the applications of these sensors, comparing their advantages and limitations relative to traditional transducers. While CMUT, PMUT, and TMUT offer distinct benefits, they also present specific limitations. The review concludes by envisioning the potential impact of micromechanical ultrasonic transducers (MUT) in emerging fields, with the expectation that ongoing technological innovations will revolutionize related industries.