Manufacturing Process of Optically Transparent Ultrasound Transducer: A Review

Ultrasound (US) transducer is a crucial component for several imaging modalities, where acoustic sensing is utilized as a part of hybrid or combination of pure optical and US imaging. However, conventional US transducers are opaque, and the optical components in the system require a different pathway to avoid any interference. The absence of coaxial integration limits the optical illumination area, adds complexity, and makes the system bulky. Moreover, the system performance is deteriorated due to the unoptimized illumination in hybrid imaging and the lack of correlation between the data acquired through the combined modalities. To overcome these drawbacks, different approaches to realize optically transparent ultrasound transducers (TUTs) have been explored that include piezoelectric-based and microelectromechanical system-based capacitive and piezoelectric ultrasonic transducers. Unlike conventional opaque transducers, each component of TUTs requires specific materials and a certain recipe which all together determine the overall performance of the transducer. In this article, we have performed a comparative analysis on the materials and on the fabrication process used to make different types of TUT.