Comparison of piezoelectric (thickness mode) and MEMS transducers

An increasing interest for MEMS solutions applied to electro-acoustic transducers has been observed over the last years. This study proposes a comparison of main characteristic between these new technologies and state of the art. Although we focus on medical imaging array requirements, conclusions apply to other domains. MEMS ultrasonic transducers (MUT) are significantly known through academic results: capacitive MUT are widely published, while alternative structures (like thin film piezoelectric actuation) are at a lower investigation level in the open literature. Main characteristics analyzed in this comparative study are relative bandwidth, sensitivity and dynamic range, electrical and acoustical matching issues, crosstalk and directivity pattern. Comparisons are based both on theoretical (analytical and numerical) and experimental data coming from literature, as well as from results of European R&D projects (Growth/Parmenide and Eureka/Umic). Standard technology is considered not only through demonstrated performances in industry but also in the perspective of improvement (e.g. single crystal and multilayered) Conclusion gives fair and quantified comparison, making a distinction between technological and intrinsic design limitations.