Performance and reliability of new CMUT design with improved efficiency

Abstract The performance and reliability issues of a new capacitive micro-machined ultrasonic transducer (CMUT) are presented in this paper. To enhance the moving efficiency, by obtaining a piston-like motion, an indirectly clamped membrane structure is proposed. The CMUT with indirectly clamped membrane is composed of three parts which are a circular moving plate, a ring-shaped bridge layer and an upper plate. By connecting circular moving plate to upper plate vertically through a ring-shaped bridge layer, this new structure was expected to produce the piston-like and more flexural motion. It also exhibited 1.7 times higher output pressure and 14.7% wider fractional bandwidth when compared to conventional basic structure. Environmental tests were carried out to verify the robustness and resistance to stress from temperature and humidity. For device's durability and lifetime estimation, an accelerated long-term operating test has also been performed. The derived mean time to failure (MTTF) was more than 2.29 × 10 11 vibration cycles, which translates to about 2650 h of guaranteed operational time.