P2P-1 Multilayer cMUT Structure for Improved Sensitivity and Bandwidth

The electrical and mechanical behavior of cMUTs is currently under investigation. The mechanical characteristics of the membranes as well as the air-gap size determine the sensitivity, the maximum pressure level and the operating frequencies of cMUT devices. In this work, we report on a novel multilayer cMUT vibrating structure made of a stack of flexural membrane layers, conveniently interconnected by means of equally spaced pillars. Each membrane layer is metallized in order to apply and detect the electrical signals. A simple analytical lumped parameters model shows that a multilayer cMUT structure can achieve higher sensitivity and maximum pressure level while mantaining broadband behavior. We report finite element modeling (FEM) of possible configurations of multilayer cMUTs for broadband immersion operation in the MHz frequency range. The results obtained show enhanced sensitivity and bandwidth performances in respect of conventional cMUTs