A model to predict baffle effects in linear array of cMUTs

Overview & Synopsis

cMUTs are a very promising alternative to the piezoelectricity in echographic imaging probes. Many authors have modeled cMUT arrays but only few works have been dedicated to the simulation of devices working in real configuration, i.e. where each element is made of a finite number of cMUTs. In previous studies, we pointed out that, in such conditions, interactions between cMUTs could cause some strong cut-off frequencies in the useful frequency bandwidth, leading to undesirable oscillations at the end of the impulse response. This phenomenon is comparable with baffle effects in multi-source radiators. Even if origins of these cut-off frequencies are well known in sonar arrays, this phenomenon have poorly been explored for arrays of cMUTs. This paper is a deep theoretical investigation of these interactions. The linear array of cMUTs is modeled like a linear system. Input electrical quantities (voltage applied to each element of the array) are linked to output acoustic quantities (pressure emitted by each element) with a global transfer matrix. The Eigenvalues decomposition of the transfer matrix is used to discuss and to explain origins of cut-off frequencies in the radiated pressure spectrum.