Directivity Theory and Analysis of 2D Capacitive Micro-Machined Ultrasonic Transducer Array

The ultrasonic transducer and its array are the key component for ultrasonic imaging. A 2D image can be acquired by means of linear array, and a 3D or 4D image can be obtained based on 2D array. This paper, based micro-electro-mechanical systems (MEMS), designs a new-type capacitive micro-machined ultrasonic transducer (CMUT) and proposes a 2D CMUT array. Several different directivity functions of the array are deduced based on the structural features of CMUT. Through the directivity analysis, it can be found that the directivity of CMUT is weak due to its small size, however the directivity of the 2D array is very strong. In order to further suppress the side lobe interference and improve the resolution and the imaging quality of the system, we employed the Dolph-Chebyshev weighting method to process side lobe suppression, which obtains good results and meet the actual requirements.