The characteristics of transmitting and receiving sound field of rectangular capacitive micromechanical ultrasonic transducer in silicone oil medium
Compared with the traditional piezoelectric ultrasonic transducer,the capacitive micromachined ultrasonic transducer(CMUT)based on micro-electro-mechanical system(MEMS)micromachining technology has the advantages of wide frequency band,high sensitivity,good consistency,easy integration and so on,and has broad application prospects in medical ultrasonic imaging.Aiming at the rectangular CMUT device developed,this paper carries out theoretical analysis and experimental verification of the sound field characteristics of CMUT emission and reception in silicone oil medium.Firstly,according to the structural characteristics and working principle of CMUT array elements,the directional function analysis model of rectangular CMUT array elements is established according to the directional function theory and Bridge product principle.On this basis,the influence of the number of micro elements and resonant frequency on the directivity of CMUT is analyzed.Finally,the emission and reception characteristics of 7 mm × 7 mm two-dimensional rect-angular CMUT in silicone oil medium are experimentally verified.The test shows that the emission directivity curve is basically consistent with the simulation theoretical curve;In addition,the test of CMUT receiving and transmitting directivity shows that the receiving and transmitting directivity is consistent,which verifies the reciprocity of the sound field.The research of this paper has important reference value for the packaging design of CMUT devices and the development of breast ultrasound CT imaging system based on CMUT array.
Capacitive micromechanical ultrasonic transducerRectangular array elementDirectivitySound field reciprocity