Design And Fabrication Of Gradient Matching Layer For Broadband Ultrasonic Transducer

Ultrasonic transducer is a kind of device which can transform acoustic signal into electrical signal,and it is a essential part of ultrasonic system.The core components of ultrasonic transducer are piezoelectric material,matching layer and backing.As a kind of transparent material,matching layer can realize the impedance transition from the piezoelectric element to objects,thus greatly improving the acoustic energy transmittance and the bandwidth of transducers.In traditional commercial transducers,the matching layer is mostly single-layer,and the transmission efficiency of ultrasonic is not high.In this paper,we try to manufacture single-layer matching layers by centrifugation,and then manufacture double-layer and three-layer matching layers,so as to increase the transmission efficiency of the traditional matching layer,and thus improve the bandwidth of the ultrasonic transducer.At the same time,because of the vigorous development of the field of composite materials,scholars found that the design of composite materials can meet the acoustic impedance requirements of the matching layer,so this paper considered the selection of composite materials for the design and preparation of gradient matching layer.In this paper,a series of matching layers with different acoustic impedances were prepared by centrifugation with different particle sizes,different filler types and different active fractions.In this paper,the velocity,impedance and attenuation of these matching layers are characterized and analyzed.The impedance range of the matching layer is 3-15 MRayls.The results showed that the matching layer prepared by centrifugal method can meet the acoustic impedance range of common matching layer by selecting different kinds of fillers and different particle sizes.On the basis of discussing the feasibility of gradient matching layer design,the simulation of single matching layer,double matching layer and triple matching layer is carried out by Piezo CAD software.The simulation results showed that with the increase of the number of matching layers,the energy utilization efficiency of the transducer will be further increased,and the bandwidth of-6d B will be increased.Finally,this paper manufactured real ultrasonic transducers with different numbers of matching layers.Through the verification,it is confirmed that the ultrasonic transducer with gradient matching layer has a wider bandwidth.At the same time,the feasibility of making ultrasonic transducer with gradient impedance matching layers is discussed.