Performance of a 1-3 mode piezocomposite ultrasonic transducer in relation to the properties of its polymer matrix

For the further development of a 1-3 mode piezocomposite ultrasonic transducer, this paper investigates both experimentally and theoretically the effects of a polymer matrix on the performance of a transducer and identifies the direct relationship. It is important for a polymer matrix to have a low density and low acoustic impedance in order to facilitate a high sensitivity, large bandwidth and small ringdown time in the transducer. In addition, a polymer should comply with the structural requirement of good adhesion to the piezoceramic pillars, with no inclusion of pores. However, adhesion strength does not play a vital role once it exceeds a certain level. Thus, when selecting a matrix polymer a higher priority should be placed on the exclusion of pores after curing. The importance of these requirements was verified through experimentation. After testing many types of commercially available polymers, UPR (Unsaturated Polyester Resin) matched all the requirements and gave the best performance in line with the theoretical simulation results. The results in this paper can be directly utilized in the selection of appropriate polymers for matrices for 1-3 mode piezocomposite materials and in the further development of high performance ultrasonic transducers.