Biaxial Excitation and Reception Method Applied to Ultrasound Imaging.

The biaxial method consists of the utilization of orthogonal electric fields in single-element piezoceramics both in transmission and reception. This study demonstrates the application of the biaxial method to broadband transducers. We developed a three-element biaxial transducer array to demonstrate the feasibility of biaxial method in imaging applications. Finite element analysis was used to model the response of a single transducer element. An electric characterization was performed at each transducer element to determine their driving frequency. Each transducer was driven at 6.25 MHz and tested in different phases to determine the phase that produced the maximum pressure amplitude and shortest pulsewidth. Both simulations and experimental results showed that the acoustic pressure and half-pulsewidth followed a sinusoidal response as a function of the difference in phase applied to the lateral electrodes, as it has been described in our previous work. An imaging test was performed by placing a 0.36-mm diameter nylon wire 20 mm away from the transducer while driving and receiving each element with different combinations of conventional and biaxial driving. By applying a biaxial rephasing at the receiving electrodes during the data analysis, we obtained a maximum reduction in the axial resolution from 4.6 to 1.3 mm and signal-to-noise ratio (SNR) improvements from 15.2 to 24.4 dB, when compared to conventional driving.