4F-1 Optimization of Single Crystal Composite Arrays for Harmonic Imaging

The design concept for a single-active layer ultrasound transducer array for simultaneous sub- and second-harmonic imaging of contrast agents was tested for feasibility. Using PMN-PT single crystal in a 1-3 composite, multiple matching layers and a back plate, a design for imaging at 2, 4 and 8 MHz was implemented in a series of transducers. The effects of array pitch and piezocomposite thickness were examined. Transmit and receive sensitivities show the pitch and piezoelectric thickness can vary effects across the passband by more than 10 dB for different transducer parameters. Maximum transmit sensitivities of 230 dB re 1 uPa/V at 1 mm were achieved for the arrays. Contrast agent testing using Definityreg showed the second harmonic could be detected. The sub-harmonic was not detected, and could be due to a low peak pressure from the unfocused array sub- aperture.