Development of a 1-D Linear Phased Ultrasonic Array for Intravascular Sonoporation

摘要

Therapeutic efficiency of sonoporation is hampered by ultrasound attenuation, low focusing efficiency due to beam scattering from the variety of tissues in the propagation path, and heating. This paper describes the manufacturing and characterization of miniature 1-3 connectivity 1-D linear phased arrays of the size of an 8 Fr catheter for intracorporeal sonoporation. Their advantage over external transducers is that ultrasound is delivered closer to the target tissue which reduces aberration in the propagation path. Four arrays with resonant frequencies of 1.5 MHz and 3.0 MHz were manufactured using the traditional dice and fill method. The piezoelectric materials were ceramic (PZT-5H) and single crystal (PMN-29%PT). The piezocomposite design was optimised for lowest peak negative pressure (PNP) through a simulation approach using PZFlex (Onscale, CA, US). A comparison between the simulated electrical impedance of individual array elements and the experimental data shows the coupling coefficient (kt) is reduced in the real transducers, but the electrical resonance frequency and modes are well predicted by the simulation. The lower kt and the lack of electrical interconnects in the simulation led to lower measured PNP values than the simulation. However, the normalized beam shapes strongly agree between the two cases.