Active acoustic field modulation of ultrasonic transducers with flexible composites

The simple acoustic field generated by conventional transducers limits the development of ultrasound applications. Current methods rely on passive acoustic lenses or active arrays to manipulate ultrasonic waves, but they face challenges such as low transmission efficiency with bulky morphology for lenses, and complex systems with high-cost for arrays. Here, we propose a method exploiting flexible piezoelectric ultrasonic transducers (FPUT) with 1-3 PZT8/PDMS composites to achieve a high-frequency and diversified ultrasonic field. The FPUT at a center frequency of 1.5 MHz exhibits a high electromechanical coupling coefficient ( k t ~ 0.74), excellent transmission efficiency, and mechanical conformability. We showcase two dynamic functionalities of our setup, namely variable acoustic focus and multi-order vortex generated by circular and spiral shape transducers. Finally, we show that the FPUT achieves high-resolution underwater ultrasonic imaging at a wide spatial range (>12λ) via ultrasonic collimation, offering a viable technological alternative for active acoustic fields manipulation and ultrasonic applications.