<i>Janus</i> Piezoelectric Composite Design for High-Performance Ultrasonic Transducers and Imaging Applications

Inspired by the Roman "two-faced god" Janus, a heterogeneous ultrasonic transducer is proposed with double-sided 1-3 piezoelectric composites, exhibiting bidirectional acoustic radiation and matching. The transducer features a "dense-monolithic-sparse" distribution, optimizing acoustic impedance matching and enhancing electroacoustic energy conversion efficiency in the thickness direction. Finite element simulations confirm its superior vibration mode performance. The Janus transducer maintains a high electromechanical coupling coefficient and wide bandwidth while achieving an improved echo voltage amplitude (∼3.35 V). Furthermore, it enables high-quality photoacoustic imaging through fabricated transducers, validating its exceptional performance. The proposed heterogeneous composite design offers an effective approach for high-performance ultrasonic transducers and their application in underwater ultrasonic imaging and photoacoustic imaging.