Versatile additive manufacturing of piezoelectric ceramic transducers for conformal nondestructive testing

Three-dimensional (3D) printing enables the fabrication of complex structures that are difficult to realize using conventional methods, thereby offering broad applicability across various industries. In the field of piezoelectric devices, ceramic-based materials provide excellent performance but demonstrate unsatisfactory processability, whereas polymer-based materials are easier to shape but lack sufficient piezoelectric output. This study addresses this trade-off by employing direct ink writing (DIW) to fabricate complex piezoelectric structures using Sm-doped Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ (Sm-PMN-PT) powder. The printed structures are fully sintered after shaping, thereby obviating the necessity for residual matrix materials that typically degrade device performance. The resulting devices maintain high piezoelectric properties, achieving a figure of merit (FOM) of 17.29 × 10^–12 m²/N even after sintering, which is among the highest values reported for DIW-printed piezoelectric ceramics. To validate their functionality, the printed piezoelectric components were integrated into ultrasonic transducers and applied in nondestructive testing. The conformal design demonstrates strong coupling to curved surfaces and generates symmetric guided waves, thus improving defect signal clarity. This study highlights a viable strategy for creating high-performance, geometrically adaptable piezoelectric devices via 3D printing, thereby facilitating the development of advanced ultrasonic inspection technologies.