3D Printing and Processing of Miniaturized Transducers with Near-pristine Piezoelectric Ceramics for Localized Cavitation

Abstract The performance of ultrasonic transducers is largely determined by the piezoelectric properties and geometries of their active elements. Due to the brittleness of piezoceramics, existing processing tools for piezoelectric elements only achieve simple geometries, including flat disks, cylinders, cubes and rings. While advances in additive manufacturing give rise to free-form fabrication of piezoceramics, the resultant transducers suffer from high porosity, weak piezoelectric responses, and limited geometrical flexibility. We introduce optimized piezoceramic printing and processing strategies to produce highly responsive piezoelectric microtransducers that operate at ultrasonic frequencies. The 3D printed dense piezoelectric elements achieve high piezoelectric coefficients and complex architectures. The resulting piezoelectric charge constant, d33, and coupling factor, kt, of the 3D printed piezoceramic reach 583 pC/N and 0.65, approaching the properties of pristine ceramics. The integrated printing of transducer packaging materials enables miniaturized ultrasonic transducers capable of localized cavitation within millimeter-sized channels, paving the way for intravascular drug delivery.