Three-dimensional printing of piezoelectric materials with designed anisotropy and their applications in underwater transducers

We describe design and manufacturing routes to previously inaccessible classes of piezoelectric materials that have arbitrary piezoelectric coefficient tensors. Our scheme is based on the manipulation of electric displacement maps from families of structural cell patterns. We implement our designs by additively manufacturing free-form, perovskite-based piezoelectric nanocomposites with complex three-dimensional architectures. The resulting voltage response of the activated piezoelectric metamaterials at a given mode can be selectively suppressed, reversed or enhanced with applied stress. To demonstrate our novel design method and fabrication capability, we designed and fabricated underwater transducers consisting of rationally designed metamaterials to accommodate diverse situations, in which the piezoelectric composites convert mechanical vibrations into electrical voltages and vice versa. Through tuning geometry of the micro-architectures, resonance frequencies of these transducers can vary from 100Hz to 10MHz while the impedance is close to water. Moreover, we showed the feasibility and applicability of these transducers for the purpose of source detection, liquid quality monitoring, and directional sensing.