Bulk Ferroelectric Metamaterial with Enhanced Piezoelectric and Biomimetic Mechanical Properties from Additive Manufacturing.

Three-dimensional (3D) ferroelectric materials are electromechanical building blocks for achieving human-machine interfacing, energy sustainability, and enhanced therapeutics. However, current natural or synthetic materials cannot offer both a high piezoelectric response and desired mechanical toughness at the same time to meet the practicality. Here, a lamellar ferroelectric metamaterial was created with a ceramic-like piezoelectric property and a bone-like fracture toughness through a low-voltage-assisted 3D printing technology. The one-step printed bulk structure, consisting of periodically intercalated soft ferroelectric and hard electrode layers, exhibited a significantly enhanced longitudinal piezoelectric charge coefficient (d33) of over 150 pC N-1, as well as a superior fracture resistance of ∼5.5 MPa·m1/2, more than three times higher than conventional piezo-ceramics. The excellent printability together with the combination of both high piezoelectric and mechanical behaviors allowed us to create a bone-like structure with tunable anisotropic piezoelectricity and bone-comparable mechanical properties, showing a potential of manufacturing practical, high-performance, and smart biological systems.