One-step solvent evaporation-assisted 3D printing of piezoelectric PVDF nanocomposite structures

The development of a 3D printable material system, possessing inherent piezoelectric properties, to fabricate integrable sensors in a single-step printing process without poling is of importance to the creation of a wide variety of smart structures. Here, we study the effect of addition of barium titanate nanoparticles in nucleating piezoelectric β-polymorph in 3D printable polyvinylidene fluoride (PVDF) and fabrication of the layer-by-layer and self-supporting piezoelectric structures at micro to millimeter scale by solvent evaporation-assisted 3D printing at room temperature. The nanocomposite formulation, obtained after a comprehensive investigation of composition and processing techniques, possesses a piezoelectric coefficient, d31, of 18 pC N-1 which is comparable to typical poled and stretched commercial PVDF film sensors. A 3D contact sensor that generates up to 4 V upon gentle finger taps demonstrates the efficacy of the fabrication technique. Our one-step 3D printing of piezoelectric nanocomposites can form ready-to-use complex-shaped, flexible and lightweight piezoelectric devices. When combined with other 3D printable materials, they could serve as stand-alone or embedded sensors in aerospace, biomedicine and robotic applications.