Simultaneous 3D Printing and Poling of PVDF and Its Nanocomposites

Given the ever-increasing demand for customization and miniaturization, in situ three-dimensional (3D) printing of piezoelectric polymers comes as an efficient means to cater to smart structures via multimaterial printing. Applying our hybrid printing technique to polyvinylidene-fluoride–barium-titanate (PVDF–BaTiO₃) nanocomposites, to combine the fabrication and high-voltage poling steps, shrinks the manufacturing time, overcomes the disadvantages of adherence in nonconformal piezoelectric films or fabrics, and increases the sensitivity and scope for on-demand applications. A remarkable 300% improvement in piezoelectric charge output is achieved upon the addition of 10 wt % BaTiO₃ nanoparticles and application of an electric field of 1 MV m^–1, compared with printed unpoled neat PVDF. We demonstrate the application of the in situ poling process in the form of sensors printed directly on a shoe insole for gait analysis. The sensors fabricated in this work effectively distinguish between walking and stamping as both portable in-shoe sensor as well as sensors attached to the ground.