A novel microwave assisted multi-material 3D printing strategy to architect lamellar piezoelectric generators for intelligent sensing

While the advances in thermoplastic additive manufacturing (3D printing) cover the free-form fabrication of piezoelectric materials , the chief obstacles to the use of 3D printed piezoelectric generator (PEG) are the weak weld within the part and imperfect polarization. Herein, a microwave assisted multi-material 3D printing strategy is proposed to fabricate multiple PEGs consisting of periodically intercalated piezoelectric & conductive layers. The interfacial regulation performed between piezoelectric ceramics and matrix leads to sufficient polarization under the electric field, thus generating the substantially enhanced piezoelectricity. Benefiting from the unique design of embedded electrode with 3D graphene nanoplatelets (GNPs) network, the polarization charge density greatly increases. Then the microwave irradiation technology is employed to realize the intense selective heating of the GNPs to weld polymer interfaces, further improving the piezoelectric output. As a result, the output current of the 3D lamellar PEG is nearly 18 times higher than that of conventional sandwich structure PEG. With significant advantages of the enhanced electromechanical coupling performance, the fabrication strategy is expected to create multifunctional sensors with complex geometries. Based on the above method, the 3D printed biomimetic lamellar denture is developed for health monitoring and Morse code transmission, demonstrating its enormous potential in real-life applications.