Patent No. 11,014,268

Description:
"This patent application embodies 3D printing of piezoelectric devices for pressure sensor application using poly(vinylidene) fluoride (PVDF) and BaTiO3 (BTO) nanocomposites through in-situ electric poling 3D printing process was invented. PVDF polymer is a piezo- and pyro-electric material extensively studied for applications in sensor and energy harvesting areas. PVDF has the potential to be polarized through several conventional methods which require complicated and time-consuming procedures. Recently developed electric poling-assisted additive manufacturing (EPAM) process can print a piezoelectric layer by incorporating polarizing processes that include mechanical stretching, heat press, and electric field poling simultaneously. However, this process is limited to a single layer PVDF fabrication. In addition, quantitative material characterization such as piezoelectric coupling coefficient and β phase percentage was not investigated. In this paper we propose an enhanced EPAM process to apply higher electric field during 3D printing. To further increase piezoelectric response, BTO ceramic nanoparticle (NP) was used as fillers in PVDF matrix to further enhance the piezoelectric coupling coefficient. Solvent-casting was processed to uniformly mix PVDF with BTO NPs as filament precursor for fused deposition modeling (FDM) 3D printing. Then a filament extruder was used to fabricate the filament, which is then loaded in an FDM 3D printer for sensor fabrication. It was found that a 55.91% PVDF β-phase content was nucleated at 15wt% of BTO. The output current and β-phase content gradually increased as the BTO weight percent increase. Scanning Electron Microscopy (SEM) analysis demonstrated that larger agglomerates were formulated with the increase of BTO NPs contents and resulted in increased toughness and decreased tensile strength. In addition, the highest fatigue strength was seen at 3wt.%-BTO and it gradually decreased as the NPs contents increased due to defect propagation, poor load transmission, stress accumulation from agglomerates and aggregated NPs during fatigue life measurement. "

Abstract:
Embodiments of the invention are directed to methods, devices, and compositions for 3D printing of piezoelectric devices. The piezoelectric devices can be used for sensor applications using poly(vinylidene) fluoride (PVDF) and BaTiO3 (BTO) nanocomposites through in-situ electric poling 3D printing process.


UTEP Docket No: 2017-015