On the Development of 3D-Printed e-Skin of Polyvinylidene Fluoride-Sm Doped ZnO Composite

Recently, studies have been reported on ZnO and rare-earth metal-doped ZnO nanofillers for sensing applications. However, little has been testified on the doping of Sm in ZnO for the possible 3D printing of the polyvinylidene fluoride (PVDF) matrix for electronic (e)-skin applications. This study reports the development of PVDF-Sm doped ZnO composite-based filaments for further processing by 3D printing (material extrusion) (for e-skin applications). The various compositions/proportions of PVDF composites were prepared by varying PVDF (94-100 wt.%) and Sm-doped ZnO reinforcement (1-6 wt.%). The results suggest that the sample with a composition of 97% PVDF-3% (Sm-1-Doped-ZnO) and a melt flow index (MFI) (per ASTM D-1238) of 8.51 g/(10 min) was selected as the best option for possible e-skin 3D printing based on various material characterizations. The selected sample has a maximum Young’s modulus (E) of 558.91 MPa, with a greater presence of β-phase [observed in Fourier transformation infrared (FTIR) spectroscopy]. The maximum heat absorbed during melting (− 40.54 J/g) and maximum heat release during cooling (48.21 J/g) (highlighting kinetics–thermodynamics mismatch) due to partially crystalline behavior ensured by differential scanning calorimetry (DSC), and maximum percentage of residue (31.2611%) observed after the thermogravimetric analysis (TGA), suggested that the selected sample has more crystalline behavior (compared to other available options) and is acceptable for the 3D printing of e-skin. The morphological analysis based on scanning electron microscopy (SEM), porosity (%) (per ASTM-B-276), and grain size number (per ASTM-E112) supported the result.