Fabrication, Characterization and Investigation of Novel PVDF/ZnO and PVDF-TrFE/ZnO Nanocomposites with Enhanced β-Phase and Dielectricity

Abstract

To date, flexible, sensitive and biocompatible pressure sensors for fluctuation signals in human body have been mainly demonstrated for detecting body and muscle motion, pulse rate, heart rate and arterial blood pressure. However, because of the lack of sufficient sensitivity and flexibility, pulse signals with relatively low intensity cannot be identified and captured, such as signals derived from microcirculation in human body. As confirmed and validated by researchers, once PVDF and its copolymer based nanocomposite sensing material are applied in piezoelectric sensors, its sensitivity and piezoelectricity are highly relevant. Therefore, as one of the most effective methods to improve the permittivity and piezoelectricity of PVDF and its copolymer based nanocomposite, the effect of increasing the content of β-phase crystal was investigated in this work. In this project, the sensor possessing a novel sensing layer with the nanofiller was investigated and fabricated. The proposed sensor was designed in a simple but efficient sandwich structure. The sensing layer of the proposed sensor was made of polyvinylidene fluoride (PVDF) and polyvinylidenefluoride-trifluoroethylene (PVDF-TrFE) based nanocomposite with Zinc Oxide (ZnO) nanostructure acting as a filler portion which was fabricated by the method of Chemical Bath Deposition (CBD). The fabricated nanocomposite sensing layers were characterized. The microstructures and morphologies of pristine PVDF (P), PVDF-TrFE (PT), PVDF/ZnO (P/Z) and PVDF-TrFE/ZnO (PT/Z) with different concentration were characterized by Scanning Electron Microscope (SEM). The degree of crystallinity for P, PT, P/Z and PT/Z was obtained by X-ray Diffraction meter (XRD). In conclusion, PT exhibited better performance in both morphology and crystallinity as a sensing membrane material. More β‐phase in PT was obtained than that in P. ZnO, as a semiconductor filler, would have substantial influence on enhancing the dielectric constant by acting as a nucleating agent and forming a nanostructure with large aspect ratio.