With the development of human healthcare devices, smart sensors, e-skins, and pressure sensors with outstanding sensitivity, flexibility, durability and biocompatibility have attracted more and more attention. In this paper, to develop a novel flexible pressure sensor with high sensitivity, different poly (vinylidene fluoride-trifluoroethylene) (PVDF-TrFE)-based composite membranes were fabricated, characterized and tested. To improve the β-phase crystallinity and piezoelectricity of the membranes, and for the purpose of comparison, nano ZnO particles with different concentrations (99:1, 9:1 in a weight ratio of PVDF-TrFE to ZnO) were, respectively added into PVDF-TrFE polymer acting as a nucleating agent and dielectric material. To facilitate the formation of β-phase crystal, the membranes were fabricated by electrospinning method. After the electrospinning, an annealing process was conducted to the fabricated membranes to increase the size and content of β-phase crystal. Then, the fabricated PVDF-TrFE membranes, acting as the core sensing layer, were, respectively built into multiple prototype sensors in a sandwich structure. The sensitivity of the prototype sensors was tested by an auto-clicker. The stimulation of the auto-clicker on the prototype sensors generated electrical signals, and the electrical signals were collected by a self-built testing platform powered by LabVIEW. As a result, combining the addition of ZnO nanofillers and the annealing process, a highly sensitive pressure sensor was fabricated. The optimal peak-to-peak voltage response generated from the prototype sensor was 1.788 V which shows a 75% increase compared to that of the pristine PVDF-TrFE sensor. Furthermore, a human pulse waveform was captured by a prototype sensor which exhibits tremendous prospects for application in healthcare devices.Keywords:PVDF-TrFE;PVDF-TrFE/ZnO;β phase crystal;human pulsation sensor
Wenbin Sun,Huazhen Liu,Zilong Guo,Anqi Li,Chuang Gao,Chunxiang Lu,Wenjing Zhou,Jiantao Zhang,Yuanyuan Liu
Piezoelectric materials can actively provide a bioelectric microenvironment by converting mechanical stimulations into electrical signals. Combining the excellent flexibility of piezoelectric polymers and the outstanding piezoelectric properties of piezoelectric ceramics, piezoelectric composites are attractive in tissue repair due to their high response to micromechanical stimulations. However, issues such as agglomeration, dielectric differences, and poor interfacial contact with polymers have limited the role of ceramics in improving the overall properties of the composites. In this work, functionalized multiwalled carbon nanotubes (F-MWCNTs) are applied to disperse zinc oxide (ZnO) in the PVDF–TrFE matrix to prepare electrospun composite fiber films. Through the assistance of hydrogen bonding, F-MWCNTs act as bridges connecting ZnO nanoparticles with PVDF–TrFE, which improves the content and crystallinity of the β phase. Furthermore, this strategy enhances the local electric field and reduces dielectric differences, resulting in improved polarization and piezoelectric properties. Results show that the composite fiber film with 0.35 wt % F-MWCNTs could obtain an open-circuit voltage of up to 8.2 V, a β phase content of 83.36%, and a crystallinity of 57.63%. Meanwhile, due to the synergistic effect of F-MWCNTs and ZnO, the tensile strength and Young’s modulus are increased from 3.5 and 11.0 to 6.6 and 19.49 MPa, respectively. Additionally, cellular experiments show that composite fiber films have good bioactivity and promote cell proliferation and adhesion, especially with 0.35 wt % F-MWCNTs. In conclusion, the composite fiber film possesses good piezoelectric and mechanical properties and enhances the cellular activity, making it a good tissue engineering scaffold.
危险品化学品经营许可证（带存储）