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. 2021 May 23;12(6):602.
doi: 10.3390/mi12060602.

Novel Flexible PVDF-TrFE and PVDF-TrFE/ZnO Pressure Sensor: Fabrication, Characterization and Investigation

Mingran Liu  1 , Yang Liu  1 , Limin Zhou  2
Affiliations

Novel Flexible PVDF-TrFE and PVDF-TrFE/ZnO Pressure Sensor: Fabrication, Characterization and Investigation

Mingran Liu et al. Micromachines (Basel). .

Abstract

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; human pulsation sensor; β phase crystal.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
(a) Molecular conformation and crystal structures β-phases of PVDF [7]; (b) Schematic drawing of VDF-TrFE copolymer molecule in β phase (all-trans) conformation (right image) [8].
Figure 2
Figure 2
(a) Diagram and (b) image of the prototype sensor compared with a coin.
Figure 3
Figure 3
(a–g) SEM figures of the unannealed and annealed electrospinning membrane samples made of PVDF-TrFE doped with 0/1/10 wt% ZnO nanoparticles
Figure 4
Figure 4
The sectional view of sample PT10Zad.
Figure 5
Figure 5
XRD diagrams for eight comparison groups.
Figure 6
Figure 6
Histogram for β phase crystal size.
Figure 7
Figure 7
(a–f) The auto-clicking test results for six samples.
Figure 7
Figure 7
(a–f) The auto-clicking test results for six samples.
Figure 8
Figure 8
Histogram for peak-to-peak voltage.
Figure 9
Figure 9
The human pulse waveform captured by sample PT10Zad.
See this image and copyright information in PMC

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