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. 2022 Feb 25;7(9):7981-7988.
doi: 10.1021/acsomega.1c07101. eCollection 2022 Mar 8.

Design and Fabrication of a Graphene/Polyvinylidene Fluoride Nanocomposite-Based Airflow Sensor

Surendra Maharjan  1 , Victor K Samoei  1 , Omid Amili  1 , Keiichiro Sano  2 , Hideo Honma  3 , Ahalapitiya H Jayatissa  1
Affiliations

Design and Fabrication of a Graphene/Polyvinylidene Fluoride Nanocomposite-Based Airflow Sensor

Surendra Maharjan et al. ACS Omega. .

Abstract

In recent years, flexible and stretchable sensors have been a subject of intensive research to replace the traditional sensors made up of rigid metals and semiconductors. In this paper, a piezoresistive airflow sensor was designed and tested to measure the speed of air inside a pipe. Graphene/polyvinylidene fluoride nanocomposite films were prepared using a solvent-cast technique on a flexible polyethylene substrate as a piezoresistive material. Three different solutions were studied as a function of graphene concentration. The microstructure of the nanocomposite was characterized by X-ray diffraction, scanning electron microscopy, and optical microscopy. The effect of temperature on electrical conductivity was investigated by heating and cooling the sample between the room temperature and 150 °C. The stretchability of the nanocomposite film was studied with a tensile test, and the same procedure was employed to determine the breakdown point of the electrical conductivity. The sensor response was measured in terms of the resistance change caused by air pressure and found to increase with the concentration of graphene in the composite. The sensing characteristics were simulated using the COMSOL Multiphysics software, and the modeled data were compared favorably with the experimental result. The sensitivity of the sensor was found to be 1.21% kPa-1 in the range of 0-2.7 kPa. This piezoelectric sensor possesses unique characteristics such as being lightweight, flexible, and exhibiting fast response; hence, it can have potential applications in various sectors such as ventilators, commercial HVAC, and automotive industries.

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Conflict of interest statement

The authors declare no competing financial interest.

Figures

Figure 1
Figure 1
Schematic diagram of a sensor in (a) normal condition and (b) deflection under stressed condition.
Figure 2
Figure 2
(a) Schematic diagram of the experimental setup to measure the sensor resistance at various speeds and (b) an enlarged view of the sensor attached to the lid at 30o.
Figure 3
Figure 3
Experimental setup for the tensile test used in this work.
Figure 4
Figure 4
XRD pattern of the graphene/PVDF nanocomposite.
Figure 5
Figure 5
(a) Optical image of graphene, (b) optical image of pure PVDF at 400× magnification, and (c) SEM image of the graphene/PVDF nanocomposite.
Figure 6
Figure 6
Response of the sensor measured at (a) various air speeds for C1, C2, and C3 and (b) various pressures for C3.
Figure 7
Figure 7
Time response and repeatability test at various air speeds (left side), and an enlarged view of one of the responses for the high speed (for clarity) (right side).
Figure 8
Figure 8
Tensile test of the nanocomposite to study stretchability. Data were presented without any post processing so some noise can be noticed.
Figure 9
Figure 9
Effect of temperature on the electrical conductivity of the nanocomposite.
Figure 10
Figure 10
(a) Simulation model of the sensor, (b) velocity contour of the airflow across pipe cross-section, (c) displacement distribution, and (d) stress distribution at an air speed of 10.7 m/s.
Figure 11
Figure 11
Response of the flow sensor at various air speeds for both measured and simulated data.
See this image and copyright information in PMC

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