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. 2021 Feb 22;14(4):1037.
doi: 10.3390/ma14041037.

Highly Sensitive Humidity Sensors Based on Polyethylene Oxide/CuO/Multi Walled Carbon Nanotubes Composite Nanofibers

Waqas Ahmad  1 , Bushra Jabbar  1 , Imtiaz Ahmad  1 , Badrul Mohamed Jan  2 , Minas M Stylianakis  3 , George Kenanakis  3 , Rabia Ikram  2
Affiliations

Highly Sensitive Humidity Sensors Based on Polyethylene Oxide/CuO/Multi Walled Carbon Nanotubes Composite Nanofibers

Waqas Ahmad et al. Materials (Basel). .

Abstract

Polymer composites are favorite materials for sensing applications due to their low cost and easy fabrication. In the current study, composite nanofibers consisting of polyethylene oxide (PEO), oxidized multi-walled carbon nanotubes (MWCNT) and copper oxide (CuO) nanoparticles with 1% and 3% of fillers (i.e., PEO-CuO-MWCNT: 1%, and PEO-CuO-MWCNT: 3%) were successfully developed through electrospinning for humidity sensing applications. The composite nanofibers were characterized by FTIR, XRD, SEM and EDX analysis. Firstly, they were loaded on an interdigitated electrode (IDE), and then the humidity sensing efficiency was investigated through a digital LCR meter (E4980) at different frequencies (100 Hz-1 MHz), as well as the percentage of relative humidity (RH). The results indicated that the composite nanofibers containing 1% and 3% MWCNT, combined with CuO in PEO polymer matrix, showed potent resistive and capacitive response along with high sensitivity to humidity at room temperature in an RH range of 30-90%. More specifically, the PEO-CuO-MWCNT: 1% nanocomposite displayed a resistive rapid response time within 3 s and a long recovery time of 22 s, while the PEO-CuO-MWCNT: 3% one exhibited 20 s and 11 s between the same RH range, respectively.

Keywords: composite nanofibers; copper oxide; electrospinning; humidity sensors; oxidized multi-walled carbon nanotubes; polyethylene oxide.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
SEM micrographs of (a) pure PEO (b) CuO nanoparticles (c) multi-walled carbon nanotubes (MWCNT) (d) PEO: CuO: MWCNT: 1% nanofibers (e) PEO: CuO: MWCNT: 3% nanofibers.
Figure 2
Figure 2
FTIR spectra of pure PEO (purple), CuO nanoparticles (red) and MWCNTs (blue), PEO–CuO–MWCNT: 1% (black) and PEO–CuO–MWCNT: 3% (orange) composite nanofibers.
Figure 3
Figure 3
Resistivity response of PEO–CuO–MWCNT: 1% nanocomposite at different % RH.
Figure 4
Figure 4
Resistivity Sensitivity of PEO-CuO-MWCNT:1% nanocomposite at different % RH.
Figure 5
Figure 5
Resistive linearity of PEO−CuO−MWCNT: 1% nanocomposites.
Figure 6
Figure 6
Capacitance response of PEO−CuO−MWCNT: 3% nanocomposite at different % RH.
Figure 7
Figure 7
Capacitive Sensitivity of PEO−CuO−MWCNT: 3% nanocomposite at different % RH.
Figure 8
Figure 8
Capacitive linearity of PEO−MWCNT−CuO: 3% nanocomposites.
Figure 9
Figure 9
Resistivity response/recovery time for PEO−CuO−MWCNT: 1% nanocomposites.
Figure 10
Figure 10
Capacitance response/recovery time for PEO−MWCNT−CuO: 3% nanocomposites.
Figure 11
Figure 11
Schematic presentation of adsorption of H2O molecules on the surface of PEO−MWCNT−CuO nanocomposites.
See this image and copyright information in PMC

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