Publication: Water based reduced graphene oxide ink for temperature sensor application
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Date
2024-06-01
Authors
Junaid, Mohammad Khan
Journal Title
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Abstract
The adoption of eco-friendly water-based inks, as alternatives to organic
solvent-based inks, is a key strategy for minimizing environmental impacts. Graphene
oxide (GO) nanofillers can be used as a filler to produce water-based conductive ink for
printed electronics applications. However, the higher surface tension and lower stability
are major drawbacks which limit its printing properties. The objective of this study is to
produce an eco-friendly ink using GO with long term stability and capability to print
using inkjet printer for applications in printed electronics and sensors. The methodology
utilized probe sonication to produce aqueous GO ink with natural surfactants (cellulose
nanocrystals, gum arabic, and alkali lignin) for improving wetting and dispersion
stability. Varying concentrations of alkali lignin and viscosity were assessed for
smoother inkjet printing experience. An in-situ reduction process was carried out using
natural substances (tea, coffee, ascorbic acid) through inkjet printing, enabling
continuous manufacturing of GO-based inks without external processes. Finally, the
application of the GO ink was demonstrated by fabricating a flexible temperature
sensor. Among different natural surfactants, the GO ink produced with alkali lignin
showed the highest zeta potential of -36.53 mV as compared cellulose nanocrystals and
gum arabic assisted GO ink. The GO ink also demonstrated improved stability, with a
25% increase in zeta potential and 84.3% higher maximum absorption at 3 mg/ml of
alkali lignin concentration along with continuous morphological properties of printed
patterns. In-situ reduction using ascorbic acid restored electrical conductivity (1250
ā1
Sm
), indicating enhanced conductive networks. The electrical conductivity was found to be reduced by only 2.6 % after 100 bending cycles, whereas a decrease of only 0.6 %
was observed after 10 rolling and straightening cycles indicating excellent flexibility
which is very important for printed electronics applications. The ascorbic acid reduced
sample showed an increase in the ID/IG from 1.058 to 1.15, and the interlayer distance
decreased from 0.395 to 0.385 nm indicating good reduction efficiency. The resulting
temperature sensor exhibited a notable thermal coefficient of resistance (TCR) of 1.21,
showcasing heightened sensitivity and response within the temperature range of 25 to
52 ā. These results highlight the potential of alkali lignin as a natural surfactant for
improving the performance and applicability of inkjet-printable GO inks in printed and
flexible electronics.