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@PHDTHESIS{Beale:911035,
author = {Beale, Christopher},
title = {{S}ol-{G}el-{S}ynthese, {T}intenstrahldruck und
{B}litzlampentemperung von {T}antaloxid-{D}ünnschichten zur
p{H}-{M}essung},
volume = {87},
school = {RWTH Aachen University},
type = {Dissertation},
address = {Jülich},
publisher = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
reportid = {FZJ-2022-04361},
isbn = {978-3-95806-656-4},
series = {Schriften des Forschungszentrums Jülich Reihe Information
/ Information},
pages = {xlix, 339},
year = {2022},
note = {Dissertation, RWTH Aachen University, 2022},
abstract = {The measurement of pH and temperature plays an important
role in many applications, including food analysis,
environmental monitoring, chemical manufacturing, and
medicine. Integration of pH and temperature sensors into
packaging and electronic devices will continue to grow in
importance as the world moves further towards Industry 4.0
and the Internet of Things, particularly as more industries
become data-driven. New applications would also become
possible by fabricating sensors on flexible substrates.
Furthermore, building and operating a pH sensor without a
reference electrode would provide many advantages, such as
simpler manufacturing processes and long-term stability of
the sensor. In a step towards achieving this goal, additive
manufacturing of tantalum oxide films for pH sensing was
explored in this work. Specifically, the sol-gelprocess and
flash lamp annealing were used to deposit these films on
gold metallized polyethylene terephthalate (PET) foils.
After deposition of the sensing layers on the foil, both an
extended-gate field-effect transistor (EGFET) and an
impedimetric configuration were used to test the tantalum
oxide layers for pH sensing. Additionally, a discovered
negative temperature coefficient (NTC) in solgel derived
ruthenium-tantalum oxide layers was examined for use as a
temperature sensor, where the layers were thermally annealed
with no photocuring on borosilicate wafer.In preparing the
tantalum sol-gel solution for eventual layer deposition via
photocuring, an optimized synthesis procedure for
β-diketonate and β-ketoester complex formation with
tantalum in 1,3-propanediol was conducted and the thin films
characterized for photosensitivity in the near-UV range.
Suboptimal synthesis procedures still work for device
fabrication and were used in the production of the pH
sensors. These solutions are stable in atmosphere, which is
important for inkjet printing the solutions both in a
laboratory and in an industrial environment. Inkjet printing
of the solutions to form layers was then performed, followed
by thermal annealing and flash lamp treatment of the layers.
Photocured tantalum oxide layers derived from these
solutions were characterized via various material
characterization techniques. Exposure of the material to
acidic and basic solutions in an EGFET configuration for pH
sensing was also performed, and the layer was shown to
withstand solutions in the range between pH 2 and pH 12. A
photocured tantalum oxide layer was then tested for pH
sensing in an impedimetric configuration on interdigitated
electrodes (IDEs) without a reference electrode. A pH
dependent double layer capacitance was found in solutions of
high ionic strength. The data was fitted with an equivalent
circuit consisting of a double layer capacitance in parallel
with an interfering ion specific adsorption
capacitance.Finally, the NTC of sol-gel derived
ruthenium-tantalum oxide layers was characterized. A first
material was tested from 20°C to 100°C, and then down to
cryogenic temperatures. This was followed by investigating a
second material, with an improved preparation procedure from
the first material, and tested from -20°C to 60°C. In both
cases, a reproducible NTC was observed which could
potentially be combined as a temperature sensor with the
fabricated pH sensor in a single device},
cin = {IBI-3},
cid = {I:(DE-Juel1)IBI-3-20200312},
pnm = {899 - ohne Topic (POF4-899)},
pid = {G:(DE-HGF)POF4-899},
typ = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
urn = {urn:nbn:de:0001-2022112365},
url = {https://juser.fz-juelich.de/record/911035},
}