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@PHDTHESIS{Hamacher:1047702,
      author       = {Hamacher, Stefanie},
      title        = {{D}evelopment of a {N}ew, {M}iniaturized and {F}lexible
                      {T}emperature {S}ensor},
      volume       = {303},
      school       = {RWTH Aachen University},
      type         = {Dissertation},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2025-04468},
      isbn         = {978-3-95806-863-6},
      series       = {Schriften des Forschungszentrums Jülich Reihe
                      Schlüsseltechnologien / Key Technologies},
      pages        = {XXII, 153},
      year         = {2025},
      note         = {Dissertation, RWTH Aachen University, 2025},
      abstract     = {Temperature is one of the most important scientific
                      quantities and plays a fundamental part in our daily life.
                      While permanent temperature sensors were primarily used to
                      control air conditioning, fridges and freezers, nowadays
                      they are utilized in many more fields, such as healthcare,
                      manufacturing and agriculture. Over the centuries several
                      different devices were developed that were able to determine
                      changes in temperature. In the beginning, such a thermometer
                      was simply based on the expansion and contraction of air or
                      water and the dilation of liquids is still in use in the
                      common mercury thermometer. However, many more devices are
                      known today that are based on the change of different
                      physical quantities that can be related to temperature.
                      Common examples are the change in resistance used in
                      resistance temperature detectors (RTDs) or thermistors or
                      the change in spectral characteristics detected via IR
                      measurements. Depending on the purpose of the temperature
                      measurement an appropriate technique is chosen, since all of
                      the known devices have their advantages and drawbacks, e.g.
                      a small temperature range or low relative change of the
                      specific parameter per degree. To overcome such drawbacks, a
                      miniaturized temperature sensor based on a new approach was
                      developed in this work. As a sensing principle, the
                      dependence of the diffusion coefficient on fluid viscosity,
                      which in turn is temperature dependent, was exploited. Using
                      Faradaic electrochemical currents from a redox mediator
                      dissolved in fluid, a relation between current and
                      temperature can be obtained. Here, three different ionic
                      liquids (ILs) and mixtures of them were investigated along
                      with different redox species, such as ferrocene,
                      hydroquinone and methylene blue to establish a stable
                      temperature sensor that is suitable over a large temperature
                      range and shows long-term stability. Several thin-film
                      sensor prototypes were fabricated and characterized using
                      custom-made electronics as well as a potentiostat. First,
                      the peak current dependence on temperature using cyclic
                      voltammetry (CV) was demonstrated. Afterwards a screening of
                      the most feasible redox species was conducted using CV.
                      Thereby it was found that ferrocene is not stable over a
                      longer period of time, which is why other redox couples were
                      examined and methylene blue was found to be the best.
                      Additionally, the IL 1-ethylimidazolium nitrate ([EIM][NO3])
                      was used as redox species and solvent medium simultaneously.
                      In order to establish an easy to handle sensor, the
                      sensitive layer had to be fixed upon the substrate. This was
                      achieved by adding two monomers and a photo initiator to the
                      IL mixture that were cured using UV light. Finally, the
                      prepared temperature sensors were characterized using the
                      chronoamperometric technique and four different pulse
                      lengths. Compared to standard resistance temperature
                      detectors, this novel sensor shows a higher per degree
                      sensitivity and can be utilized in a broad temperature
                      range, for example for cold-chain monitoring of
                      perishables.},
      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:0001-2602091348143.817852468181},
      doi          = {10.34734/FZJ-2025-04468},
      url          = {https://juser.fz-juelich.de/record/1047702},
}