Abstract
Organic as-grown films obtained by rf plasma excitation have, in
general, unstable properties that appear with time, which induce
deviations from accurate values of the relative humidity (RH). In this
paper, the improvement of the humidity properties of the as-grown
films by heat treatment, and the extension of lifetime through the
arrangement of electrodes of the sensors are
described. Plasma-polymerized polycresol (PC) films, used as a
material to sense water vapor, are subjected to two different heat
treatments, i.e., the continuous heat cycle and the alternative
trapezoidal form of the temperature cycle in vacuum. These heat
treatments led to the evaporation of small unreacted molecules, and at
the same time, dissociation, repolymerization and cross-linking with
radicals of the polymer chain. Thus, these treatments cause a decrease
in the concentration of hydrophilic groups (OH) and in free volume,
which limits the amount of adsorbable water molecules in the
film. Consequently, improved and stable RH sensors were obtained.
Subject
General Physics and Astronomy,Physics and Astronomy (miscellaneous),General Engineering
Cited by
2 articles.
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