The increasing demand for automated devices requires high-performance gas sensors to control living environment conditions, for preserving and processing food, pharmaceutical processing, and healthcare. Metal oxide (MOX) semiconductor-based humidity sensors have received considerable attention in this field owing to their advantages regarding the requirements of low cost, stability, large-scale manufacture, and long-term use. At room temperature metal oxide semiconductors are generally characterized by high electrical resistance, with evident problems regarding the measurements with conventional instrumentation. Electrical resistance vs. the humidity of the sensors has been evaluated in a system constituted by an enclosure in which the temperature and the relative humidity are externally and remotely controlled. In such scenario the electrical characterization of the sensing films towards long-term stability and electrical reliability is mandatory. The developed system is primarily focused on the electrical evaluation of sensing films which aimed for material development and optimization; in such task, it is important to perform resistance measurement of high value samples in order to reach the right balance between film thickness, baseline resistance, and sensing performance.
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