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Abstract
Humidity sensors are fabricated based on nanoporous alumina, using hard anodization technique. In order to investigate the effect of the anion incorporated in the alumina template during anodization, two different kinds of sensors, wall and barrier layer sensor, with various current densities at 38 V and 44 V anodization voltages are fabricated. The effect of frequency measurement, ranging from 3 to 40 kHz, different applied voltages and relative humidity amplitudes (40% to 90%) are investigated using impedance spectrometry at room temperature. Higher sensitivity is seen for the barrier layer sensors as well as for sensors made at higher anodization current density. It is also found that the sensitivity is inversely proportional to the frequency, and also variation of the applied voltage has no effect on the sensitivity.
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