SWCNT-Pt-P2O5-Based Sensor for Humidity Measurements

An integrated SWCNT-Pt-P
₂
O
₅
-based sensor type was fabricated by direct deposition of the films on a commercial planar sensor substrate without any conventional coating and using the dropcast procedure. For the humidity sensing experimental work, two sensors were prepared by the authors using this facile solution and a system for data acquisition. The measurements showed that the integrated SWCNT sensors exhibit high and fast response (of approximately 25 s) toward a humidity range from 1% to 90% AH. The high sensitivity and dynamic reproducibility of these sensors materials reveal that the proposed composition and morphology can be applied to fabricate sensing devices for detecting water humidity in nitrogen gas from low to medium concentration range. The experimental results also confirm that the proposed solution fits in the class of proper structures for humidity sensing in inert gas and can show remarkable sensing and recovery capabilities for industrial usage. The sensing mechanism is attributed to the fact that electrical changes in sensors resistance, as a function of the AH, are related to the attraction and trapping of water molecules produced on the surface of the film. Due to this physical behavior, a resistive path is formed between the microelectrodes. The resistivity of the system increases as the AH increases, or decreases when the AH values decreases due to an electrolysis process taking place under sensors supply voltage and using Pt catalyst.