Synthesis, Characterization and Applications of Single Walled Carbon Nanotube–Pt–P2O5 Sensors for Absolute Humidity Measurements

Abstract

We report the synthesis and characterization of sensors based on integrated single walled carbon nanotube–Pt–P₂O₅ active layer, for absolute humidity (AH) measurements. The sensors were obtained by direct deposition of an active doped layer to the surface of an interdigitated planar sensor type, by the drop cast method. For the experimental investigation, two sensors with the same active layer were fabricated and tested for detecting water humidity in inert gas at room temperature. The sensing mechanism of the fabricated sensors is characterized by the electrical variations in the sensors resistance, as a function of the AH related to the water trapping effect produced at the surface of the active layer. This physical behavior confirms the existence of a resistive path formed between the structured microelectrodes. The resistivity of the layer increases or decreases proportional to the raise or decline of the AH values in a range of 1 to 90% for the tested gas. This is caused by an electrolysis process that takes place under the sensors supply voltage and is influenced further by Pt catalyst. These sensors, compared to classical industrial humidity sensors, exhibit noteworthy sensing, stability and recovery capabilities and have a tremendous potential for integration in lowpowered sensor-platforms for instrumentation and device fabrication processes.