Tracing paper substrate used for development of interdigitated graphite electrode and its application as humidity sensor

• Performance of the IGEs prepared by LPT as humidity sensors.
• Change in roughness was evidence of an alteration in the morphology of the surface after IGE fabrication.
• It was possible to show that the sensors present 215% of sensitivity and 99% of reversibility.
• Tracing paper can be applied to the design and fabrication of extremely low-cost electrodes.

In this paper tracing paper was used as the support on which interdigitated graphite electrodes (IGE) were deposited by a line patterning technique (LPT). This substrate was characterized before and after the patterning procedure by thermogravimetric analysis, atomic force microscopy (AFM) and field emission scanning electron microscopy (FE-SEM). The performance of the IGEs prepared by LPT as humidity sensors were evaluated in an electronic nose system, under different humidities (in triplicate) at room pressure and temperature in a closed chamber. The relative humidity (RH) in the chamber was varied from 20 to 70% using dry nitrogen as a carrier gas, which was passed through a bubbler containing water to generate humidity. Slight changes in the morphology of the tracing paper were noted after the processes used to produce the IEG, but these changes did not prevent these sensors performing well under varied environmental conditions, as part of an electronic nose system to detect humidity. The results showed that humidity sensors were sensitive (215% ± 1.02) and provided good repeatability and reversibility (99% ± 0.01) after several cycles of exposure to RH.