Low-cost hydrogen sulfide gas sensor on paper substrates; fabrication and demonstration

Drop-casted deprotonated Emeraldine base (poly)aniline (PANI) - copper chloride films on paper substrates containing ink-jet printed silver electrodes have been prepared and are shown to be promising low-cost gas-sensors for H2S at room temperature. These films showed large changes in the conductivity (three to four orders of magnitude) upon exposure to low concentrations of H₂S (10ppm) due to the formation of CuS and concurrent protonation of PANI. This large response of the sensor can be explained by the relatively large roughness and porosity of the paper substrate. Furthermore, the minimum resistances are low enough to allow LED lamps to be switched on using a low-voltage battery, thus serving as a proof-of-concept for mass-produced H₂S-sensors for, for example, the food packaging industry.