Flexible room temperature ammonia sensor based on polyaniline

Here we present, a useful ammonia (NH3) gas sensor based on polyaniline (PANI) film as an active sensing layer. The PANI films were successfully deposited on a polyethylene terephthalate (PET) flexible substrate by a simple in-situ polymerization technique. Ammonia (NH3) gas-sensing properties of the films prepared at optimum conditions were examined at room temperature in the range of 5-1000 ppm. The room temperature functioning of the sensor is critical, which facilitates low-power operation and also enhances the life time of a sensor. The observed variation in resistance of PANI film corresponding to 1000 ppm and 200 ppm of NH3 exposure, is approximately 520 and 110 times of that observed for ∼5 ppm of NH3. Furthermore, good reproducibility and long-term stability were also observed over a concentration range from 5 to 1000 ppm. Moreover the sensor is mechanically robust and can be bent sharply without damage, demonstrating excellent mechanical stability and exhibiting no lack in performance even after several bending cycles. These results indicate that the PANI films on flexible substrates are promising for portable on-site detection.