PSS-PANI/PVDF composite based flexible NH3 sensors with sub-ppm detection at room temperature

Improved ammonia (NH3) sensor is proposed based on polyaniline (PANI) with poly(styrene sulfonic acid) (PSS) as an additive, which was produced by in-suit polymerization of aniline on flexible porous polyvinylidene-fluoride (PVDF) membranes and then treated with PSS aqueous solution. The whole film sensor fabrication process was low-cost and convenient in operation, suitable for large-scale commercial production. The results demonstrated that the appropriate addition of PSS could significantly improve the sensor response to NH3. The PSS-PANI/PVDF film sensor response was improved to approximately 70%, which was 2.8 times higher than that of the pure PANI/PVDF film with 25% response towards 1 ppm NH3 at room temperature. Furthermore, it still showed an excellent response of 9.4% for 0.1 ppm NH3. The fabricated film sensor showed remarkable long-term stability with response decreases less than 5% after 30 days, and excellent flexibility under 10,000 repeated bending times with a response value degradation of only 15.1% towards 1 ppm NH3. The flexible PSS-PANI/PVDF film offers potential applications in smart wearable devices for detecting sub-ppm NH3 under ambient conditions.