Flexible Chemiresistive pH Sensor Based on Polyaniline / Carbon Nanotube Nanocomposite for IoT Applications

This study presents a screen-printed and flexible chemiresistive pH sensor based on a nanocomposite of polyaniline emeraldine salt (PANI(ES)) and single-walled carbon nanotubes (SWCNTs). An optimized solution of SWCNTs/PANI(ES) (60/40 wt%) solution was drop-casted on top of flexible silver electrodes screen-printed on polyethylene terephthalate substrate. The sensor was annealed at an optimized temperature of 90 °C for 1 hour with a subsequent PANI(ES) drop_cast and annealing step. The developed chemiresistive pH sensor achieved high signal stability, sensitivity of 2.72 Ω/pH, linearity in the pH range of 2 – 10, and response times of 70 seconds. The pH’s sensitivity of the SWCNTs/PANI nanocomposite depends on the protonation/deprotonation process. The proposed sensor is an excellent candidate for smart medical bandage and wound monitoring applications.