Fully Printed pH Sensor Based in Carbon Black/Polyaniline Nanocomposite

In this work, a fully screen-printed and flexible potentiometric pH sensor was designed and fabricated by incorporating a carbon black (CB) paste/polyaniline emeraldine salt (PANI-ES) nanocomposite as the working electrode and Ag/AgCl as the quasi-reference electrode. Rather than the PANI electrochemical polymerization deposition method, the PANI-ES was blended with a commercial CB paste for screen-printing, enabling a fully printed and scalable process. As a result, a nanocomposite mixture of 99.1% CB and 0.9% PANI-ES emerged as a promising nanocomposite candidate to develop high-performance pH sensors. The sensor exhibited a near Nernstian sensitivity of 50 mV/pH, response time of 15 s at room temperature, high linearity in the pH range between 3 and 11 and reversible pH sensing performance. The sensing mechanism depends mainly on the degree of the oxidation states transition of PANI-ES at different pH levels. The proposed flexible pH sensor can be used to monitor a patient’s health and water quality.