Evaluating pH sensing performance of polyaniline and reduced graphene oxide-polyaniline composites for salivary biosensors

Monitoring saliva pH intraorally is highly significant, serving as a crucial biomarker for prognosis and diagnosis that reflects oral health and various metabolic conditions. However, the scarcity of easily wearable intraoral pH sensors presents a considerable challenge. This paper presents synthesising and assessing conductive polymer polyaniline compounds in pH biosensing, with the objective of developing potential salivary biosensors for the future. The sensors underwent thorough evaluation for sensitivity, repeatability, response time, stability, and pH range to comprehensively understand their performance. Both reduced graphene oxide-polyaniline (rGO-PANI) and polyaniline (PANI) were utilised as sensing materials, and electrodeposition was employed to fabricate sensors for both materials. A comparative analysis of the performance of the two sensing materials was conducted using zero current potentiometry electrochemical analysis for the pH sensors. Subsequent testing with artificial saliva and various common oral fluids revealed that the rGO-PANI-based pH sensor outperformed the PANI-based pH sensor. These findings suggest that this sensor could be a reliable tool for detecting pH changes in salivary analytes.