Bi2O3/Nb2O5 thick film capacitive pH sensor using AD5933 impedance converter

The novel system is presented that utilises change in the resonant frequency and impedance as an indicator of the pH level of the solution, brought in contact with a sensor. Mixed metal oxides of Bi₂O₃ and Nb₂O₅ formed the basis for thick film capacitive sensors investigated in this research work. AD5933 impedance converter was used to monitor real-time changes in the electrical properties of tested capacitors. The system showed superior sensitivity to the pH level, with instant response being recorded. Heating the sensors restored their initial properties, and they were repeatedly used for pH sensing. It is envisaged that findings of this work would form the basis for compact system employed for real-time pH monitoring.