Performance of miniaturised thick-film solid state pH sensors

The performance of novel solid state thick-film pH sensors for water quality sampling that are designed for deployment in remote catchment areas is described. These miniaturised screen printed planar pH sensors are an alternative to conventional glass pH electrodes that have many disadvantages such as high-cost, large size, mechanical fragility and limited shape. The approach adopted here for improvement of the ruggedness of the pH electrode is through its implementation as a screen printed metal oxide (RuO2) ion selective electrode used in combination with a screen printed silver/silver chloride (Ag/AgCl) reference electrode. Various choices of materials have been evaluated for the fabrication of the thick-film pH sensors resulting in a device with a sensitivity of approximately 30 mV/pH at ambient temperature.