Sol-Gel Iridium Oxide-Based pH Sensor Array on Flexible Polyimide Substrate

Iridium oxide pH sensing film is demonstrated with wide pH-sensing ranges, high durability, and small drifts in potentials. Using sol-gel process, a lower fabrication cost and less labor-intensive method, to deposit iridium oxide thin films for pH sensing is reported previously by our group with expected advantages. In this paper, we fabricate and test pH sensing characteristics of 4 × 4 anhydrous iridium oxide thin-film electrode arrays on flexible substrates. The sensors in arrays exhibit Nernstian potential responses in the range of 57.0-63.4 mV/pH. Stability, repeatability, and hysteresis effects of the pH sensor arrays are examined. A multichannel recording system is built to demonstrate the functionality of the pH sensor arrays in monitoring spatial and temporal pH changes across a surface.