Characterization and Optimization of Thermally Grown Iridium Oxide and Its Application to pH Sensors

In this study, we evaluate the thermal oxidization methods of iridium to simplify the fabrication of Ir/IrOx pH microsensors. Iridium oxide (IrOx) is a typical pH-sensing material. Specifically, three parameters of the previously reported "carbonate-melt" method are modified, namely, the oxidization temperature, oxidization time, and annealing process after oxidization. Then, we compare the characteristics of the fabricated sensors (i.e., the initial pH responsivity, time required to reach the steady state, and potential drift). The pH response depends on oxidization temperature and time.