The effects of sensing electrode thickness on ruthenium oxide thin-film pH sensor

Recent Developments in R.F. Magnetron Sputtered Thin Films for pH Sensing Applications—An Overview

“…On the other hand, electrochemical methods are typically straightforward and inherently quantitative, and require simpler operation and setups. Electrochemical methods, however, have downsides, such as long-term instability and vulnerability to electrode fouling, but nevertheless, they are the most commonly used methods for pH detection, whereby the potential (potentiometric) [20,21,[51][52][53][54][55][56], current (amperometric) [57][58][59][60][61][62][63], or charge in an electrochemical cell serve as the analytical signals. Indeed, the glass electrode is currently the most commonly used electrochemical sensor for potentiometric pH measurements.…”

“…The Nernst's mathematical equation predicting the potential between the sensing and reference electrodes versus the pH value is given by [21]:…”

“…To evaluate the reversibility, the pH sensor potential is measured in different pH solutions in the acid-to-base direction and vice versa [5,21].…”

“…An Agilent 34410A high performance digital multimeter was used for real-time potential recording, which has a built-in web interface that makes it easy to setup and transfer readings using only a PC with web browser. Figure 3 shows measured sensor potential versus pH value for different RuO2 thin-film thicknesses [21]. Furthermore, effect of RuO2 sensing electrode thickness on the performance of pH sensing was investigated.…”

“…In recent years, a number of metal oxides based pH sensors have been developed incorporating IrO2 [16][17][18][19], RuO2 [20][21][22][23][24], PtO2 [25], SnO2 [25], TaO2 [25], TiO2 [25,26] and Ta2O5 [27,28]. pH sensors have been developed using a variety of deposition techniques including magnetron sputtering [20][21][22], sol-gel [17,29], screen-printing [24,30] and plasma enhanced chemical vapour deposition (PECVD) [31,32] and electroplating [33][34][35]. Among the different thin film deposition techniques, magnetron sputtering has become the process of choice for the deposition of a wide range of materials.…”