The paper reports on the preparation, properties and application of potentiometric pH sensors with thick film RuO2–Ta2O5 sensing electrode and Ag/AgCl/KCl reference electrode screen printed on an alumina substrate. Furthermore, it presents fabrication procedure and characterization of a new miniaturized pH sensor on LTCC (low temperature cofired ceramics) substrate, destined for wireless monitoring. The crystal structure, phase and elemental composition, and microstructure of the films were investigated by X-ray diffractometry, Raman spectroscopy, scanning electron microscopy and energy dispersive spectroscopy. Potentiometric characterization was performed in a wide pH range of 2–12 for different storage conditions and pH loops. The advantages of the proposed thick film pH sensors are: (a) low cost and easy fabrication, (b) excellent sensitivity close to the Nernstian response (56 mV/pH) in the wide pH range, (c) fast response, (d) long lifetime, (e) good reproducibility, (f) low hysteresis and drift effects, and (g) low cross-sensitivity towards Li+, Na+ and K+ as interfering ions. The applicability of the sensors for pH measurement of river, tap and distilled water, and some drinks was also tested.
Manjakkal, L., Zaraska, K., Cvejin, K., Kulawik, J., & Szwagierczak, D. (2016). Potentiometric RuO2–Ta2O5 pH sensors fabricated using thick film and LTCC technologies. Talanta, 147, 233-240. https://doi.org/10.1016/j.talanta.2015.09.069