TiO₂-Based Thick Film pH Sensor

Abstract

Abstract-Miniaturized electrochemical pH sensors are increasingly in demand for application such as online monitoring of water quality and health monitoring. The metal oxides are the best candidates for sensing electrodes of such sensors as they offer high chemical stability. In this work, we present a novel approach to obtain interdigitated conductimetric pH sensor using screen printing of TiO 2 thick film on an alumina substrate. The microstructural and crystalline properties of the TiO 2 sensitive film were examined with scanning electron microscopy and Raman spectroscopy. The impedance spectroscopic studies of the fabricated thick film sensor were carried out in the frequency range of 5-20 kHz for the test solutions in the pH range of 4-10 and it was observed that the impedance of the film distinctly dependent on pH. Using the measured impedance data, we have also proposed an equivalent RC network model for the fabricated pH sensor. The physical meaning of the model parameters was determined by electrochemical impedance spectroscopic (EIS) analysis, and through statistical analysis it was found that all parameters are distinctly pH-dependent.

Flexible potentiometric pH sensors for wearable systems

“…MO x have recently gained increasing interest for electrochemical and biosensing applications due to their unique electrical, electrochemical and highly sensitive properties which assert their utility in healthcare and water and food quality monitoring applications. 32,[187][188][189] Due to high surface to volume ratio, the morphology of nano structured MO x enhances the sensitivity, response time, selectivity and catalytic activity of sensitive electrodes. 47 For example, in comparison to ZnO nanorods (sensitivity 28.4 mV pH À1 ) ZnO nanotubes show high sensitivity (45.9 mV pH À1 ) due to their low dimensionality and higher levels of surface and subsurface oxygen vacancies.…”

Stretchable pH sensing patch in a hybrid package

“…The variation of complex impedance with pH of solution is due to the change of electrical properties of electrochemical double layer (EDL) formed between the graphite electrode-pH solution interface [10,13]. The straight line in Nyquist plot represent the ion diffusion across the sensitive electrode from the pH solution.…”

“…Furthermore, the materials for packaging have to be chemically, electrically and thermally stable. Conventional packaging often realized in microfluidic channels [4], molded blocks [9] and multi-layered lamination [7,10] is insufficient for health applications. These techniques are either difficult to be implemented in real-time electrochemical sensing due to the fully sealed structure or difficult to be stretchable due to its rigidity.…”

Flexible Printed Reference Electrodes for Electrochemical Applications

“…For example, being a quasi-RE (i.e., absence of KCl layer), the majority of thin film REs exhibit fluctuations in the open circuit potential (OCP) while reacting with Cl − ions. [25,26] The performance of FRE has been evaluated through electrochemical This work presents screen-printed thick film reference electrodes (REs) on a polyethylene terephthalate substrate. The absence of KCl in thin film REs also increases the issue of cross-sensitivity [23] and for this reason thick film RE have been explored.…”

“…[25,26] The performance of FRE has been evaluated through electrochemical This work presents screen-printed thick film reference electrodes (REs) on a polyethylene terephthalate substrate. [25,26] The performance of FRE has been evaluated through electrochemical This work presents screen-printed thick film reference electrodes (REs) on a polyethylene terephthalate substrate.…”