Microstructural, impedance spectroscopic and potentiometric analysis of Ta2O5 electrochemical thick film pH sensors

Two types of pH sensors based on Ta2O5 thick films, interdigitated conductimetric and potentiometric ones, were screen printed on an alumina substrate. Their properties were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, electrochemical impedance spectroscopy and potentiometry. The impedance spectroscopic studies of the fabricated thick film sensors were carried out in the frequency range of 10 Hz–2 MHz in test solutions of pH 3–12. The conductance, capacitance and impedance of the fabricated conductimetric Ta2O5 sensor were found to be distinctly pH-dependent at low frequencies. For potentiometric sensors, a sub-Nernstian behavior was obtained