Screen-printed sensing electrodes attract much attention for water pollution monitoring due to their small size, physical and chemical durability, and low cost. This paper presents the fabrication and broad potentiometric characterization of RuO₂ pH sensing electrodes deposited by screen printing on alumina substrates and sintered in the 800–900 °C temperature range. All the fabricated electrodes showed close to Nernstian sensitivity, good linearity, fast response, small drift, low hysteresis, and low cross-sensitivity toward various interfering cations and anions. Furthermore, decreasing the sintering temperature led to better adhesion of the RuO₂ layer and a negligible response to interfering ions. The measurements in real-life samples from different water sources showed that the fabricated electrodes are on par with conventional glass electrodes with a maximum deviation of 0.11 pH units, thus indicating their potential for application in water quality monitoring.

Purpose: The purpose of this work was to characterize NiMn₂O₄ spinel-based thermistor powder, to use it in screen printing technology to fabricate temperature sensors, to study their performance for different sintering temperatures of thermistor layer, with and without insulative cover, as well as to investigate stability of the fabricated thermistors and their applicability in water quality monitoring. Design/methodology/approach: After the characterization of starting NiMn₂O₄ spinel-based thermistor powder, it was converted to thick film paste which was screen printed on alumina substrate. Thermistor layers were sintered at four different sintering temperatures: 980°C, 1050°C, 1150°C and 1290°C. An interdigitated pattern of Ag-Pd conductive layer was used to reduce the resistance. Temperature-resistance characteristics were investigated in air and water, with and without insulative cover atop the thermistor layer. Stability of the fabricated thermistors after aging at 120°C for 300 h was also examined. Findings: Thick film NiMn₂O₄ spinel thermistors, prepared by screen printing and sintering in the temperature range 980°C–1290°C, exhibited good negative temperature coefficient (NTC) characteristics in the temperature range −30°C to 145°C, including high temperature coefficient of resistance, good stability and applicability in water. Originality/value: This study explores the range of sintering temperature that can be applied for NiMn₂O₄ thermistor thick films without compromising on the temperature sensing performance in air and water, as well as stability of the thermistors after aging at elevated temperatures.

Water quality monitoring is an essential tool in effective environmental and public health protection. This study presents a new screen-printed Co₂O₃–RuO₂-based electrode for electrochemical pH sensing and its comprehensive morphological, compositional, potentiometric, and thermal characterization. This novel electrode is used to measure the pH of different types of environmental water (river, lake, and sea) in Poland and the pH along the water column of a lake in Germany using an underwater multi-sensor probe, the development and demonstration of which are also described. The thick film pH electrode exhibits super-Nernstian sensitivity of 70.6 ± 2.2 mV pH⁻¹, a short response time of 2–13 s, and a stable response in media with a conductivity of up to 118 mS cm⁻¹ at temperatures ranging from −2 to 60 °C in the pH range 1–13. The electrodes have a high level of accuracy in comparison to the commercial glass electrodes, which they maintain over a period of 3 years. The superior potentiometric characteristics such as high sensitivity, selectivity, stability, and undisturbed sensing under extreme conditions are among the significant advantages of the developed miniaturized and low-cost pH-sensing electrode. The developed underwater probe is portable, rechargeable, submersible, autonomous, provides significant water data, and does not require scientific staff for operation.

The application of conventional glass electrodes for pH measurement in food samples has a serious drawback: glass is fragile and should be handled with care in order to prevent breaking and thus contaminating the food with dangerous shattered fragments. The implementation of all-solid-state sensors allows for pH measurements without this contamination risk but their application in food samples is scarce due to their inability to be used in complex food matrices that contain fats, proteins, yeasts, etc. We can solve this problem by coating solid-state RuO₂ electrodes with a semi-permeable protective Nafion^TM membrane layer. We show that covering screen printed potentiometric RuO₂ electrodes with Nafion membrane using a drop-casting technique does not alter the performance of the electrodes in milk samples and provides similar results to the conventional glass electrode. Furthermore, we discovered that thermal treatment of Nafion-layers at 80 °C for 2 h after each layer deposition optimises the performance of the electrodes, makes them usable even in heated aqueous solutions, and increases their lifetime.

With the growing demand for sustainable energy solutions, particularly for energy supply in transient sensor systems, this study focused on environmentally friendly materials in organic photovoltaics (OPV) and their key photovoltaic parameters.

Water is critical for the sustenance of life and pH is an important parameter in monitoring its quality. Solid-state pH sensors provide a worthy alternative to glass-based electrodes due to many advantages such as low cost, longer shelf life, simpler manufacturing, easier operation, miniaturization, and integration into electronic systems. Cobalt oxides are relatively cheaper and more abundantly available than ruthenium oxide. This work aims to reduce the environmental impact of screen-printed pH sensors by mixing Co3O4 and RuO2 in five molar proportions (30%, 40%, 50%, 60%, and 70%) and investigating the influence of oxide proportions on the pH-sensing properties of the resulting composition using potentiometric characterization, scanning electron microscopy, X-ray diffraction, surface profilometry, and electron dispersive spectroscopy. Although all the developed compositions showed super- or near-Nernstian sensitivity with good linearity, the sensors based on 50 mol% Co3O4-50 mol% RuO2 were the best due to superior sensitivity, selectivity, and stability. Fabricated sensors were applied in real-life environmental, municipal, and commercial water samples, including those from various depths in the Baltic Sea, and were found to be accurate in comparison to a glass electrode.