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This work aims at a broad overview of the results obtained with metal-sulfide materials in the field of chemoresistive gas sensing. Indeed, despite the well-known electrical, optical, structural and morphological features previously described in the literature, metal sulfides present lack of investigation for gas sensing applications, a field in which the metal oxides still maintain a leading role owing to their high sensitivity, low cost, small dimensions and simple integration, in spite of the wide assortment of sensing materials. However, despite their great advantages, metal oxides have shown significant drawbacks, which have led to the search for new materials for gas sensing devices. In this work, Cadmium Sulfide and Tin (IV) Sulfide were investigated as functional materials for thick-film chemoresistive gas-sensors fabrication and they were tested both in thermo- and in photo-activation modes. Furthermore, electrical characterization was carried out in order to verify their gas sensing properties and material stability, by comparing the results obtained with metal sulfides to those obtained by using their metal-oxides counterparts. The results highlighted the possibility to use metal sulfides as a novel class of sensing materials, owing to their selectivity to specific compounds, stability, and the possibility to operate at room temperature. [ABSTRACT FROM AUTHOR]

A thick-film electrochemical sensor with an iridium-carbon working electrode was used for determining polyphenols and their antioxidant capacity in white wine. Caffeic acid was used as a model species because it has the ability to produce the highest oxidation current. The correlation coefficient of 0.9975 was obtained between sensor response and caffeic acid content. The total phenolic content (TPC) and scavenging activity on 1,1-diphenyl-2-pycrylhydrazyl (DPPH·) radical were also found to be strongly correlated with the concentration of caffeic acid, with a correlation coefficient of 0.9823 and 0.9958, respectively. The sensor prototype was proven to be a simple, efficient and cost effective device to evaluate the antioxidant capacity of substances. [ABSTRACT FROM AUTHOR]

A three-electrode based CO2 sensor was fabricated using thick-film technology. The performance of this sensor was further enhanced by incorporating platinum nanoparticles onto the working electrode surface. An eight-fold increase in the signal output was obtained from the electrode with the platinum nanoparticles. The sensing output was linearly related to the CO2 presented. Stability measurements demonstrated that the decline of the active surface area and the sensitivity of the sensor were 8% and 13%, respectively, over a two week period of time. The sensor response appeared to be a structural dependence of the crystallographic orientation of platinum electrode. [ABSTRACT FROM AUTHOR]

This paper is focused on a new copper-nickel thick film resistive paste which was designed and experimentally developed for the realization of low-ohmic power resistors. This copper-nickel paste has been designed for use in combination with thick printed copper conductors and in comparison with conventional ruthenium-based thick film resistor pastes allows firing in a nitrogen protective atmosphere. The copper-nickel paste was prepared from copper and nickel microparticles, glass binder particles and a combination of organic solvents optimized for its firing in a nitrogen atmosphere. This paper covers a detailed description of copper-nickel paste composition and its thermal properties verified by simultaneous thermal analysis, a description of the morphology of dried and fired copper-nickel films, as well as the electrical parameters of the final printed resistors. It has been proven by electron microscopy with element distribution analysis that copper and nickel microparticles diffused together during firing and created homogenous copper-nickel alloy film. This film shows a low temperature coefficient of resistance ±45 × 0−6 K−1 and low sheet resistance value 45 mΩ/square. It was verified that formulated copper-nickel paste is nitrogen-fireable and well-compatible with thick printed copper pastes. This combination allows the realization of power substrates with directly integrated low-ohmic resistors. [ABSTRACT FROM AUTHOR]