Desenvolvimento de sistemas multissensoriais híbridos, língua e narizes eletrônicos para a avaliação de combustíveis.

Abstract

The simultaneous use of different sensor technologies is an efficient method to increase the performance of sensor systems. Aiming to contribute to a better quality control of Brazilian fuels, sensors were developed in this work to be used in electronic tongue and electronic noses. These multisensor systems were used separately and simultaneously integrating them to evaluation the quality of gasoline and ethanol. Thus, two types of multisensor hybrid systems were manufactured. The first system was composed by the integration of an Electronic Tongue (LE) and an Electronic Nose (NE), called SH-1. In this multisensor system, the electrical impedance of all the different sensors, based on nanostructured films of conducting polymers deposited on different gold microelectrodes, was measured simultaneously in both liquid and vapor fuel samples. The second multisensor hybrid system, SH-2, was composed by the union of two types of NEs and was fabricated by integrating sensors made from quartz microbalance and an array of capacitors, both functionalized with the same sensitive materials, conducting polymers and metalloporphyrins. The oscillation frequency of quartz crystal, and the capacitance of the array of capacitors were measured in the fuel vapor. These hybrid systems are easy to fabricate, simple to operate and sensitive to a wide variety of chemicals of interest. Tools for multivariate analysis were used for calibration and validation of the sensors, as well as for the interpretation of results.

Interdigitated Electrode for Electrical Chacarcterization of Commercial Pseudo-Binary Biodiesel-Diesel Blends

“…Also, the electrodes showed a greater response to ethanol compared to other fuels. As mentioned earlier, this behavior is attributed to biodiesel's values of the dielectric constants, diesel, and gasoline being lower than the dielectric constant of ethanol [28].…”

“…However, no deposition irregularities or defects were observed in any electrode, such as extensive cracks and/or regions with deposition failure, which prevented the use of the electrode; these characteristics guarantee a better distribution of charges electrodes, allowing a large area of interaction with the analyte. According to [28], to apply interdigitated electrodes such as sensors, biosensors, and even electronic tongue and nose systems, metal electrodes are needed to display precise patterns on their surface, obtained by removing metallic layers, producing the digits. These results indicate that the electrodes obtained by this method were appropriate for the fabrication of structured devices suitable in biosensors and molecular electronics.…”