Desenvolvimento de sensores poliméricos para detecção de metais pesados e avaliação da qualidade da água / Sensors made with polymers for detecting heavy metals and assessing water quality

AUTOR(ES)

Carlos Eduardo Borato

DATA DE PUBLICAÇÃO

2007

RESUMO

Electronic tongues based on nanostructured films and employing impedance spectroscopy as the principle of detection have proven excellent to distinguish between basic tastes and detect trace amounts of impurities in liquid samples. The main limitation for a commercial use, though, is the need to replace the sensing units of the sensor array, which requires recalibration, owing to the relatively poor stability of the nanostructured films. In this thesis we introduce a new arrangement for the sensing units, which are produced from electrodeposited chrome electrodes, with no need to adsorb an organic film. Using an array with 5 or 10 nominally identical chrome electrodes, we obtained an electronic tongue capable of detecting basic tastes and copper ions in water down to the 1μM level. The differences in electrical properties for the electrodes arose from differences in morphology. Furthermore, this high sensitivity could be exploited in the analysis of wines, and water samples collected from various rivers and lakes. Similarly to electronic tongues made with nanostructured films, the sensor array with electrodeposited chrome electrodes was capable of distinguishing wines from the same grape and producer, but different vintages, or from the same producer and vintage but different grapes. We also attempted to optimize the performance of electronic tongues by combining sensing units made of chitosan and poly(o-ethoxyaniline). In spite of the interesting properties deriving from the interaction between these components, especially when chitosan nanoparticles were used, the performance of the sensor array was similar to that of the electronic tongue obtained with bare chrome electrodes.

ASSUNTO(S)

filmes finos impedance língua eletrônica chrome electrodes nanopartículas de quitosana chitosan nanoparticles impedância eletrodos de cromo thin films electronic tongue

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