Development of methods based on voltammetry for the characterisation of liquids

The growing interest into multi-sensor systems able to determine general attributes of a process under monitoring, has recently involved the qualitative analysis of liquids; various methodologies to develop taste sensors, often referred to as “e-tongues” have been presented in the literature. The common concept in the different approaches, lies in the combination of signals originated by poorly specific sensors for the characterization of liquids. The fundamental idea of this PhD work is to investigate how an adequate signal processing approach, applied to a mature and affordable sensor technique (voltammetry), can address the issue of extracting an aggregate chemical information, useful to characterize the liquid under measurement. In this Thesis, a general description of electronic taste sensor systems is given, followed by a description of the working principles of e-tongues based on voltammetry. Then, the methodology that represents the core of this PhD Thesis work is introduced: the sensor device, the control software and the data processing approach are described in this sequence. Finally, a few case studies are shown, selected according to their relevancy with respect to the peculiarities of the approach described in this Thesis

A novel method based on voltammetry for the qualitative analysis of water.

This paper deals with the use of voltammetric techniques for the qualitative analysis of water, where we focus on the signal analysis approach and its evaluation in terms of discrimination capability. The prototype described in this paper and the signal analysis chain has been designed in the framework of the development of a field instrument for classification and change detection purposes. The common concept in the various approaches presented in the literature lies in the combination of poorly selective sensors for the characterization of liquids. The fundamental idea of this paper is to investigate how an adequate signal processing approach applied to a mature and affordable sensor technique (voltammetry) can address the issue of extracting aggregate chemical information, which is useful to characterize the liquid under measurement. In the proposed approach, dimensionality reduction is performed in a transformed domain via discrete cosine transform with an appropriate selection of a low dimensionality subset of the transformed coefficients. The novel methodological approach to the signal processing, two application experiments, and the test set that has been built for the experiments are described here. Finally, the capability of discriminating between different kinds of water is discussed