ABSTRACT
In the present thesis, the results obtained in the design and characterization of two different kinds of solid state sensors, as well as their application in the field of recognition and determination of chemical species are exposed.  
The first part of the work is focused in the design and characterization of sensor arrays, namely electronic tongues (ET). A first ET based on potentiometry is prepared for the qualitative and quantitative analysis of both saline solutions and mineral waters. The potentiometric ET was composed by five metal-based sensors as working electrodes, namely gold, silver, platinum, cooper and zinc; encapsulated into a stainless steel cylinder.  The capabilities of the ET for recognition of samples based in the differences in the anionic content have been verified.  The capabilities for predicting anionic levels have been verified as well, showing good results in prediction of chloride, as well as moderate results for both sulfate and bicarbonate.  
A second ET based on voltammetry was evaluated in the prediction of bisulfites in wine samples. The ET was composed by four metal-based working electrodes (gold, platinum, stainless steel and rhodium) encapsulated in a stainless steel cylinder used as seudoreference/counter electrode. Ascorbic acid and histamine were also included in the analysis of prediction. Hence, an experimental design was used for explaining the correlation and confounding between the three analytes. Calibration of the measurement system was performed as well as validation of created prediction models. The results of calibration showed good prediction of bisulfites, and acceptable for both ascorbic acid and histamine. In validation process, a decreasing in capabilities of prediction of all species was detected caused mainly due to a matrix effect.   
The third ET consisted in the simultaneous use of two measurement methodologies namely pulse voltammetry and electrochemical impedance spectroscopy (EIS) for the determination of the saline content in minced meat. The capabilities of the “hybrid” ET resulted good in the analysis of chloride, meanwhile prediction of both nitrite and nitrate can be considered as moderate.  
The second part of the thesis describes the design and characterization of a thick-film sensor made of ruthenium oxide used as pH sensor; and the statement/verification/validation of theoretical models for the study of interfering processes in solid state sensors as well. The thick-film sensor showed a strong resistance both chemical and mechanical, as well as a near nerstian sensibility. Interfering process have been found due to the presence of common anions in the samples. The interferences are caused due to reactions between interfering species and the lead oxides included in the composition of the ruthenium oxide resistive paste. Theoretical models able to describe both the behavior of potentiometric response and the interfering process of solid state sensors have been proposed and validated/verified. Validation/verification of models has been carried out for simple systems such as metal-based sensors M/MO/MX, and also in a complex system such as the thick-film sensor of ruthenium oxide.