Thermally reduced Graphene Oxide: a well promising way to transparent flexible electrodes.

L'elaborato tratta dell'ottimizzazione del processo di riduzione termica dell'ossido di grafene in termini di conduttività e trasmittanza ottica. Definiti gli standard di deposizione tramite spin-coating e riduzione termica, i film prodotti vengono caratterizzati tramite XPS, AFM, UPS, TGA, ne vengono testate la conducibilità, con e senza effetto di gate, e la trasmittanza ottica, ne si misura l'elasticità tramite spettroscopia di forza, tutto al fine di comprendere l'evoluzione del processo termico di riduzione e di individuare i parametri migliori al fine di progredire verso la produzione di elettrodi flessibili e trasparenti a base di grafen ossido ridotto.

Energy harvesting from piezoelectric devices embedded in a 3D printed wing

This thesis work has been carried out at Clarkson University in Potsdam NY, USA and involved the design of a low elongation wing, consisting of parts made by polylactide (PLA) using the fused deposition model (FDM) technology of Rapid Prototyping, then assembled together in a thin aluminum spar. The aim of the research is to evaluate the feasibility of collecting electrical energy by converting mechanical energy from the vibration of the wing flutter. With this aim piezoelectric stripes were glued in the inner part of the wing, as well as on the aluminum spar, as monomorphic configuration. During the phases of the project, particular attention was given to the geometry and the materials used, in order to trigger the flutter for low flow velocity. The CAD software SolidWorks® was used for the design of the wing and then the drawings were sent to the Clarkson machine shop in order to to produce the parts required by the wing assembly. FEM simulations were performed, using software MSC NASTRAN/PATRAN®, to evaluate the stiffness of the whole wing as well as the natural vibration modes of the structure. These data, in a first approximation, were used to predict the flutter speed. Finally, experimental tests in the Clarkson wind tunnel facility were carried out in order to validate the results obtained from FEM analysis. The power collected by the piezoelectrics under flutter condition was addressed by tuning the resistors downstream the electronic circuit of the piezoelectrics.