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Int. J. Electroactive Mater. 3 (2015) 10-14

Non-destructive Tomato Ripeness Determination Using Carbon Nanostructure Based Chemical Sensors. Application of Tristimulus and Princial Component Analysis Methods

Márcia Greenshields1, Bruno Cunha2, Messai Mamo3, Neil Coville4, Ivo H�mmelgen5*

1Departamento de Física, Universidade Federal do Paraná, Curitiba, PR, Brazil
2Departamento de Fisica, Universidade Federal do Paraná, Curitiba, PR, Brazil
3Department of Applied Chemistry, University of Johannesburg, Johannesburg, Gauteng, South Africa
4Molecular Sciences Institute, University of the Witwatersrand, Johannesburg, Gauteng, South Africa
5Departamento de F�sica, Universidade Federal do Paran�, Curitiba, PR, Brazil

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Abstract : Chemical sensors based on carbon nanostructure composites are used to assess the ripeness stages of tomato ripeness (Solanum lycopersicum L.) as a function of their shelf-life. The chemical sensors were fabricated by depositing a thin film of composites of carbon nanotubes (undoped or doped with nitrogen) or carbon nanocoils and poly (vinyl alcohol) (PVA) by casting onto interdigitated electrodes. The changes in conductance and capacitance of the nanocomposite based sensors were measured at 27 kHz during the full ripening process. The ripening stage of the tomatoes can be electronically identified through the analysis of variations in G and C of the set of sensors using tristimulus vector space projection representation or principal component analysis.

Keywords : chemical sensor,carbon nanostructures,electronic transport,composite materia