In Situ Formation of Dendrites in Eumelanin Thin Films between Gold Electrodes |
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Authors: | Julia Wünsche Luis Cardenas Federico Rosei Fabio Cicoira Reynald Gauvin Carlos F. O. Graeff Suzie Poulin Alessandro Pezzella Clara Santato |
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Affiliation: | 1. Département de génie physique, école Polytechnique de Montréal, CP 6079, Succursale Centre‐Ville, Montréal, Québec H3C 3A7, Canada;2. INRS‐EMT, Université du Quebec, 1650 Boul. Lionel Boulet, Varennes, Québec J3X 1S2, Canada;3. Département de génie chimique, école Polytechnique de Montréal V, CP 6079, Succursale Centre‐Ville, Montréal, Québec H3C 3A7, Canada;4. Department of Mining and Materials Engineering, McGill University, 3610 rue University Montreal, Quebec H3A 0C5, Canada;5. DF‐FC, Universidade Estadual Paulista, Av. Eng. Luiz Edmundo Carrijo Coube 14‐01, 17033‐360 Bauru, Brazil;6. Department of Chemical Sciences, University of Naples Federico II, Via Cintia 4, 80126 Napoli, Italy |
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Abstract: | Eumelanin is a ubiquitous pigment in the human body, animals, and plants, with potential for bioelectronic applications because of its unique set of physical and chemical properties, including strong UV‐vis absorption, mixed ionic/electronic conduction, free radical scavenging and anti‐oxidant properties. Herein, a detailed investigation is reported of eumelanin thin films grown on substrates patterned with gold electrodes as a model system for device integration, using electrical measurements, atomic force microscopy, scanning electron microscopy, fluorescence microscopy, and time‐of‐flight secondary ion mass spectroscopy. Under prolonged electrical biasing in humid air, one can observe gold dissolution and formation of gold‐eumelanin nanoaggregates, the assembly of which leads to the formation of dendrites forming conductive pathways between the electrodes. Based on results collected with eumelanins from different sources, a mechanism is proposed for the formation of the nanoaggregates and dendrites, taking into account the metal binding properties of eumelanin. The surprising interaction between eumelanin and gold points to new opportunities for the fabrication of eumelanin‐gold nanostructures and biocompatible memory devices and should be taken into account in the design of devices based on eumelanin thin films. |
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Keywords: | metal chelation eumelanin thin films gold nanostructures resistive change bioelectronics |
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