Electrochemical and structural characterization of nanocomposite Ag-y:TiNx thin films for dry bioelectrodes: the effect of the N/Ti ratio and Ag content

• Tipo: Artigo em Revista Científica Internacional
• Data: 2015

Autores

Pedrosa, P (Autor) Outra; Machado, D (Autor) Outra; Fiedler, P (Autor) Outra; Alves, E (Autor) Outra; Barradas, NP (Autor) Outra; Haueisen, J (Autor) Outra; Vaz, F (Autor) Outra; C. Fonseca (Autor) FEUP

Revista

Título: Electrochimica Acta

Vol. 153

Páginas: 602-611

ISSN: 0013-4686

Editora: Elsevier

Indexação

ISI Web of Knowledge - 8 Citações

Scopus - 9 Citações

Outras Informações

ID Authenticus: P-00A-360

DOI: 10.1016/j.electacta.2014.12.020

Abstract (EN): Ag-y:TiNx nanocomposite thin films sputtered with different N/Ti atomic ratios and Ag atomic contents were characterized from the structural and morphological points of view. Their electrochemical behaviour was studied in a synthetic sweat solution, aiming at selecting a suitable material for biolectrode applications. An increase of the N/Ti atomic ratio, which is accompanied by an increase of the Ag atomic content, leads to a substantial increase of the roughness and porosity of the samples, especially for N/Ti ratios >0.2. For N/Ti atomic ratios up to 0.3 (15 at.% Ag) no metallic Ag segregation is visible in the TiNx matrix. Hence, the possible formation of TiAg and Ti2Ag intermetallics or even a Ag/TiAg/Ti2Ag phase mixture, although not demonstrated, should not be disregarded. As for the N/Ti atomic ratio = 0.7 (32 at.% Ag) sample, the Ag phases are predominantly concentrated near the interface with the substrate. The amount of Ag phases at the surface of the films remains somewhat low for all TiN under-stoichiometric films, even for Ag atomic contents up to 32 at.%. When the TiNx matrix reaches the stoichiometric condition (sample with N/Ti atomic ratio = 1 and 20 at.% Ag), Ag segregation occurs and metallic Ag aggregates are visible at the surface of the film, leading to a substantially different electrochemical behaviour. The impedance of the Ag-y: TiNx films in synthetic sweat solution is mainly ruled by the roughness/porosity variation, thus the higher the N/Ti atomic ratio, the lower the impedance. The interfacial film/sweat electrochemical noise and drift were similar for all films and comparable to the results obtained for commercial Ag/AgCl electrodes (except for the N/Ti atomic ratio = 1 and 20 at.% Ag film). In view of the results, it may be concluded that the samples with N/Ti atomic ratios = 0.3 (15 at.% Ag) and 0.7 (32 at.% Ag) are the most appropriate for further bioelectrode development.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 10