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https://hdl.handle.net/1822/52548
Título: | Electrochemical and structural characterization of nanocomposite Agy:TiNx thin films for dry bioelectrodes: the effect of the N/Ti ratio and Ag content |
Autor(es): | Pedrosa, Paulo Eduardo Teixeira Baptista Machado, D. Fiedler, P. Alves, E. Barradas, N. P. Haueisen, J. Vaz, F. Fonseca, C. |
Palavras-chave: | Biopotential Dry electrodes EIS voltammetry TiN Ag-doping Sputtering EIS voltammetry |
Data: | 2015 |
Editora: | Elsevier |
Revista: | Electrochimica Acta |
Resumo(s): | 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. |
Tipo: | Artigo |
URI: | https://hdl.handle.net/1822/52548 |
DOI: | 10.1016/j.electacta.2014.12.020 |
ISSN: | 0013-4686 |
Arbitragem científica: | yes |
Acesso: | Acesso restrito autor |
Aparece nas coleções: | CDF - GRF - Artigos/Papers (with refereeing) |
Ficheiros deste registo:
Ficheiro | Descrição | Tamanho | Formato | |
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AgyTiNx_Electrochim Acta 2015.pdf Acesso restrito! | 1,71 MB | Adobe PDF | Ver/Abrir |