Applied Physics A

, Volume 119, Issue 1, pp 169–178 | Cite as

Ag y :TiN x thin films for dry biopotential electrodes: the effect of composition and structural changes on the electrical and mechanical behaviours

  • P. PedrosaEmail author
  • D. Machado
  • J. Borges
  • M. S. Rodrigues
  • E. Alves
  • N. P. Barradas
  • N. Martin
  • M. Evaristo
  • A. Cavaleiro
  • C. Fonseca
  • F. Vaz


In the present work, Ag y :TiN x thin films, obtained by reactive DC magnetron sputtering, with decreasing [N]/[Ti] atomic ratios (from 1 to 0.1) and a fixed amount of Ag pellets placed in the erosion zone of a pure Ti target, were studied envisaging their application as biopotential electrodes. The strongly under-stoichiometric samples, [N]/[Ti] = 0.1 and 10 at.% Ag; [N]/[Ti] = 0.2 and 8 at.% Ag, were found to be composed of a N-doped hcp-Ti structure, with possible formation of TiAg or Ti2Ag intermetallics. These samples exhibit high electrical resistivity values and low hardness and reduced modulus. In the set of samples indexed to a transition zone, [N]/[Ti] = 0.3 and 15 at.% Ag; [N]/[Ti] = 0.7 and 32 at.% Ag, a hcp-Ti to fcc-TiN phase transformation took place, giving rise to a disaggregated N-deficient TiN matrix. It correlates with the high resistivity values as well as the higher hardness and reduced modulus values that were obtained. The last identified zone comprised the stoichiometric Ag:TiN x sample—[N]/[Ti] = 1 and 20 at.% Ag. Extensive metallic Ag segregation was detected, contributing to a significant decrease of the resistivity and hardness values.


Atomic Ratio Rutherford Backscattering Spectrometry Flexible Polymeric Substrate Poisoning Phenomenon 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



This research is partially sponsored by FEDER funds through the program COMPETE—Programa Operacional Factores de Competitividade and by national funds through FCT—Fundação para a Ciência e a Tecnologia, under the projects PEst-C/EME/UI0285/2011, PTDC/SAU-ENB/116850/2010, PTDC/CTM-NAN/112574/2009 and Programa Pessoa 2012/2013 Cooperação Portugal/França, Project No. 27306 UA “Porous architectures in GRAded CERamic thin films for biosensors”—GRACER. The authors would also like to acknowledge CEMUP for SEM analysis. P. Pedrosa acknowledges FCT for the Ph.D. Grant SFRH/BD/70035/2010. J. Borges acknowledges the support by the European social fund within the framework of the project “Support of inter-sectoral mobility and quality enhancement of research teams at Czech Technical University in Prague”, CZ.1.07/2.3.00/30.0034.


  1. 1.
    E. McAdams, Encyclopedia of Medical Devices and Instrumentation (Wiley, New York, 1998)Google Scholar
  2. 2.
    A. Searle, L. Kirkup, A direct comparison of wet, dry and insulating bioelectric recording electrodes. Physiol. Meas. 21, 271 (2000)CrossRefGoogle Scholar
  3. 3.
    M. Teplan, Fundamentals of EEG measurement. Meas. Sci. Rev. 2, 1–11 (2002)Google Scholar
  4. 4.
    L.T. Cunha, P. Pedrosa, C.J. Tavares, E. Alves, F. Vaz, C. Fonseca, The role of composition, morphology and crystalline structure in the electrochemical behaviour of TiNx thin films for dry electrode sensor materials. Electrochim. Acta 55, 59–67 (2009)CrossRefGoogle Scholar
  5. 5.
    P. Pedrosa, E. Alves, N.P. Barradas, P. Fiedler, J. Haueisen, F. Vaz, C. Fonseca, TiNx coated polycarbonate for bio-electrode applications. Corros. Sci. 56, 49–57 (2012)CrossRefGoogle Scholar
  6. 6.
    G. Gargiulo, R.A. Calvo, P. Bifulco, M. Cesarelli, C. Jin, A. Mohamed, A. van Schaik, A new EEG recording system for passive dry electrodes. Clin. Neurophysiol. Off. J. Int. Fed. Clin. Neurophysiol. 121, 686–693 (2010)CrossRefGoogle Scholar
  7. 7.
    C. Fonseca, J.P.S. Cunha, R.E. Martins, V.M. Ferreira, J.P.M. de Sá, M.A. Barbosa, A.M. da Silva, A novel dry active electrode for EEG recording. IEEE Trans. Biomed. Eng. 54, 162–165 (2007)CrossRefGoogle Scholar
  8. 8.
    K.P. Hoffmann, R. Ruff, Flexible dry surface-electrodes for ECG long-term monitoring, 2007 Annual International Conference of the IEEE Engineering in Medicine and Biology Society, vol. 1–16 (IEEE, New York, 2007), pp. 5740–5743Google Scholar
  9. 9.
    J.-Y. Baek, J.-H. An, J.-M. Choi, K.-S. Park, S.-H. Lee, Flexible polymeric dry electrodes for the long-term monitoring of ECG. Sens. Actuators A 143, 423–429 (2008)CrossRefGoogle Scholar
  10. 10.
    A. Gruetzmann, S. Hansen, J. Muller, Novel dry electrodes for ECG monitoring. Physiol. Meas. 28, 1375–1390 (2007)CrossRefGoogle Scholar
  11. 11.
    V. Marozas, A. Petrenas, S. Daukantas, A. Lukosevicius, A comparison of conductive textile-based and silver/silver chloride gel electrodes in exercise electrocardiogram recordings. J. Electrocardiol. 44, 189–194 (2011)CrossRefGoogle Scholar
  12. 12.
    C.-Y. Chen, C.-L. Chang, T.-F. Chien, C.-H. Luo, Flexible PDMS electrode for one-point wearable wireless bio-potential acquisition. Sens. Actuators A 203, 20–28 (2013)CrossRefGoogle Scholar
  13. 13.
    P. Salvo, R. Raedt, E. Carrette, D. Schaubroeck, J. Vanfleteren, L. Cardon, A 3D printed dry electrode for ECG/EEG recording. Sens. Actuators A 174, 96–102 (2012)CrossRefGoogle Scholar
  14. 14.
    S. Kaitainen, A. Kutvonen, M. Suvanto, T.T. Pakkanen, R. Lappalainen, S. Myllymaa, Liquid silicone rubber (LSR)-based dry bioelectrodes: the effect of surface micropillar structuring and silver coating on contact impedance. Sens. Actuators A 206, 22–29 (2014)CrossRefGoogle Scholar
  15. 15.
    P. Pedrosa, D. Machado, C. Lopes, E. Alves, N.P. Barradas, N. Martin, F. Macedo, C. Fonseca, F. Vaz, Nanocomposite Ag:TiN thin films for dry biopotential electrodes. Appl. Surf. Sci. 285(Part A), 40–48 (2013)CrossRefADSGoogle Scholar
  16. 16.
    P. Pedrosa, E. Alves, N.P. Barradas, N. Martin, P. Fiedler, J. Haueisen, F. Vaz, C. Fonseca, Electrochemical behaviour of nanocomposite Agx:TiN thin films for dry biopotential electrodes. Electrochim. Acta 125, 48–57 (2014)CrossRefGoogle Scholar
  17. 17.
    P. Pedrosa, C. Lopes, N. Martin, C. Fonseca, F. Vaz, Electrical characterization of Ag:TiN thin films produced by glancing angle deposition. Mater. Lett. 115, 136–139 (2014)CrossRefGoogle Scholar
  18. 18.
    P. Pedrosa, D. Machado, M. Evaristo, A. Cavaleiro, C. Fonseca, F. Vaz, Ag:TiN nanocomposite thin films for bioelectrodes: the effect of annealing treatments on the electrical and mechanical behavior. J. Vac. Sci. Technol. A 32, 031515 (2014)CrossRefGoogle Scholar
  19. 19.
    S. Jin, Y. Zhang, Q. Wang, D. Zhang, S. Zhang, Influence of TiN coating on the biocompatibility of medical NiTi alloy. Colloids Surf. B 101, 343–349 (2013)CrossRefGoogle Scholar
  20. 20.
    R. Tian, J. Sun, Corrosion resistance and interfacial contact resistance of TiN coated 316L bipolar plates for proton exchange membrane fuel cell. Int. J. Hydrogen Energy 36, 6788–6794 (2011)CrossRefGoogle Scholar
  21. 21.
    F. Vaz, P. Machado, L. Rebouta, P. Cerqueira, Ph Goudeau, J.P. Rivière, E. Alves, K. Pischow, J. de Rijk, Mechanical characterization of reactively magnetron-sputtered TiN films. Surf. Coat. Technol. 174–175, 375–382 (2003)CrossRefGoogle Scholar
  22. 22.
    P.J. Kelly, T. vom Braucke, Z. Liu, R.D. Arnell, E.D. Doyle, Pulsed DC titanium nitride coatings for improved tribological performance and tool life. Surf. Coat. Technol. 202, 774–780 (2007)CrossRefGoogle Scholar
  23. 23.
    L.A. Geddes, L.E. Baker, A.G. Moore, Optimum electrolytic chloriding of silver electrodes. Med. Biol. Eng. 7, 49–56 (1969)CrossRefGoogle Scholar
  24. 24.
    H. Köstenbauer, G.A. Fontalvo, J. Keckes, C. Mitterer, Intrinsic stresses and stress relaxation in TiN/Ag multilayer coatings during thermal cycling. Thin Solid Films 516, 1920–1924 (2008)CrossRefADSGoogle Scholar
  25. 25.
    J. Zhao, H.J. Feng, H.Q. Tang, J.H. Zheng, Bactericidal and corrosive properties of silver implanted TiN thin films coated on AISI317 stainless steel. Surf. Coat. Technol. 201, 5676–5679 (2007)CrossRefGoogle Scholar
  26. 26.
    T.L. Alford, L. Chen, K.S. Gadre, Stability of silver thin films on various underlying layers at elevated temperatures. Thin Solid Films 429, 248–254 (2003)CrossRefADSGoogle Scholar
  27. 27.
    L. Gao, J. Gstöttner, R. Emling, M. Balden, C. Linsmeier, A. Wiltner, W. Hansch, D. Schmitt-Landsiedel, Thermal stability of titanium nitride diffusion barrier films for advanced silver interconnects. Microelectron. Eng. 76, 76–81 (2004)CrossRefGoogle Scholar
  28. 28.
    M. Zhang, L. Hu, G. Lin, Z. Shao, Honeycomb-like nanocomposite Ti–Ag–N films prepared by pulsed bias arc ion plating on titanium as bipolar plates for unitized regenerative fuel cells. J. Power Sources 198, 196–202 (2012)CrossRefGoogle Scholar
  29. 29.
    C. Lopes, C. Gonçalves, P. Pedrosa, F. Macedo, E. Alves, N.P. Barradas, N. Martin, C. Fonseca, F. Vaz, TiAgx thin films for lower limb prosthesis pressure sensors: effect of composition and structural changes on the electrical and thermal response of the films. Appl. Surf. Sci. 285(Part A), 10–18 (2013)CrossRefADSGoogle Scholar
  30. 30.
    N.P. Barradas, C. Jeynes, R.P. Webb, Simulated annealing analysis of Rutherford backscattering data. Appl. Phys. Lett. 71, 291–293 (1997)CrossRefADSGoogle Scholar
  31. 31.
    A.F. Gurbich, Evaluated differential cross-sections for IBA. Nucl. Instrum. Methods Phys. Res. Sect. B 268, 1703–1710 (2010)CrossRefADSGoogle Scholar
  32. 32.
    L.J. Van Der Pauw, A method of measuring specific resistivity and Hall effect of discs of arbitrary shape. Philips Res. Rep. 13, 1–9 (1958)Google Scholar
  33. 33.
    Q. Kan, W. Yan, G. Kang, Q. Sun, Oliver–Pharr indentation method in determining elastic moduli of shape memory alloys—a phase transformable material. J. Mech. Phys. Solids 61, 2015–2033 (2013)CrossRefADSGoogle Scholar
  34. 34.
    F. Vaz, P. Machado, L. Rebouta, J.A. Mendes, S. Lanceros-Méndez, L. Cunha, S.M.C. Nascimento, P. Goudeau, J.P. Rivière, E. Alves, A. Sidor, Physical and morphological characterization of reactively magnetron sputtered TiN films. Thin Solid Films 420–421, 421–428 (2002)CrossRefGoogle Scholar
  35. 35.
    F. Vaz, J. Ferreira, E. Ribeiro, L. Rebouta, S. Lanceros-Méndez, J.A. Mendes, E. Alves, P. Goudeau, J.P. Rivière, F. Ribeiro, I. Moutinho, K. Pischow, J. de Rijk, Influence of nitrogen content on the structural, mechanical and electrical properties of TiN thin films. Surf. Coat. Technol. 191, 317–323 (2005)CrossRefGoogle Scholar
  36. 36.
    C.-S. Shin, S. Rudenja, D. Gall, N. Hellgren, T.-Y. Lee, I. Petrov, J.E. Greene, Growth, surface morphology, and electrical resistivity of fully strained substoichiometric epitaxial TiNx(0.67 < x < 1.0) layers on MgO(001). J. Appl. Phys. 95, 356–362 (2004)CrossRefADSGoogle Scholar
  37. 37.
    J.F. Pierson, D. Wiederkehr, A. Billard, Reactive magnetron sputtering of copper, silver, and gold. Thin Solid Films 478, 196–205 (2005)CrossRefADSGoogle Scholar
  38. 38.
    A.G. Spencer, R.P. Howson, R.W. Lewin, Pressure stability in reactive magnetron sputtering. Thin Solid Films 158, 141–149 (1988)CrossRefADSGoogle Scholar
  39. 39.
    D. Depla, S. Heirwegh, S. Mahieu, J. Haemers, R. De Gryse, Understanding the discharge voltage behavior during reactive sputtering of oxides. J. Appl. Phys. 101, 013301 (2007)CrossRefADSGoogle Scholar
  40. 40.
    D. Depla, G. Buyle, J. Haemers, R. De Gryse, Discharge voltage measurements during magnetron sputtering. Surf. Coat. Technol. 200, 4329–4338 (2006)CrossRefGoogle Scholar
  41. 41.
    D. Depla, S. Mahieu, R. De Gryse, Magnetron sputter deposition: linking discharge voltage with target properties. Thin Solid Films 517, 2825–2839 (2009)CrossRefADSGoogle Scholar
  42. 42.
    J.A. Thornton, Magnetron sputtering: basic physics and application to cylindrical magnetrons. J. Vac. Sci. Technol. 15, 171–177 (1978)CrossRefADSGoogle Scholar
  43. 43.
    J.M. Chappé, F. Vaz, L. Cunha, C. Moura, M.C. Marco de Lucas, L. Imhoff, S. Bourgeois, J.F. Pierson, Development of dark Ti(C, O, N) coatings prepared by reactive sputtering. Surf. Coat. Technol. 203, 804–807 (2008)CrossRefGoogle Scholar
  44. 44.
    J. Borges, F. Vaz, L. Marques, AlNxOy thin films deposited by DC reactive magnetron sputtering. Appl. Surf. Sci. 257, 1478–1483 (2010)CrossRefADSGoogle Scholar
  45. 45.
    J. Borges, N. Martin, N.P. Barradas, E. Alves, D. Eyidi, M.F. Beaufort, J.P. Riviere, F. Vaz, L. Marques, Electrical properties of AlNxOy thin films prepared by reactive magnetron sputtering. Thin Solid Films 520, 6709–6717 (2012)CrossRefADSGoogle Scholar
  46. 46.
    R. Arvinte, J. Borges, R.E. Sousa, D. Munteanu, N.P. Barradas, E. Alves, F. Vaz, L. Marques, Preparation and characterization of CrNxOy thin films: the effect of composition and structural features on the electrical behavior. Appl. Surf. Sci. 257, 9120–9124 (2011)CrossRefADSGoogle Scholar
  47. 47.
    S. Mahieu, D. Depla, Reactive sputter deposition of TiN layers: modelling the growth by characterization of particle fluxes towards the substrate. J. Phys. D Appl. Phys. 42, 053002 (2009)CrossRefADSGoogle Scholar
  48. 48.
    V.S. Smentkowski, Trends in sputtering. Prog. Surf. Sci. 64, 1–58 (2000)CrossRefADSGoogle Scholar
  49. 49.
    L.A. Rocha, E. Ariza, J. Ferreira, F. Vaz, E. Ribeiro, L. Rebouta, E. Alves, A.R. Ramos, P. Goudeau, J.P. Rivière, Structural and corrosion behaviour of stoichiometric and substoichiometric TiN thin films. Surf. Coat. Technol. 180–181, 158–163 (2004)CrossRefGoogle Scholar
  50. 50.
    B.-Y. Oh, M.-C. Jeong, D.-S. Kim, W. Lee, J.-M. Myoung, Post-annealing of Al-doped ZnO films in hydrogen atmosphere. J. Cryst. Growth 281, 475–480 (2005)CrossRefADSGoogle Scholar
  51. 51.
    S. Nagarjuna, K. Balasubramanian, D.S. Sarma, Effect of Ti additions on the electrical resistivity of copper. Mater. Sci. Eng. A 225, 118–124 (1997)CrossRefGoogle Scholar
  52. 52.
    K.-Y. Chan, T.-Y. Tou, B.-S. Teo, Thickness dependence of the structural and electrical properties of copper films deposited by dc magnetron sputtering technique. Microelectron. J. 37, 608–612 (2006)CrossRefGoogle Scholar
  53. 53.
    M.E. Day, M. Delfino, J.A. Fair, W. Tsai, Correlation of electrical resistivity and grain size in sputtered titanium films. Thin Solid Films 254, 285–290 (1995)CrossRefADSGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • P. Pedrosa
    • 1
    • 2
    • 3
    Email author
  • D. Machado
    • 3
  • J. Borges
    • 4
  • M. S. Rodrigues
    • 3
  • E. Alves
    • 5
  • N. P. Barradas
    • 6
  • N. Martin
    • 7
  • M. Evaristo
    • 1
  • A. Cavaleiro
    • 1
  • C. Fonseca
    • 1
    • 2
  • F. Vaz
    • 3
  1. 1.SEG-CEMUC–Department of Mechanical EngineeringUniversity of CoimbraCoimbraPortugal
  2. 2.Universidade do Porto, Faculdade de Engenharia, Departamento de Engenharia Metalúrgica e de MateriaisPortoPortugal
  3. 3.Centro de FísicaUniversidade do MinhoBragaPortugal
  4. 4.Department of Control Engineering, Faculty of Electrical EngineeringCzech Technical University in PraguePrague 6Czech Republic
  5. 5.Instituto de Plasmas e Fusão Nuclear, Instituto Superior TécnicoUniversidade de LisboaLisbonPortugal
  6. 6.Centro de Ciências e Tecnologias Nucleares, Instituto Superior TécnicoUniversidade de LisboaBobadela LRSPortugal
  7. 7.Institut FEMTO-ST, UMR 6174, CNRS, ENSMM, UTBMUniversité de Franche-ComtéBesançon CedexFrance

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