Skip to main content
SpringerLink
Log in

Ionic conductivity in hydrogels for contact lens applications

  • Published:
Ionics Aims and scope Submit manuscript

Abstract

Biphasic hydrogel polymers are in the forefront of new extended wear contact lens development. In the biphasic hydrogel the objective is to produce co-continuous domains of siloxane units for high oxygen permeability, coupled with hydrophilic units forming aqueous channels for hydraulic and ion mobility. These are distributed in phase separated nano-scale regions such that the material is optically clear while achieving the required properties to maintain corneal health and lens movement.

This paper describes how Impedance Spectroscopy permits a rapid measurement of ion conductivity in a range of silicone and non-silicone hydrogel materials with water contents ranging from 18% to 75% equilibrium water content. For non-silicone hydrogels relative sodium ion conductivity follows a typical percolation curve. However, for silicone hydrogels ion mobility is three orders of magnitude higher than conventional hydrogels of the same equilibrium water content.

The influence of electrolyte concentration, interfacial electrode sample contact pressure and temperature are also reported.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Similar content being viewed by others

References

  1. O. Witcherle and D. Lim, Hydrophillic gels for biological use, Nature185, 117–118 (1960).

    Google Scholar 

  2. T. Hirt, US patent 6039913 (2000).

  3. J. Kunzler, R. Ozark, Fluorosilicone hydrogels, US patent 5321108 (1994).

  4. J. Kunzler, R. Ozark, Hydrogels based on hydrophilic side-chains siloxanes, Journal of Applied Polymer Science55, 611–619 (1994).

    Article  Google Scholar 

  5. Y. Lai, Role of Bulky Polysiloxanylalkyl methacrylates in oxygen-permeable hydrogel materials, Journal of applied polymer science56, 317–324 (1995).

    Article  CAS  Google Scholar 

  6. P.C. Nicolson, J. Vogt, Soft contact lens polymers: an evolution, Biomaterials22, 3273–3283 (2001).

    Article  CAS  Google Scholar 

  7. A. Domschke, D. Lohman, L. Winterton, On-eye mobility of soft oxygen permeable contact lenses, Proceedings of the ACS Spring National Meeting, San Francisco: PMSE. (1997).

    Google Scholar 

  8. D. Austin, D. Champeney, A Technique for Measuring the Alternating Current Electrical Conductivity of Hydrogels, Journal of the BCLA18, 115–118. (1995).

    Google Scholar 

  9. D. Austin, The Electrical Conductivity of Soft Contact Lens Hydrogels, MPhil Thesis, School of Physics, UEA, Norwich, UK. (1996).

    Google Scholar 

  10. C.M. Weikart, M. Miyama, H.K. Yasuda, Surface modification of conventional polymers by depositing plasma polymers of trimethylsilane and Trimethlysilane+O2, Journal of Colloid and interfacial Science211, 28–38 (1999).

    Article  CAS  Google Scholar 

  11. B.J. Tighe, Silicone Hydrogel Materials-How do they work? in: Silicone Hydrogels: the rebirth of extended wear contact lenses (D. Sweeney, Ed.) Butterworth Heinemann, 2000.

  12. B. Tighe, Hydrogel materials: The patents and the products, Optician pp. 17–24 (1989).

  13. P.H. Corkhill, A.M. Jolly, C.O. Ng and B.J. Tighe, Synthetic Hydrogels: 1. Hydroxyalkyl acrylate and methacrylate copolymers-water binding studies, Polymer28, 1758–1765 (1987).

    Article  CAS  Google Scholar 

  14. V.J. McBrierty, S.J. Martin, F.E. Karasz, Understanding hydrated polymers: the perspective of NMR, Journal of Molecular Liquids80, 179–205, (1999).

    Article  CAS  Google Scholar 

  15. A. Lopez-Alemany, V. Compan, M. Refojo, Porous Structure of Purevision versus Focus Night & Day and Conventional Hydrogel Contact Lenses, Journal of Biomedical Material Research63, 319–325 (2002).

    Article  CAS  Google Scholar 

  16. D.L. Koch and A.S. Sangani, The AC Electrical Impedance of a Fractal Boundary to an Electrolytic Solution, J. Electrchem. Soc.138, No. 2, 475 (1991).

    CAS  Google Scholar 

  17. E. Barsoukov, J.R. Macdonald, Impedance Spectroscopy, Theory, Experiment and Applications, Wiley, 87 (2005).

  18. J.E.B. Randles, Kinetics of Rapid Electrode Reactions, Disc. Faraday Soc.1, 11–19 (1947).

    Google Scholar 

  19. B.B. Damaskin, The Principles of Current Methods for the Study of Electrochemical Reactions, Mc Graw Hill Inc. 61–78 (1965).

  20. L. Nyikos and T. Pajkossy, Fractal Dimension and Fractional Power Frequency-Dependent Impedance of Blocking Electrodes, Electrochimica Acta30, 1533–1540 (1985).

    Article  CAS  Google Scholar 

  21. R. De Levie, On Porous Electrodes in Electrolyte Solutions, Electrochimca Acta9, 1231–1245 (1964).

    Article  Google Scholar 

  22. R. De Levie, The Influence of Surface Roughness of Solid Electrodes on Electrochemical Measurements, Electrochimca Acta10, 113–130 (1965).

    Article  Google Scholar 

  23. J.R. Macdonald, Impedance Spectroscopy: Old Problems and New developments, Electrochimica Acta30, No. 10, 1483–1492 (1990).

    Article  Google Scholar 

  24. W. Scheider, Theory of the Frequency Dispersion of Electrode Polarization, Topology of Networks with Fractional Frequency Dependence, The Journal of Physical Chemistry79, No. 2. 127–135 (1975).

    Article  CAS  Google Scholar 

  25. P.H. Bottelberghs, Low-Frequency Measurements on Solid Electrolytes and Their Interpretations, in: Solid Electrolytes (P. Hagenmuller and W. Van Gool, Eds.) Academic Press, 1978.

  26. L. Nyikos, and T. Pajkossy, Diffusion to Fractal Surfaces, Electrochimica Acta31, 1347–1350 (1986).

    Article  CAS  Google Scholar 

  27. X. Qian et al., Methods to study the ionic conductivity of polymeric electrolytes using a.c. impedance spectroscopy, J. Solid State Electrochem.6, 8–15 (2001).

    Article  CAS  Google Scholar 

  28. T. Isono, J. Chem. Eng. Data29(1), 45–52 (1984).

    Article  CAS  Google Scholar 

  29. N. Lakshminararayanaiah, Transport Phenomena in Membranes, Academic Press, 1969, p. 226.

  30. R.A. Robinson and R.H. Stokes, Electrolyte Solutions, Butterworths, 1968, p. 133–147.

  31. R.A. Robinson and R.H. Stokes, Electrolyte Solutions, Butterworths, 1968, p. 87.

Download references

Author information

Authors and Affiliations

  1. Department of Optometry & Ophthalmic Dispensing, APU Cambridge, CB1 1PT, UK

    David Austin

  2. Department of Materials Science and Metallurgy, University of Cambridge, CB2 3QZ, UK

    David Austin & R. V. Kumar

Authors
  1. David Austin
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. R. V. Kumar
    View author publications

    You can also search for this author in PubMed Google Scholar

Rights and permissions

Reprints and permissions

About this article

Cite this article

Austin, D., Kumar, R.V. Ionic conductivity in hydrogels for contact lens applications. Ionics 11, 262–268 (2005). https://doi.org/10.1007/BF02430387

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1007/BF02430387

Keywords

Search

Navigation