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Safety of multi-channel stimulation implants: a single blocking capacitor per channel is not sufficient after single-fault failure

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Abstract

One reason given for placing capacitors in series with stimulation electrodes is that they prevent direct current flow and therefore tissue damage under fault conditions. We show that this is not true for multiplexed multi-channel stimulators with one capacitor per channel. A test bench of two stimulation channels, two stimulation tripoles and a saline bath was used to measure the direct current flowing through the electrodes under two different single fault conditions. The electrodes were passively discharged between stimulation pulses. For the particular condition used (16 mA, 1 ms stimulation pulse at 20 Hz with electrodes placed 5 cm apart), the current ranged from 38 to 326 μA depending on the type of fault. The variation of the fault current with time, stimulation amplitude, stimulation frequency and distance between the electrodes is given. Possible additional methods to improve safety are discussed.

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Acknowledgments

The authors thank Prof. Stéphane Godet and Benoit Haut for their help on this study.

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Authors and Affiliations

  1. Biomedical Stimulation and Monitoring Research Group (BISTIMO), Université Libre de Bruxelles, Avenue F.D. Roosevelt 50 CP165/51, 1050, Brussels, Belgium

    Antoine Nonclercq & Laurent Lonys

  2. Implanted Devices Group, Department of Medical Physics and Bioengineering, Malet Place Engineering Building, Gower Street, London, WC1E 6BT, UK

    Anne Vanhoestenberghe & Nick Donaldson

  3. Department of Electronic and Electrical Engineering, Malet Place Engineering Building, Gower Street, London, WC1E 6BT, UK

    Andreas Demosthenous

Authors
  1. Antoine Nonclercq
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  2. Laurent Lonys
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  3. Anne Vanhoestenberghe
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  4. Andreas Demosthenous
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  5. Nick Donaldson
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Correspondence to Antoine Nonclercq.

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Nonclercq, A., Lonys, L., Vanhoestenberghe, A. et al. Safety of multi-channel stimulation implants: a single blocking capacitor per channel is not sufficient after single-fault failure. Med Biol Eng Comput 50, 403–410 (2012). https://doi.org/10.1007/s11517-012-0889-5

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  • DOI: https://doi.org/10.1007/s11517-012-0889-5

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