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A novel measurement strategy to evaluate the human head as a transition medium for inductive ear-to-ear communication

  • Jan-Christoph Edelmann EMAIL logo , Dominik Mair and Thomas Ussmueller
Published/Copyright: June 12, 2018
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Biomedical Engineering / Biomedizinische Technik
From the journal Biomedical Engineering / Biomedizinische Technik Volume 64 Issue 2

Abstract

This manuscript introduces a novel concept for measuring coil coupling for extremely loose-coupled coils (coupling factors k<10−6; mutual inductance values M<10−10 H). Such a coupling is found everywhere where the ratio of solenoid diameter to coil spacing is >50. Measuring these quantities with a low-power technology requires a sophisticated setup that goes beyond the sensitivity of state-of-the art approaches. The methodology is validated using laboratory measurements with three sets of solenoids (two ferrite-cored, one air-cored) and numerical simulations with COMSOL Multiphysics 5.2a, Stockholm, Sweden. The concept is then employed to investigate the channel characteristics for inductive through-the-head communication within the 3.155–3.195 MHz band. This selected part of the spectrum is in accordance with International Telecommunication Union Radio Regulation 5.116 for low-power wireless hearing aids. By applying a phantom solution, we demonstrate that human tissue layers are transparent for magnetic fields within these frequencies. However, the influence from the relative coil arrangement is evaluated in detail as it restricts the communication range significantly. The coupling results for off-the-shelf Sonion, Roskilde, Denmark, RF 02 AA 10 solenoids considering both lateral and axial displacements might be of special interest for a number of near-field applications.

Keywords: coils; coupling factor; ear-to-ear; hearing aid; inductive communication; mutual inductance

Acknowledgment

The authors would like to thank the SONION Corporation, Roskilde, Denmark, for sponsoring the RF 02 AA 10 NFMI solenoids. Numerical studies were performed using resources of the Research Area Scientific Computing at University of Innsbruck, Austria.

  1. Author Statement

  2. Research funding: Authors state no funding involved.

  3. Conflict of interest: Authors state no conflict of interest.

  4. Informed consent: Informed consent is not applicable.

  5. Ethical approval: The conducted research is not related to either human or animals use.

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Received: 2017-09-06
Accepted: 2018-05-14
Published Online: 2018-06-12
Published in Print: 2019-04-24

©2019 Walter de Gruyter GmbH, Berlin/Boston

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https://doi.org/10.1515/bmt-2017-0157
Keywords for this article
coils; coupling factor; ear-to-ear; hearing aid; inductive communication; mutual inductance

Articles in the same Issue

  1. Frontmatter
  2. Review
  3. The peripheral cannulas in extracorporeal life support
  4. Research articles
  5. Determination of optimal positive end-expiratory pressure based on respiratory compliance and electrical impedance tomography: a pilot clinical comparative trial
  6. Simulation of personalised haemodynamics by various mounting positions of a prosthetic valve using computational fluid dynamics
  7. Recovery of signal loss adopting the residual bootstrap method in fetal heart rate dynamics
  8. Optimal level and order detection in wavelet decomposition for PCG signal denoising
  9. Simple gastric motility assessment method with a single-channel electrogastrogram
  10. Analysis of on-surface and in-air movement in handwriting of subjects with Parkinson’s disease and atypical parkinsonism
  11. Wavelet-enhanced convolutional neural network: a new idea in a deep learning paradigm
  12. Digital microscopic evaluation of vertical marginal discrepancies of CAD/CAM fabricated zirconia cores
  13. Modelling the degree of porosity of the ceramic surface intended for implants
  14. How Hedstrom files fail during clinical use? A retrieval study based on SEM, optical microscopy and micro-XCT analysis
  15. A novel measurement strategy to evaluate the human head as a transition medium for inductive ear-to-ear communication
  16. Short communication
  17. Force plates may be used for dynamic analyses of endoprostheses explantation procedures
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