Loading...

Capacitive Copling for Energy Transmission to Implant

Ashiri, Mehrangiz | 2013

961 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: English
  3. Document No: 45196 (55)
  4. University: Sharif University of Technology, International Campus, Kish Island
  5. Department: Science and Engineering
  6. Advisor(s): Zahedi, Edmond; Vosughi Vahdat, Bijan
  7. Abstract:
  8. Neural prostheses (NPs) based on capacitive coupling method including sur-face NPs, implanted or subcutaneous NPs and Stimulus Route System (SRS) are the common NPs used for rehabilitation applications. SRS is a kind of capacitive coupling and the latest version of the mentioned neural prosthesis used for restoring sensory and motor functions caused by spinal cord and brain disorders. In addition to some superiorities of capacitive coupling compared to other methods (inductive coupling, batteries, energy harvesters and so on) such as at plates structure and consequently ease of manufacturing, ability to transfer data and power with different operating frequency and hence remov-ing electromagnetic interferences, SRS takes the advantages of more selectivity and eliminating internal stimulator to excite targeted nerve or muscle. To at-tain an appropriate performance when SRS is applied to human body, several factors must be considered. Electrical excitation waveform shape, frequency,duration of pulses, conffguration of electrodes, number of intervals, thermal conditions and electrode material are some of these factors that affect the obtained performance. This study aims to investigate the effect of each pa-rameters using numerical modeling and verify the results of the simulation by fabricating a proper phantom that mimics the electrical properties of human forearm and applying SRS on it.Simulation result shows that only 2.02% of the applied waveform (square wave-form, 50 Hz, current source) diverted through implanted conductor placed inside human forearm with different tissues. This value is very close to the practical experiments based on [8] with a small error equal to 0.12%. To vali-date the result of simulation, two semi-solid phantoms (P1, P2) were fabricated which mimic the electrical properties of human muscle. SRS applied to these phantoms separately. The two models were different at implanted onductors and backing insulation. One of them had a simple delivery terminal without any insulation at the end of wire and the other had a helical-form delivery terminal. P1 and P2 had different Capture Ratio (CR used as an indicator of system effciency) at the frequency of 50 Hz and for the voltage source applied to them. The values of CR were 30% and 11.65% in average at the frequency of 50 Hz and for the voltage amplitude ranged between 0:2_5V . This difference may be due to the different shape of delivery terminals, backing insulation and dissimilar water-content of the phantoms caused by temperature changes and precision of measuring instruments
  9. Keywords:
  10. Simulation ; Stimulus Router System ; Finite Element Method ; Equivalent-Man Phantom ; Neuroprosthesis

 Digital Object List

 Bookmark

  • Title Page
  • Graduate Committee Approval
  • Author's declaration
  • Abstract
  • Abstract
  • Acknowledgments
  • Table of Contents
  • List of Figures
  • List of tables
  • 1 Preface
    • 1.1 Introduction
    • 1.2 Literature review
      • 1.2.1 Methods of energy transmission to implants
      • 1.2.2 Simulation of current in human tissues
      • 1.2.3 Properties of applied current and determining type of current and related parameters
      • 1.2.4 Determining the appropriate waveform
      • 1.2.5 The effect of skin impedance
      • 1.2.6 Optimum shape/area of electrodes
      • 1.2.7 Materials
      • 1.2.8 Electrode position
      • 1.2.9 Surface electrodes
      • 1.2.10 Electrode consideration
      • 1.2.11 Properties of the Stimulus Router System (SRS)
      • 1.2.12 Types of phantoms
  • 2 Methods
    • 2.1 SRS simulation
      • 2.1.1 Stimulus Router System (SRS)
      • 2.1.2 Simulation parameters
    • 2.2 Model design
      • 2.2.1 SRS components and fabrication processes
      • 2.2.2 Phantom fabrication
  • 3 Results
    • 3.1 Simulation results
    • 3.2 Experimental Results
  • 4 Concluding Remarks
    • 4.1 Significance of the Results
    • 4.2 Future Works
  • A Amount of voltages across the two 100 ohms resistors for P1
  • B Amount of voltages across the two 100 ohms resistors for P2
  • References
  • Curriculum Vitae
...see more