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Optomechanical measurement and FE modeling of tympanic membrane mechanics

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Presentation about my PhD work given at the Philips Research Centre, Eindhoven on 5th October 2012.

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Optomechanical measurement and FE modeling of tympanic membrane mechanics

  1. 1. Optomechanical measurement and FE modelingof tympanic membrane mechanicsJef AernoutsLaboratory of Biomedical Physics (BIMEF)University of AntwerpPresentation at Philips Group InnovationOctober 5, 2012
  2. 2. Optomechanical measurement and FE modelingof tympanic membrane mechanics 1
  3. 3. The human ear tympanic membrane 2
  4. 4. Function of the earConvert sound (20-20000 Hz) > nerve activity in our brain What is role middle ear? 3
  5. 5. Why study TM mechanics?• Middle ear finite element modeling tympanic membrane! normal(Aerts J, Aernouts J. 2012) reconstructed diseased (Kelly et al., 2003) (Gan et al., 2009) 4
  6. 6. Outline1. Tympanic membrane elasticity2. Tympanic membrane vibrations3. Middle ear modeling 5
  7. 7. Outline1. Tympanic membrane elasticity2. Tympanic membrane vibrations3. Middle ear modeling 6
  8. 8. Human tympanic membrane- Base diameter: 9 mm- Apex height: 1.7 mm 7
  9. 9. Needle indentation• Approach - Apply indentations - Measure forces (1) TM, (2): force transducer, (3): piston, (4): LVDT , (5): signal generator, (6): feedback control unit 8
  10. 10. Needle indentation• Approach - Apply indentations - Measure forces• Sample preparation 9
  11. 11. Needle indentation• Approach - Apply indentations - Measure forces• Sample preparation• Shape measurement 10
  12. 12. Needle indentation In rest• Approach - Apply indentations - Measure forces• Sample preparation Indented• Shape measurement• Finite element model 11
  13. 13. Needle indentation• Approach - Apply indentations - Measure forces• Sample preparation• Shape measurement• Finite element model - Fit experiments 12
  14. 14. 13
  15. 15. Outline1. Tympanic membrane elasticity2. Tympanic membrane vibrations3. Middle ear modeling 14
  16. 16. TM vibrations• Sample 15
  17. 17. TM vibrations• Sample• Stroboscopic holography - Sounds: 0.5 kHz – 19 kHz, 80-120 dB - Full-field displacement 16
  18. 18. Holography• Principle CCD 17
  19. 19. Holography• Principle• Stroboscopic holography 18
  20. 20. probe microphone speaker holography setupsample camera
  21. 21. FE model• Geometry (from micro-CT)• Boundary conditions & Loadings sound wave 20
  22. 22. TM full-field displacement- Measured with stroboscopic holography: 21
  23. 23. TM full-field displacement- Measured with stroboscopic holography:- Finite element outcome 22
  24. 24. Outline1. Tympanic membrane elasticity2. Tympanic membrane vibrations3. Middle ear modeling 23
  25. 25. Middle ear FE model results1000 Hz 7000 Hz 16000 Hz (x8e3) (x3e4) (x2e5) 24
  26. 26. Thanks for your attention!• Questions? I’m all ears… 25
  27. 27. TM curvature• Cochlear load at umbo (tip malleus)• Natural curved versus artificially flat 26
  28. 28. TM curvature 800 Hz – 4 kHz:• Umbo velocity response 17.5 dB difference 27

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