Artificial cochlear epithelium using a piezoelectric membrane
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Artificial cochlear epithelium using a piezoelectric membrane

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Artificial cochlear epithelium using a piezoelectric membrane Artificial cochlear epithelium using a piezoelectric membrane Presentation Transcript

  • Purnima Sharma (Registration number- 13813) Bionics/Biomimeitics,SS2013 Hochschule Rhine-Waal University of Applied Science,Germany 1
  •  Introduction  What is happening in the EAR?  Why hair cells are important for hearing?  How piezoelectric material can be used as artificial cochlea epithelium ?  Effect of kanamycin and ethacrynic acid on Guinea pig ear  How the transmission of sound waves is done through piezoelectric material?  Conclusion  Future work  References 2
  •  Mammalian Ear composed of three parts- external, middle and inner.  In inner ear, cochlea is present which is responsible for hearing mechanism.  The Human ear is able to hear sound in frequency range from high (20kHz) to low (20Hz).  Cochlear hair cells convert sound signals into electric signals.  Electric signals are transmitted to brain through auditory nerve. 3
  •  Damaged hair cells causes Deafness (Sensorineural Hearing loss).  Piezoelectric membrane generate electric potentials in response to sound stimuli.  Piezoelectric membrane can be implanted in cochlea and it will work as cochlear epithelium.  In this paper, experiment was done on guinea pig.  Hearing devices can be developed using piezoelectric material. 4
  •  Sound will travel from external ear to middle ear by putting pressure on tympanic membrane.  This will vibrate the stapes which is connected to oval window.  Pressure on Oval window will help in movement of fluids present in inner ear.  These vibrations leads to the oscillatory movement of basilar membrane.  These movement leads to bending of inner hair cells which is connected to auditory nerve. 5
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  •  In the organ of corti, two types of hair cells are present .  One row of inner hair cells and three row of outer hair cells.  Outer hair cells is responsible for amplifying and filtering the signals.  Inner hair cells are responsible for transmission of sound stimuli to auditory neurons. 7
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  •  The Conversion of sound stimuli to electrical signals is performed by the external speech processor and transmitter and interior receiver and stimulator[1].  Array of 24 platinum-iridium ball electrodes are implanted into scala tympani.  The vibration of basilar membrane in response to sound stimuli should be transmitted to piezoelectric membrane, generating electric output.  It produced maximum electric output when placed at maximum vibration site. 9
  •  A prototype device containing PVDF membrane which is used as transducer.  It will response to frequency range of 16- 32KHz. 10 polyvinyl difluoridepolyvinyl difluoride
  • 11  Kanamycin and ethacrynic acid is injected into the guinea ear  Total damage of hair cell can be seen after administrating the drug  Auditory primary neurons remained to measure the action potential.  No loss of spiral ganglion is seen after administrating the drug.
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  •  Piezoelectric device is basically based on the traveling wave theory(Von Bekesy et.al).  A glass bead was placed on the basilar membrane and its movement is measured by Laser Doppler Vibrometer.  Piezoelectric membrane is coated with silicon frame.  In following figure , Frequency change of 9Hz can be seen in basilar membrane and piezoelectric membrane. 13
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  •  Piezoelectric membrane mimic the function of basilar membrane and inner hair cells using travelling wave theory and microelectromechanical system.  The electric output of this device is not sufficient.  An ex vivo model of guinea temporal bone is able to generate high electric output. 15
  •  By optimizing the location of piezoelectric device in cochlea for obtaining maximum oscillation.  Additional mechanisms are required for mimicking the outer hair cells[1].  Examine other piezoelectric materials for generation of electric output. 16
  •  Takatoshi Inaokaa,1, Hirofumi Shintakub,1, Takayuki Nakagawaa,2, Satoyuki Kawanob, Hideaki Ogitaa,Tatsunori Sakamotoa, Shinji Hamanishic, Hiroshi Wadad, and Juichi Itoa, Piezoelectric materials mimic the function of the cochlear sensory epithelium(june,2011)  http://faculty.plattsburgh.edu/roger.hamernik/cds_344/pdf_files /auditory2.pdf  http://www.youtube.com/watch?v=L4F4zaRqQdk,Prof. Leslie Samuel at the Interactive-Biology website  Diagram derived from Chittka L, Brockmann A (2005): Perception Space — The Final Frontier, www.plosbiology.org).  http://embryology.med.unsw.edu.au/notes/ear6.htm  Supporting Information,Inaoka et al. 10.1073/pnas.1110036108 17
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