1. Purnima Sharma (Registration number- 13813)
Bionics/Biomimeitics,SS2013
Hochschule Rhine-Waal University of Applied Science,Germany
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2.  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
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3.  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.
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4.  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.
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5.  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.
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7.  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.
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9.  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.
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10.  A prototype device containing PVDF
membrane which is used as transducer.
 It will response to frequency range of 16-
32KHz.
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polyvinyl difluoridepolyvinyl difluoride

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 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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13.  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.
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15.  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.
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16.  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.
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17.  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
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