Artificial cochlear epithelium using a piezoelectric membrane
Purnima Sharma (Registration number- 13813)
Hochschule Rhine-Waal University of Applied Science,Germany
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
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
Cochlear hair cells convert sound signals into
Electric signals are transmitted to brain
through auditory nerve.
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
In this paper, experiment was done on
Hearing devices can be developed using
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.
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
The Conversion of sound stimuli to electrical
signals is performed by the external speech
processor and transmitter and interior receiver
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
It produced maximum electric output when
placed at maximum vibration site.
A prototype device containing PVDF
membrane which is used as transducer.
It will response to frequency range of 16-
polyvinyl difluoridepolyvinyl difluoride
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.
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
In following figure , Frequency change of
9Hz can be seen in basilar membrane and
Piezoelectric membrane mimic the function
of basilar membrane and inner hair cells
using travelling wave theory and
The electric output of this device is not
An ex vivo model of guinea temporal bone is
able to generate high electric output.
By optimizing the location of piezoelectric
device in cochlea for obtaining maximum
Additional mechanisms are required for
mimicking the outer hair cells.
Examine other piezoelectric materials for
generation of electric output.
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
Samuel at the Interactive-Biology website
Diagram derived from Chittka L, Brockmann A (2005): Perception
Space — The Final Frontier, www.plosbiology.org).
Supporting Information,Inaoka et al. 10.1073/pnas.1110036108