Download bionic eye powered by nanogenerator

2011 International Conference on Life Science and Technology
IPCBEE vol.3 (2011) © (2011) IACSIT Press, Singapore
BIONIC EYE POWERED BY NANOGENERATOR
Design of electronic eye for visually impaired
Praveenkumar Narayanan
Guhan Senthil
Department of Electronics and Instrumentation
Panimalar engineering college
Chennai, India
[email protected]
Department of Electronics and Communication
Panimalar engineering college
Chennai, India
[email protected]
cells in the retina. The cone cells are responsible for colour
recognition of the image viewed and the rod cells distinguish
the movement and the contrast of the image on the retina.
The retina is connected to a nerve called the optic nerve that
connects the brain and the eye. The eye ball is placed in a
protective cone shaped cavity in the skull called the orbit or
the socket and measures approximately one inch in diameter.
Abstract—Bionic eye is an artificial electronic eye. The main
purpose of bionic eye is to provide vision, partially to the
visually challenged people by the use of modern day electronic
devices like charge coupled device (CCD) camera and bionic
eye implant. The implant is a small chip that is surgically
implanted behind the retina in the eye ball. It could restore the
eye sight of the people who suffer from age related blindness.
There are two basic methodologies of bionic eye, multiple unit
artificial retina chip system (MARC) and artificial silicon
retina system (ASR). However, this paper presents a novel idea
of integrating a new approach of bionic eye with the
nanogenerator. The nanogenerator is multifaceted when
compared to the external batteries providing better power,
compactness and higher efficiency. The potential advantage of
proposed method is to be able to remove the blindness to a
feasible extent by making advance in the present research and
improving manufacturing technology.
Keywords-bionic eye; artificial eye; nanogenerator
applications; electronic eye; Retina damage; eye replacement;
blindness
I.
INTRODUCTION
Figure 1. Human eye structure.
Bionic eye is a bio-electronic eye. Bionic eye replaces the
functionality of a part or whole of the eye. An external
camera is worn on a pair of dark glasses which sends the
images in digital form to the radio receiver placed in the eye.
The radio receiver is attached to the implant chip on the
retina. The implantation is of two types, epiretinal implant
and subretinal implant, based on whether the implant is
placed on or behind the retina. In our proposed method of
bionic eye, a small and a powerful camera powered by
nanogenerator, is implanted inside the patient’s eye rather
than worn on a pair of glasses. The camera is small and
consumes very low power.
Fig. 1 shows interior structure of the human eye in its
basic form. The light signals enter the eye through the cornea.
The cornea focuses the rays of light falling on eye. The light
then passes the pupil and the lens of eye, which leads to the
formation of an inverted image on the retina of the eyeball.
The retina sends electrical signals to the brain through the
optic nerve. The brain interprets the signals sent from the
retina and forms the image.
B. Basic Eye Disorders
The Eye disorders dealt here are listed below:
• Retinitis Pigmentosa
• Macular Degeneration
A. The Human eye : Structure and function
The Human eyes operate on the same principle as that of
a camera. The Human eye is an organ that reacts to light for
several purposes. The Human eye ball is roughly spherical in
shape. The important part of the eye responsible for the
vision is the retina. The retina is a light sensitive tissue lining
the inner surface of the eye. Light falling on the eye is
focused on to a sheet of light sensitive cells. The
photosensitive ganglion cells in the retina that receive the
light signals affect the adjustment of the size of the pupil.
The ganglion cells are connected to the rods and the cone
1) Retinitis Pigmentosa
Retinitis Pigmentosa (RP) is the name given to a group of
hereditary diseases of the retina of the eye. RP is a
progressive blinding disorder of the outer retina which
involves degeneration of neurons [1]. RP may be caused by a
breakdown in the function of the rods or the cones in some
part of the retina. The retina is so complex that, breakdowns
may occur in a variety of ways and so RP is not a single
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disorder but a great number of disorders. The breakdown of
cone function may be called Macular Degeneration.
retina in patients suffering with AMD and RP types of
conditions. Current generated by the device in response to
the light stimulation will alter the membrane potential of the
overlying neurons and thereby activate the visual system.
2) Macular Degeneration
Macular Degeneration is a medical condition which
usually affects older adults. Macular Degeneration is mainly
due to the breakdown of the cones in the retina. The cone
cells are responsible for distinguishing the colours of the
image formed on the retina. In macular degeneration, a layer
beneath the retina, called the retinal pigment epithelium
(RPE), gradually wears out from its lifelong duties of
disposing of retinal waste products. A large proportion of
macular degeneration cases are age- related and it can make
it difficult to read or recognize faces, although enough
peripheral vision remains to allow other activities of daily
life. Age related Macular Degeneration (AMD) usually
affects people over the age of 50 and there are two distinct
types - wet AMD and dry AMD. Wet AMD results from the
growth of new blood vessels in the choroids, causing an
accumulation of fluid in the macula which leads to retinal
damage. Dry AMD represents at least 80% of all AMD cases
and results in atrophy of the Retina. Usually yellowish-white
round spots called drusen first appear in a scattered pattern
deep in the macula [1].
II.
Figure 3. ASR system.
Fig. 3 shows the ASR methodology in the bionic eye
system. The ASR is powered solely by incident light and
does not require the use of external wires or batteries. When
surgically implanted under the retina, in a location known as
the sub retinal space, the ASR is designed to produce visual
signals similar to those produced by the photoreceptor layer.
From their sub retinal location these artificial "photoelectric"
signals from the ASR are in a position to induce biological
visual signals in the remaining functional retinal cells which
may be processed and sent via the optic nerve to the brain.
BIONIC EYE
A visual prosthesis or bionic eye is a form of neural
prosthesis intended to partially restore lost vision or amplify
existing vision. It usually takes the form of an externallyworn camera that is attached to a stimulator on the retina,
optic nerve, or in the visual cortex, in order to produce
perceptions in the visual cortex. Fig. 2 shows the schematic
diagram of the bionic eye system.
1) Creation of artificial sight
A visually challenged person can be made to see light by
stimulating the ganglion cells behind the retina by passing
electrical signals. The nerves behind the retina function even
after the retina degenerates. Hence, scientists set out to create
a device that could translate images and electrical pulses that
could restore vision.
Figure 2. Bionic eye system.
Figure 4. ASR on a penny.
A. Artificial silicon retina
Artificial Silicon Retina (ASR) is a solid state
biocompatible chip which contains an array of
photoreceptors, and is implanted to replace the functionality
of the defective photoreceptor. The ASR is a silicon chip 2
mm in diameter and 1/1000 inch in thickness. It contains
approximately 3,500 microscopic solar cells called micro
photodiodes, each having its own stimulating electrode.
These micro photodiodes are designed to convert the light
energy from images into thousands of tiny electrical
impulses to stimulate the remaining functional cells of the
Fig. 4 shows ASR on a penny. The dot above the year on
the penny is the full size of the ASR. As you can see in the
picture at the top of this page, the ASR is an extremely tiny
device, smaller than the surface of a pencil eraser. It has a
diameter of just 2 mm (.078 inch) and is thinner than a
human hair. In order for an artificial retina to work it has to
be small enough so that doctors can transplant it in the eye
without damaging the other structures within the eye.
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An external camera acquiires the image of the viewerr. The
im
mages acquiredd by the cameera are encodeed into data sttream
annd transmitted via RF telemeetry to an intraaocular transcceiver.
A data signall will be trransmitted by
y modulatingg the
mplitude of a higher frequuency carrier signal. The signal
s
am
wiill be rectifiedd and filtered, and the MAR
RC will be cap
pable
off extracting power, dataa, and a cllock signal. The
suubsequently derived
d
inforrmation signaals will thenn be
stiimulated uponn the retina off the patient. The
T MARC sy
ystem
coonsists of twoo parts whichh separately reside exteriorr and
innterior to the eyeball. Eachh part is equiipped with bo
oth a
traansmitter and a receiver. T
The primary coil
c can be driven
d
wiith a 0.5- 10 MHz
M carrier siignal, accomppanied by a 100 kHz
am
mplitude modu
ulated (AM/A
ASK) signal which
w
providess data
foor setting the configuration
c
oof the stimulatting electrodess.
B. The MARC
C system
system consists
The Multiiple unit Artifficial Retina Chip
C
c
of an externall camera that ssends the imaages to the seccondary
receiving coill in the form of electric sig
gnals. The seccondary
receiving coill is mounted in close proxximity to the cornea.
c
The other schhematic compoonents of the MARC system
m are a
a
power and signal transcceiver and processing
p
c
chip,
stimulation-cuurrent driver, and a propoosed electrodee array
fabricated on a material succh as siliconee rubber, thin silicon,
s
c
connectting the devicees. The
or polyimide with ribbon cables
and its
biocompatibillity of polyim
mide is being studied,
s
i thin,
lightweight consistency suuggests its posssible use as a none
arrayy. Titanium taacks or
intrusive material for an electrode
t electrode array
a
cyanoacrylatee glue may be used to hold the
in
place. Fig. 5 represents thhe schematic diagram of MARC
M
mage formationn on the retinaa in the
system. Fig. 6 shows the im
MARC system
m methodologgy.
Figure 7. Functtional block diagrram.
Figure 5. MARC system
m.
Fig. 7 reprresents the fuunctional blocck diagram of the
bionic eye systtem. A DC poower supply is
i obtained byy the
T receiver on the
rectification of the incomingg RF signal. The
fo each pixel from
seecondary side extracts four bits of data for
thhe incoming RF
R signal and pprovides filteriing, demodulaation,
annd amplification. The extraacted data is interpreted byy the
eleectrode signaal driver whicch finally gen
nerates approppriate
cuurrents for the stimulating ellectrodes in teerms of magniitude,
puulse width andd frequency. T
The optic nervve must be at least
paartly functionaal to provide siight.
III.
Figuure 6. Image forrmation with MA
ARC system.
PROPO
OSED METHO
OD:
In the propposed system of bionic eyye, we replacee the
exxternal batteries with the nnanogenerators placed on bblood
veessels. The puupil and the foocusing lens part
p of the eyye are
replaced with a small circularr thin wafer siized printed ciircuit
booard (PCB). This
T printed ciircuit board iss placed insidde the
eyye in between the glass lensses [5]. The prrinted circuit bboard
alsso consists of
o the transm
mitter and th
he processor. The
prrocessor incluudes the analoog to digital converter and
d the
video bufferer. The printed circuit board is connected with
ultra thin wiress to the retinaal implant thaat is placed onn the
i connected tto the
retina. The retinnal implant viia electrodes is
t prostheticc lens
opptic nerves off the brain. Fig. 8 shows the
ussed in the propposed system oof bionic eye.
1) Workinng of bionic eyye implant
A bionic eye implannt is an exttraordinary ceramic
c
photocell thaat uses space technology that could reepair a
malfunctionin
ng human eye [2]. Camera captures imagges and
sends inform
mation to the microprocesssor. Microproocessor
converts dataa to an electtronic signal and transmitts it to
receiver. Receiver sends siignals throughh a tiny cablee to an
electrode pannel implanted on back wall of eye retinaa. Brain
perceives paatterns of ligght which corresponds
c
to the
electrodes stim
mulated on thee retinal implaant.
2) Overalll system functtionality
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PCB is responsible for capturing the images of the viewer
and processing the captured images into digital signals,
compressing and transmitting them to the retinal implant. Fig.
11 shows the printed circuit board where the size of the PCB
is compared to that of a 1 cent coin.
Figure 8. Prosthetic eye lens.
A. Nanogenerator powersupply
Nanogenerators are devices that are made up of Zinc
oxide nanowires which when bent and released produce
electric charges [3]. By building interconnected arrays
containing millions of such nano wires, we can produce
enough power supply for small scale devices [4]. Fig. 9
shows the internal structure of the nanogenerator, which
consists of the PZT nanofibers placed on the silicon substrate.
Figure 11. Printed circuit board.
C. Proposed system functionality
The working of the proposed system is explained as
following. The camera captures the images of the viewer and
converts the analog images into digital signals and
compresses it. The digital image signals are then sent via the
transmitter through the wires to the retinal implant on the
retina. The retinal implant is connected to the optic nerve of
the brain. The brain forms the image with the electrical
signals obtained from the retinal implant. Fig. 12 shows the
schematic diagram of the proposed system of bionic eye.
Figure 9. Nanogenerator structure.
In the case of the proposed method, the nanogenerator is
used on the blood vessels to produce the sufficient potential
to run the camera and the transmitter on the printed circuit
board. Fig. 10 shows the nanogenerator in a crystal casing.
Figure 12. Proposed bionic eye system in the eyeball.
IV.
CONCLUSION
Bionic devices are being studied and worked upon to do
more than replacement of the defective parts. Bionic Eye is a
system that is still under research. Providing power to run the
bionic eye implants has been a major challenge for the
researchers. With the upcoming development in the field of
nanotechnology, Nanogenerators are the future of power
supply for small scale devices. The major advantages of the
proposed bionic eye system are listed below:
• The Patient does not have to carry external batteries
along and the lifetime of the power supply is more.
• The system becomes more compact and efficient.
• There will be no external wiring to the human body.
Figure 10. Nanogenerator in a crystal casing.
B. Prosthetic eye
The prosthetic eye consists of a printed circuit board
(PCB) placed in between the lenses set in the front part of the
eye replacing the iris and the lens in the human eye [5]. The
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[4]
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