8/6/2019 bitirmeee

1/37

I

BLINK SIGNAL ANALYSIS

by

Aylin Nuholu

Engineering Project Report

Department of Biomedical Engineering

Faculty of Engineering and Architecture

Yeditepe University

June 2011, Istanbul, Turkey

8/6/2019 bitirmeee

2/37

II

BLINK SIGNAL ANALYSIS

APPROVED BY:

Assoc.Prof.Dr. Ali mit KESKN (Supervisor)

Prof. Dr. Fuat BAYRAKEKEN .

Assist.Prof. Yusuf YUSUFOLU

DATE OF APPROVAL: 02.06.2011

8/6/2019 bitirmeee

3/37

III

ACKNOWLEDGEMENTS

I want to thank to my supervisor Prof. Dr. Ali mit Keskin at Yeditepe University of

Biomedical Engineering Department for his help, sharing his experience and superior

support during this project. I also thank Res. Assistant Mr. Hakan BOZKURT from

the Department of Biomedical Engineering for his generous help.

8/6/2019 bitirmeee

4/37

IV

ABSTRACT

Electrodes placed on the skin adjacent to the eyes measure changes in standing potential

between the front and back of the eyeball as the eyes move; a sensitive electrical test for

detection of retinal pigment epithelium dysfunction called oculography.

Eye movement measurements: Usually, pairs of electrodes are placed either above and

below the eye or to the left and right of the eye. If the eye is moved from the center position

towards one electrode, this electrode "sees" the positive side of the retina and the opposite

electrode "sees" the negative side of the retina. Consequently, a potential difference occurs

between the electrodes. Assuming that the resting potential is constant, the recorded potential

is a measure for the eye position.

The eye acts as a dipole in which the anterior pole is positive and the posterior pole is

negative.1.Left gaze; the cornea approaches the electrode near the outer canthus resulting in a

positive-going change in the potential difference recorded from it. 2.Right gaze; the cornea

approaches the electrode near the inner canthus resulting in a positive-going change in the

potential difference recorded from it (A, an AC/DC amplifier).

This Project is focused on design of an EOG device and experimental results. Proteus are

used for simulation and the signals received from the scalp are transferred into digital form.

8/6/2019 bitirmeee

5/37

V

ZET

Gz kaslarnn hareketine dayanarak elde edilen deney sonularndan yaplan karmlardorultusunda uyuukluk halinin etkisi llmtr. stemsiz gz krpma hareketinin hangiartlar altnda hangi iddette gerekletii dikkate alnarak deneklerde yaplan anketlerinsonular deerlendirilmitir.

Din ve uyuukluk (yorgun) hallerde alnan datalar kyaslanarak 3 farklhaldeki iaretlergz nnde bulundurularak sonuca ulalmtr.

Denek zerinde deney yaplmadan nce alnan anket sonular dorultusunda ortam

artlar da gz nnde bulundurularak alnan sonularda karlatrmaya gidilmitir.

Bu sayede gz kaslma hareketinin (istemsiz gz krpma) winkten farkn ortaya koyarak blink hareketininn kendi iinde farkl durumlarda deiik artlar altnda ayrldna dikkatekilmitir.

8/6/2019 bitirmeee

6/37

VI

TABLE OF CONTENTS

ACKNOWLEDGEMENTS .................................................................................................. III

ABSTRACT ............................................................................................................................ IV

ZET........................................................................................................................................ V

TABLE OF CONTENTS ....................................................................................................... VI

LIST OF FIGURES ............................................................................................................ VIII

LIST OF ABBREVIATIONS ................................................................................................ IX

1. INTRODUCTION ............................................................................................................. 1

1.1 WHAT IS EOG ? .............................................................................................................. 1

1.1.2 PUPPILARY DILATATION .................................................................................... 1

1.1.3 SACCADES .............................................................................................................. 1

1.1.5 LIGHT RESPONSE ................................................................................................... 2

1.1.6 MEASUREMENT OF AN EOG ............................................................................... 3

1.1.7 NORMAL VALUES ................................................................................................. 6

1.1.8 REPORTING THE EOG ........................................................................................... 6

1.2 ELECTRODE LOCATION ............................................................................................. 6

1.2.1 SKIN ELECTRODES ................................................................................................ 7

1.2.2 LIGHT SOURCES ..................................................................................................... 7

1.2.3. ELECTRONIC RECORDING EQUIPMENT ......................................................... 8

1.3 WHAT IS EMG? .............................................................................................................. 9

1.4 ELECTROMYOGRAM (EMG) AND NERVE CONDUCTION STUDIES ............... 10

2. CIRCUIT DESIGN OF AN EOG ..................................................................................... 11

2.1 INSTRUMENTATION AMPLIFIER ............................................................................ 11

2.2 NON-INVERTING AMPLIFIER ............................................................................... 12

2.2.1 NON-INVERTING AMPLIFIER CONFIGURATION .......................................... 13

2.2.3 EQUIVALENT POTENTIAL DIVIDER NETWORK ........................................... 14

2.2.4 NON-INVERTING AMPLIFIER CIRCUIT ........................................................... 15

3. ANATOMY OF AN EYE .................................................................................................. 16

3.1 EYE STRUCTURE ........................................................................................................ 16

8/6/2019 bitirmeee

7/37

VII

3.2 EYE SIGNALS............................................................................................................... 16

3.3 OPTIC AND CILIARY MUSCELS .............................................................................. 16

3.4 WHAT IS BLINK? ......................................................................................................... 23

4. EXPERIMENTAL RESULTS .......................................................................................... 24

5.CONCLUSION .................................................................................................................... 26

6.REFERENCES .................................................................................................................... 28

8/6/2019 bitirmeee

8/37

VIII

LIST OF FIGURES

FIGURE 1 Appearance of EOG saccadic recordings with DC (top) or AC (bottom)

amplification. .............................................................................................................................. 3

FIGURE 2. Examples of an idealized (top) and a practical (bottom) EOG record .................... 5

FIGURE 3 International 10-20 electrode placement .................................................................. 6

FIGURE 4. Non-inverting Amplifier ....................................................................................... 13

FIGURE 5.Potential Divider Network ..................................................................................... 14

FIGURE 6 . Connection of non-inverting amplifier ................................................................ 15

FIGURE 7. Non-inverting Amplifier circuit ............................................................................ 15

FIGURE 8 . Ekstraocular muscles ........................................................................................... 16FIGURE 9 Motor Nerve ........................................................................................................... 17

FIGURE 10 Oblique Muscles .................................................................................................. 17

FIGURE 11 Oblique Muscles .................................................................................................. 18

FIGURE 12 Orbita Fasya System ............................................................................................ 18

FIGURE 13 Eye Cover ............................................................................................................ 19

FIGURE 14 Orbita Fasya System ............................................................................................ 19

FIGURE 15 Eye Cover ............................................................................................................ 20

FIGURE 16 Orbitalis Oculi...................................................................................................... 20

FIGURE 17 Orbital Septum ..................................................................................................... 21

FIGURE 18 Lid Retractors ...................................................................................................... 21

FIGURE 19 Lid Retractors ...................................................................................................... 22

FIGURE 20 Tarsal Disc and Tarsal Sempatic Muscles ........................................................... 22

FIGURE 21 Example 1 ............................................................................................................ 24

FIGURE 22 Example 2 ............................................................................................................ 24

FIGURE 23 Example 3 ............................................................................................................ 24

FIGURE 24 data 1 .................................................................................................................... 25

FIGURE 25 data 2 .................................................................................................................... 25

FIGURE 26 data 3 .................................................................................................................... 25

FIGURE 27 Simulation with Proteus ....................................................................................... 26

FIGURE 28 Example of Proteus .............................................................................................. 26

8/6/2019 bitirmeee

9/37

IX

LIST OF ABBREVIATIONS

EOG: Electrooculogram

EMG:Electromyogram

ISCEV:International Society for Clinical Electrophysiology of Vision

8/6/2019 bitirmeee

10/37

1

1. INTRODUCTION

Biomedical signals used in the present study are EOG: horizontal and vertical eye

movements and voluntary eye blinks generate electrical activity. Therefore, positive potential

is charged at cornea side, whereas negative potential is charged at the retina side, constant

potential difference (corneal-retinal potential) is charged between the cornea and the retinas.

Body surface electrodes situated around the eyeball socket can detect potential changes

according to eye movements. (1)

On the other hand, eye blinks are classified into two categories: one is involuntary eye

blink, which occurs frequently or is evoked spontaneously by an external stimulus such as a

flash light; the other is a voluntary wink that is caused by intentional eye closing. These

phenomena can also be detected with the same electrodes as a potential change with opening

and closing of eyelids. (1)

1.1 WHAT IS EOG ?

1.1.2 PUPPILARY DILATATION

EOGs may be performed with pupils either dilated or undilated. Pupillary dilatation

provides better control of illumination levels, but adds time to the test and may make the test

somewhat more uncomfortable for certain patients. The critical parameter in producing a light

response of the standing potential is the level of retinal illumination. Thus, the light

levels which are used to perform the test will be different according to the state of the pupil.

(2)

1.1.3 SACCADES

Saccades are typically induced by illuminating the fixation lights alternately, but

patients could be instructed by other means to look back and forth at a steady rate between

fixation targets. ISCEV suggests that the eyes alternate direction every 1 to 2.5 seconds

(equivalent to a complete back and forth cycle every 2-5 seconds). Faster alterations become

uncomfortable and unstable, whereas alternations at the slow end make it more difficult for

subjects to maintain a steady alternating rhythm. Since continuous saccadic movement

becomes tiresome, it is recommended that a set number of saccades (minimum of 10) be

recorded once per minute throughout the test. Testing at least once per minute is necessary to

recognize the relevant peaks and troughs.(2)

8/6/2019 bitirmeee

11/37

2

1.1.4 PRE-ADAPTATION

Patients should be in ordinary room light, or be pre-adapted to room light levels, for at

least 15 minutes prior to the dark phase of testing. This pre-adaptation phase light should

measure between 35 and 70 lux looking ahead (not at the ceiling or close to a white wall).

Dimmer pre-adaptation light levels may fail to suppress rod function and will diminish the

size of the dark trough (although they would be acceptable for the baseline method of

recording described below). Stronger light levels or sudden changes in illumination may

excessively stimulate the dark trough and slow oscillations, and they will make it more

difficult to reach a steady baseline. Unusual bright light exposure such as sunlight,

ophthalmoscopy or fluorescein angiography should be avoided within 60 minutes of EOG

testing.(2)

1.1.5 LIGHT RESPONSEThe light stimulus should be turned on, and the EOG recorded, until the light peak has

occurred and the signal amplitudes have clearly begun to descend (at which point the

recording can be stopped). If there is no clear light peak, then recording should continue for at

least 20 minutes to insure that a delayed light peak is not missed. The choice of luminance

levels for the stimulus will depend on whether the pupil is dilated.

a. Dilated pupils: The stimulus intensity should be a fixed value (for each laboratory) within

the range of 50 and 100 cd/m2.

b. Undilated pupils: The stimulus intensity should be a fixed value (for each laboratory)

within the range of 400 and 600 cd/m2.

c. Technical note: These ranges of illumination are recommended to accommodate the typical

range of dilated or undilated pupil sizes. Technically speaking, the EOG would be better

standardized by the use of trolands (cd/m2

x mm2

of pupillary area) which would insure

similar levels of retinal illumination regardless of pupil size. ISCEV considers the range of

1000 to 3000 trolands (3 to 3.5 log trolands) to be optimal. For practical purposes, however, it

is difficult to measure pupillary diameter during the test, while the patient is looking into the

diffusing sphere, and most commercial stimulus units do not have the capability of finely

adjusting the luminance of the sphere. Thus, the Standard recommends separate fixed light

8/6/2019 bitirmeee

12/37

3

intensities for dilated and undilated pupils, as the best compromise between an adjustable

light level and the reality of clinical testing.

FIGURE 1 Appearance of EOG saccadic recordings with DC (top) or AC (bottom)

amplification. Measurement of saccade amplitude (brackets) should avoid the artifact of

overshoot.

1.1.6 MEASUREMENT OF AN EOG

a. Saccadic amplitudes: The measurement of EOG oscillations must take into account

the potential artifacts of overshoot (positive or negative) and falloff (Figure 1). Overshoot

occurs when subjects look beyond the fixation target and then return to a stable position.

Falloff occurs during AC recording, as the amplitude fades from its maximal value. Sharp

overshoots can be ignored and the stable amplitude level used for measurement. If there is

significant falloff from AC filtering of the signal, we recommend measurement of the leading

edge, or at least the initial stable value.(3)

8/6/2019 bitirmeee

13/37

4

b. The ratio of light peak to dark trough (Arden ratio): Measurement of the lowest dark-

adapted point (dark trough) and highest light point (light peak) should be made. However,

examiners should be aware that there is often some random variation in these values, and the

curves should be visually or otherwise "smoothed" to identify the true trough and peak points.

c. The ratio of light peak to dark baseline: The average stable baseline value in the dark is

determined. The light peak is determined as in the preceding section. The value of the light

peak to dark baseline ratio will typically be lower than the Arden ratio.

d. Latency (implicit time) of the light peak: The latency is the time between the onset of the

light phase and the peak of the light response. It can be of clinical relevance in addition to the

Arden- or baseline-ratios.

e. Amplitude of dark trough or dark baseline: It is important to measure the standing potential

amplitude in microvolts at either the bottom of the dark trough (if the Arden ratio method is

used) or at the dark-adapted baseline, since low values may have clinical significance and

may lead to the calculation of ratios of uncertain physiologic meaning. (These baseline

amplitudes should be normalized to microvolts per degree if a visual angle other than the

standard 30 is used). (3)

8/6/2019 bitirmeee

14/37

5

FIGURE 2. Examples of an idealized (top) and a practical (bottom) EOG record of saccadic

amplitude versus time. The points often must be "smoothed" visually or mathematically to

accurately estimate the dark trough and light peak.

8/6/2019 bitirmeee

15/37

6

1.1.7 NORMAL VALUES

ISCEV recommends that each laboratory establish or confirm normal values for its

own equipment and patient population, and that EOG reporting (whether for local records or

publication) include normal values. Some manufacturers may choose to distribute norms for

their standard protocols. An effort will be underway to establish world-wide norms.

Although normal values for the Arden ratio may be larger than those for the light peak vs.

dark baseline method, the two methods are roughly comparable in terms of variability of the

response (in the range of 10% variance about the mean for repeated testing on an experienced

subject). Norms from one method cannot and must not be used for the other.(4)

1.1.8 REPORTING THE EOG

ISCEV recommends that reports or communications of EOG data state clearly whether

the ratio of light peak to dark trough (Arden ratio), or light peak to dark baseline, method has

been used. EOG reports should include the latency of the light peak and the amplitude of the

dark trough or dark baseline in microvolts per degree of visual cycle. Published clinical

reports should indicate whether the recording technique meets the International Standard.

Research reports should indicate pupil size, spatial arrangement and measured intensity of the

light stimulus, conditions of pre-and dark-adaptation, time intervals of stimulation and filtercharacteristics of the recording equipment. (4)

1.2 ELECTRODE LOCATION

FIGURE 3 International 10-20 electrode placement

8/6/2019 bitirmeee

16/37

7

We determine the optimum electrode position with a minimum number of electrodes for the

EOG communication system. Two necessary conditions exist to decide electrode disposition:

i) Potential changes for eye movements of the four orientation axesup, down, right, and left

must be detected separately to generate four directional inputs. Thereby, two directional

channels are required to clearly distinguish vertical and horizontal eye movements, including

their directions.

ii) A potential change of voluntary eye blink is used for selection in the present system. The

blink simulates a mouse button click. Voluntary and involuntary eye blinks should be

distinguishable for this reason. Moreover, the detected signal from a voluntary eye blink

should be repeatable whether both eyes blink or one eye blinks; also, they should not be

affected by an electromyogram.

Two skin electrodes should be used for each eye, placed as close to each canthus as possible.

Avoid large size electrodes that fit poorly and increase the distance of separation. A ground

electrode should be attached to the middle of the forehead, or some other neutral site.

1.2.1 SKIN ELECTRODES

A. Construction: Electrodes should be made of relatively non-polarizable material such as

silver-silver chloride or gold.

B. Electrode application: The skin should be cleansed of oils with alcohol or a commercial

skin-preparing material. The electrodes should be applied with a conductive paste.

C. Cleaning: If non-disposable electrodes are used, they should be suitably cleaned after each

use to prevent transmission of infectious agents. The cleaning protocol should follow current

standards for devices that contact the skin. (4)

1.2.2 LIGHT SOURCES

a. Luminance: Illumination may be provided by one or several lamps, but they should produce

visibly white light, and be situated so that the full-field diffusing sphere is evenly illuminated

from the vantage point of the patient. Areas of focal intensity ("hot spots") or shadows shouldbe avoided.

8/6/2019 bitirmeee

17/37

8

b. Adjustment: The light source should be adjustable by the use of filters or other means, to

allow for calibration of the unit. Large variation in stimulus intensity will need to be available

if patients with both dilated and undilated pupils are to be studied.

c. Calibration: The luminance produced by the full-field stimulator should be measured in

cd/m2

with a photometer that meets international standards for photometric measurements

based on the photopic luminosity curve. ISCEV recommends that in the future, manufacturers

of stimulators provide a suitable photometer as a part of the equipment. Since light output

may vary with time, from changes in light bulbs or filters, it is important that the luminance

be periodically recalibrated. Self-calibrating units are to be encouraged. (4)

1.2.3. ELECTRONIC RECORDING EQUIPMENT

a. Basis of measurement of the standing potential: Because of the dipole effect of the eye,

with the cornea positive to the back of the globe, saccadic eye movements result in current

flows around the orbit that are proportional to the magnitude of the standing potential of each

eye. These voltage changes can be measured from skin electrodes placed at the nasal and

temporal canthal regions of the eye.

b. Amplification systems: Direct current (DC) amplification most faithfully reproduces the

square wave voltage changes that occur when a subject looks back and forth. However, for

practical purposes the use of alternating current (AC) recording systems is easier since the

problems of drift and stability are minimized. In general, it is recommended that an AC

system with a low frequency cutoff at 0.1 Hz or lower, and a high frequency cutoff no lower

than 20 Hz (but preferably below 50 or 60 Hz to minimize interference). DC recording may

be utilized by experienced laboratories, but will usually require some type of electronic

baseline compensation to avoid drift

.c. Display system: It is very important that the original waveforms be displayed during the

recording of the EOG. This allows the individual performing the test to judge whether the

signals are stable, and to observe artifacts, jerky saccades, unacceptable overshoot, etc., which

might necessitate re-application of electrodes, re-instruction of the patient, or an altered

interpretation of the results. In systems which automatically measure the amplitude of

collections (epoches) of waveforms, and plot the values, it is important that the raw data be

displayed transiently as it is gathered, to allow for these judgments.

8/6/2019 bitirmeee

18/37

9

d. Patient isolation: It is recommended that the amplifiers be electrically isolated from the

patient, according to current standards for safety of biological recording systems used

clinically.

1.3 WHAT IS EMG?

Electromyography is a term meaning "electrical muscle recording." Because muscle is an

electrical tissue, the needle electrode in the muscle, when connected to an amplifier and an

oscilloscope screen, can show the muscle's electrical activity as a series of voltage-

fluctuations. Moreover, the signal is also fed through a speaker, so you and the

electromyographer can listen to what the muscle has to say. Each muscle is analyzed while

you tense it, and again while you relax it. (5)

Normal muscles display typical patterns to the eye and ear through the oscilloscope and

speaker. Abnormal muscles show altered patterns. Sometimes the abnormality is more

evident on the oscilloscope, and sometimes more evident on the speaker. Muscles that are

themselves sick (myopathy) show one pattern, while muscles that are connected to sick

nerves (neuropathy) or spinal roots (radiculopathy) can show yet another pattern. (5)

Electromyography is often paired with nerve conduction studies performed at the same

testing session by the same doctor and with the same equipment. Each testEMG and nerve

conduction studieshas its own story to tell, as well as its own strengths and weaknesses in

its ability to show signs of disease. The results of the electromyography and nerve conduction

studies are considered together to come up with a more complete, combined test-outcome and

report. (5)

The time required for testing can depend on the nature of the problem. Also, the

electromyographer might add or subtract additional testing depending on how the initialcomponents turn out. Overall, a typical session might last between 45 and 90 minutes. That

doesn't mean that the patient is subjected to unpleasantries during that whole period of time.

Actually, much of the time is devoted to getting all the little pieces and parts of equipment

organized and in place for each "mini-test" comprising the overall testing session. (5)

8/6/2019 bitirmeee

19/37

10

1.4ELECTROMYOGRAM (EMG) AND NERVE CONDUCTION STUDIES

An electromyogram (EMG) measures the electrical activity of muscles at rest and during

contraction. Nerve conduction studies measure how well and how fast the nerves can send

electrical signals. Nerves control the muscles in the body by electrical signals (impulses), and

these impulses make the muscles react in specific ways. Nerve and muscle disorders cause the

muscles to react in abnormal ways.

Measuring the electrical activity in muscles and nerves can help find diseases that damage

muscle tissue (such as muscular dystrophy) or nerves (such as amyotrophic lateral sclerosis or

peripheral neuropathies). EMG and nerve conduction studies are often done together to give

more complete information. (6)

Why It Is Done

An electromyogram (EMG) is done to:

Find diseases that damage muscle tissue, nerves, or the junctions between nerve andmuscle (neuromuscular junctions). These disorders may include a herniated disc,

amyotrophic lateral sclerosis (ALS), or myasthenia gravis (MG).

Find the cause of weakness, paralysis, or muscle twitching. Problems in a muscle, thenerves supplying a muscle, the spinal cord, or the area of the brain that controls amuscle can cause these symptoms. The EMG does not show brain or spinal cord

diseases.

Nerve conduction studies are done to:

Find damage to the peripheral nervous system, which includes all the nerves that leadaway from the brain and spinal cord and the smaller nerves that branch out from those

nerves. Nerve conduction studies are often used to help find nerve disorders, such as

carpal tunnel syndrome or Guillain-Barr syndrome.

Both EMG and nerve conduction studies can help diagnose a condition called post-polio

syndrome that may develop months to years after a person has had polio. (6)

http://www.webmd.com/hw-popup/duchenne-muscular-dystrophyhttp://www.webmd.com/hw-popup/amyotrophic-lateral-sclerosis-alshttp://www.webmd.com/hw-popup/peripheral-neuropathyhttp://www.webmd.com/hw-popup/electromyogramhttp://www.webmd.com/hw-popup/herniated-disc-7991http://www.webmd.com/hw-popup/myasthenia-gravishttp://www.webmd.com/hw-popup/nerve-conduction-studieshttp://www.webmd.com/hw-popup/carpal-tunnel-syndrome-8276http://www.webmd.com/hw-popup/guillain-barre-syndromehttp://www.webmd.com/hw-popup/guillain-barre-syndromehttp://www.webmd.com/hw-popup/guillain-barre-syndromehttp://www.webmd.com/hw-popup/post-polio-syndromehttp://www.webmd.com/hw-popup/post-polio-syndromehttp://www.webmd.com/hw-popup/poliohttp://www.webmd.com/hw-popup/poliohttp://www.webmd.com/hw-popup/post-polio-syndromehttp://www.webmd.com/hw-popup/post-polio-syndromehttp://www.webmd.com/hw-popup/guillain-barre-syndromehttp://www.webmd.com/hw-popup/carpal-tunnel-syndrome-8276http://www.webmd.com/hw-popup/nerve-conduction-studieshttp://www.webmd.com/hw-popup/myasthenia-gravishttp://www.webmd.com/hw-popup/herniated-disc-7991http://www.webmd.com/hw-popup/electromyogramhttp://www.webmd.com/hw-popup/peripheral-neuropathyhttp://www.webmd.com/hw-popup/amyotrophic-lateral-sclerosis-alshttp://www.webmd.com/hw-popup/duchenne-muscular-dystrophy

8/6/2019 bitirmeee

20/37

11

2. CIRCUIT DESIGN OF AN EOG

2.1 INSTRUMENTATION AMPLIFIERAn instrumentation (or instrumentational) amplifier is a type of differential amplifier

that has been outfitted with input buffers, which eliminate the need for input impedance

matching and thus make the amplifier particularly suitable for use in measurement and test

equipment. Additional characteristics include very low DC offset, low drift, low noise, very

high open-loop gain, very high common-mode rejection ratio, and very high input

impedances. Instrumentation amplifiers are used where great accuracy and stability of the

circuit both short- and long-term are required.(7)

Although the instrumentation amplifier is usually shown schematically identical to a

standard op-amp, the electronic instrumentation amp is almost always internally composed of

3 op-amps. These are arranged so that there is one op-amp to buffer each input (+,), and one

to produce the desired output with adequate impedance matching for the function.[1][2]

The most commonly used instrumentation amplifier circuit is shown in the figure. The gain of

the circuit is

(Equ.1)

The rightmost amplifier, along with the resistors labelled R2 and R3 is just the standard

differential amplifier circuit, with gain = R3 / R2and differential input resistance = 2R2. The

two amplifiers on the left are the buffers. With Rgain removed (open circuited), they are simple

unity gain buffers; the circuit will work in that state, with gain simply equal to R 3 / R2 and

high input impedance because of the buffers. The buffer gain could be increased by putting

resistors between the buffer inverting inputs and ground to shunt away some of the negative

feedback; however, the single resistor Rgain between the two inverting inputs is a much more

elegant method: it increases the differential-mode gain of the buffer pair while leaving the

common-mode gain equal to 1. This increases the common-mode rejection ratio (CMRR) of

the circuit and also enables the buffers to handle much larger common-mode signals without

clipping than would be the case if they were separate and had the same gain. Another benefitof the method is that it boosts the gain using a single resistor rather than a pair, thus avoiding

http://www.answers.com/topic/differential-amplifierhttp://www.answers.com/topic/electronic-test-equipmenthttp://www.answers.com/topic/electronic-test-equipmenthttp://www.answers.com/topic/direct-currenthttp://www.answers.com/topic/drift-telecommunicationhttp://www.answers.com/topic/noise-level-1http://www.answers.com/topic/open-loop-gainhttp://www.answers.com/topic/common-mode-rejection-ratiohttp://www.answers.com/topic/input-impedancehttp://www.answers.com/topic/input-impedancehttp://www.answers.com/topic/accuracyhttp://www.answers.com/topic/bibo-stabilityhttp://www.answers.com/topic/electrical-networkhttp://www.answers.com/topic/instrumentation-amplifier#cite_note-0http://www.answers.com/topic/instrumentation-amplifier#cite_note-0http://www.answers.com/topic/instrumentation-amplifier#cite_note-0http://www.answers.com/topic/instrumentation-amplifier#cite_note-0http://www.answers.com/topic/instrumentation-amplifier#cite_note-0http://www.answers.com/topic/electrical-networkhttp://www.answers.com/topic/bibo-stabilityhttp://www.answers.com/topic/accuracyhttp://www.answers.com/topic/input-impedancehttp://www.answers.com/topic/input-impedancehttp://www.answers.com/topic/common-mode-rejection-ratiohttp://www.answers.com/topic/open-loop-gainhttp://www.answers.com/topic/noise-level-1http://www.answers.com/topic/drift-telecommunicationhttp://www.answers.com/topic/direct-currenthttp://www.answers.com/topic/electronic-test-equipmenthttp://www.answers.com/topic/electronic-test-equipmenthttp://www.answers.com/topic/differential-amplifier

8/6/2019 bitirmeee

21/37

12

a resistor-matching problem (although the two R1s need to be matched), and very

conveniently allowing the gain of the circuit to be changed by changing the value of a single

resistor. A set of switch-selectable resistors or even a potentiometer can be used for R gain,

providing easy changes to the gain of the circuit, without the complexity of having to switch

matched pairs of resistors.

The ideal common-mode gain of an instrumentation amplifier is zero. In the circuit

shown, common-mode gain is caused by mismatches in the values of the equally-numbered

resistors and by the mis-match in common mode gains of the two input op-amps. Obtaining

very closely matched resistors is a significant difficulty in fabricating these circuits, as is

optimizing the common mode performance of the input op-amps.

An instrumentation amp can also be built with 2 op-amps to save on cost and increase

CMRR, but the gain must be higher than 2 (+6 dB).

Instrumentation amplifiers can be built with individual op-amps and precision resistors,

but are also available in integrated circuit form from several manufacturers (including Texas

Instruments, National Semiconductor, Analog Devices, Linear Technology and Maxim

Integrated Products). An IC instrumentation amplifier typically contains closely matched

laser-trimmed resistors, and therefore offers excellent common-mode rejection. Examples

include AD620, MAX4194, LT1167 and INA128.

Instrumentation Amplifiers can also be designed using "Indirect Current-feedback

Architecture", which extend the operating range of these amplifiers to the negative power

supply rail, and in some cases the positive power supply rail. This can be particularly useful in

single-supply systems, where the negative power rail is simply the circuit ground (GND).

Examples of parts utilizing this architecture are MAX4208/MAX4209 and AD8129/AD8130.

2.2 NON-INVERTING AMPLIFIER

The second basic configuration of an operational amplifier circuit is that of a Non-

inverting Amplifier. In this configuration, the input voltage signal, (Vin) is applied directly to

the non-inverting (+) input terminal which means that the output gain of the amplifier

becomes "Positive" in value in contrast to the "Inverting Amplifier" circuit we saw in the last

tutorial whose output gain is negative in value. The result of this is that the output signal is

"in-phase" with the input signal.(8)

Feedback control of the non-inverting amplifier is achieved by applying a small part of

the output voltage signal back to the inverting (-) input terminal via a Rf - R2 voltage divider

network, again producing negative feedback. This closed-loop configuration produces a non-

http://www.answers.com/topic/resistor-1http://www.answers.com/topic/integrated-circuithttp://www.answers.com/topic/texas-instrumentshttp://www.answers.com/topic/texas-instrumentshttp://www.answers.com/topic/national-semiconductorhttp://www.answers.com/topic/analog-devices-inchttp://www.answers.com/topic/linear-technology-corphttp://www.answers.com/topic/maxim-integrated-products-1http://www.answers.com/topic/maxim-integrated-products-1http://www.answers.com/topic/laser-trimminghttp://www.analog.com/en/amplifiers-and-comparators/instrumentation-amplifiers/ad620/products/product.htmlhttp://www.maxim-ic.com/quick_view2.cfm/qv_pk/2006http://www.linear.com/1167http://focus.ti.com/docs/prod/folders/print/ina128.htmlhttp://www.maxim-ic.com/quick_view2.cfm/qv_pk/4925http://www.analog.com/en/audiovideo-products/video-ampsbuffersfilters/ad8129/products/product.htmlhttp://www.analog.com/en/audiovideo-products/video-ampsbuffersfilters/ad8129/products/product.htmlhttp://www.maxim-ic.com/quick_view2.cfm/qv_pk/4925http://focus.ti.com/docs/prod/folders/print/ina128.htmlhttp://www.linear.com/1167http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2006http://www.analog.com/en/amplifiers-and-comparators/instrumentation-amplifiers/ad620/products/product.htmlhttp://www.answers.com/topic/laser-trimminghttp://www.answers.com/topic/maxim-integrated-products-1http://www.answers.com/topic/maxim-integrated-products-1http://www.answers.com/topic/linear-technology-corphttp://www.answers.com/topic/analog-devices-inchttp://www.answers.com/topic/national-semiconductorhttp://www.answers.com/topic/texas-instrumentshttp://www.answers.com/topic/texas-instrumentshttp://www.answers.com/topic/integrated-circuithttp://www.answers.com/topic/resistor-1

8/6/2019 bitirmeee

22/37

13

inverting amplifier circuit with very good stability, a very high input impedance, Rin

approaching infinity, as no current flows into the positive input terminal, (ideal conditions)

and a low output impedance, Rout as shown below.

2.2.1 NON-INVERTING AMPLIFIER CONFIGURATION

FIGURE 4. Non-inverting Amplifier

In the previous Inverting Amplifier tutorial, we said that "no current flows into the input"

of the amplifier and that "V1 equals V2". This was because the junction of the input and

feedback signal (V1) are at the same potential in other words the junction is a "virtual earth"

summing point. Because of this virtual earth node the resistors, Rf and R2 form a simple

potential divider network across the non-inverting amplifier with the voltage gain of the

circuit being determined by the ratios of R2 and Rf as shown below. (8)

http://www.electronics-tutorials.ws/opamp/opamp_2.htmlhttp://www.electronics-tutorials.ws/opamp/opamp_2.html

8/6/2019 bitirmeee

23/37

14

2.2.3 EQUIVALENT POTENTIAL DIVIDER NETWORK

FIGURE 5.Potential Divider Network

Then using the formula to calculate the output voltage of a potential divider network, we

can calculate the closed-loop voltage gain (Av) of the Non-inverting Amplifier as follows:

that the overall closed-loop gain of a non-inverting amplifier will always be greater but

never less than one (unity), it is positive in nature and is determined by the ratio of the values

of Rf and R2. If the value of the feedback resistor Rf is zero, the gain of the amplifier will be

exactly equal to one (unity). If resistor R2 is zero the gain will approach infinity, but in

practice it will be limited to the operational amplifiers open-loop differential gain, (Ao).

We can easily convert an inverting operational amplifier configuration into a non-inverting

amplifier configuration by simply changing the input connections as shown.

8/6/2019 bitirmeee

24/37

15

FIGURE 6 . Connection of non-inverting amplifier

2.2.4 NON-INVERTING AMPLIFIER CIRCUIT

The basic circuit for the non-inverting operational amplifier is relatively straightforward. In

this circuit the signal is applied to the non-inverting input of the op-amp. However the

feedback is taken from the output of the op-amp via a resistor to the inverting input of the

operational amplifier where another resistor is taken to ground. It is the value of these two

resistors that govern the gain of the operational amplifier circuit. (8)

FIGURE 7. Non-inverting Amplifier circuit

8/6/2019 bitirmeee

25/37

16

3. ANATOMY OF AN EYE

3.1 EYE STRUCTUREVision is one of our most valued senses and during the course of each day our eyes are

constantly moving. Attached to the globe of the eye, there are three antagonistic muscle pairs,

which relax and contract in order to induce eye movement. These pairs of muscles are

responsible for horizontal, vertical and torsional (clockwise and counter clockwise)

movement. (9)

3.2 EYE SIGNALSTwo specific categories exist which can be used to classify the four different types of

conjugate eye movements: 1. Reflex eye movements - These provide stabilization of eye

position in space during head

movement. 2. Voluntary eye movements - These are conscious eye movements involved in

the redirection of

the line of sight in order to pursue a moving target (pursuit movement) or to focus on a new

target of interest. (9)

3.3 OPTIC AND CILIARY MUSCELS

FIGURE 8 . Ekstraocular muscles

8/6/2019 bitirmeee

26/37

17

FIGURE 9 Motor Nerve

FIGURE 10 ObliqueMuscels

8/6/2019 bitirmeee

27/37

18

FIGURE 11 Oblique Muscles

FIGURE 12 Orbita Fasya System

8/6/2019 bitirmeee

28/37

19

FIGURE 13 Orbita Fasya System

FIGURE 14 Orbita Fasya System

8/6/2019 bitirmeee

29/37

20

FIGURE 15 . Eye Cover

FIGURE 16 Orbitalis Oculi

8/6/2019 bitirmeee

30/37

21

FIGURE 17 Orbital septum

FIGURE 18 Lid Retractors (10)

8/6/2019 bitirmeee

31/37

22

FIGURE 19 Lid Retractor

FIGURE 20 Tarsal Disc and Tarsal Sempatic Muscels

8/6/2019 bitirmeee

32/37

8/6/2019 bitirmeee

33/37

24

4. EXPERIMENTAL RESULTS

FIGURE 21. Example 1

FIGURE 22. Example 2

FIGURE 23. Example 3

8/6/2019 bitirmeee

34/37

25

FIGURE 24. data 1

FIGURE 25. data 2

FIGURE 26. data 3

V

ol

t

Sampling Period : 10ms

V

o

l

t

Sampling Period : 10ms

A

a

8/6/2019 bitirmeee

35/37

26

FIGURE 27. simulation with proteus

FIGURE 28. Example of proteus

8/6/2019 bitirmeee

36/37

27

5.CONCLUSION

In this Project a system is designed to detect blink signal analysis. Main purposes of this

project is identify the signal from various people with using EOG. Many factors have been

determined to affect blink rate. Dry eye patients have been reported to have in- creased blink

rate. Contact lenses disrupts the tear film, resulting in an increased blink rate. Fatigue,

anxiety, and mental activities are known correlate to blink rate. Blink rate has even been

reported as an index for visual efficiency. Research findings indicate there are physiologic

and psychological/perceptual factors as- sociated with blinking. The fact that blindness and/or

binocular enucleation did not reduce the blink rate to zero suggests there may be

undetermined factors that cause endogenous blinking. It has been suggested that a blink

clock is located in the brainstem. This may be the reason for the effect of mental activities

on blink rates. The mechanism involved in blinking is, however, not fully understood.

8/6/2019 bitirmeee

37/37