medical electronics full 2marks and 16 marks

8/20/2019 Medical Electronics Full 2marks and 16 Marks

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EC1001-MEDICAL ELECTRONICS

(IV Year ECE)

Unit -1

ELECTRO PHYSIOLOGY AND BIO POTENTIAL RECORDING

The origin of bio-potentials-Bio-potential Electrodes-Biological amplifier-ECG-EEG-EMG-PCG-EOG-Lead systems and recording methods- Typical waveforms and signal characteristics

PART-A (2Marks)

1. What is meant by cell?

The basic living unit of the body is cell. The function of organs and other Structure of the body isunderstood by cell organization.

2. Give the abbreviation form for RNA, DNA?

RNA – Ribo Nucleic Acid DNA — De- Oxy Nucleic Acid

3. What are resting and action potential, bio electric potential?

The membrane potential caused by the different concentration of ions is called resting potential. Itis caused by very rapid change of membrane Permeability to sodium ions followed by recovery period.

The positive potential of the cell membrane during excitation is called action potential. Certainsystems of the body generate their own monitoring signals conveying useful information about thefunctions they represent. Such signals are bio electric potentials and are related to nerve conduction, brainactivity, heart beat etc.


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4. What is meant by measurement?

Measurement is an act or the result of comparison between the quantity and a predefined standard.

5. Mention the basic requirements of measurement.

The standard used for comparison purpose must be accurately defined and should be commonlyaccepted. The apparatus used and the method adopted must be provable.

6. What are the 2 methods for measurement?

1.Direct method and 2. Indirect method.

7. Explain the function of measurement system.

The measurement system consists of a transuding element which converts the quantity to be measured inan analogous form the analogous signal is then processed by some intermediate means and is then fed tothe end device which presents the results of the measurement.

8. Define Instrument.

Instrument is defined as a device for determining the value or magnitude of a quantity or variable.

9. List the types of instruments?

The 3 types of instruments are1) Mechanical Instruments 2) Electrical Instruments and3) Electronic Instruments.

10. Classify instruments.

1)Absolute Instruments 2) Secondary Instruments


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11. What is meant by Resting Potential?

Equilibrium is reached with a potential difference across the membrane such that negative on inside and positive on outside. This membrane potential caused by the different concentration of irons is calledResting Potential.

12.What is meant by Action Potential?

Cell has a slightly positive potential on the inside due to imbalance of potassium ions. This positive potential of the cell membrane during excitation is called Action Potential and is about 20 mV.

13.Give any 4 factors to be considered when we design any medical Instrument?

Accuracy, Frequency Response, Linearity, S/N ratio, Stability, sensitivity

14.What is Electrode Potential?

The voltage developed at an electrode-electrolyte interface is known as Electrode Potential.

15.What is the purpose of electrode paste?

The electrode paste decreases the impedance of the contact the artifacts resulting from the movement of theelectrode or patient.

16.Give the different types of electrodes?

Microelectrodes, Depth and needle electrodes, Surface electrodes

17.Give the different types of Surface electrodes?

1) Metal Plate electrodes 2) Suction cup electrodes3) Adhesive tape electrodes 4) Multi point electrodes5) Floating electrodes.


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18. What is PH electrode?

The chemical balance of human body is identified by measurement of Ph content of blood and other body fluids. PH is defined as logarithm of reciprocal of hydrogen ion concentration.

19. Define polarized and non polarized electrode .

Electrodes in which no net transfer of charge occurs across the metal electrolyte interface is called as perfectly polarized electrodes. Electrodes in which un hindered exchange of charge occurs across themetal electrode interface is called perfectly non polaraisable electrodes.

20. What is plethysmograph?

The instrument used for measuring blood volume is called plethysmograph

PART-B

1. Explain in detail about Polarization and non-polarization (8)Write down the Nernst Equation. (4) -April 2005

Nernst Equation:When two aqueous ionic solutions of different concentration are separated by an ion-selective semi-

permeable membrane, an electric potential exists across the membrane.The Nernst equation for half cell potential is

where E0 : Standard Half Cell Potential E : Half Cell Potentiala : Ionic Activity (generally same as concentration)n : Number of valence electrons involved

B A

DC

aaaa

nF RT

E E ln0


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Perfectly Polarizable ElectrodesThese are electrodes in which no actual charge crosses the electrode-electrolyte interface when a current isapplied. The current across the interface is a displacement current and the electrode behaves like acapacitor. Example : Ag/AgCl ElectrodePerfectly Non-Polarizable ElectrodeThese are electrodes where current passes freely across the electrode-electrolyte interface, requiring noenergy to make the transition. These electrodes see no

Over potentials. Example : Platinum electrodeEquivalent Circuit

Cd : capacitance of electrode-eletrolyte interface Rd : resistance of electrode-eletrolyte interface Rs : resistance of electrode lead wire Ecell : cell potential for electrode

2.What is Half Cell Potential. ? (8Marks,Nov-2007) A characteristic potential difference established by the electrode and its surrounding electrolyte whichdepends on the metal, concentration of ions in solution and temperature (and some second order factors) .Half cell potential cannot be measured without a second electrode. The half cell potential of the standard hydrogen electrode has been arbitrarily set to zero. Other half cell

potentials are expressed as a potential difference with this electrode.Reason for Half Cell Potential : Charge Separation at InterfaceOxidation or reduction reactions at the electrode-electrolyte interface lead to a double-charge layer, similarto that which exists along electrically active biological cell membranes.Measuring Half Cell Potential


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3. Name basic types of biopotential electrodes and their applications. (16marks,Dec-2006)

Metal plate electrodes – Large surface: Ancient, therefore still used, ECG – Metal disk with stainless steel; platinum or gold coated – EMG, EEG – smaller diameters

– motion artifacts – Disposable foam-pad: Cheap!


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(a) Metal-plate electrode used for application to limbs.(b) Metal-disk electrode applied with surgical tape.(c)Disposable foam-pad electrodes, often used with ECG

Suction electrodes- No straps or adhesives required- precordial (chest) ECG- can only be used for short periods

Floating electrodes- metal disk is recessed- swimming in the electrolyte gel- not in contact with the skin- reduces motion artifact


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Flexible electrodes- Body contours are often irregular- Regularly shaped rigid electrodes

may not always work.- Special case : infants- Material :

Double-sidedAdhesive-tapering Electrolyte gel

in recess

(a) (b)

(c)

Snap coated with Ag-AgCl External snap

Plastic cup

Tack

Plastic disk

Foam padCapillary loops

Dead cellular materialGerminating layer

Gel-coated sponge


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- Polymer or nylon with silver- Carbon filled silicon rubber

(Mylar film)

(a) Carbon-filled silicone rubber electrode.(b) Flexible thin-film neonatal electrode.(c) Cross-sectional view of the thin-film electrode in (b).

4. Discuss about biopotential amplifiers. (16Marks,Apr-2005)• These are very important part of modern medical instrumentation• We need to amplify biopotentials which are generated in the body at low levels with a high sourceimpedance• Biopotentials amplifiers are required to increase signal strength while maintaining fidelityBasic Requirements of Biopotential AmplifiersEssential functions of a bioamplifier are:• To take a weak biopotential and increase its amplitude so that it can be processed, recorded or displayed• To amplify voltage, but it could be considered as a power amplifier as well• To amplify current since in some cases a biopotential amplifier is used to isolate the load from the source

current gain only


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Input Impedance (Zin)• All biopotential amplifiers must have high input impedance minimize loading (remember thecharacteristics of biopotential electrodes resulting into loading and distortion if inputimpedance of the amplifier is not high enough) – typical values of Zin over the frequency range of themeasurand = 10 MΩ (remember the loading rule)Protection & Isolation• The input circuit of a biopotential amplifier must provide protection to the live measurandVbio• Any potential or current at amplifier’s input terminals can affect Vbio• Electric currents produced by the biopotential amplifier can result in microshock and macroshock• The bioamplifier must have isolation and protection circuitry so that the current through the electrodes

can be kept at safe levels and any artifact generated by such current can be minimizedOutput Impedance (Zout)• The o utput circuit does not present any critical problems, all it needs to do is to drive the load• Output impedance must be low with respect to the load impedance and it must be capable of satisfyingthe power requirements of the loadBandwidth (BW)Frequency response requirements• The biopotential amplifier must be sensitive to important frequency components of the biosignal• Since biopotentials are low level signals, it is important to limit bandwidth optimize signal-to-noiseratioGain (G)• Biopotential amplifiers have a gain of 1000 or greaterMode of Operation

• Very frequently biosignals are obtained from bipolar electrodes • Electrodes symmetrically located with respect to ground need differential amplification• High CMRR required because:1. Common mode signals much greater than the biosignal appear on bipolar electrodes2. Symmetry with respect to ground is not perfect (mismatch between electrode impedances) – more onthis laterCalibration Signal• Medical and clinical equipment require quick calibration • The gain of the biopotential amplifier must becalibrated to provide us with an accurate indication of the signal’s amplitude • Push button to apply standard signal to the input of the biopotential amplifier• Adjustable gain switch carefully selects calibrated fixed gains (in microprocessor – based systems, gainadjustment can be


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5. Draw the typical ECG waveform with its characteristics (16)Electrocardiography♥ A very widely used medical i nstrument, which is utilized to diagnose and monitor cardiac beatabnormalities is theelectrocardiograph♥ It measures the electrical activity of the heart (more precisely biopotential differences arising from theelectrical activity of myocardium). We’ve already talked about the genesis of theECG signal.♥ The ECG machine uses surface electrodes and high input impedance♥ Differential amplifiers with good common mode rejection ratio to record the electrocardiogram♥ Normal ECG amplitude ranges between 0. 5-4 mV. Normal frequency content of ECG (for diagnostic

purposes) is 0.05-100 Hz. A typical ECG waveform is shown below:

Obviously all human hearts are not the same and this leads intovariability in different parts of the ECG signalSignificant diagnostic features of the ECG signal are:♥ Duration of component parts of the signal ♥ Polarities and magnitudes ♥ The details of the ECG signal and the degree of variability in different

parts of the ECG signal is shown below:


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The QRS amplitude, polarity, time duration, the RR interval (indicator of heartbeat per min.) and the T-wave amplitude are some very important and distinctive features of the ECG signal.The heart rate in BPM = Beats Per Minute) is simply = 60 (RR interval in seconds)Some ECG waveform abnormalities that may indicate illness are:♥ An extended PR interval may be diagnosed as AV node block ♥ A widening of the QRS complex may indicate conduction problems in the bundle of His

♥ An elevated ST segment may indicate occurrence of myocardial Infarction ( MI )♥ A negative polarity in the T wave may be due to coronary insufficiencyECG Leads

Normal ECG recordings for the standard lead connections leads I, II and III (Lead II providesthe strongest signal)


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Obviously, all human hearts are not the same and this results into a high degree of variability♥ Note the degree of variability of different parts of the ECG Signal


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Some abnormalities that may indicate illness:♥ An extended P -R interval may be diagnosed as AV node block♥ Widening of the QRS complex conduction problems in the bundle of His♥ Elevated ST segment may indicate occurrence of MI ♥ Negative polarity T wave may be due to coronary insufficiency QRS amplitude, polarity, time domain,PR interval (indicator of heat beat per min. & T-wave amplitude are some very importantdistinctive features.

1. Loss

6. Discuss the different lead configurations used in ECG. (16Marks,Apr-2008))♥ Standard Limb Leads (I, II, III)


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The lead wires are color-coded according to some conventions. One example is: White – RA (Right Arm),Black – LA ( Left Arm ), Green – RL ( Right Leg ), Red – LL ( Left Leg ), and Brown – C (Chest)Note: There is a CM (common mode) amplifier connected to the right leg. We will discuss this in detaillater.Augmented Limb LeadsThese leads offer a free 50% increase over leads VR, VL , and VF connections (unipolar leads) withrespect to Wilson terminal AVR = -I – III /2, AVL = I – II /2, aVF = II – I /2


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Each measurement is made from the reflected limb and the average of the other two limbs.

Chest Leads (Precordial)

Chest Lead Anatomical PositionsV1 - 4th intercostal space – Right sternal margin


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V2 - 4th intercostal space – Left sternal marginV3 – Midway between V2 & V4V4 – 5th intercostal space on mid-clavicular lineV5 – Same as V4, on the anterior axillary line

V6 – Same as V5, on the mid-axillary line

12 Lead Clinical Electrocardiography


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7.With a neat block diagram explain the working of an ECG machine. (16Marks,Nov-2005)Ref: block diagram in text bookThe ECG MachineMost representative Specs:• Zin = 10 MΩ • Frequency response = 0.05 – 100 Hz• Strip Chart Recorder Speed = 25 mm/sec. • Fast Speed = 100 mm/sec.

8. Discuss about EEG & ERG (8Marks,Apr-2008)

The Electroencephalogram EEGEEG is the graphical representation of the electrical activity of the brain Very commonly used to diagnose certain neurological disorders, such as epilepsy More recently, also investigated whether it can detect various forms of dementia

or schizophrenia EEG is the specific recording obtained using the scalp electrodes from the

surface of the skull During surgery, electrodes may also be placed directly on the cortex. The

resulting signal is then electrocorticogram (ECoG). Just like ECG, EEG is also obtained using several different electrodes places on

different regions of the head / brain

ERPs are really EEGs obtained under a specific protocol that requires the


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patient to response to certain stimuli – hence event related potentials. Also called evoked potentials these signals can be used to diagnose certain

neurological disorders such as dementia, and they can also be used as a liedetector• The oddball paradigm• The gui lty knowl edge test

Electroretinogram ERGThe ERG is the record of the retinal action currents produced by the retina inresponse to a light stimulus.

It measures the electrical responses of the light-sensitive cells (such as rods and cones).The stimuli are often a series of light flashes or rotating patterns

The ERG is recorded using contact lens electrode that the subject wears while watching

the stimuli.


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Ultrasound:

• Mechanical waves in different modalities (longitudinal/lateral) needs medium to be propagated(solid, liquid, gas)

• > 20 kHz• Continuous/pulsed• Spherical/planar/narrow beam/surface wave/Lamb-wave

Physical phenomena behind ultrasound measurements

Transmission• • reflection• transit time• differences in propagation velocities

• returns to transit time• doppler-shift in frequency

• flow velocity• change of acoustic impedance

• comparing to reference• interference of ultrasound waves (holography)• interaction of ultrasound and light (photoacousticz)• ultrasound needs medium for propagation it doesn’t propagate in vacuum

• because mechanical waves need moving massunits and spring forces between them• in acoustic emission the medium creates ultrasound (for example, during pressure changes), whichis received by sensors

• pulsed mode more common than continuous• continuous reguires separate transducers for transmitting and receicving• in pulsed mode an ultrasound burst is sent to the object and the same transducer is switched to listen

echoes• standing wave problem

• in us-therapy pulsed mode gives more effective care without too much heatingThe Doppler Equation describes the relationship of the Doppler frequency shift to target velocity.The frequency difference is equal to the reflected frequency (FR) minus the originating frequency (FT). Ifthe resulting frequency is higher, then there is a positive Doppler shift and the object ismoving toward the transducer, but if the resulting frequency is lower, there is a negative Doppler


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UNIT – II

BIO – CHEMICAL AND NON ELECTRICAL PARAMETER MEASUREMENTPH – PO2 – PCO2 – PHCO3 – Electrophoresis – Colorimeter – Photometer – Autoanalyzer – Blood flow meter – Cardiac output – Respiratory measurement – Blood

pressure – Temperature – Pulse – Blood cell counters

PART-A(2maRKS)

1.Mention various types of chemical electrodes .

Hydrogen electrode, ph electrode, po2 electrode, pco2 electrode.

2..Define circulation and respiration?

We can define from the engineering point of view, the circulation is a high resistance circuit witha large pressure gradient between the arteries and veins The exchange of any gases in any biological

process is termed as respiration

3.What is mean by transducer?

It is a device which detects or senses the bio signal and converts it in to an electrical signal for bio signal processing

4 What is electrophoresis?

Electrophoresis is a technique used to separate biological molecules, such as nucleic acids,carbohydrates, and amino acids, based on their movement due to the influence of a direct electric current ina buffered solution. Positively charged molecules move toward the negative electrode, while negativelycharged molecules move toward the positive electrode.


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5.What are the different methods to measure the blood pressure?

1.Indirect method using sphygmomanometer. 2.Direct method.

6.What is the use of blood flowmeter in bio medical instrumentation?

Blood flow meters are used to monitor the blood flow in various blood vessels and it also helps tomeasure cardiac output.

7. What are the different types of blood flow meters?

Electromagnetic blood flow meter, Ultrasonic blood flow meter, Laser Doppler Blood flow meter, NMR Blood flow meter.

8.Give some applications of electromagnetic blood flow meters.

Blood flow measurements during cardiac surgery, blood flow measurements during shunt operations, blood flow measurements during carotid artery, blood flow measurements in rural arteries, blood flowmeasurements during organ transplantation.

9. What is cardiac output?

Cardiac output is the quantity of blood delivered by the heart to the aorta per minutes. It is a majordeterminant of oxygen delivery to the tissues.

10.What happens when there is a fall in cardiac output?

A fall in cardiac output may result in low blood pressure, reduces tissues oxygenation, acidosis, poorrenal function and shock.


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11.What are the different types of dilution methods?

Indicator dilution method, Dye dilution method, Thermal dilution method.

12.How Cardiac output is measured in thermal dilution method?

A thermal indicator of known volume introduced into either the right or left atrium Will produce aresultant temperature change in the pulmonary artery or in the aorta respectively, the integral of which isinversely proportional to the cardiac output.

Cardiac output=a constant X(blood temp-inject ate temp)/area under dilution curve.

13.What is the use of blood flow meter in bio medical instrumentation?

Blood flow meters are used to monitor the blood flow in various blood vessels and it also helps tomeasure cardiac output.

14.What are the two different principles used in ultrasonic blood flow measurement?

Transit Time method: In this method, a peizo electric crystal emits a brief pulse of ultrasound which propagates diagonally across the blood vessel.

Doppler effect based method: In this method , as per Doppler effect, there is a change in frequency ofreflected ultrasonic wave, due to motion of blood , when it crosses blood.

15. Define transit time principle of ultrasonic blood flow meter.

In Transit time method a piezo electric crystal emits a brief pulse of ultrasound which propagatesdiagonally across the blood vessel.

The pulse reaches a receiving crystal situated on the opposite side wall of the blood vessel.

Electronic circuitry attached externally interprets transit time to velocity.


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16.What is Sphygmomanometer?

Sphygmomanometer is a dvice used by the physician to measure blood pressure.

It is used for indirect BP measurement and it consists of inflatable rubber bladder called the cuff, arubber squeeze ball pump and value assembly and a manometer.

17.What is BSR?

BSR means based skin response, which gives the baseline value of skin resistance.

18.What is GSR?

GSR means galvanic skin response, which gives the measure of average activity of the sweat glandsand is a measure of phasic activity of sweat glands.

19. What is plethysmograph?

Plethysmograph is used to measure the constant volume changes or constant pressure changes in thechamber.

20..What is korotkoff sound?

In the BP measurement, When the systolic pressure exceeds the cuff pressure, then the doctor can hearsome crashing , snapping sound through the stethoscope. This is known as korotkoff sound.

.


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PART-B

1. Draw the block diagram of Doppler blood flow meter and its operation (16Marks,Apr-2006)Block diagram: Ref text bookThe Doppler AngleThe ultrasound beam usually approaches the moving target at an angle called the Doppler angle Thisreduces the frequency shift in proportion to the cosine of thisangle. If this angle is known then the flow velocity can be calculated.The Doppler Equation≡ Doppler shift frequency (the difference between the transmitted and received frequencies)≡ transmitted frequency ≡ reflected frequency V ≡ velocity of the blood flow towards the transducer C ≡ velocity of sound in tissue θ ≡ the angle between the sound beam and the direction of moving bloodWhere:The Doppler angle ( ) is also known as the angle of insonation. It is estimated by the sonographer by a

process known as angle correction, which involves aligning an indicator on the duplex image along thelongitudinal axis of the vessel.There are a few considerations that affect the performance of a Doppler examination that are inherent in theDoppler equation, which are:

– The cosine of 90° is zero, so if the ultrasound beam is perpendicular to the direction of blood flow, therewill be no Doppler shift and it will appear as if there is no flow in the vessel.

– Appropriate estimation of the angle of insonation, or angle correction, is essential for the accuratedetermination of Doppler shift and blood flow velocity.

The angle of insonation should also be less than 60° at all times, since the cosine function has a steepercurve above this angle, and errors in angle correction will be magnified.The simplest Doppler devices use continuous wave (CW Doppler), rather than the pulsed wave used inmore complex devices. CW Doppler uses two transducers (or a dual element transducer) that transmit andreceive ultrasound continuously. The transmit and receive beams overlap in a Doppler sample volumesome distance from the transducer face, as shown in the diagram below.


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volume) is the region of transmitting and receiving beam overlap (shaded region). Because there iscontinuous transducer transmission and reception, echoes from all depths within the area arrive at thetransducer simultaneously.So although CW Doppler can determine the direction of flow, it cannot discriminate the different depthswhere the motion originates. The usefulness of CW Doppler devices is limited, but they are used clinicallyto confirm blood flow in superficial vessels, as they are good at detecting low velocities. As they are easily

portable, this can be done at the bedside or in the operating room. Most other clinical applicationsrequire pulsed wave Doppler.Pulsed Wave Doppler (PW Doppler)Pulsed wave Doppler (PW Doppler) uses a single-element transducer that emits brief

pulses of ultrasound energy. The time interval between transmitting and then receiving the echoing soundcan be used to calculate the depth from where the echo arises.

The Doppler sample volume can be chosen as to shape, depth, and position in sampling the flow data. Forexample, the depth is chosen by processing only the signals that return to the transducer in a stipulatedtime. For this technique, the ultrasound system transmits a short pulse. The eceiver is opened to detect thereturning echoes only after a controlled delay, and only for a specific duration. This time-based gating ofthe receiving channel allows the definition of a fixed easuring distance which is often referred to as theSample volume or Doppler gate.

Then the next ultrasound wave is transmitted. The number of pulses transmitted by the system within asecond is referred to as the pulse repetition frequency (PRF). The upper PRF limit is given by the timeinterval required for the echoes to arrive from a sample volume located at a certain depth. The greater thesample-volume depth, the longer the time before the echoes are returned, and the longer the delay between

pulse transmission. The greater the sample volume depth, the lower will be the maximum PRF setting.Errors in the accuracy of the information arise if the velocities exceed a certain speed. The highest velocityaccurately measured is called the Nyquist limit. Beyond this limit, the errors that occur are referred to asaliasing .


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2.What is Pneumotachograph? Give its important pulmonary function analysis. (16Marks,Nov-2005)

VentilationDistributionDiffusionLung volumes and capacitiesSpirometer

3. Explain the measurement techniques for cardiac output. (16Marks,Apr-2008)

Cardiac Output Defn: vol of blood pumped by the heart per min CO = SV x HR Norm ~ 5 l/min Cardiac index – corrected for body surface area Affected by :

Met. Rate – pregnancy, hyperthyroid, septic


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Preload / contractility / afterload Clinical indicators of CO imprecise Affected by anaesthetic agents used in everyday practice Provides estimate of:

whole body perfusion oxygen delivery left ventricular function

Persistently low CO assoc. with poor outcome Methods:

Fick method Dilution techniques – dye / thermal / lithium Pulse contour analysis- LiDCO & PiCCO

Oesophageal doppler TOE Transthoracic impedance plethysmography Inert gas through flow Non-invasive cardiac output measurement

Fick Principle: measure volume displacement

1st proposed 1870 ―the total uptake or release of a substance by an organ is the product of the blood flow

through that organ and the arteriovenous concentration difference of the substance‖ CO = O2 consumption (ml/min) art – mixed venous O2 conc.

(ml/l) Limited by cumbersome equipment, sampling errors, need for invasive monitoring and

steady-state haemodynamic and metabolic conditions Indicator dilution techniques―An indicator mixed into a unit volume of co nstantly flowing blood can be used to identify that volume of

blood in time, provided the indicator remains in the system between injection and measurement and mixescompletely in the blood‖

Dye dilution Inert dye – indocyanin green Injected into pulmonary artery and arterial conc. measured using a calibrated cuvette

densitometer Plot indicator dilution curve (see diagram) CO derived from area under curve


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Indicator Dilution Curve


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Cardiac Output Measurement

4 How a cuff measures blood pressure? (8Marks,Nov-2007)) For each 20 mm rise in systolic blood pressure or 10 mm rise in diastolic blood pressure over115/75:

◦ Risk of stroke increases◦ Risk of heart disease doubles◦ Risk of renal failure increases

Systolic and diastolic blood pressure : Systolic blood pressure is the highest pressure in the arteries, just after the heart beats Diastolic blood pressure is the lowest pressure in the arteries, just before the heart beats Blood pressure is measured indirectly by blood pressure cuff (sphygmomanometer)


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Inflating cuff increases pressure until it cuts off arterial circulation to the arm Deflating cuff, decrease pressure by 2 to 3 mm of mercury per second until blood first enters the

artery, creating turbulence; this causes a sound with each heartbeat Sounds continue with each heartbeat until pressure lowers to the lowest pressure in the artery; then

turbulence stops, so the sound stops Systolic blood pressure is the cuff pressure at the first sounds; diastolic is the cuff pressure just

before the sounds stop Phase 1: sharp thuds, start at systolic blood pressure Phase 2: blowing sound; may disappear entirely (the auscultatory gap ) Phase 3: crisp thud, a bit quieter than phase 1

Phase 4: sounds become muffled Phase 5: end of sounds -- ends at diastolic blood pressure

5. Explain how the various physiological parameters listed below could be measure. (16Marks,Nov-2007)

i) To measure the B.P (any technique)ii) To measure respiratory measurement

Make sure the cuff is the right size - its width should be at least 40% of the arm's circumference.The cuff will overestimate blood pressure if too small and underestimate if too large.


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Place the cuff snugly on patient's proximal arm, on skin ( not cloth), centered over the brachialartery (most cuffs have markings)

Support the patient's arm at heart level, using your arm or a desk Your patient should sit in the chair for 5 minutes before BP is measured, and should have no

caffeine or nicotine for 30 minutes before (JAMA 273, p.1211-1218, 1995) With fingers palpating radial or brachial artery, inflate cuff rapidly until you can't feel the pulse,

then 20 mm higher Release cuff at 2 to 3 mm Hg per second until you again feel the pulse; this is the palpable systolic

pressure Wait 30 seconds before measuring blood pressure Measuring palpable pressure first avoids risk of seriously underestimating blood pressure because

of the auscultatory gap (mistaking Korotkoff phase 3 for phase 1). Many doctors skip this step for

time reasons and instead pump cuff to 200 mm Hg at the next step) Phase 2 of the Korotkoff sounds can be inaudible - especially in older patients with systolichypertension, who are at especially high risk of stroke. Inflating the cuff until you don't hear soundscan give you a reading of 140/86 when the patient's actual blood pressure is 220/86. Most

physicians are pressed for time, so they instead inflate the cuff to 200 mm, which is beyond theauscultatory gap in most patients. But palpable systolic blood pressure is, according to research,more reliable.

Place bell of stethoscope (diaphragm is acceptable) over brachial artery Rapidly pump the cuff to 20 to 30 mm Hg above palpable systolic pressure Release pressure in the cuff by 2 to 3 mm Hg per second and listen for Korotkoff sounds, including

systolic (first) and diastolic (last) Record as systolic/diastolic. Check in both arms the first time you check a patient's blood pressure.

It may differ by 10 mm Hg or more.

If the sounds continues to zero, record diastolic blood pressure as the point when sounds becomemuffled (phase 4) over zero: e.g. 130/70/0, or just as 130/70.

Rate – Number of beats in 30 seconds x 2

Strength – Bounding, strong, or weak (thready)

Regularity – Regular or irregular

You need three readings on two occasions to diagnose hypertension, unless blood pressure is veryhigh


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Normal blood pressure in children is: – 102/55 at 1 year, 112/69 at 5 years, 119/78 at 10 years

Blood pressures in adults (JNC VII: JAMA 289:2560-72, 2003): – Normal: 100

Adult: 60 to 100 Newborn: 120-170 1 year: 80-160 3 years: 80-120 6 years: 75-115

10 years: 70-110

Respiration Method: How to measure: observe rise and fall of chest In infants, count for 60 seconds; in adults, 15 or 30 seconds Normal respiration: Adults: 12 to 20 Children:

newborn 30-80 1 year 20-40 3 years 20-30 6 years 16-22

Rate Number of breaths in 30 seconds x 2

Quality Character of breathing

Rhythm Regular or irregular

Effort Normal or labored

Noisy respiration Normal, stridor, wheezing, snoring, gurgling


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Depth Shallow or deep

6.Explain the method for measuring blood pCO 2 . Draw a neat sketch of pCO 2 electrode(8Marks,Apr-2008))

pH electrode

Governing equation is the Nernst Equation

pCO2 ElectrodeThe measurement of pCO2 is based on its linear relationship with pH over the range of 10 to 90 mm Hg.

The dissociation constant is given by

Taking logarithms pH = log[HCO3-] – log k – log a – log pCO2

E RT nF H H H i

ln 0

H O CO H CO H HCO2 2 2 3 3

k

H HCO

a pCO

3

2


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7. Explain in detail about Autoanalyzer with neat diagram (8 Marks, Apr-2008)The autoanalyzer is sequentially measures blood chemistry and displays this on a graphic readoutThis is accomplished by

– Mixing – reagent – Reaction – Colorimetric measurement in continuous streamElements of Autoanalyzer:SamplerProportioning pump and manifold DialyzerHeating bath Colorimeter Record

Fig: Auto analyzer

diagram


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Sampler:Aspirates samples, standards, and wash solutions to the autoanalyzer system..Proportioning pumpIntroduces samples with reagents to e ffect the proper chemical color reaction to be read by thecolorimeter.

Pumps fluids at precise flow rates to other modules, as proper color development depends on reaction timeand temperature

8.With neat sketches explain the working of electromagnetic blood flow meter. (16Marks,Apr-2007)

Diagram:


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Electromagnetic Flow Meter:

An Electromagnetic Flow Meter is a device capable of measuring the mass flow of a fluid. Unlike thecommon flow meter you can find on the market it has no moving parts, and for this reason it can be madeto withstand any pressure (without leakage) and any fluid (corrosive and non corrosive).This kind of flow meter use a magnet and two electrodes to peek the voltage that appear across the fluidmoving in the magnetic field.

The Neumann Law (or Lenz Law) states that if a conductive wire is moving at right angle through amagnetic field, a voltage E [Volts] will appear at the end of the conductor (Fig.1):

E=B*L*V

whereB = Magnetic Induction [Weber/m2]L = Length of the portion of the wire 'wetted' by the magnetic field [m]V = Velocity of the wire [m/sec]


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Now imagine you have a plastic tube with two electrodes on the diameter and Mercury flowing into it(fig.2). A voltage will appear on the electrodes and it will be

E=B*L*V

as in the previous example ( L in this case is the inner diameter of the tube).

Mercury as tiny conductive wires next to each other : each wire, moving in the tube, will touch the twoelectrodes ,and thus you can measure their voltage.


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An interesting fact is that if you reverse the flow, you still get a voltage but with reverse polarity (Fig.1).Till now we have talked about a conductive fluid ,Mercury, but this stuff will also work with nonconductive fluid ,provided that you use an alternating magnetic field.Two physicists, Mittlemann and Cushing, in an unpublished work, stated that when using a non conductivefluid, if the frequency of the alternating magnetic field is v the voltage at the electrodes will be attenuated

by a factor a so that:

E=B*L*V* a

were:

ï = Relative Permittivity [Adimensional]

ïo = Permittivity of Free Space [Farads / m]

s = Electrical Conductivity [MV / m]

v = Frequency [1 / sec]ï and s depends on the substance used and can be found on a good chemistry book. ïo is a constant = 8.86E-12 [Farads / m].If an alternating magnetic field is used, an alternating voltage will appear on the electrodes and itsamplitude will be E. That is, the output is an amplitude modulated wave.

Measuring the flow:

Measuring the flow present some difficulties.

A perfect axisimmetric construction cannot be achieved and thus some magnetic flux lines will 'wet' theconnecting wires to the electrodes. The alternating magnetic field will create an offset voltage in this wiresand even if the fluid is not moving, the measured voltage will not be zero.


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If you plan to use the flow meter with a volt-meter you'll need to build a 'compensator circuit' to zero thevoltage when the mass flow is zero, unless you want to calculate the difference between the measuredvoltage and the offset voltage every time.

Fig.3 shows the typical output of an E.F.M.


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UNIT – III

ASSIST DEVICES AND BIO – TELEMETRY

Cardiac pacemakers – DC defibrillator – Telemetry principles – Frequency selection – Bio-telemetry – Radio – Pill and tele-stimulation

PART-A(2Marks)

1. Define circulatory system

it is a type of transport system. It helps in supplying the oxygen and digested foodto different parts of our body and removing CO2 from the blood. The heart is the centerof the circulatory system.

2.Define heart, lung?

Heart is a pumping organ which eats regularly and continuously for years. It

beats seventy times a minute at rest. Contraction is systole and relaxation is diastole.

3.Define circulation and respiration?

We can define from the engineering point of view, the circulation is a high resistance circuit with alarge pressure.


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4. Classify the pacemakers

Fixed rate pacemakers.

Ventricular Synchronous pacemakers

Demand pacemakers

Atrial Synchronous pacemakers

5. Different methods of stimulation

External stimulation,Internal stimulation

6.What is a Defibrillator?

A defibrillator is an electronic device that creates a sustained myocardial depolarization of a patient s heartin order to stop ventricular fibrillation or artial

fibrillation.

7.What are the characteristics of a DC amplifier?

It may need balanced differential inputs giving a high common mode rejection ratio (CMRR).

It should have an extremely good thermal and long term stability.

8. Enumerate the merits and demerits of a dc amplifier?

It is easy to calibrate at low frequencies.

It is able to recover from an overload condition unlike it ’s AC counterpart.


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9.Give the purpose of bridge circuits. What are the different types?

The bridge circuits are used in instrumentation systems for the measurement of resistance , inductance andcapacitance.

Types:

DC type and

AC type.

10.What are the 2 types of wheatstone bridge?

Null type bridge

Deflection type bridge.

11What are the different types of AC bridges?

AC bridge using push-pull transducers

AC bridge with push-pull inductive transducers

Inductive transducer Blumlein Bridge

Capacitive transducer Blumlein Bridge

12.Define slew rate

Slew rate is defined as the maximum output voltage change per unit time.


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13.List the requirements of an instrumentation amplifier

Low drift

High i/p impedance

High linearity

High CMRR

High noise rejection capability

14.Give few applications of instrumentation amplifier.

The instrumentation amplifier finds increasing application in the amplification of the output signalsobtained from thermocouples, strain gauge bridge and biological electrode.

15.What is a filter?

A filter is often a frequency selective circuit that passes a specified band of frequencies and blocks orattenuated signal of frequencies outside this band.

49.List the different types of filters.

Analog or digital filters

Passive or active filters

Audio (AF) or radio (RF) filters.


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16.Specify the advantages of an active filter

Gain and frequency adjustment flexibility

No loading problem

Low cost

17.What is frequency scaling?

The procedure of converting a cutoff frequency to a new cutoff frequency is called frequency scaling.

18.What is quality factor?

The ratio of resonant frequency to bandwidth is known as the quality factor Q.

19.What is acquisition time of S/H circuit?

Acquisition time is the time required for the capacitor to charge up to the value of the input voltage afterthe switch is first started.

20.What is aperture time of S/H circuit?

The aperture time is the time required for the switch to change from ON state to OFF state.


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PART-B

1.Differentiate two types of pacemakers(8Marks,Apr,2007)

External ImplantedIs placed outside the body. It may be in theform of wrist watch or in the pocket, from thatone terminal will go in the heart through thevein.

Is a surgically implanted when if the skin nearthe chest or abdomen, with its output’s leads areconnected directly to the heart muscle.

Endocardiac electrodes are applied to the heart.They are in contact with the inner surface of theheart chamber.

Myocardiac electrodes are in contact with theouter wall of the myocardium (heart muscle)

It does not require open chest surgery It requires open chest minor surgery to the placethe pacemaker

Battery can be easily replaced and any defectcan be easily attended without the help fromdoctor

Battery can be replaced by only minor surgeryand doctor’s help is needed to rectify thedefects.

During the placement of pacemaker swellingand pain do not arise to minimum foreign bodyreaction.

During placement only by minor surgery anddoctor’s help is needed to rectify the defects.

There is no safety for the pacemaker ,Particularly in the case of child carrying the

pacemaker.

There is 100% safety for the circuit from theexternal disturbances.

The external pacemaker are used for temporaryheat regularity

Are used for permanent heart regularity.


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2.What is DC Defibrillator? Explain D.C defibrillator with neat diagram.(16Marks, Apr-2008)

Defibrillation:Defibrillation is the definitive treatment for the life-threatening cardiac arrhythmias ventricular fibrillation and pulseless ventricular tachycardiaVentricular fibrillation results from:

¾ Coronary occlusion

¾ Electrical shock

¾ Abnormalities of body chemistry

This irregular contraction of the muscle fibers causes non effectively blood pumping and thatresults in a steep fall of cardiac output

Ventricular fibrillation can be converted into a mor efficient rhythm by applying high energy shock to theheart. This causes all muscle fibers to contract simultaneously, which may then respond to normal

physiological pacemaking pulses Restoration of normal rhythm in fibril as achieved by direct currentshock (arrow) across the chest wall horizontal line after the shock shows that the cardiograph was blockedor disconnected for its protection during the period of shock

Restoration of normal rhythm in fibril as achieved by direct current shock (arrow) across the chestwall.horizontal line after the shock shows that the cardiograph was blocked or disconnected for its

protection during the period of shock


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Defibrillator

Defibrillator is a device that deliver a therapeutic dose of electrical energy (electric shock) to the affectedheart (fibrillated heart or other shockable rhythm) to force the heart to produce more normal cardiacrhythm

The shock can be delivered by means electrodes placed on the chest of the patient (external defibrillation)or the electrodes may be held directly against the heart when the chest is open (internal defibrillation).

Higher voltage are required for external defibrillation than internal defibrillation

DC Defibrillator:

An energy storage capacitor is charged at a relatively slow rate from:¾ The AC line by means of a step-up transformer and rectifier arrangement or.¾ A battery and DC to DC converter arrangement

During defibrillation the energy stored in the capacitor is then delivered (Discharged) at a relativelyrapid rate (in order of milliseconds) to the chest of subject through the patient’s own resistance

Energy level of defibrillators is from 2 to 400 Joules (J) (depends on the size of the patient and skin resistance)

Required voltage in the range of 1000 to 6000 V (depend on the duration of the DC pulse) Current range is from 1 to 20 A

A variable auto-transformer T 1 forms the primary of A high

voltage transformer T 2 Rectifying the output of the transformer by a diode D (half wave rectification)

High voltage change-over switch 1, 2 (vacuum type) Oil-filed 16

micro-farad [ μF] capacitor C

L current limiting inductor to protect the patient (disadvantage: own resistance → dissipation of a part of

energy during the discharge process, The voltmeter AC is to indicate the energy stored in C


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DC Defibrillator diagram:

Energy level of a defibrillator can be controlling:

The voltage amplitude V P of the defibrillator by varying the setting on the varactor or ¾ Duration of the defibrillator pulse

The energy ( W A) stored in the capacitor C and available for the defibrillation is:


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Lown waveform: Curve 1 shows a typical discharge pulse of defibrillator which called ―Lown‖waveform.

¾ I rises rapidly to app. 20 A¾ Then I decays to 0 with 5 ms

¾ A negative pulse is produced for 1 to 2 ms¾ The pulse width defined as the time that elapses between the start of the impulse and the moment

that the current intensity passes the zero line for the first time and changes direction (5 ms or 2.5 ms)


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3.Explain the operation of external defibrillator with diagram(8 Marks, Apr-2009)

External Defibrillator:

A unit based on computer technology and designed to analyze the heart rhythm itself, and then advisewhether a shock is required.

It is designed to be used by lay persons, who require li ttle training.

It is usually limited in their interventions to delivering high joule shocks for VF and VT rhythms

The automatic units also take time (generally 10-20 seconds) to diagnose the rhythm, where a professionalcould diagnose and treat the condition far quicker with a manual unit

Automated external defibrillators are generally either held by trained personnel who will attend incidents,or are public access units which can be found in places including corporate and government offices,shopping centers, airports, restaurants ,

AED S require self-adhesive electrodes instead of hand-held paddles for the two following reasons:¾ The ECG signal acquired from self-adhesive electrodes usually contains less noise and has higher

quality ⇒ allows faster and more accurate analysis of the ECG ⇒ better shock decisions¾ ―Hands off‖ defibrillation is a safer procedure for the operator, especially if the operator

has little or no training


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4.What is telemetry?Mention the application of telemetry(8Marks,Apr-2007)

This article has multiple issues. Please help improve it or discuss these issues on the talk page .

It needs additional references or sources for verification. Tagged since January 2009. It may require general cleanup to meet Wikipedia's quality standards. Tagged since January 2009. It is incomplete and may require expansion or cleanup. Tagged since January 2009.

Telemetry is a technology that allows remote measurement and reporting of information. The word isderived from Greek roots tele = remote, and metron = measure. Systems that need external instructions anddata to operate require the counterpart of telemetry, telecommand.

Although the term commonly refers to wireless data transfer mechanisms (e.g. using radio or infraredsystems), it also encompasses data transferred over other media, such as a telephone or computer network,optical link or other wired communications. Many modern telemetry systems take advantage of the lowcost and ubiquity of GSM networks by using SMS to receive and transmit telemetry data.

Appl ica t ions

Motor racing

Telemetry is a key factor in modern motor racing, allowing race engineers to interpret the vast amount ofdata collected during a test or race, and use that to properly tune the car for optimum performance. Systemsused in some series, namely Formula One, have become advanced to the point where the potential lap timeof the car can be calculated and this is what the driver is expected to meet. Some examples of usefulmeasurements on a race car include accelerations (G forces) in 3 axis, temperature readings, wheel speed,and the displacement of the suspension. In Formula 1, the driver inputs are also recorded so that the teamcan assess driver performance and, in the case of an accident, the FIA can determine or rule out driver erroras a possible cause.

Later developments saw two way telemetry, that allowed the engineers the ability to update calibrations onthe car in real time, possibly while it is out on the track. In Formula 1, two-way telemetry surfaced in theearly nineties from TAG electronics, and consisted of a message display on the dashboard which the teamcould update. Its development continued until May 2001, at which point it was first allowed on the cars. By

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2002 the teams were able to change engine mapping and deactivate particular engine sensors from the pitswhile the car was on track. [citation needed ] For the 2003 season, the FIA banned two-way telemetry fromFormula 1, [citation needed ] however the technology still exists and could eventually find its way into otherforms of racing or road cars.

In addition to that telemetry has also been applied to the use of Yacht racing. [clarification needed For what purpose? Bywhom? ] The technology was applied to the Oracle's USA-76. [citation needed ]

Agriculture

Most activities related to healthy crops and good yields depend on timely availability of weather and soildata. Therefore, wireless weather stations play a major role in disease prevention and precision irrigation.

These stations transmit major parameters needed for good decisions to a base station: air temperature andrelative humidity, precipitation and leaf wetness (for disease prediction models), solar radiation and windspeed (to calculate evapotranspiration) , water deficit stress (WDS) leaf sensors and soil moisture, crucial tounderstand the progress of water into soil and roots for irrigation decisions.

Because local micro-climates can vary significantly, such data needs to come from right within the crop.Monitoring stations usually transmit data back by terrestrial radio though occasionally satellite systems areused. Solar power is often employed to make the station independent from local infrastructure.

] Water management

Telemetry has become indispensable for water management applications, including water quality andstream gauging functions. Major applications include AMR (automatic meter reading) , groundwatermonitoring, leak detection in distribution pipelines and equipment surveillance. Having data available inalmost real time allows quick reactions to occurrences in the field.

Defense, space and resource exploration systems

Telemetry is an enabling technology for large complex systems such as missiles, RPVs, spacecraft, oil rigsand chemical plants because it allows automatic monitoring, alerting, and record-keeping necessary forsafe, efficient operations. Space agencies such as NASA, ESA, and other agencies usetelemetry/telecommand systems to collect data from operating spacecraft and satellites.

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Telemetry is vital in the development phase of missiles, satellites and aircraft because the system might bedestroyed after/during the test. Engineers need critical system parameters to analyze (and improve) the

performance of the system. Without telemetry, these data would often be unavailable.

Rocketry

In rocketry, telemetry equipment forms an integral part of the rocket range assets used to monitor the progress of a rocket launch. Some special problems are the extreme environment (temperature,accelerations, vibrations...), the energy supply, the precise alignment of the antenna and (at long distances,e.g. in spaceflight) the signal travel time.

Flight test

Flight test programs typically telemeter data collected from on-board flight test instrumentation over aPCM /RF link .[4] This data is analyzed in real-time for safety reasons and to provide feedback to the test

pilot. Particular challenges for telemetering this data includes fading, multipath propagation and theDoppler effect. The bandwidth of the telemetry link is often insufficient to transfer all the data acquiredand therefore only a limited set is sent to the ground for real-time processing while an on-board recorderensures the full dataset is available for post flight analysis.

Enemy intelligence

Telemetry was a vital source of intelligence for the US and UK when Soviet missiles were tested. For this purpose, the US operated a listening post in Iran. Eventually, the Russians discovered this kind of USintelligence gathering and encrypted their telemetry signals of missile tests. Telemetry was a vital sourcefor the Soviets who would operate listening ships in Cardigan Bay to eavesdrop on the UK missile testscarried out there.

Energy monitoring

In factories, buildings, and houses, energy consumption of systems such as HVAC are monitored atmultiple locations, together with the related parameters (e.g. temperature) via wireless telemetry to onecentral location. The information is collected and processed enabling intelligent decisions regarding themost efficient use of energy to be implemented. Such systems also facilitate predictive maintenance.

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Resource distribution

Many resources need to be distributed over wide areas. Telemetry is essential in these cases, since it allowsthe system to channel resources to where they are needed.

Medicine

Telemetry also is used for patients (biotelemetry) who are at risk of abnormal heart activity, generally in acoronary care unit. Such patients are outfitted with measuring, recording and transmitting devices. A datalog can be useful in diagnosis of the patient's condition by doctors. An alerting function can alert nurses ifthe patient is suffering from an acute or dangerous condition.

Also a system that is available in medical-surgical nursing to monitor a condition where heart conditionmay be ruled out. Or to monitor a response to antiarrhythmic medications such as Digoxin.

Fisheries and wildlife research and management

Common Seal with a transceiver on its back

Telemetry is now being used to study wildlife, and has been particularly useful for monitoring threatenedspecies at the individual level. Animals under study may be fitted with instrumentation ranging fromsimple tags to cameras, GPS packages and transceivers to provide position and other basic information toscientists and stewards.

Telemetry is used in hydroacoustic assessments for fish which have traditionally employed mobile surveysfrom boats to evaluate fish biomass and spatial distributions. Conversely, fixed-location techniques use

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stationary transducers to monitor passing fish. While the first serious attempts to quantify fish biomasswere conducted in the 1960s, major advances in equipment and techniques took place at hydropower damsin the 1980s. Some evaluations monitored fish passage 24 hours a day for over a year, producing estimatesof fish entrainment rates, fish sizes, and spatial and temporal distributions.

In the 1970s, the dual-beam technique was invented, permitting direct estimation of fish size in-situ via itstarget strength. The first portable split-beam hydroacoustic system was developed by HTI in 1991, and

provided more accurate and less variable estimates of fish target strength than the dual-beam method. Italso permitted tracking of fish in 3D, giving each fish’s swimming path and absolute direction ofmovement. This feature proved important for evaluations of entrained fish in water diversions as well asfor studies of migratory fish in rivers. In the last 35 years, tens of thousands of mobile and fixed-locationhydroacoustic evaluations have been conducted worldwide.

[edit] Retail businesses

At a 2005 workshop in Las Vegas, a seminar noted the introduction of telemetry equipment that wouldallow vending machines to communicate sales and inventory data to a route truck or to a headquarters [citationneeded ]. This data could be used for a variety of purposes, such as eliminating the need for the driver to makea first trip to see what items need to be restocked before bringing the inventory inside.

Retailers are also beginning to make use of RFID tags to track inventory and prevent shoplifting. Most ofthese tags passively respond to RFID readers (e.g. at the cashier), but active RFID tags are available that

periodically transmit telemetry to a base station.

Law enforcement

Telemetry hardware is useful for tracking persons and property in law enforcement. An ankle collar worn by convicts on probation can warn authorities if a person violates the terms of his or her parole, such as bystraying from authorized boundaries or visiting an unauthorized location. Telemetry equipment has alsogiven rise to the concept of bait cars, where law enforcement can rig a car with cameras and trackingequipment and leave it somewhere they expect it to be stolen. When stolen, the telemetry equipmentreports the location of the vehicle, and gives law enforcement the ability to deactivate the engine and lockthe doors once it is stopped by responding officers.

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Electrical energy providers

In some countries telemetry is used to assess the amount of electrical energy users have consumed. Theelectricity meter communicates with a concentrator and the latter sends that information through GPRS orGSM to the electrical energy provider's server.

Falconry

In falconry, "telemetry" means a small radio transmitter carried by a falconry bird to let the bird's ownertrack it when it is out of sight.

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UNIT-IV

RADIOLOGICAL EQUIPMENTS

Ionosing radiation – Diagnostic X-ray equipments – Use of radio isotope in diagnosis – Radiation therapy.

PART-A(2Marks)

1.List the important features of CRT.

Size

Phosphor

Operating voltages

Deflection voltages

Viewing screen .

2.What is meant by deflection sensitivity in CRT?

The deflection sensitivity of the CRT is usually stated as the DC voltage

required for each cm of deflection of the spot on the screen.

3.What is meant by recurrent sweep in CRT?

When the saw tooth, being an AC voltage alternates rapidly, the display

occurs respectively, so that a lasting image is seen by the eye. This repeated

operation is known as recurrent sweep.

4.Mention the methods that are used for generating the 2 electron beams

within the CRT.

The methods that are used for generating the 2 electron beams within the

CRT are the double gun tube and split beam method.

5.Explain CRO and its function.

Cathode Ray Oscilloscope (CRO) is a very careful and versatile laboratory

instrument used for display measurement and analysis of waveforms and other

phenomena in electrical and electronic circuits. CRO is in fact a very fast X-Y


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plotter displaying an input signal versus another signal or time.

6.Name the components of a CRO.

CRO consists of a cathode ray tube (CRT) along with electron gun

assembly, deflection plate assembly, fluorescent screen, glass envelope and base.

7.What is an electron gun?

The source of focused and accelerated electron beam is the electron gun.

The electron gun which emits electrons and forms them into a beam consists of a

heater, a cathode, a grid a pre-accelerating anode, a focusing anode and an

accelerating anode.

8.Name the basic circuitry of CRO.

Vertical (Y) deflection system

Horizontal (X) deflection system

Synchronization

Blanking circuit

Intensity (z-axis) modulation

Positioning controls

Focus control

Intensity control

Calibration control

9.Write notes on LVDT

It is the linear variable differential transformer which is used to translate the linear motion intoelectrical signals. It consists of a single primary winding and 2 secondary winding.

95.List the advantages of LVDT

High range of displacement measurement

Friction & electrical isolation

Immunity from external effects


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High I/p and high sensitivity

Ruggedness

Low hysterisis & low power consumption.

10.What is a digitizer?

It is a digital encoding transducer that enables a linear or rotary displacement to be directlyconverted into digital form without intermediate forms of analog to digital (A/D) conversion.

Heart is a pumping organ which eats regularly and continuously for years. It

beats seventy times a minute at rest. Contraction is systole and relaxation is diastole.

11.Define circulation and respiration?

We can define from the engineering point of view, the circulation is a high resistance circuit with alarge pressure gradient between the arteries and veins

The exchange of any gases in any biological process is termed as respiration

12.What is mean by transducer?

It is a device which detects or senses the bio signal and converts it in to an electrical signal for biosignal processing

13.Define strain gauge?

It is a electrical device which is used to measure stress or pressure in terms of strain using the principle of change of resistively due to mechanical stress

14.How are transducer are classified?

They can be classified into different types based on the energy conversion, application and so on.They are two types

Active transducer : A transducer that gives its output without the use of an

15.What are applications of X-ray?1.To visible skeletal structures2.TO take chest radiograph3.o identify lung tumors4.Gastroimtestinal tract and urinary tract can be examined .

16.Define macro shock.A physiological response to a current applied to the surface of the body that produces unwantedstimulation like tissue injury or muscle contraction is called macro shock.


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17.Define micro shockA physiological response to a current applied to the surface of the heart that results in unnecessarystimulation like muscle contraction or tissue injury

18.What are the devices used to protect against electrical hazards ?1.Ground fault interrupter

2.Isolation transformer

19. What are advantages of laser surgery? High sterile Highly localized and precise Non contact and bloodless surgery Short period of surgical time and painless surgery

20.Name the types of lasers used in medicine Pulsed Nd-YaG laser Continuous wave CO2 laser

Continuous wave organ ion laser

PART-B

1.What is Fluoroscopy? Explain (8Marks,Apr-2009)

Fluoroscopy

Fluoroscopy is the method that provides real-time X ray imaging that is especially useful forguiding a variety of diagnostic and interventional procedures.

The ability of fluoroscopy to display motion is provided by a continuous series of images produced at a maximum rate of 25-30 complete images per second. This is similar to the wayconventional television or video transmits images.

While the X ray exposure needed to produce one fluoroscopic image is low (compared toradiography), high exposures to patients can result from the large series of images that areencountered in fluoroscopic procedures. Therefore, the total fluoroscopic time is one of the majorfactors that determines the exposure to the patient from fluoroscopy.


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Because the X ray beam is usually moved over different areas of the body during a procedure,there are two very different aspects that must be considered. One is the area most exposed by the

beam, which results in the highest absorbed dose to that specific part of the skin and to specificorgans.

The other is the total radiation energy imparted to the patient’s body, which is related to theKerma Area Product (KAP or P AK ), a quantity that is easily measurable.

The absorbed dose to a specific part of the skin and other tissues is of concern in fluoroscopy fortwo reasons: one is the need for minimizing the dose to sensitive organs, such as the gonads and

breast, by careful positioning of the X ray beam and using shielding when appropriate.

The second is the possible incidence of the radiation beam to an area of the skin for a long timethat can result in radiation injuries in cases of very high exposure.

On the other hand, the total radiation energy imparted to the patient’s body duri ng a procedure isclosely related to the effective dose ) and to the risk of radiation induced cancer.

In fluoroscopy, as in all types of X ray imaging, the minimum exposure required to form an imagedepends on the specific image information requirements.An important characteristic of afluoroscopic system is its sensitivity, i.e. the amount of exposure required to produce images.

The use of intensifier tubes and more modern digital flat panel receptors make it possible tooptimize the balance of patient exposure with image quality so as not to expose the patient tounnecessary radiation.

Non-intensified fluoroscopy with just a fluorescent screen for a receptor should not be used because of the excessive exposure to the patient.

2.What is radioisotopes? Explain its use in medical diagnosis. (16Marks, Apr-2007)

Nuclear medicine uses radiation to provide diagnostic information about the functioning ofa person's specific organs, or to treat them. Diagnostic procedures are now routine.

Radiotherapy can be used to treat some medical conditions, especially cancer, usingradiation to weaken or destroy particular targeted cells.

Tens of millions of nuclear medicine procedures are performed each year, and demand forradioisotopes is increasing rapidly.

Radiation is used to both detect and treat abnormalities in the body. We've already discussed the

use of iodine-131 therapy for hyperthyroidism. Iodine-131 can also be used in a diagnostic procedure to monitor the function of the thyroid. The rate at which the thyroid rakes up the iodine-131 can be monitored with a scanning device to see if it is functioning properly.

What makes radioisotopes so useful in diagnostic procedures is that the body treats the taggedisotope in the same way that it treats the nonradioactive element. Therefore, the tagged isotopegoes right to the area of the body where you want it to go. For example, iodine, whether it'sradioactive or not, goes right to the thyroid, where it is incorporated into the amino acid thyroxine(the only molecule in the body that contains iodine). Therefore, iodine-131 is perfect formonitoring the thyroid gland.


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Chromium, in the form of sodium chromate, attaches strongly to the hemoglobin of red bloodcells. This makes radioactive chromium-151 an excellent isotope for determining the flow of

blood through the heart. This isotope is also useful for determining the lifetime of red blood cells,which can be of great importance in the diagnoses of anemias.

Radioactive cobalt (cobalt-59 or cobalt-60) is used to study defects in vitamin B 12 absorption.Cobalt is the metallic atom at the center of the B 12 molecule. By injecting a patient with vitaminB12, labeled with radioactive cobalt, the physician can study the path of the vitamin through the

body and discover any irregularities.

One method is teletherapy, in which a high-energy beam of radiation is aimed at the canceroustissues. A second method is brachytherapy, in which a radioactive isotope is placed into the area to

be treated. This is usually done by means of a seed, which could be a glass bead containing theisotope. In this way the isotope delivers a constant beam of radiation to the affected area.

The third method is called radiopharmaceutical therapy. This method involves oral or intravenousadministration of the isotope. The isotope then uses the normal body pathway to seek its target.This is the method that is used to get iodine-131 to the thyroid gland.

A synthetic radioisotope is a radionuclide that is not found in nature: no natural process ormechanism exists which produces it, or it is so unstable that it decays away in a very short periodof time. Examples include technetium- 95 and promethium- 146. Many of these are found in, andharvested from, spent nuclear fuel assemblies. Some must be manufactured in particleaccelerators.

Production

Some synthetic radioisotope are extracted from spent nuclear reactor fuel rods, which containvarious fission products. For example, it is estimated that up to 1994, about 49,000 T Bq (78 metric

ton) of technetium was produced in nuclear reactors, which is by far the dominant source ofterrestrial technetium .[1] However, only a fraction of the production is used commercially. Othersynthetic isotopes are produced in significant quantities by fission but are not yet being reclaimed.Other isotopes are manufactured by neutron irradiation of parent isotopes in a nuclear reactor (forexample, Tc-97 can be made by neutron irradiation of Ru-96) or by bombarding parent isotopeswith high energy particles from a particle accelerator .[2]

Uses

Most synthetic radioisotopes are extremely radioactive and have a short half life. Though a healthhazard, radioactive materials have many medical and industrial uses.

Nuclear medicine

The general field of nuclear medicine covers any use of radioisotopes for diagnosis or treatment.

Diagnosis

Radioactive tracer compounds are used to observe the function of various organs and bodysystems. These compounds use a chemical tracer which is attracted to or concentrated by theactivity which is being studied. That chemical tracer incorporates a short lived radioactive isotope,usually one which emits a gamma ray which is energetic enough to travel through the body and be

http://en.wikipedia.org/wiki/Radionuclidehttp://en.wikipedia.org/wiki/Technetiumhttp://en.wikipedia.org/wiki/Promethiumhttp://en.wikipedia.org/wiki/Particle_acceleratorhttp://en.wikipedia.org/wiki/Particle_acceleratorhttp://en.wikipedia.org/wiki/Nuclear_reactorhttp://en.wikipedia.org/wiki/Becquerelhttp://en.wikipedia.org/wiki/Tonnehttp://en.wikipedia.org/wiki/Tonnehttp://en.wikipedia.org/wiki/Technetiumhttp://en.wikipedia.org/wiki/Synthetic_radioisotope#cite_note-0http://en.wikipedia.org/wiki/Synthetic_radioisotope#cite_note-0http://en.wikipedia.org/wiki/Synthetic_radioisotope#cite_note-0http://en.wikipedia.org/wiki/Neutronhttp://en.wikipedia.org/wiki/Synthetic_radioisotope#cite_note-1http://en.wikipedia.org/wiki/Synthetic_radioisotope#cite_note-1http://en.wikipedia.org/wiki/Synthetic_radioisotope#cite_note-1http://en.wikipedia.org/wiki/Half_lifehttp://en.wikipedia.org/wiki/Nuclear_medicinehttp://en.wikipedia.org/wiki/Gamma_rayhttp://en.wikipedia.org/wiki/Gamma_rayhttp://en.wikipedia.org/wiki/Nuclear_medicinehttp://en.wikipedia.org/wiki/Half_lifehttp://en.wikipedia.org/wiki/Synthetic_radioisotope#cite_note-1http://en.wikipedia.org/wiki/Neutronhttp://en.wikipedia.org/wiki/Synthetic_radioisotope#cite_note-0http://en.wikipedia.org/wiki/Technetiumhttp://en.wikipedia.org/wiki/Tonnehttp://en.wikipedia.org/wiki/Tonnehttp://en.wikipedia.org/wiki/Tonnehttp://en.wikipedia.org/wiki/Becquerelhttp://en.wikipedia.org/wiki/Nuclear_reactorhttp://en.wikipedia.org/wiki/Particle_acceleratorhttp://en.wikipedia.org/wiki/Particle_acceleratorhttp://en.wikipedia.org/wiki/Particle_acceleratorhttp://en.wikipedia.org/wiki/Promethiumhttp://en.wikipedia.org/wiki/Technetiumhttp://en.wikipedia.org/wiki/Radionuclide


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captured outside by a gamma camera to map the concentrations. Gamma cameras and othersimilar detectors are highly efficient, and the tracer compounds are generally very effective atconcentrating at the areas of interest, so the total amounts of radioactive material needed are verysmall.

The metastable nuclear isomer Tc-99m is a Gamma-emitter widely used

medical electronics full 2marks and 16 marks

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