Transcript UNIT 3 Biomedical - SNGCE DIGITAL LIBRARY

MEDICAL ELECTRONICS
Mr. DEEPAK P.
Associate Professor
ECE Department
SNGCE
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UNIT 3
ECG, EMG, Telemetry
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EEG
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Electroencephalography (EEG)
 Electroencephalography (EEG) is the recording of electrical
activity along the scalp.
 EEG measures voltage fluctuations resulting from ionic current
flows within the neurons of the brain.
 Electroencephalogram (EEG) was first measured in humans by
Hans Berger in 1929.
 EEG is most often used to diagnose epilepsy, which causes
abnormalities in EEG readings.
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Electroencephalography (EEG)
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Electroencephalography (EEG)
 It is also used to diagnose sleep disorders, coma, and brain
death
 Among the basic waveforms are the alpha, beta, theta, and
delta rhythms.
 Alpha waves occur at a frequency of 8 to 12 cycles per second
in a regular rhythm.
 They are present only when you are awake but have your eyes
closed.
 Usually they disappear when you open your eyes or start
mentally concentrating.
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Electroencephalography (EEG)
 Beta waves occur at a frequency of 13 to 30 cycles per second.
 They are usually associated with anxiety, depression, or the
use of sedatives.
 Theta waves occur at a frequency of 4 to 7 cycles per second.
 They are most common in children and young adults.
 Delta waves occur at a frequency of 0.5 to 3.5 cycles per
second.
 They generally occur only in young children during sleep.
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Electroencephalography (EEG)
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Electroencephalography (EEG)
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Electroencephalography (EEG)
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Evoked Potentials
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Electroencephalography (EEG)
 EEG machine consists of the following components
 1- Electrodes.
 2- Amplifiers.
 3- Filters.
 4- Recording unit.
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Analog EEG
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Digital EEG
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EEG Electrodes
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EEG Electrodes
 There are two system of electrode placement:
 1- 10-20 international system: includes 21 electrodes.
 2- 10-10 international system: includes 64 electrodes.
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EEG Electrodes
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EMG
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Electromyogram (EMG)
 Electromyography (EMG) is a technique for evaluating and
recording the electrical activity produced by skeletal muscles.
 EMG is performed using an instrument called an
electromyograph
 An Electromyograph detects the electrical potential generated
by muscle cells when these cells are electrically or
neurologically activated
 Measured EMG potentials range between less than 50 μV and
up to 20 to 30 mV, depending on the muscle under observation.
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Electromyogram (EMG)
 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.
 Body temperature can affect the results of this test.
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Electromyogram (EMG)
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Electromyogram (EMG)
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Electromyogram (EMG)
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Electromyogram (EMG)
 EMG is used clinically for the diagnosis of neurological and
neuromuscular problems.
 There are two kinds of EMG in widespread use:
1. Surface EMG
2. Intramuscular (needle and fine-wire) EMG.
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A surface electrode may be used to monitor the general
picture of muscle activation
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To perform intramuscular EMG, a needle electrode or a
needle containing two fine-wire electrodes is inserted through
the skin into the muscle tissue.
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Electromyogram (EMG)
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Electromyogram (EMG)
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Simple Block diagram (EMG)
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pre-amplifier
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Properties of an ideal pre-amplifier
 High common mode rejection ratio
 Very high input impedance
 Short distance to the signal source
 Strong DC signal suppression
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Analog EMG Block diagram
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Digital EMG Block diagram
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Digital EMG Block diagram
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Bed -Side Monitor
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Patient Monitoring
In medicine, monitoring is the observation of a disease,
condition or one or several medical parameters over time.
It can be performed by continuously measuring certain
parameters by using a medical monitor
Transmitting data from a monitor to a distant monitoring
station is known as telemetry or biotelemetry.
Vital signs (often shortened to just vitals) are used to measure
the body’s basic functions
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Patient Monitoring
Vital measurements are taken to help assess the general
physical health of a person, give clues to possible diseases.
There are four primary vital signs: body temperature, blood
pressure, pulse (heart rate), and breathing rate (respiratory
rate).
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Patient Monitoring in ICU
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Simple Block Diagram of Patient Monitoring
Automatic
control
Patient
Clinician
Transducers
equipment
Computer
Display
Reports
Mouse and
keyboard
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DBMS
Bed-Side Monitor
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Measuring Parameters
Cardiac monitoring: Electrocardiography Cardiac output
Hemodynamic blood pressure and blood flow
Respiratory monitoring: Pulse oximetry,Capnography, airway
respiratory rate)
Blood glucose monitoring
Childbirth monitoring
Body temperature monitoring
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Central Monitor
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Central Monitoring
Bedside Monitors
Physiological data
Hard wire Remote Link
From other beds
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Central Monitor Console
Central Monitoring
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Bio Telemetry
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Bio-Telemetry
 The term telemetry is derived from the two Greek terms: “tele”
and “metron”, which mean “remote” and “measure”.
 In general, a physical variable or quantity under
measurement, whether local or remote, is called a measurand.
 Telemetry is a technology that allows the remote
measurement and reporting of information of interest to the
system designer or operator.
 Literally, biotelemetry is the measurement of biological
parameters over a distance.
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Elements of Telemetry
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Elements of Telemetry
Transducer or Sensor:
• Converts the physical variable to be telemetered into an
electrical quantity.
2. Signal Conditioner-1:
• Converts the electrical output of the transducer (or sensor)
into an electrical signal compatible with the transmitter.
3. Transmitter:
• Its purpose is to transmit the information signal coming
from the signal conditioner-1 using a suitable carrier signal to
the receiving end.
1.
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Elements of Telemetry
 The transmitter may perform one or more of the following
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functions:
(i) Modulation: Modulation of a carrier signal by the
information signal.
(ii) Amplification: As and if required for the purpose of
transmission.
(iii) Signal Conversion: As and if required for the purpose of
transmission.
(iv) Multiplexing: If more than one physical variables need to
be telemetered simultaneously from the same location, then
either frequency-division multiplexing (FDM) or time-division
multiplexing (TDM) is used.
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Elements of Telemetry
 Receiver: Its purpose is to receive the signal(s) coming from
the transmitter (located at the sending end of the telemetry
system) via the signal transmission medium and recover the
information from the same.
 It may perform one or more of the following functions:
Amplification
2. Demodulation:
3. Reverse Signal Conversion
4. De-multiplexing
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Elements of Telemetry
 Signal Conditioner-2: Processes the receiver output as
necessary to make it suitable to drive the given end device.
 End Device: The element is so called because it appears at the
end of the system.
 End device may be performing one of the following
functions:
1. Analog Indication:
2. Digital Display
3. Digital Storage
4. Data Processing
5. Closed-Loop Control
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Subsystems of Telemetry System
 (a) Measurement Subsystem:
 It comprises the transducer (or sensor), signal
conditioner and the end device, like any conventional
measurement system.
 (b) Communication Subsystem:
 It comprises the transmitter and receiver along with the
transmission medium linking the two, like any
communication system.
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Telemetry Classification Based on Transmission
Medium
Wire-Link Telemetry or Wire Telemetry
2. Radio Telemetry or Wireless Telemetry
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Wired Telemetry
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Elements of Wired Bio-Telemetry(Analog)
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Elements of Wired Bio-Telemetry(Digital)
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Elements of Wired Bio-Telemetry
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Elements of Wireless Bio-Telemetry
 A typical biotelemetry system comprises:
Sensors appropriate for the particular signals to be
monitored
2. Battery-powered, Patient worn transmitters
3. A Radio Antenna and Receiver
4. A display unit capable of concurrently presenting
information from multiple patients
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It is two types
1. Short-Range Radio Telemetry
2. Satellite-Radio Telemetry
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Elements of Basic Wireless Bio-Telemetry
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Elements of Wireless Bio-Telemetry
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Wireless Bio-telemetry Transmitter
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Wireless Bio-telemetry Receiver
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Elements of Wireless Bio-Telemetry
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Telemetry Classification Based on Modulation Method
DC Telemetry Systems
 1. Direct voltage telemetry system
 2. Direct current telemetry system
AC Telemetry Systems
 1. Amplitude modulation (AM) telemetry system
 2. Frequency modulation (FM) telemetry system
 Pulse Telemetry Systems
 1. Pulse amplitude modulation (PAM) telemetry system
 2. Pulse width modulation (PWM) telemetry system
 3. Pulse phase modulation (PPM) telemetry system
 4. Pulse frequency modulation (PFM) telemetry system
 5. Pulse code modulation (PCM) telemetry system
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Direct Current Telemetry
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FM Radio Telemetry
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Single Channel PWM Telemetry
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Single Channel PCM Telemetry
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Portable Telemetry
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Portable Telemetry
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Cardiac Tachometer
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Tachometer
Tachometer is generally used for measuring the speed
Tachometer can be classified in to
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Analog Tachometer– It consists of needle and dial
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Digital Tachometer-- It consists of memory, LCD and LED
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Contact Tachometer–Sensor is directly contact with rotor
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Non Contact Tachometer
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Time/ Frequency measurement Tachometer
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Tachometer
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Applications Tachometer
• It is commonly used in automobiles and machineries.
• It is used in automobiles to indicate the rotation rate of crank
shaft of engine.
• Used to estimate the traffic speed of vehicles.
• Used in medical field to measure the heart rate , blood flow
rate, respiratory gas flow rate.
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Cardiac Tachometer
• It senses the heart beat from finger tip using IR reflection
method
• When heart contracts, the volume of blood in the finger tip
decreases.
• When heart expands, the volume of blood in the finger tip
increases.
• The resultant pulsing of blood volume inside the tip is
proportional to heart rate.
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Cardiac Tachometer
• IR TX-RX pair is placed in finger tip with close contact.
• The reflected IR wave is sensed by the circuit.
• The intensity of the reflected wave is proportional to the
volume of blood in the finger tip.
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Block Diagram of Cardiac Tachometer
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Cardiac Tachometer
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IR Sensor
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Cardiac Tachometer
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Cardiac Tachometer
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Cardiac Tachometer
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Cardiac Tachometer
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Cardiac Tachometer
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Cardiac Tachometer
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Cardiac Tachometer
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Alarms
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Comparator Alarm Circuits
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Alarm Circuits using Cardiac Tachometer
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Lead Fault Indicator
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Lead fault indicator
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Lead fault indicator
When a monitor electrode or lead wire comes loose, the
appearance of display will be either a base line or 60Hz
interface.
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