Biomedical Engineering Division

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Biomedical Engineering Division
Presentation on Final Year Project

• Prepared by Chu
• Date 990324

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THE CHINESE UNIVERSITY OF HONG KONG Department
of Electronic EngineeringERG4920B -Thesis II
Project Seminar
Student Chu Wing LeungSupervisor Prof. Y. T.
ZhangCo-examiner Prof. F. Y. Chang
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Telemedicine

• Use of advanced telecommunication technologies
  to remotely deliver medical services

Telemetry System !
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Telemetry System

• A group project including 3 parts
• Data Acquisition Unit (Chu Wing Leung)
• Infra Red Communication Unit (Yuen Ka Fai)
• Medical Data Network (Au Yeung Kin Lung)

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Overview of Telemetry System

• Data Acquisition Unit (DAU)
• pick up biological signals from human body

• Infra Red Communication Unit (IrCU)
• transmit data by wireless IR link

• Medical Data Network (MDN)
• transfer received medical data to the network

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Presentation Flow

• Data Acquisition Unit (W. L. Chu)
• Infra Red Communication Unit (K. F. Yuen)
• Medical Data Network (K.L. Au Yeung)
• Demonstration (all)
• Q A Section (all)

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Project TitleTelemetry System -Data
Acquisition Unit
Biological Signal (e.g. ECG)
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Objective

• To design and make a
• Data Acquisition Unit or
• so called theFront-End Circuit
• for a Biomedical Telemetry System

To perform 3 main functions 1. detect and
amplify the biological signals 2. covert the
signals into digital data 3. transmit data
through the microprocessor
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Data Acquisition Unit
Implementation of Front-end Circuit 1. Signal
Detection 2. Signal Amplification 3. Signal
Conversion Data Collection 4. Data Transmission
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1. Signal Detection

• Signal ?
• Aiming to detect ECG
• Electrodes ?
• Use Body-surface Monitoring Electrode
• Lead Connection ?
• Use Lead I connection

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What is ECG? ? Electrocardiogram
Signal Detection

• Low Frequency
• 0.05 100Hz
• Low Voltage
• 0.5 5mV

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Signal Detection

• Basic Elements of an Electrode
• Metal Plate with Electrode Gel
• Adhesive Tape
• Plastic Capsule for connection
• Wire (Thin Flexible Coaxial Cable)

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Signal Detection

• Monitoring Electrode
• with Foam Tape and Solid Gel
• Easy to use
• Improve accuracy of monitoring
• Coaxial Cable with Plug-in Jack
• Against 50 Hz pick-up
• Secure Connection

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Signal Detection
Lead I Connection

• Three electrodes connected to
• Right Arm, Left Arm
• and Right Leg (as a Ref. GND)

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Signal Detection

• For more advanced ECG detection (12-Lead
  Diagnosis)
• Electrode Contact to different chest positions

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2. Signal Amplification

• ECG Amplifer Specifications
• High Gain
• High Input Impedance
• Good Common-mode Rejection

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Instrumental Amplifier by Single Chip INA118
Signal Amplification

• FEATURES
• LOW OFFSET VOLTAGE
• LOW DRIFT
• LOW INPUT CURRENT
• HIGH CMRR
• ADJUSTABLE GAIN

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Signal Amplification

• Safety Concern Right Leg Driven Circuitry

1. In case of electrical sock, isolation
between the patient and ground 2. Reduction in
Common Mode Voltage
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Signal Amplification

• Stages of Signal Conditioning

Filter out DC offset and EMG signal
Pick up signal
Tunable Amplification
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3. Signal Conversion Data Collection

• Analog-to-Digital Converter (ADC0801)
• 8-bit resolution
• 1 MHz Sampling Rate
• Assembly Programming in Microprocessor for Data
  Collection
• Multi-tasking Ability
• Control ADC and Data Transmission

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Block Diagram of Hardware Interface
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Circuit Diagrams
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4. Data Transmission

• Digital signals are transmitted through the IR
  data link
• Send by RS232 protocol
• IR RX Connected to COM port
• Visual Basic Program to recovery the signal by
  software D/A conversion

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What have we done?
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Prototyping

• Transmitter (Original Model)

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Prototyping
Packaging Design - Transmitter
Front View
Side View
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Prototyping
Transmitter (Latest Version)
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Prototyping
Packaging - Receiver

• Front View

Back View
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Prototyping

• Receiver

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Further Development

• Improvement on Prototype
• Miniature, Small in Size Portable
• Low Power Operation
• Increase of Signal Channels
• Multi-Channel ADC with TDMA method
• Plug-in Device with Isolation
• Direct connection to the computer

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Acknowledgements

• Thanks for advice from
• Prof Y. T. Zhang
• Prof F. Y. Chang, FIEEE
• Mr S. M. Chu
• Mr Brian S.W. Leung

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Thank you!
End of Presentation