OPTICAL HEART-RATE MONITOR

1
OPTICAL HEART-RATE MONITOR

• Senior Design Project
• Tomasz Bala
• Doris Chan
• Brian Sobocinski

2
Introduction

• Design a Circuit to Sample Heart-Rate
• Display Heart Rate
• Display Heart Beats
• Display Blood Pressure

3
Motivations

• Interest in medical technology
• Interest in learning LabVIEW
• Opportunity to try something different

4
Overview

• Design Considerations
• Hardware
• Software
• Cost Analysis
• Modifications to Original Plans
• Strengths and Weaknesses

5
Block Diagram
Amplifier Filter Circuit
Digital Display
Sensors
Analog Display
Converter Circuit
Analog Recorder
Blood Pressure Circuit
Digital Display
6
Hardware Diagram
Sensor
7
Honeywell HLC1395

• New, inexpensive product
• More Comfortable than Electrodes
• Features
• Designed for short distance detection
• Highly Sensitive
• Outputs 500uV ac Signal

8
Amplifier and Filter Circuit

• Signal from sensor amplified x25
• Filters reject ambient electrical and optical
  noise (mostly 60Hz)
• Second stage amplifiers
• Signal to Comparator to extract digital signal

9
Frequency to Voltage Circuit

• Required for Analog Output
• Added to Design as an Extra Challenge
• Based on medical instrumentation book
• Analog output of 1V100 bpm

10
LabVIEW VI

• LabVIEW is a Graphical programming Language
• Useful for real time Data Acquisition
• Input from NI-DAQ PC Interface
• Front Panel Display

11
LabVIEW Hierarchy

• Data Acquisition
• Frequency measurement
• Determing Pulse
• Heartbeat waveform

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Data Acquisition

• AI waveform available in LabVIEW takes signal
  from DAQ board
• Number of scans and scan rate are minmum 1000
  scans/sec
• Measure voltage of TTL signal
• Display DAQ input on a graph

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Frequency Measurement

• Power spectrum VI available in the advanced
  analysis library in LabVIEW
• Power spectrum VI takes voltage data and does an
  FFT to determine the main frequency component of
  the signal
• Calculate TTL input frequency by using scan rate
  and number of scans

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Determining Pulse

• Count ten pulses and calculate average frequency
• BPM 60 1/f
• Displays average frequency and BPM

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Heart beat Waveform

• Use average frequency to generate heart rate
  pulse
• Major peak to peak is the rate of heart beat
• Display analog output waveform

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LabVIEW Program
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LabVIEW Front Panel

• Simple Operation
• Displays Both Rate in BPM and a Graph

18
Cost Analysis

• PARTS
• Sensors, Op amps, transistors 35
• Resistors, capacitors 8
• Magnetic Tape Recorder 20
• PSPICE Software available
• LabVIEW Software available
• Oscilloscope available
• NI-DAQ available
• LABOR 9000
• TOTAL 9063

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Conclusion

• Future Feature Packages
• Blood Pressure Monitor
• Analog Option
• Strengths and Weaknesses
• Sensor reliability
• Room for more testing
• Added new technology to an outdated design
• Questions?