1. Pulse Rate Monitor Ying Wang
Department of Electrical and Computer Engineering
University of Illinois at Urbana-Champaign

2. Outlines Project Objective Modules and Design Review
Power Module
Sensor Module
Microcontroller Module
Display Module
Requirements and Verifications
Test Results
Outlook

3. Objective
This project intends to realize a device that can read the human pulse rate from a fingertip. The pulse rate in the unit of beats per minute (BPM) will be displayed by a 16 by 2 LCD display.

4. BLOCK DIAGRAM

5. Power Module
5 V REGULATOR CIRCUIT
0.6 V
5.6 V

6. Sensor Module: IR Emitter and Detector

7. Output of IR detector (Raw Data)
5 V
Measured by Processing
0 V
0 s
1 s
2 s
3 s
4 s
5 s

8. Sensor Module: Filter
From detector output

9. Sensor Module: Amplifier
Gain= (R6+R7)/R7

10. Sensor Module Output 5 V 0 V Measured by Processing 0 s 1 s 2 s 3 s

11. Microcontroller: Arduino Uno
Find a peak
Data[i] > Data[i-1] && Data[i] > Data[i+1];
Currentpeak = Data[i];
Currentime = millis();
|currentpeak-Refpeak|< PeakTol && |Reftime-Currenttime|> timeTol
Refpeak = Currentpeak;
Reftime= Currenttime; NO
Find a newpeak;
Currentpeak = newpeak;
Currenttime = millis();
YES
Pulserate = 60000/ (currenttime - Reftime)
Currentpeak-Refpeak > PeakTol
YES NO

12. Requirements and Verifications
1. Power Supply
take a 9V battery input and output a stable 5V(+/-0.4V) voltage to the rest of circuit and within +/-0.2A of needed current.
Put a voltmeter across the output of regulator circuit, the voltage should be within 5V+-0.4V. The components of the circuit should all work properly without any short or overload.
2. Pulse Sensor
The pulse sensor should output an accurate periodic analog signal to microcontroller. The periodic wave should correspond to the pulse of the testing people within 5 beats per minute.
The output of the pulse sensor circuit could be verified by using a free software called “Processing” It could sketch the output of the pulse sensor circuit synchronously to a PC screen. Then we can count the pulse per minute based on the waveform (the window duration time of “Processing” is set to 5 seconds) and compare it with the result of iPhone App “Heart Rate”
3. Microcontroller
The Microcontroller takes the output of the Pulse Sensor and correctly calculate the beats per Module minute and output to the display module. The beats per minute should be accurate within 5 beats/min
The calculated beats per minute can be displayed by 16 y 2 LCD display then we can compare the output of the microcontroller with the waveform generated by pulse module and results from iPhone App “Heart Rate”. The testing people can put one hand on pulse sensor and the other hand on iPhone.
4. Display Module
Takes the output of the microcontroller and convert it to sixteen by two LCD display. Display beats per minute on LCD screen
To be compared with the beats per minute value displayed by iPhone App “Heart Rate” by putting one hand on pulse sensor and the other hand on iPhone.

13. Test Results
All modules worked

14. Test Results Some problems:
Fingers have to maintain a stable pressure, if peak height varies too much, a peak might be missed
PCB board didn’t work, might have some soldering problem

15. More can be done… Study the heart rate variation
Calculate the target heart rate (THR zone is 50%-85% of maximum heart rate)