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

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

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.

BLOCK DIAGRAM

Power Module 5 V REGULATOR CIRCUIT 0.6 V 5.6 V

Sensor Module: IR Emitter and Detector

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

Sensor Module: Filter From detector output

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

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

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

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.

Test Results All modules worked

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

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