Measure 2 (Post Exercise) In A Heartbeat 1Bella Fishman 2Ava Hedayatipour 1Knoxville Catholic High School, 2The University of Tennessee, Knoxville OBJECTIVES Research, build, and design a heart rate monitoring system using Arduinos. Test this heart rate monitor to find its accuracy compared to other heart monitors BACKGROUND Pulse oximetry is a method that measures the oxygen saturation in one’s blood by shining red and infrared light through the skin of a finger, toe, or earlobe. Oxygenated hemoglobin absorbs more infrared light than deoxygenated hemoglobin. Therefore, the amount of infralight reflected by the finger to the detector reveals the heart rate. The TCRT1000 sensor in the monitor emits and detects light in the finished board The light source gives off light which is reflected to the phototransistor. METHODS Learning about each component of the heart monitor is vital to constructing the monitor. Arduino is the circuit and programming for each project. Eagle is the program used to design the Printed Circuit Board (PCB). Transmitters and Receivers Step 1: Learn about circuitry Voltmeter Transmitters and receivers send and amplify signals. The voltmeter was built and tested using the Arduino program. The voltmeter is a key part as it displays the heart rate. Step 2: Design the PCB Printed Circuit Board (PCB) Design The program, Eagle was used to design the PCB. The schematic for the PCB was made and then it was converted to board mode in Eagle. After completing the design of the PCB in Eagle, it was built. Original PCB model layout. PCB in Eagle Schematic Routed PCB in Eagle Board Layout Step 3: Test the Monitor Testing the Accuracy of the Heart Rate Monitor The completed PCB was connected to the LCD and various machines, so it could display a pulse. Then, it was tested based on accuracy compared to aa commercial pulse oximeter which was compared to a heart rate monitoring app. RESULTS Measure 1 (Resting) Phone App 76 67 66 69 Pulse oximeter 68 64 61 The lab-made heart monitor accuracy was proven by the commercial pulse oximeter equaling its readings. The lab-made system’s analog to digital converter has 5 volts divided by 1024 (10 bits) while commercial pulse oximeters have at least 12 to 16 bits, so the commercial pulse oximeter is more accurate than a lab-made one. The commercial heart monitor was compared to the app, “Heart Rate Monitor,” which uses the flashlight and camera of the phone to emit and detect light as a pulse oximeter would. However in most of the tests, the commercial and phone monitors did not give the same heart rate. While the commercial monitor constantly updates the heart rate, the phone app gives only one reading, so they were difficult to compare. Measure 2 (Post Exercise) Phone App 97 107 130 89 Pulse oximeter 95 109 84 CONCLUSION The tests suggest that pulse oximeters, specifically commercial pulse oximeters are very accurate compared to other heart rate monitoring apps because of their advanced technology. The tests show how much improvement is still left to be made for phone heart monitors.